Merge "[AT-SPI] Add SetTextContents, InsertText and DeleteText" into devel/master
[platform/core/uifw/dali-toolkit.git] / dali-toolkit / internal / text / layouts / layout-engine.cpp
index 01a5786..25f83d1 100644 (file)
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * Copyright (c) 2021 Samsung Electronics Co., Ltd.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
 #include <dali-toolkit/internal/text/layouts/layout-engine.h>
 
 // EXTERNAL INCLUDES
-#include <limits>
-#include <dali/public-api/math/vector2.h>
 #include <dali/devel-api/text-abstraction/font-client.h>
 #include <dali/integration-api/debug.h>
+#include <cmath>
+#include <limits>
 
 // INTERNAL INCLUDES
+#include <dali-toolkit/internal/text/bidirectional-support.h>
+#include <dali-toolkit/internal/text/cursor-helper-functions.h>
+#include <dali-toolkit/internal/text/glyph-metrics-helper.h>
 #include <dali-toolkit/internal/text/layouts/layout-parameters.h>
-#include <dali-toolkit/internal/text/bidirectional-line-info-run.h>
 
 namespace Dali
 {
-
 namespace Toolkit
 {
-
 namespace Text
 {
-
+namespace Layout
+{
 namespace
 {
-
 #if defined(DEBUG_ENABLED)
-  Debug::Filter* gLogFilter = Debug::Filter::New(Debug::Concise, true, "LOG_TEXT_LAYOUT");
+Debug::Filter* gLogFilter = Debug::Filter::New(Debug::Concise, true, "LOG_TEXT_LAYOUT");
 #endif
 
-const float MAX_FLOAT = std::numeric_limits<float>::max();
-const bool RTL = true;
+const float              MAX_FLOAT      = std::numeric_limits<float>::max();
+const CharacterDirection LTR            = false;
+const CharacterDirection RTL            = !LTR;
+const float              LINE_SPACING   = 0.f;
+const float              MIN_LINE_SIZE  = 0.f;
+const Character          HYPHEN_UNICODE = 0x002D;
+
+inline bool isEmptyLineAtLast(const Vector<LineRun>& lines, const Vector<LineRun>::Iterator& line)
+{
+  return ((*line).characterRun.numberOfCharacters == 0 && line + 1u == lines.End());
+}
 
 } //namespace
 
@@ -55,80 +64,110 @@ const bool RTL = true;
 struct LineLayout
 {
   LineLayout()
-  : glyphIndex( 0u ),
-    characterIndex( 0u ),
-    numberOfGlyphs( 0u ),
-    numberOfCharacters( 0u ),
-    length( 0.f ),
-    extraBearing( 0.f ),
-    extraWidth( 0.f ),
-    wsLengthEndOfLine( 0.f ),
-    ascender( 0.f ),
-    descender( MAX_FLOAT )
-  {}
+  : glyphIndex{0u},
+    characterIndex{0u},
+    numberOfGlyphs{0u},
+    numberOfCharacters{0u},
+    ascender{-MAX_FLOAT},
+    descender{MAX_FLOAT},
+    lineSpacing{0.f},
+    penX{0.f},
+    previousAdvance{0.f},
+    length{0.f},
+    whiteSpaceLengthEndOfLine{0.f},
+    direction{LTR}
+  {
+  }
 
   ~LineLayout()
-  {}
+  {
+  }
 
   void Clear()
   {
-    glyphIndex = 0u;
-    characterIndex = 0u;
-    numberOfGlyphs = 0u;
+    glyphIndex         = 0u;
+    characterIndex     = 0u;
+    numberOfGlyphs     = 0u;
     numberOfCharacters = 0u;
-    length = 0.f;
-    extraBearing = 0.f;
-    extraWidth = 0.f;
-    wsLengthEndOfLine = 0.f;
-    ascender = 0.f;
-    descender = MAX_FLOAT;
+    ascender           = -MAX_FLOAT;
+    descender          = MAX_FLOAT;
+    direction          = LTR;
   }
 
-  GlyphIndex     glyphIndex;         ///< Index of the first glyph to be laid-out.
-  CharacterIndex characterIndex;     ///< Index of the first character to be laid-out.
-  Length         numberOfGlyphs;     ///< The number of glyph which fit in one line.
-  Length         numberOfCharacters; ///< The number of characters which fit in one line.
-  float          length;             ///< The addition of the advance metric of all the glyphs which fit in one line.
-  float          extraBearing;       ///< The extra width to be added to the line's length when the bearing of the first glyph is negative.
-  float          extraWidth;         ///< The extra width to be added to the line's length when the bearing + width of the last glyph is greater than the advance.
-  float          wsLengthEndOfLine;  ///< The length of the white spaces at the end of the line.
-  float          ascender;           ///< The maximum ascender of all fonts in the line.
-  float          descender;          ///< The minimum descender of all fonts in the line.
+  GlyphIndex         glyphIndex;                ///< Index of the first glyph to be laid-out.
+  CharacterIndex     characterIndex;            ///< Index of the first character to be laid-out.
+  Length             numberOfGlyphs;            ///< The number of glyph which fit in one line.
+  Length             numberOfCharacters;        ///< The number of characters which fit in one line.
+  float              ascender;                  ///< The maximum ascender of all fonts in the line.
+  float              descender;                 ///< The minimum descender of all fonts in the line.
+  float              lineSpacing;               ///< The line spacing
+  float              penX;                      ///< The origin of the current glyph ( is the start point plus the accumulation of all advances ).
+  float              previousAdvance;           ///< The advance of the previous glyph.
+  float              length;                    ///< The current length of the line.
+  float              whiteSpaceLengthEndOfLine; ///< The length of the white spaces at the end of the line.
+  CharacterDirection direction;
 };
 
-struct LayoutEngine::Impl
+struct LayoutBidiParameters
+{
+  void Clear()
+  {
+    paragraphDirection = LTR;
+    bidiParagraphIndex = 0u;
+    bidiLineIndex      = 0u;
+    isBidirectional    = false;
+  }
+
+  CharacterDirection        paragraphDirection = LTR;   ///< The paragraph's direction.
+  BidirectionalRunIndex     bidiParagraphIndex = 0u;    ///< Index to the paragraph's bidi info.
+  BidirectionalLineRunIndex bidiLineIndex      = 0u;    ///< Index where to insert the next bidi line info.
+  bool                      isBidirectional    = false; ///< Whether the text is bidirectional.
+};
+
+struct Engine::Impl
 {
   Impl()
-  : mLayout( LayoutEngine::SINGLE_LINE_BOX ),
-    mHorizontalAlignment( LayoutEngine::HORIZONTAL_ALIGN_BEGIN ),
-    mVerticalAlignment( LayoutEngine::VERTICAL_ALIGN_TOP ),
-    mEllipsisEnabled( false )
+  : mLayout{Layout::Engine::SINGLE_LINE_BOX},
+    mCursorWidth{0.f},
+    mDefaultLineSpacing{LINE_SPACING},
+    mDefaultLineSize{MIN_LINE_SIZE}
   {
-    mFontClient = TextAbstraction::FontClient::Get();
   }
 
   /**
    * @brief Updates the line ascender and descender with the metrics of a new font.
    *
-   * @param[in] fontId The id of the new font.
+   * @param[in] glyphMetrics The metrics of the new font.
    * @param[in,out] lineLayout The line layout.
    */
-  void UpdateLineHeight( FontId fontId, LineLayout& lineLayout )
+  void UpdateLineHeight(const GlyphMetrics& glyphMetrics, LineLayout& lineLayout)
   {
     Text::FontMetrics fontMetrics;
-    mFontClient.GetFontMetrics( fontId, fontMetrics );
-
-    // Sets the maximum ascender.
-    if( fontMetrics.ascender > lineLayout.ascender )
+    if(0u != glyphMetrics.fontId)
     {
-      lineLayout.ascender = fontMetrics.ascender;
+      mMetrics->GetFontMetrics(glyphMetrics.fontId, fontMetrics);
     }
-
-    // Sets the minimum descender.
-    if( fontMetrics.descender < lineLayout.descender )
+    else
     {
-      lineLayout.descender = fontMetrics.descender;
+      fontMetrics.ascender           = glyphMetrics.fontHeight;
+      fontMetrics.descender          = 0.f;
+      fontMetrics.height             = fontMetrics.ascender;
+      fontMetrics.underlinePosition  = 0.f;
+      fontMetrics.underlineThickness = 1.f;
     }
+
+    // Sets the maximum ascender.
+    lineLayout.ascender = std::max(lineLayout.ascender, fontMetrics.ascender);
+
+    // Sets the minimum descender.
+    lineLayout.descender = std::min(lineLayout.descender, fontMetrics.descender);
+
+    // Sets the line size
+    lineLayout.lineSpacing = mDefaultLineSize - (lineLayout.ascender + -lineLayout.descender);
+    lineLayout.lineSpacing = lineLayout.lineSpacing < 0.f ? 0.f : lineLayout.lineSpacing;
+
+    // Add the line spacing
+    lineLayout.lineSpacing += mDefaultLineSpacing;
   }
 
   /**
@@ -137,311 +176,526 @@ struct LayoutEngine::Impl
    * @param[in,out] lineLayout The line layout.
    * @param[in] tmpLineLayout A temporary line layout.
    */
-  void MergeLineLayout( LineLayout& lineLayout,
-                        const LineLayout& tmpLineLayout )
+  void MergeLineLayout(LineLayout&       lineLayout,
+                       const LineLayout& tmpLineLayout)
   {
     lineLayout.numberOfCharacters += tmpLineLayout.numberOfCharacters;
     lineLayout.numberOfGlyphs += tmpLineLayout.numberOfGlyphs;
-    lineLayout.length += tmpLineLayout.length;
 
-    if( 0.f < tmpLineLayout.length )
-    {
-      lineLayout.length += lineLayout.wsLengthEndOfLine;
+    lineLayout.penX            = tmpLineLayout.penX;
+    lineLayout.previousAdvance = tmpLineLayout.previousAdvance;
 
-      lineLayout.wsLengthEndOfLine = tmpLineLayout.wsLengthEndOfLine;
-    }
-    else
+    lineLayout.length                    = tmpLineLayout.length;
+    lineLayout.whiteSpaceLengthEndOfLine = tmpLineLayout.whiteSpaceLengthEndOfLine;
+
+    // Sets the maximum ascender.
+    lineLayout.ascender = std::max(lineLayout.ascender, tmpLineLayout.ascender);
+
+    // Sets the minimum descender.
+    lineLayout.descender = std::min(lineLayout.descender, tmpLineLayout.descender);
+  }
+
+  void LayoutRightToLeft(const Parameters&               parameters,
+                         const BidirectionalLineInfoRun& bidirectionalLineInfo,
+                         float&                          length,
+                         float&                          whiteSpaceLengthEndOfLine)
+  {
+    const Character* const  textBuffer               = parameters.textModel->mLogicalModel->mText.Begin();
+    const Length* const     charactersPerGlyphBuffer = parameters.textModel->mVisualModel->mCharactersPerGlyph.Begin();
+    const GlyphInfo* const  glyphsBuffer             = parameters.textModel->mVisualModel->mGlyphs.Begin();
+    const GlyphIndex* const charactersToGlyphsBuffer = parameters.textModel->mVisualModel->mCharactersToGlyph.Begin();
+
+    const float      outlineWidth                = static_cast<float>(parameters.textModel->GetOutlineWidth());
+    const GlyphIndex lastGlyphOfParagraphPlusOne = parameters.startGlyphIndex + parameters.numberOfGlyphs;
+
+    CharacterIndex characterLogicalIndex = 0u;
+    CharacterIndex characterVisualIndex  = bidirectionalLineInfo.characterRun.characterIndex + *(bidirectionalLineInfo.visualToLogicalMap + characterLogicalIndex);
+
+    if(RTL == bidirectionalLineInfo.direction)
     {
-      lineLayout.wsLengthEndOfLine += tmpLineLayout.wsLengthEndOfLine;
+      while(TextAbstraction::IsWhiteSpace(*(textBuffer + characterVisualIndex)))
+      {
+        const GlyphInfo& glyphInfo = *(glyphsBuffer + *(charactersToGlyphsBuffer + characterVisualIndex));
+
+        whiteSpaceLengthEndOfLine += glyphInfo.advance;
+
+        ++characterLogicalIndex;
+        characterVisualIndex = bidirectionalLineInfo.characterRun.characterIndex + *(bidirectionalLineInfo.visualToLogicalMap + characterLogicalIndex);
+      }
     }
 
-    if( tmpLineLayout.ascender > lineLayout.ascender )
+    const GlyphIndex glyphIndex = *(charactersToGlyphsBuffer + characterVisualIndex);
+
+    // Check whether the first glyph comes from a character that is shaped in multiple glyphs.
+    const Length numberOfGLyphsInGroup = GetNumberOfGlyphsOfGroup(glyphIndex,
+                                                                  lastGlyphOfParagraphPlusOne,
+                                                                  charactersPerGlyphBuffer);
+
+    GlyphMetrics glyphMetrics;
+    GetGlyphsMetrics(glyphIndex,
+                     numberOfGLyphsInGroup,
+                     glyphMetrics,
+                     glyphsBuffer,
+                     mMetrics);
+
+    float penX = -glyphMetrics.xBearing + mCursorWidth + outlineWidth;
+
+    // Traverses the characters of the right to left paragraph.
+    for(; characterLogicalIndex < bidirectionalLineInfo.characterRun.numberOfCharacters;)
     {
-      lineLayout.ascender = tmpLineLayout.ascender;
+      // Convert the character in the logical order into the character in the visual order.
+      const CharacterIndex characterVisualIndex = bidirectionalLineInfo.characterRun.characterIndex + *(bidirectionalLineInfo.visualToLogicalMap + characterLogicalIndex);
+      const bool           isWhiteSpace         = TextAbstraction::IsWhiteSpace(*(textBuffer + characterVisualIndex));
+
+      const GlyphIndex glyphIndex = *(charactersToGlyphsBuffer + characterVisualIndex);
+
+      // Check whether this glyph comes from a character that is shaped in multiple glyphs.
+      const Length numberOfGLyphsInGroup = GetNumberOfGlyphsOfGroup(glyphIndex,
+                                                                    lastGlyphOfParagraphPlusOne,
+                                                                    charactersPerGlyphBuffer);
+
+      characterLogicalIndex += *(charactersPerGlyphBuffer + glyphIndex + numberOfGLyphsInGroup - 1u);
+
+      GlyphMetrics glyphMetrics;
+      GetGlyphsMetrics(glyphIndex,
+                       numberOfGLyphsInGroup,
+                       glyphMetrics,
+                       glyphsBuffer,
+                       mMetrics);
+
+      if(isWhiteSpace)
+      {
+        if(RTL == bidirectionalLineInfo.direction)
+        {
+          length += glyphMetrics.advance;
+        }
+        else
+        {
+          whiteSpaceLengthEndOfLine += glyphMetrics.advance;
+        }
+        penX += glyphMetrics.advance;
+      }
+      else
+      {
+        if(LTR == bidirectionalLineInfo.direction)
+        {
+          whiteSpaceLengthEndOfLine = 0.f;
+        }
+        length = std::max(length, penX + glyphMetrics.xBearing + glyphMetrics.width);
+        penX += (glyphMetrics.advance + parameters.interGlyphExtraAdvance);
+      }
     }
+  }
+
+  void ReorderBiDiLayout(const Parameters&     parameters,
+                         LayoutBidiParameters& bidiParameters,
+                         const LineLayout&     currentLineLayout,
+                         LineLayout&           lineLayout,
+                         bool                  breakInCharacters)
+  {
+    const Length* const charactersPerGlyphBuffer = parameters.textModel->mVisualModel->mCharactersPerGlyph.Begin();
+
+    // The last glyph to be laid-out.
+    const GlyphIndex lastGlyphOfParagraphPlusOne = parameters.startGlyphIndex + parameters.numberOfGlyphs;
 
-    if( tmpLineLayout.descender < lineLayout.descender )
+    const Vector<BidirectionalParagraphInfoRun>& bidirectionalParagraphsInfo = parameters.textModel->mLogicalModel->mBidirectionalParagraphInfo;
+
+    const BidirectionalParagraphInfoRun& bidirectionalParagraphInfo = bidirectionalParagraphsInfo[bidiParameters.bidiParagraphIndex];
+    if((lineLayout.characterIndex >= bidirectionalParagraphInfo.characterRun.characterIndex) &&
+       (lineLayout.characterIndex < bidirectionalParagraphInfo.characterRun.characterIndex + bidirectionalParagraphInfo.characterRun.numberOfCharacters))
     {
-      lineLayout.descender = tmpLineLayout.descender;
+      Vector<BidirectionalLineInfoRun>& bidirectionalLinesInfo = parameters.textModel->mLogicalModel->mBidirectionalLineInfo;
+
+      // Sets the visual to logical map tables needed to reorder the text.
+      ReorderLine(bidirectionalParagraphInfo,
+                  bidirectionalLinesInfo,
+                  bidiParameters.bidiLineIndex,
+                  lineLayout.characterIndex,
+                  lineLayout.numberOfCharacters,
+                  bidiParameters.paragraphDirection);
+
+      // Recalculate the length of the line and update the layout.
+      const BidirectionalLineInfoRun& bidirectionalLineInfo = *(bidirectionalLinesInfo.Begin() + bidiParameters.bidiLineIndex);
+
+      if(!bidirectionalLineInfo.isIdentity)
+      {
+        float length                    = 0.f;
+        float whiteSpaceLengthEndOfLine = 0.f;
+        LayoutRightToLeft(parameters,
+                          bidirectionalLineInfo,
+                          length,
+                          whiteSpaceLengthEndOfLine);
+
+        lineLayout.whiteSpaceLengthEndOfLine = whiteSpaceLengthEndOfLine;
+        if(!Equals(length, lineLayout.length))
+        {
+          const bool isMultiline = mLayout == MULTI_LINE_BOX;
+
+          if(isMultiline && (length > parameters.boundingBox.width))
+          {
+            if(breakInCharacters || (isMultiline && (0u == currentLineLayout.numberOfGlyphs)))
+            {
+              // The word doesn't fit in one line. It has to be split by character.
+
+              // Remove the last laid out glyph(s) as they doesn't fit.
+              for(GlyphIndex glyphIndex = lineLayout.glyphIndex + lineLayout.numberOfGlyphs - 1u; glyphIndex >= lineLayout.glyphIndex;)
+              {
+                const Length numberOfGLyphsInGroup = GetNumberOfGlyphsOfGroup(glyphIndex,
+                                                                              lastGlyphOfParagraphPlusOne,
+                                                                              charactersPerGlyphBuffer);
+
+                const Length numberOfCharacters = *(charactersPerGlyphBuffer + glyphIndex + numberOfGLyphsInGroup - 1u);
+
+                lineLayout.numberOfGlyphs -= numberOfGLyphsInGroup;
+                lineLayout.numberOfCharacters -= numberOfCharacters;
+
+                AdjustLayout(parameters,
+                             bidiParameters,
+                             bidirectionalParagraphInfo,
+                             lineLayout);
+
+                if(lineLayout.length < parameters.boundingBox.width)
+                {
+                  break;
+                }
+
+                if(glyphIndex < numberOfGLyphsInGroup)
+                {
+                  // avoids go under zero for an unsigned int.
+                  break;
+                }
+
+                glyphIndex -= numberOfGLyphsInGroup;
+              }
+            }
+            else
+            {
+              lineLayout = currentLineLayout;
+
+              AdjustLayout(parameters,
+                           bidiParameters,
+                           bidirectionalParagraphInfo,
+                           lineLayout);
+            }
+          }
+          else
+          {
+            lineLayout.length = std::max(length, lineLayout.length);
+          }
+        }
+      }
     }
   }
 
+  void AdjustLayout(const Parameters&                    parameters,
+                    LayoutBidiParameters&                bidiParameters,
+                    const BidirectionalParagraphInfoRun& bidirectionalParagraphInfo,
+                    LineLayout&                          lineLayout)
+  {
+    Vector<BidirectionalLineInfoRun>& bidirectionalLinesInfo = parameters.textModel->mLogicalModel->mBidirectionalLineInfo;
+
+    // Remove current reordered line.
+    bidirectionalLinesInfo.Erase(bidirectionalLinesInfo.Begin() + bidiParameters.bidiLineIndex);
+
+    // Re-build the conversion table without the removed glyphs.
+    ReorderLine(bidirectionalParagraphInfo,
+                bidirectionalLinesInfo,
+                bidiParameters.bidiLineIndex,
+                lineLayout.characterIndex,
+                lineLayout.numberOfCharacters,
+                bidiParameters.paragraphDirection);
+
+    const BidirectionalLineInfoRun& bidirectionalLineInfo = *(bidirectionalLinesInfo.Begin() + bidiParameters.bidiLineIndex);
+
+    float length                    = 0.f;
+    float whiteSpaceLengthEndOfLine = 0.f;
+    LayoutRightToLeft(parameters,
+                      bidirectionalLineInfo,
+                      length,
+                      whiteSpaceLengthEndOfLine);
+
+    lineLayout.length                    = length;
+    lineLayout.whiteSpaceLengthEndOfLine = whiteSpaceLengthEndOfLine;
+  }
+
   /**
    * Retrieves the line layout for a given box width.
    *
-   * @note This method lais out text as it were left to right. At this point is not possible to reorder the line
-   *       because the number of characters of the line is not known (one of the responsabilities of this method
-   *       is calculate that). Due to glyph's 'x' bearing, width and advance, when right to left or mixed right to left
-   *       and left to right text is laid out, it can be small differences in the line length. One solution is to
-   *       reorder and re-lay out the text after this method and add or remove one extra glyph if needed. However,
-   *       this method calculates which are the first and last glyphs of the line (the ones that causes the
-   *       differences). This is a good point to check if there is problems with the text exceeding the boundaries
-   *       of the control when there is right to left text.
+   * @note This method starts to layout text as if it was left to right. However, it might be differences in the length
+   *       of the line if it's a bidirectional one. If the paragraph is bidirectional, this method will call a function
+   *       to reorder the line and recalculate its length.
    *
+
    * @param[in] parameters The layout parameters.
+   * @param[] bidiParameters Bidirectional info for the current line.
    * @param[out] lineLayout The line layout.
-   * @param[in,out] paragraphDirection in: the current paragraph's direction, out: the next paragraph's direction. Is set after a must break.
    * @param[in] completelyFill Whether to completely fill the line ( even if the last word exceeds the boundaries ).
    */
-  void GetLineLayoutForBox( const LayoutParameters& parameters,
-                            LineLayout& lineLayout,
-                            CharacterDirection& paragraphDirection,
-                            bool completelyFill )
+  void GetLineLayoutForBox(const Parameters&     parameters,
+                           LayoutBidiParameters& bidiParameters,
+                           LineLayout&           lineLayout,
+                           bool                  completelyFill)
   {
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "-->GetLineLayoutForBox\n" );
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  initial glyph index : %d\n", lineLayout.glyphIndex );
-    // Stores temporary line layout which has not been added to the final line layout.
-    LineLayout tmpLineLayout;
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "-->GetLineLayoutForBox\n");
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  initial glyph index : %d\n", lineLayout.glyphIndex);
+
+    const Character* const      textBuffer               = parameters.textModel->mLogicalModel->mText.Begin();
+    const Length* const         charactersPerGlyphBuffer = parameters.textModel->mVisualModel->mCharactersPerGlyph.Begin();
+    const GlyphInfo* const      glyphsBuffer             = parameters.textModel->mVisualModel->mGlyphs.Begin();
+    const CharacterIndex* const glyphsToCharactersBuffer = parameters.textModel->mVisualModel->mGlyphsToCharacters.Begin();
+    const LineBreakInfo* const  lineBreakInfoBuffer      = parameters.textModel->mLogicalModel->mLineBreakInfo.Begin();
+
+    const float  outlineWidth        = static_cast<float>(parameters.textModel->GetOutlineWidth());
+    const Length totalNumberOfGlyphs = parameters.textModel->mVisualModel->mGlyphs.Count();
+
+    const bool isMultiline   = mLayout == MULTI_LINE_BOX;
+    const bool isWordLaidOut = parameters.textModel->mLineWrapMode == Text::LineWrap::WORD ||
+                               (parameters.textModel->mLineWrapMode == (Text::LineWrap::Mode)DevelText::LineWrap::HYPHENATION) ||
+                               (parameters.textModel->mLineWrapMode == (Text::LineWrap::Mode)DevelText::LineWrap::MIXED);
+    const bool isHyphenMode = parameters.textModel->mLineWrapMode == (Text::LineWrap::Mode)DevelText::LineWrap::HYPHENATION;
+    const bool isMixedMode  = parameters.textModel->mLineWrapMode == (Text::LineWrap::Mode)DevelText::LineWrap::MIXED;
 
-    const bool isMultiline = mLayout == MULTI_LINE_BOX;
-    const GlyphIndex lastGlyphIndex = parameters.totalNumberOfGlyphs - 1u;
+    // The last glyph to be laid-out.
+    const GlyphIndex lastGlyphOfParagraphPlusOne = parameters.startGlyphIndex + parameters.numberOfGlyphs;
 
     // If the first glyph has a negative bearing its absolute value needs to be added to the line length.
     // In the case the line starts with a right to left character, if the width is longer than the advance,
     // the difference needs to be added to the line length.
-    const GlyphInfo& glyphInfo = *( parameters.glyphsBuffer + lineLayout.glyphIndex );
+
+    // Check whether the first glyph comes from a character that is shaped in multiple glyphs.
+    const Length numberOfGLyphsInGroup = GetNumberOfGlyphsOfGroup(lineLayout.glyphIndex,
+                                                                  lastGlyphOfParagraphPlusOne,
+                                                                  charactersPerGlyphBuffer);
+
+    GlyphMetrics glyphMetrics;
+    GetGlyphsMetrics(lineLayout.glyphIndex,
+                     numberOfGLyphsInGroup,
+                     glyphMetrics,
+                     glyphsBuffer,
+                     mMetrics);
 
     // Set the direction of the first character of the line.
-    lineLayout.characterIndex = *( parameters.glyphsToCharactersBuffer + lineLayout.glyphIndex );
-    const CharacterDirection firstCharacterDirection = ( NULL == parameters.characterDirectionBuffer ) ? false : *( parameters.characterDirectionBuffer + lineLayout.characterIndex );
-    CharacterDirection previousCharacterDirection = firstCharacterDirection;
+    lineLayout.characterIndex = *(glyphsToCharactersBuffer + lineLayout.glyphIndex);
 
-    const float extraWidth = glyphInfo.xBearing + glyphInfo.width - glyphInfo.advance;
-    float tmpExtraWidth = ( 0.f < extraWidth ) ? extraWidth : 0.f;
+    // Stores temporary line layout which has not been added to the final line layout.
+    LineLayout tmpLineLayout;
 
-    float tmpExtraBearing = ( 0.f > glyphInfo.xBearing ) ? -glyphInfo.xBearing : 0.f;
+    // Initialize the start point.
 
-    tmpLineLayout.length += 1.f; // Added one unit to give some space to the cursor.
+    // The initial start point is zero. However it needs a correction according the 'x' bearing of the first glyph.
+    // i.e. if the bearing of the first glyph is negative it may exceed the boundaries of the text area.
+    // It needs to add as well space for the cursor if the text is in edit mode and extra space in case the text is outlined.
+    tmpLineLayout.penX = -glyphMetrics.xBearing + mCursorWidth + outlineWidth;
 
     // Calculate the line height if there is no characters.
-    FontId lastFontId = glyphInfo.fontId;
-    UpdateLineHeight( lastFontId, tmpLineLayout );
+    FontId lastFontId = glyphMetrics.fontId;
+    UpdateLineHeight(glyphMetrics, tmpLineLayout);
 
-    bool oneWordLaidOut = false;
+    bool       oneWordLaidOut   = false;
+    bool       oneHyphenLaidOut = false;
+    GlyphIndex hyphenIndex      = 0;
+    GlyphInfo  hyphenGlyph;
 
-    for( GlyphIndex glyphIndex = lineLayout.glyphIndex;
-         glyphIndex < parameters.totalNumberOfGlyphs;
-         ++glyphIndex )
+    for(GlyphIndex glyphIndex = lineLayout.glyphIndex;
+        glyphIndex < lastGlyphOfParagraphPlusOne;)
     {
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  glyph index : %d\n", glyphIndex );
-      const bool isLastGlyph = glyphIndex == lastGlyphIndex;
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  glyph index : %d\n", glyphIndex);
+
+      // Check whether this glyph comes from a character that is shaped in multiple glyphs.
+      const Length numberOfGLyphsInGroup = GetNumberOfGlyphsOfGroup(glyphIndex,
+                                                                    lastGlyphOfParagraphPlusOne,
+                                                                    charactersPerGlyphBuffer);
 
-      // Get the glyph info.
-      const GlyphInfo& glyphInfo = *( parameters.glyphsBuffer + glyphIndex );
+      GlyphMetrics glyphMetrics;
+      GetGlyphsMetrics(glyphIndex,
+                       numberOfGLyphsInGroup,
+                       glyphMetrics,
+                       glyphsBuffer,
+                       mMetrics);
+
+      const bool isLastGlyph = glyphIndex + numberOfGLyphsInGroup == totalNumberOfGlyphs;
 
       // Check if the font of the current glyph is the same of the previous one.
       // If it's different the ascender and descender need to be updated.
-      if( lastFontId != glyphInfo.fontId )
+      if(lastFontId != glyphMetrics.fontId)
       {
-        UpdateLineHeight( glyphInfo.fontId, tmpLineLayout );
-        lastFontId = glyphInfo.fontId;
+        UpdateLineHeight(glyphMetrics, tmpLineLayout);
+        lastFontId = glyphMetrics.fontId;
       }
 
       // Get the character indices for the current glyph. The last character index is needed
       // because there are glyphs formed by more than one character but their break info is
       // given only for the last character.
-      const Length charactersPerGlyph = *( parameters.charactersPerGlyphBuffer + glyphIndex );
-      const CharacterIndex characterFirstIndex = *( parameters.glyphsToCharactersBuffer + glyphIndex );
-      const CharacterIndex characterLastIndex = characterFirstIndex + ( ( 1u > charactersPerGlyph ) ? 0u : charactersPerGlyph - 1u );
+      const Length         charactersPerGlyph  = *(charactersPerGlyphBuffer + glyphIndex + numberOfGLyphsInGroup - 1u);
+      const bool           hasCharacters       = charactersPerGlyph > 0u;
+      const CharacterIndex characterFirstIndex = *(glyphsToCharactersBuffer + glyphIndex);
+      const CharacterIndex characterLastIndex  = characterFirstIndex + (hasCharacters ? charactersPerGlyph - 1u : 0u);
 
       // Get the line break info for the current character.
-      const LineBreakInfo lineBreakInfo = *( parameters.lineBreakInfoBuffer + characterLastIndex );
-
-      // Get the word break info for the current character.
-      const WordBreakInfo wordBreakInfo = *( parameters.wordBreakInfoBuffer + characterLastIndex );
+      const LineBreakInfo lineBreakInfo = hasCharacters ? *(lineBreakInfoBuffer + characterLastIndex) : TextAbstraction::LINE_NO_BREAK;
 
       // Increase the number of characters.
       tmpLineLayout.numberOfCharacters += charactersPerGlyph;
 
       // Increase the number of glyphs.
-      tmpLineLayout.numberOfGlyphs++;
+      tmpLineLayout.numberOfGlyphs += numberOfGLyphsInGroup;
 
       // Check whether is a white space.
-      const Character character = *( parameters.textBuffer + characterFirstIndex );
-      const bool isWhiteSpace = TextAbstraction::IsWhiteSpace( character );
+      const Character character    = *(textBuffer + characterFirstIndex);
+      const bool      isWhiteSpace = TextAbstraction::IsWhiteSpace(character);
 
-      // Used to restore the temporal line layout when a single word does not fit in the control's width and is split by character.
-      const float previousTmpLineLength = tmpLineLayout.length;
-      const float previousTmpExtraBearing = tmpExtraBearing;
-      const float previousTmpExtraWidth = tmpExtraWidth;
+      // Calculate the length of the line.
 
-      // Get the character's direction.
-      const CharacterDirection characterDirection = ( NULL == parameters.characterDirectionBuffer ) ? false : *( parameters.characterDirectionBuffer + characterFirstIndex );
+      // Used to restore the temporal line layout when a single word does not fit in the control's width and is split by character.
+      const float previousTmpPenX                      = tmpLineLayout.penX;
+      const float previousTmpAdvance                   = tmpLineLayout.previousAdvance;
+      const float previousTmpLength                    = tmpLineLayout.length;
+      const float previousTmpWhiteSpaceLengthEndOfLine = tmpLineLayout.whiteSpaceLengthEndOfLine;
 
-      // Increase the accumulated length.
-      if( isWhiteSpace )
+      if(isWhiteSpace)
       {
         // Add the length to the length of white spaces at the end of the line.
-        tmpLineLayout.wsLengthEndOfLine += glyphInfo.advance; // The advance is used as the width is always zero for the white spaces.
+        tmpLineLayout.whiteSpaceLengthEndOfLine += glyphMetrics.advance; // The advance is used as the width is always zero for the white spaces.
       }
       else
       {
-        // Add as well any previous white space length.
-        tmpLineLayout.length += tmpLineLayout.wsLengthEndOfLine + glyphInfo.advance;
+        tmpLineLayout.penX += tmpLineLayout.previousAdvance + tmpLineLayout.whiteSpaceLengthEndOfLine;
+        tmpLineLayout.previousAdvance = (glyphMetrics.advance + parameters.interGlyphExtraAdvance);
 
-        // An extra space may be added to the line for the first and last glyph of the line.
-        // If the bearing of the first glyph is negative, its positive value needs to be added.
-        // If the bearing plus the width of the last glyph is greater than the advance, the difference
-        // needs to be added.
-
-        if( characterDirection == paragraphDirection )
-        {
-          if( RTL == characterDirection )
-          {
-            //       <--
-            // |   Rrrrr|
-            // or
-            // |  Rllrrr|
-            // or
-            // |lllrrrrr|
-            // |     Rll|
-            //
-
-            tmpExtraBearing = ( 0.f > glyphInfo.xBearing ) ? -glyphInfo.xBearing : 0.f;
-          }
-          else // LTR
-          {
-            //  -->
-            // |lllL    |
-            // or
-            // |llrrL   |
-            // or
-            // |lllllrrr|
-            // |rrL     |
-            //
-
-            const float extraWidth = glyphInfo.xBearing + glyphInfo.width - glyphInfo.advance;
-            tmpExtraWidth = ( 0.f < extraWidth ) ? extraWidth : 0.f;
-          }
-        }
-        else
-        {
-          if( characterDirection != previousCharacterDirection )
-          {
-            if( RTL == characterDirection )
-            {
-              //  -->
-              // |lllR    |
-
-              const float extraWidth = glyphInfo.xBearing + glyphInfo.width - glyphInfo.advance;
-              tmpExtraWidth = ( 0.f < extraWidth ) ? extraWidth : 0.f;
-            }
-            else // LTR
-            {
-              //       <--
-              // |   Lrrrr|
-
-              tmpExtraBearing = ( 0.f > glyphInfo.xBearing ) ? -glyphInfo.xBearing : 0.f;
-            }
-          }
-          else if( characterDirection == firstCharacterDirection )
-          {
-            if( RTL == characterDirection )
-            {
-              //  -->
-              // |llllllrr|
-              // |Rr      |
-
-              tmpExtraBearing = ( 0.f > glyphInfo.xBearing ) ? -glyphInfo.xBearing : 0.f;
-            }
-            else // LTR
-            {
-              //       <--
-              // |llllrrrr|
-              // |     llL|
-
-              const float extraWidth = glyphInfo.xBearing + glyphInfo.width - glyphInfo.advance;
-              tmpExtraWidth = ( 0.f < extraWidth ) ? extraWidth : 0.f;
-            }
-          }
-        }
+        tmpLineLayout.length = std::max(tmpLineLayout.length, tmpLineLayout.penX + glyphMetrics.xBearing + glyphMetrics.width);
 
         // Clear the white space length at the end of the line.
-        tmpLineLayout.wsLengthEndOfLine = 0.f;
+        tmpLineLayout.whiteSpaceLengthEndOfLine = 0.f;
       }
 
       // Check if the accumulated length fits in the width of the box.
-      if( ( completelyFill || isMultiline ) && !isWhiteSpace &&
-          ( tmpExtraBearing + lineLayout.length + lineLayout.wsLengthEndOfLine + tmpLineLayout.length + tmpExtraWidth > parameters.boundingBox.width ) )
+      if((completelyFill || isMultiline) && !isWhiteSpace &&
+         (tmpLineLayout.length > parameters.boundingBox.width))
       {
         // Current word does not fit in the box's width.
-        if( !oneWordLaidOut || completelyFill )
+        if(((oneHyphenLaidOut && isHyphenMode) ||
+            (!oneWordLaidOut && isMixedMode && oneHyphenLaidOut)) &&
+           !completelyFill)
+        {
+          parameters.textModel->mVisualModel->mHyphen.glyph.PushBack(hyphenGlyph);
+          parameters.textModel->mVisualModel->mHyphen.index.PushBack(hyphenIndex + 1);
+        }
+
+        if((!oneWordLaidOut && !oneHyphenLaidOut) || completelyFill)
         {
-          DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  Break the word by character\n" );
+          DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  Break the word by character\n");
 
-          // The word's with doesn't fit in the control's with. It needs to be split by character.
-          if( tmpLineLayout.numberOfGlyphs > 0u )
+          // The word doesn't fit in the control's width. It needs to be split by character.
+          if(tmpLineLayout.numberOfGlyphs > 0u)
           {
             tmpLineLayout.numberOfCharacters -= charactersPerGlyph;
-            --tmpLineLayout.numberOfGlyphs;
-            tmpLineLayout.length = previousTmpLineLength;
-            tmpExtraBearing = previousTmpExtraBearing;
-            tmpExtraWidth = previousTmpExtraWidth;
+            tmpLineLayout.numberOfGlyphs -= numberOfGLyphsInGroup;
+
+            tmpLineLayout.penX                      = previousTmpPenX;
+            tmpLineLayout.previousAdvance           = previousTmpAdvance;
+            tmpLineLayout.length                    = previousTmpLength;
+            tmpLineLayout.whiteSpaceLengthEndOfLine = previousTmpWhiteSpaceLengthEndOfLine;
           }
 
           // Add part of the word to the line layout.
-          MergeLineLayout( lineLayout, tmpLineLayout );
+          MergeLineLayout(lineLayout, tmpLineLayout);
         }
         else
         {
-          DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  Current word does not fit.\n" );
+          DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  Current word does not fit.\n");
         }
 
-        lineLayout.extraBearing = tmpExtraBearing;
-        lineLayout.extraWidth = tmpExtraWidth;
+        DALI_LOG_INFO(gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox.\n");
 
-        DALI_LOG_INFO( gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox.\n" );
+        // Reorder the RTL line.
+        if(bidiParameters.isBidirectional)
+        {
+          ReorderBiDiLayout(parameters,
+                            bidiParameters,
+                            lineLayout,
+                            lineLayout,
+                            true);
+        }
 
         return;
       }
 
-      if( ( isMultiline || isLastGlyph ) &&
-          ( TextAbstraction::LINE_MUST_BREAK == lineBreakInfo ) )
+      if((isMultiline || isLastGlyph) &&
+         (TextAbstraction::LINE_MUST_BREAK == lineBreakInfo))
       {
+        LineLayout currentLineLayout = lineLayout;
+        oneHyphenLaidOut             = false;
         // Must break the line. Update the line layout and return.
-        MergeLineLayout( lineLayout, tmpLineLayout );
+        MergeLineLayout(lineLayout, tmpLineLayout);
 
-        // Set the next paragraph's direction.
-        if( !isLastGlyph &&
-            ( NULL != parameters.characterDirectionBuffer ) )
+        // Reorder the RTL line.
+        if(bidiParameters.isBidirectional)
         {
-          paragraphDirection = *( parameters.characterDirectionBuffer + 1u + characterLastIndex );
+          ReorderBiDiLayout(parameters,
+                            bidiParameters,
+                            currentLineLayout,
+                            lineLayout,
+                            false);
         }
 
-        lineLayout.extraBearing = tmpExtraBearing;
-        lineLayout.extraWidth = tmpExtraWidth;
+        DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  Must break\n");
+        DALI_LOG_INFO(gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox\n");
 
-        DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  Must break\n" );
-        DALI_LOG_INFO( gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox\n" );
         return;
       }
 
-      if( isMultiline &&
-          ( TextAbstraction::WORD_BREAK == wordBreakInfo ) )
+      if(isMultiline &&
+         (TextAbstraction::LINE_ALLOW_BREAK == lineBreakInfo))
       {
-        oneWordLaidOut = true;
-        DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  One word laid out\n" );
+        oneHyphenLaidOut = false;
+        oneWordLaidOut   = isWordLaidOut;
+        DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  One word laid-out\n");
 
         // Current glyph is the last one of the current word.
         // Add the temporal layout to the current one.
-        MergeLineLayout( lineLayout, tmpLineLayout );
+        MergeLineLayout(lineLayout, tmpLineLayout);
 
         tmpLineLayout.Clear();
       }
 
-      previousCharacterDirection = characterDirection;
-    }
+      if(isMultiline &&
+         ((isHyphenMode || (!oneWordLaidOut && isMixedMode))) &&
+         (TextAbstraction::LINE_HYPHENATION_BREAK == lineBreakInfo))
+      {
+        hyphenGlyph        = GlyphInfo();
+        hyphenGlyph.fontId = glyphsBuffer[glyphIndex].fontId;
+
+        TextAbstraction::FontClient fontClient = TextAbstraction::FontClient::Get();
+        hyphenGlyph.index                      = fontClient.GetGlyphIndex(hyphenGlyph.fontId, HYPHEN_UNICODE);
+
+        mMetrics->GetGlyphMetrics(&hyphenGlyph, 1);
+
+        if((tmpLineLayout.length + hyphenGlyph.width) <= parameters.boundingBox.width)
+        {
+          hyphenIndex      = glyphIndex;
+          oneHyphenLaidOut = true;
+
+          DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  One hyphen laid-out\n");
+
+          // Current glyph is the last one of the current word hyphen.
+          // Add the temporal layout to the current one.
+          MergeLineLayout(lineLayout, tmpLineLayout);
+
+          tmpLineLayout.Clear();
+        }
+      }
 
-    lineLayout.extraBearing = tmpExtraBearing;
-    lineLayout.extraWidth = tmpExtraWidth;
+      glyphIndex += numberOfGLyphsInGroup;
+    }
 
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox\n" );
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "<--GetLineLayoutForBox\n");
   }
 
-  void SetGlyphPositions( const GlyphInfo* const glyphsBuffer,
-                          Length numberOfGlyphs,
-                          float penY,
-                          Vector2* glyphPositionsBuffer )
+  void SetGlyphPositions(const GlyphInfo* const glyphsBuffer,
+                         Length                 numberOfGlyphs,
+                         float                  outlineWidth,
+                         float                  interGlyphExtraAdvance,
+                         Vector2*               glyphPositionsBuffer)
   {
     // Traverse the glyphs and set the positions.
 
@@ -450,427 +704,1016 @@ struct LayoutEngine::Impl
     // so the penX position needs to be moved to the right.
 
     const GlyphInfo& glyph = *glyphsBuffer;
-    float penX = ( 0.f > glyph.xBearing ) ? -glyph.xBearing : 0.f;
-    penX += 1.f; // Added one unit to give some space to the cursor.
+    float            penX  = -glyph.xBearing + mCursorWidth + outlineWidth;
 
-    for( GlyphIndex i = 0u; i < numberOfGlyphs; ++i )
+    for(GlyphIndex i = 0u; i < numberOfGlyphs; ++i)
     {
-      const GlyphInfo& glyph = *( glyphsBuffer + i );
-      Vector2& position = *( glyphPositionsBuffer + i );
+      const GlyphInfo& glyph    = *(glyphsBuffer + i);
+      Vector2&         position = *(glyphPositionsBuffer + i);
 
       position.x = penX + glyph.xBearing;
-      position.y = penY - glyph.yBearing;
+      position.y = -glyph.yBearing;
 
-      penX += glyph.advance;
+      penX += (glyph.advance + interGlyphExtraAdvance);
     }
   }
 
-  bool LayoutText( const LayoutParameters& layoutParameters,
-                   Vector<Vector2>& glyphPositions,
-                   Vector<LineRun>& lines,
-                   Size& actualSize )
+  void SetGlyphPositions(const Parameters&     layoutParameters,
+                         Vector2*              glyphPositionsBuffer,
+                         LayoutBidiParameters& layoutBidiParameters,
+                         const LineLayout&     layout)
   {
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "-->LayoutText\n" );
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  box size %f, %f\n", layoutParameters.boundingBox.width, layoutParameters.boundingBox.height );
+    const Character* const          textBuffer               = layoutParameters.textModel->mLogicalModel->mText.Begin();
+    const BidirectionalLineInfoRun& bidiLine                 = layoutParameters.textModel->mLogicalModel->mBidirectionalLineInfo[layoutBidiParameters.bidiLineIndex];
+    const GlyphInfo* const          glyphsBuffer             = layoutParameters.textModel->mVisualModel->mGlyphs.Begin();
+    const GlyphIndex* const         charactersToGlyphsBuffer = layoutParameters.textModel->mVisualModel->mCharactersToGlyph.Begin();
+    const Length* const             glyphsPerCharacterBuffer = layoutParameters.textModel->mVisualModel->mGlyphsPerCharacter.Begin();
 
-    // Set the first paragraph's direction.
-    CharacterDirection paragraphDirection = ( NULL != layoutParameters.characterDirectionBuffer ) ? *layoutParameters.characterDirectionBuffer : !RTL;
+    CharacterIndex characterLogicalIndex = 0u;
+    CharacterIndex characterVisualIndex  = bidiLine.characterRun.characterIndex + *(bidiLine.visualToLogicalMap + characterLogicalIndex);
 
-    float penY = 0.f;
-    for( GlyphIndex index = 0u; index < layoutParameters.totalNumberOfGlyphs; )
+    float penX = 0.f;
+    while(TextAbstraction::IsWhiteSpace(*(textBuffer + characterVisualIndex)))
     {
-      CharacterDirection currentParagraphDirection = paragraphDirection;
+      const GlyphIndex glyphIndex = *(charactersToGlyphsBuffer + characterVisualIndex);
+      const GlyphInfo& glyph      = *(glyphsBuffer + glyphIndex);
 
-      // Get the layout for the line.
-      LineLayout layout;
-      layout.glyphIndex = index;
-      GetLineLayoutForBox( layoutParameters,
-                           layout,
-                           paragraphDirection,
-                           false );
+      Vector2& position = *(glyphPositionsBuffer + glyphIndex - layoutParameters.startGlyphIndex);
+      position.x        = penX;
+      position.y        = -glyph.yBearing;
+
+      penX += glyph.advance;
 
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "           glyph index %d\n", layout.glyphIndex );
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "       character index %d\n", layout.characterIndex );
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "      number of glyphs %d\n", layout.numberOfGlyphs );
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  number of characters %d\n", layout.numberOfCharacters );
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "                length %f\n", layout.length );
+      ++characterLogicalIndex;
+      characterVisualIndex = bidiLine.characterRun.characterIndex + *(bidiLine.visualToLogicalMap + characterLogicalIndex);
+    }
+
+    const GlyphIndex glyphIndex = *(charactersToGlyphsBuffer + characterVisualIndex);
+    const GlyphInfo& glyph      = *(glyphsBuffer + glyphIndex);
 
-      if( 0u == layout.numberOfGlyphs )
+    penX += -glyph.xBearing;
+
+    // Traverses the characters of the right to left paragraph.
+    for(; characterLogicalIndex < bidiLine.characterRun.numberOfCharacters;
+        ++characterLogicalIndex)
+    {
+      // Convert the character in the logical order into the character in the visual order.
+      const CharacterIndex characterVisualIndex = bidiLine.characterRun.characterIndex + *(bidiLine.visualToLogicalMap + characterLogicalIndex);
+
+      // Get the number of glyphs of the character.
+      const Length numberOfGlyphs = *(glyphsPerCharacterBuffer + characterVisualIndex);
+
+      for(GlyphIndex index = 0u; index < numberOfGlyphs; ++index)
       {
-        // The width is too small and no characters are laid-out.
-        DALI_LOG_INFO( gLogFilter, Debug::Verbose, "<--LayoutText width too small!\n\n" );
-        return false;
+        // Convert the character in the visual order into the glyph in the visual order.
+        const GlyphIndex glyphIndex = *(charactersToGlyphsBuffer + characterVisualIndex) + index;
+
+        DALI_ASSERT_DEBUG(glyphIndex < layoutParameters.textModel->mVisualModel->mGlyphs.Count());
+
+        const GlyphInfo& glyph    = *(glyphsBuffer + glyphIndex);
+        Vector2&         position = *(glyphPositionsBuffer + glyphIndex - layoutParameters.startGlyphIndex);
+
+        position.x = penX + glyph.xBearing;
+        position.y = -glyph.yBearing;
+
+        penX += (glyph.advance + layoutParameters.interGlyphExtraAdvance);
       }
+    }
+  }
 
-      // Set the line position. Discard if ellipsis is enabled and the position exceeds the boundaries
-      // of the box.
-      penY += layout.ascender;
+  /**
+   * @brief Resizes the line buffer.
+   *
+   * @param[in,out] lines The vector of lines. Used when the layout is created from scratch.
+   * @param[in,out] newLines The vector of lines used instead of @p lines when the layout is updated.
+   * @param[in,out] linesCapacity The capacity of the vector (either lines or newLines).
+   * @param[in] updateCurrentBuffer Whether the layout is updated.
+   *
+   * @return Pointer to either lines or newLines.
+   */
+  LineRun* ResizeLinesBuffer(Vector<LineRun>& lines,
+                             Vector<LineRun>& newLines,
+                             Length&          linesCapacity,
+                             bool             updateCurrentBuffer)
+  {
+    LineRun* linesBuffer = nullptr;
+    // Reserve more space for the next lines.
+    linesCapacity *= 2u;
+    if(updateCurrentBuffer)
+    {
+      newLines.Resize(linesCapacity);
+      linesBuffer = newLines.Begin();
+    }
+    else
+    {
+      lines.Resize(linesCapacity);
+      linesBuffer = lines.Begin();
+    }
+
+    return linesBuffer;
+  }
 
-      DALI_LOG_INFO( gLogFilter, Debug::Verbose, "  pen y %f\n", penY );
-      if( mEllipsisEnabled &&
-          ( ( penY - layout.descender > layoutParameters.boundingBox.height ) ||
-            ( ( mLayout == SINGLE_LINE_BOX ) &&
-              ( layout.extraBearing + layout.length + layout.extraWidth > layoutParameters.boundingBox.width ) ) ) )
+  /**
+   * Ellipsis a line if it exceeds the width's of the bounding box.
+   *
+   * @param[in] layoutParameters The parameters needed to layout the text.
+   * @param[in] layout The line layout.
+   * @param[in,out] layoutSize The text's layout size.
+   * @param[in,out] linesBuffer Pointer to the line's buffer.
+   * @param[in,out] glyphPositionsBuffer Pointer to the position's buffer.
+   * @param[in,out] numberOfLines The number of laid-out lines.
+   * @param[in] penY The vertical layout position.
+   * @param[in] currentParagraphDirection The current paragraph's direction.
+   * @param[in,out] isAutoScrollEnabled If the isAutoScrollEnabled is true and the height of the text exceeds the boundaries of the control the text is elided and the isAutoScrollEnabled is set to false to disable the autoscroll
+   *
+   * return Whether the line is ellipsized.
+   */
+  bool EllipsisLine(const Parameters&     layoutParameters,
+                    LayoutBidiParameters& layoutBidiParameters,
+                    const LineLayout&     layout,
+                    Size&                 layoutSize,
+                    LineRun*              linesBuffer,
+                    Vector2*              glyphPositionsBuffer,
+                    Length&               numberOfLines,
+                    float                 penY,
+                    bool&                 isAutoScrollEnabled)
+  {
+    const bool ellipsis = isAutoScrollEnabled ? (penY - layout.descender > layoutParameters.boundingBox.height) : ((penY - layout.descender > layoutParameters.boundingBox.height) || ((mLayout == SINGLE_LINE_BOX) && (layout.length > layoutParameters.boundingBox.width)));
+
+    if(ellipsis)
+    {
+      isAutoScrollEnabled = false;
+      // Do not layout more lines if ellipsis is enabled.
+
+      // The last line needs to be completely filled with characters.
+      // Part of a word may be used.
+
+      LineRun*   lineRun = nullptr;
+      LineLayout ellipsisLayout;
+      if(0u != numberOfLines)
       {
-        // Do not layout more lines if ellipsis is enabled.
+        // Get the last line and layout it again with the 'completelyFill' flag to true.
+        lineRun = linesBuffer + (numberOfLines - 1u);
 
-        // The last line needs to be completely filled with characters.
-        // Part of a word may be used.
+        penY -= layout.ascender - lineRun->descender + lineRun->lineSpacing;
 
-        const Length numberOfLines = lines.Count();
+        ellipsisLayout.glyphIndex = lineRun->glyphRun.glyphIndex;
+      }
+      else
+      {
+        // At least there is space reserved for one line.
+        lineRun = linesBuffer;
 
-        LineRun lineRun;
-        LineLayout ellipsisLayout;
-        if( 0u != numberOfLines )
-        {
-          // Get the last line and layout it again with the 'completelyFill' flag to true.
-          lineRun = *( lines.Begin() + ( numberOfLines - 1u ) );
+        lineRun->glyphRun.glyphIndex = 0u;
+        ellipsisLayout.glyphIndex    = 0u;
 
-          penY -= layout.ascender - lineRun.descender;
+        ++numberOfLines;
+      }
 
-          ellipsisLayout.glyphIndex = lineRun.glyphIndex;
-        }
-        else
-        {
-          lineRun.glyphIndex = 0u;
-          ellipsisLayout.glyphIndex = 0u;
-        }
+      GetLineLayoutForBox(layoutParameters,
+                          layoutBidiParameters,
+                          ellipsisLayout,
+                          true);
+
+      lineRun->glyphRun.numberOfGlyphs         = ellipsisLayout.numberOfGlyphs;
+      lineRun->characterRun.characterIndex     = ellipsisLayout.characterIndex;
+      lineRun->characterRun.numberOfCharacters = ellipsisLayout.numberOfCharacters;
+      lineRun->width                           = ellipsisLayout.length;
+      lineRun->extraLength                     = std::ceil(ellipsisLayout.whiteSpaceLengthEndOfLine);
+      lineRun->ascender                        = ellipsisLayout.ascender;
+      lineRun->descender                       = ellipsisLayout.descender;
+      lineRun->ellipsis                        = true;
+
+      layoutSize.width = layoutParameters.boundingBox.width;
+      if(layoutSize.height < Math::MACHINE_EPSILON_1000)
+      {
+        layoutSize.height += (lineRun->ascender + -lineRun->descender) + lineRun->lineSpacing;
+      }
 
-        GetLineLayoutForBox( layoutParameters,
-                             ellipsisLayout,
-                             currentParagraphDirection,
-                             true );
-
-        lineRun.numberOfGlyphs = ellipsisLayout.numberOfGlyphs;
-        lineRun.characterRun.characterIndex = ellipsisLayout.characterIndex;
-        lineRun.characterRun.numberOfCharacters = ellipsisLayout.numberOfCharacters;
-        lineRun.width = ellipsisLayout.length;
-        lineRun.extraLength =  ( ellipsisLayout.wsLengthEndOfLine > 0.f ) ? ellipsisLayout.wsLengthEndOfLine - ellipsisLayout.extraWidth : 0.f;
-        lineRun.ascender = ellipsisLayout.ascender;
-        lineRun.descender = ellipsisLayout.descender;
-        lineRun.ellipsis = true;
-
-        actualSize.width = layoutParameters.boundingBox.width;
-        actualSize.height += ( lineRun.ascender + -lineRun.descender );
-
-        SetGlyphPositions( layoutParameters.glyphsBuffer + lineRun.glyphIndex,
-                           ellipsisLayout.numberOfGlyphs,
-                           penY,
-                           glyphPositions.Begin() + lineRun.glyphIndex );
-
-        if( 0u != numberOfLines )
-        {
-          // Set the last line with the ellipsis layout.
-          *( lines.Begin() + ( numberOfLines - 1u ) ) = lineRun;
-        }
-        else
+      const GlyphInfo* const glyphsBuffer = layoutParameters.textModel->mVisualModel->mGlyphs.Begin();
+      const float            outlineWidth = static_cast<float>(layoutParameters.textModel->GetOutlineWidth());
+
+      const Vector<BidirectionalLineInfoRun>& bidirectionalLinesInfo = layoutParameters.textModel->mLogicalModel->mBidirectionalLineInfo;
+
+      if(layoutBidiParameters.isBidirectional)
+      {
+        layoutBidiParameters.bidiLineIndex = 0u;
+        for(Vector<BidirectionalLineInfoRun>::ConstIterator it    = bidirectionalLinesInfo.Begin(),
+                                                            endIt = bidirectionalLinesInfo.End();
+            it != endIt;
+            ++it, ++layoutBidiParameters.bidiLineIndex)
         {
-          // Push the line.
-          lines.PushBack( lineRun );
+          const BidirectionalLineInfoRun& run = *it;
+
+          if(ellipsisLayout.characterIndex == run.characterRun.characterIndex)
+          {
+            // Found where to insert the bidi line info.
+            break;
+          }
         }
+      }
 
-        break;
+      const BidirectionalLineInfoRun* const bidirectionalLineInfo = (layoutBidiParameters.isBidirectional && !bidirectionalLinesInfo.Empty()) ? &bidirectionalLinesInfo[layoutBidiParameters.bidiLineIndex] : nullptr;
+
+      if((nullptr != bidirectionalLineInfo) &&
+         !bidirectionalLineInfo->isIdentity &&
+         (ellipsisLayout.characterIndex == bidirectionalLineInfo->characterRun.characterIndex))
+      {
+        lineRun->direction = RTL;
+        SetGlyphPositions(layoutParameters,
+                          glyphPositionsBuffer,
+                          layoutBidiParameters,
+                          ellipsisLayout);
       }
       else
       {
-        const bool isLastLine = index + layout.numberOfGlyphs == layoutParameters.totalNumberOfGlyphs;
+        lineRun->direction = LTR;
+        SetGlyphPositions(glyphsBuffer + lineRun->glyphRun.glyphIndex,
+                          ellipsisLayout.numberOfGlyphs,
+                          outlineWidth,
+                          layoutParameters.interGlyphExtraAdvance,
+                          glyphPositionsBuffer + lineRun->glyphRun.glyphIndex - layoutParameters.startGlyphIndex);
+      }
+    }
 
-        LineRun lineRun;
-        lineRun.glyphIndex = index;
-        lineRun.numberOfGlyphs = layout.numberOfGlyphs;
-        lineRun.characterRun.characterIndex = layout.characterIndex;
-        lineRun.characterRun.numberOfCharacters = layout.numberOfCharacters;
-        if( isLastLine )
-        {
-          const float width = layout.extraBearing + layout.length + layout.extraWidth + layout.wsLengthEndOfLine;
-          if( MULTI_LINE_BOX == mLayout )
-          {
-            lineRun.width = ( width > layoutParameters.boundingBox.width ) ? layoutParameters.boundingBox.width : width;
-          }
-          else
-          {
-            lineRun.width = width;
-          }
+    return ellipsis;
+  }
 
-          lineRun.extraLength = 0.f;
-        }
-        else
-        {
-          lineRun.width = layout.extraBearing + layout.length + layout.extraWidth;
-          lineRun.extraLength = ( layout.wsLengthEndOfLine > 0.f ) ? layout.wsLengthEndOfLine - layout.extraWidth : 0.f;
-        }
-        lineRun.ascender = layout.ascender;
-        lineRun.descender = layout.descender;
-        lineRun.direction = false;
-        lineRun.ellipsis = false;
+  /**
+   * @brief Updates the text layout with a new laid-out line.
+   *
+   * @param[in] layoutParameters The parameters needed to layout the text.
+   * @param[in] layout The line layout.
+   * @param[in,out] layoutSize The text's layout size.
+   * @param[in,out] linesBuffer Pointer to the line's buffer.
+   * @param[in] index Index to the vector of glyphs.
+   * @param[in,out] numberOfLines The number of laid-out lines.
+   * @param[in] isLastLine Whether the laid-out line is the last one.
+   */
+  void UpdateTextLayout(const Parameters& layoutParameters,
+                        const LineLayout& layout,
+                        Size&             layoutSize,
+                        LineRun*          linesBuffer,
+                        GlyphIndex        index,
+                        Length&           numberOfLines,
+                        bool              isLastLine)
+  {
+    LineRun& lineRun = *(linesBuffer + numberOfLines);
+    ++numberOfLines;
 
-        lines.PushBack( lineRun );
+    lineRun.glyphRun.glyphIndex             = index;
+    lineRun.glyphRun.numberOfGlyphs         = layout.numberOfGlyphs;
+    lineRun.characterRun.characterIndex     = layout.characterIndex;
+    lineRun.characterRun.numberOfCharacters = layout.numberOfCharacters;
+    lineRun.width                           = layout.length;
+    lineRun.extraLength                     = std::ceil(layout.whiteSpaceLengthEndOfLine);
 
-        // Update the actual size.
-        if( lineRun.width > actualSize.width )
-        {
-          actualSize.width = lineRun.width;
-        }
+    // Rounds upward to avoid a non integer size.
+    lineRun.width = std::ceil(lineRun.width);
 
-        actualSize.height += ( lineRun.ascender + -lineRun.descender );
+    lineRun.ascender  = layout.ascender;
+    lineRun.descender = layout.descender;
+    lineRun.direction = layout.direction;
+    lineRun.ellipsis  = false;
 
-        SetGlyphPositions( layoutParameters.glyphsBuffer + index,
-                           layout.numberOfGlyphs,
-                           penY,
-                           glyphPositions.Begin() + index );
+    lineRun.lineSpacing = mDefaultLineSize - (lineRun.ascender + -lineRun.descender);
+    lineRun.lineSpacing = lineRun.lineSpacing < 0.f ? 0.f : lineRun.lineSpacing;
 
-        penY += -layout.descender;
+    lineRun.lineSpacing += mDefaultLineSpacing;
 
-        // Increase the glyph index.
-        index += layout.numberOfGlyphs;
-      }
+    // Update the actual size.
+    if(lineRun.width > layoutSize.width)
+    {
+      layoutSize.width = lineRun.width;
     }
 
-    DALI_LOG_INFO( gLogFilter, Debug::Verbose, "<--LayoutText\n\n" );
-
-    return true;
+    layoutSize.height += (lineRun.ascender + -lineRun.descender) + lineRun.lineSpacing;
   }
 
-  void ReLayoutRightToLeftLines( const LayoutParameters& layoutParameters,
-                                 Vector<Vector2>& glyphPositions )
+  /**
+   * @brief Updates the text layout with the last laid-out line.
+   *
+   * @param[in] layoutParameters The parameters needed to layout the text.
+   * @param[in] characterIndex The character index of the line.
+   * @param[in] glyphIndex The glyph index of the line.
+   * @param[in,out] layoutSize The text's layout size.
+   * @param[in,out] linesBuffer Pointer to the line's buffer.
+   * @param[in,out] numberOfLines The number of laid-out lines.
+   */
+  void UpdateTextLayout(const Parameters& layoutParameters,
+                        CharacterIndex    characterIndex,
+                        GlyphIndex        glyphIndex,
+                        Size&             layoutSize,
+                        LineRun*          linesBuffer,
+                        Length&           numberOfLines)
   {
-    // Traverses the paragraphs with right to left characters.
-    for( LineIndex lineIndex = 0u; lineIndex < layoutParameters.numberOfBidirectionalInfoRuns; ++lineIndex )
-    {
-      const BidirectionalLineInfoRun& bidiLine = *( layoutParameters.lineBidirectionalInfoRunsBuffer + lineIndex );
+    const Vector<GlyphInfo>& glyphs = layoutParameters.textModel->mVisualModel->mGlyphs;
 
-      const CharacterIndex characterVisualIndex = bidiLine.characterRun.characterIndex + *bidiLine.visualToLogicalMap;
-      const GlyphInfo& glyph = *( layoutParameters.glyphsBuffer + *( layoutParameters.charactersToGlyphsBuffer + characterVisualIndex ) );
+    // Need to add a new line with no characters but with height to increase the layoutSize.height
+    const GlyphInfo& glyphInfo = glyphs[glyphs.Count() - 1u];
 
-      float penX = ( 0.f > glyph.xBearing ) ? -glyph.xBearing : 0.f;
-      penX += 1.f; // Added one unit to give some space to the cursor.
+    Text::FontMetrics fontMetrics;
+    if(0u != glyphInfo.fontId)
+    {
+      mMetrics->GetFontMetrics(glyphInfo.fontId, fontMetrics);
+    }
 
-      Vector2* glyphPositionsBuffer = glyphPositions.Begin();
+    LineRun& lineRun = *(linesBuffer + numberOfLines);
+    ++numberOfLines;
 
-      // Traverses the characters of the right to left paragraph.
-      for( CharacterIndex characterLogicalIndex = 0u;
-           characterLogicalIndex < bidiLine.characterRun.numberOfCharacters;
-           ++characterLogicalIndex )
-      {
-        // Convert the character in the logical order into the character in the visual order.
-        const CharacterIndex characterVisualIndex = bidiLine.characterRun.characterIndex + *( bidiLine.visualToLogicalMap + characterLogicalIndex );
+    lineRun.glyphRun.glyphIndex             = glyphIndex;
+    lineRun.glyphRun.numberOfGlyphs         = 0u;
+    lineRun.characterRun.characterIndex     = characterIndex;
+    lineRun.characterRun.numberOfCharacters = 0u;
+    lineRun.width                           = 0.f;
+    lineRun.ascender                        = fontMetrics.ascender;
+    lineRun.descender                       = fontMetrics.descender;
+    lineRun.extraLength                     = 0.f;
+    lineRun.alignmentOffset                 = 0.f;
+    lineRun.direction                       = LTR;
+    lineRun.ellipsis                        = false;
 
-        // Get the number of glyphs of the character.
-        const Length numberOfGlyphs = *( layoutParameters.glyphsPerCharacterBuffer + characterVisualIndex );
+    lineRun.lineSpacing = mDefaultLineSize - (lineRun.ascender + -lineRun.descender);
+    lineRun.lineSpacing = lineRun.lineSpacing < 0.f ? 0.f : lineRun.lineSpacing;
 
-        for( GlyphIndex index = 0u; index < numberOfGlyphs; ++index )
-        {
-          // Convert the character in the visual order into the glyph in the visual order.
-          const GlyphIndex glyphIndex = *( layoutParameters.charactersToGlyphsBuffer + characterVisualIndex ) + index;
+    lineRun.lineSpacing += mDefaultLineSpacing;
 
-          DALI_ASSERT_DEBUG( 0u <= glyphIndex && glyphIndex < layoutParameters.totalNumberOfGlyphs );
+    layoutSize.height += (lineRun.ascender + -lineRun.descender) + lineRun.lineSpacing;
+  }
 
-          const GlyphInfo& glyph = *( layoutParameters.glyphsBuffer + glyphIndex );
-          Vector2& position = *( glyphPositionsBuffer + glyphIndex );
+  /**
+   * @brief Updates the text's layout size adding the size of the previously laid-out lines.
+   *
+   * @param[in] lines The vector of lines (before the new laid-out lines are inserted).
+   * @param[in,out] layoutSize The text's layout size.
+   */
+  void UpdateLayoutSize(const Vector<LineRun>& lines,
+                        Size&                  layoutSize)
+  {
+    for(Vector<LineRun>::ConstIterator it    = lines.Begin(),
+                                       endIt = lines.End();
+        it != endIt;
+        ++it)
+    {
+      const LineRun& line = *it;
 
-          position.x = penX + glyph.xBearing;
-          penX += glyph.advance;
-        }
+      if(line.width > layoutSize.width)
+      {
+        layoutSize.width = line.width;
       }
+
+      layoutSize.height += (line.ascender + -line.descender) + line.lineSpacing;
     }
   }
 
-  void Align( const Size& layoutSize,
-              Vector<LineRun>& lines )
+  /**
+   * @brief Updates the indices of the character and glyph runs of the lines before the new lines are inserted.
+   *
+   * @param[in] layoutParameters The parameters needed to layout the text.
+   * @param[in,out] lines The vector of lines (before the new laid-out lines are inserted).
+   * @param[in] characterOffset The offset to be added to the runs of characters.
+   * @param[in] glyphOffset The offset to be added to the runs of glyphs.
+   */
+  void UpdateLineIndexOffsets(const Parameters& layoutParameters,
+                              Vector<LineRun>&  lines,
+                              Length            characterOffset,
+                              Length            glyphOffset)
   {
-    // Traverse all lines and align the glyphs.
-
-    for( Vector<LineRun>::Iterator it = lines.Begin(), endIt = lines.End();
-         it != endIt;
-         ++it )
+    // Update the glyph and character runs.
+    for(Vector<LineRun>::Iterator it    = lines.Begin() + layoutParameters.startLineIndex,
+                                  endIt = lines.End();
+        it != endIt;
+        ++it)
     {
       LineRun& line = *it;
-      const bool isLastLine = lines.End() == it + 1u;
 
-      // Calculate the alignment offset accordingly with the align option,
-      // the box width, line length, and the paragraphs direction.
-      CalculateHorizontalAlignment( layoutSize.width,
-                                    line,
-                                    isLastLine );
+      line.glyphRun.glyphIndex         = glyphOffset;
+      line.characterRun.characterIndex = characterOffset;
+
+      glyphOffset += line.glyphRun.numberOfGlyphs;
+      characterOffset += line.characterRun.numberOfCharacters;
     }
   }
 
-  void CalculateHorizontalAlignment( float boxWidth,
-                                     LineRun& line,
-                                     bool isLastLine )
+  bool LayoutText(Parameters& layoutParameters,
+                  Size&       layoutSize,
+                  bool        elideTextEnabled,
+                  bool&       isAutoScrollEnabled)
   {
-    line.alignmentOffset = 0.f;
-    const bool isRTL = RTL == line.direction;
-    float lineLength = line.width;
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "-->LayoutText\n");
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  box size %f, %f\n", layoutParameters.boundingBox.width, layoutParameters.boundingBox.height);
 
-    HorizontalAlignment alignment = mHorizontalAlignment;
-    if( isRTL &&
-        ( HORIZONTAL_ALIGN_CENTER != alignment ) )
+    layoutParameters.textModel->mVisualModel->mHyphen.glyph.Clear();
+    layoutParameters.textModel->mVisualModel->mHyphen.index.Clear();
+
+    Vector<LineRun>& lines = layoutParameters.textModel->mVisualModel->mLines;
+
+    if(0u == layoutParameters.numberOfGlyphs)
     {
-      if( HORIZONTAL_ALIGN_BEGIN == alignment )
+      // Add an extra line if the last character is a new paragraph character and the last line doesn't have zero characters.
+      if(layoutParameters.isLastNewParagraph)
       {
-        alignment = HORIZONTAL_ALIGN_END;
+        Length numberOfLines = lines.Count();
+        if(0u != numberOfLines)
+        {
+          const LineRun& lastLine = *(lines.End() - 1u);
+
+          if(0u != lastLine.characterRun.numberOfCharacters)
+          {
+            // Need to add a new line with no characters but with height to increase the layoutSize.height
+            LineRun newLine;
+            Initialize(newLine);
+            lines.PushBack(newLine);
+
+            UpdateTextLayout(layoutParameters,
+                             lastLine.characterRun.characterIndex + lastLine.characterRun.numberOfCharacters,
+                             lastLine.glyphRun.glyphIndex + lastLine.glyphRun.numberOfGlyphs,
+                             layoutSize,
+                             lines.Begin(),
+                             numberOfLines);
+          }
+        }
       }
-      else
+
+      // Calculates the layout size.
+      UpdateLayoutSize(lines,
+                       layoutSize);
+
+      // Rounds upward to avoid a non integer size.
+      layoutSize.height = std::ceil(layoutSize.height);
+
+      // Nothing else do if there are no glyphs to layout.
+      return false;
+    }
+
+    const GlyphIndex lastGlyphPlusOne    = layoutParameters.startGlyphIndex + layoutParameters.numberOfGlyphs;
+    const Length     totalNumberOfGlyphs = layoutParameters.textModel->mVisualModel->mGlyphs.Count();
+    Vector<Vector2>& glyphPositions      = layoutParameters.textModel->mVisualModel->mGlyphPositions;
+
+    // In a previous layout, an extra line with no characters may have been added if the text ended with a new paragraph character.
+    // This extra line needs to be removed.
+    if(0u != lines.Count())
+    {
+      Vector<LineRun>::Iterator lastLine = lines.End() - 1u;
+
+      if((0u == lastLine->characterRun.numberOfCharacters) &&
+         (lastGlyphPlusOne == totalNumberOfGlyphs))
       {
-        alignment = HORIZONTAL_ALIGN_BEGIN;
+        lines.Remove(lastLine);
       }
     }
 
-    switch( alignment )
+    // Retrieve BiDi info.
+    const bool hasBidiParagraphs = !layoutParameters.textModel->mLogicalModel->mBidirectionalParagraphInfo.Empty();
+
+    const CharacterIndex* const                  glyphsToCharactersBuffer    = hasBidiParagraphs ? layoutParameters.textModel->mVisualModel->mGlyphsToCharacters.Begin() : nullptr;
+    const Vector<BidirectionalParagraphInfoRun>& bidirectionalParagraphsInfo = layoutParameters.textModel->mLogicalModel->mBidirectionalParagraphInfo;
+    const Vector<BidirectionalLineInfoRun>&      bidirectionalLinesInfo      = layoutParameters.textModel->mLogicalModel->mBidirectionalLineInfo;
+
+    // Set the layout bidirectional paramters.
+    LayoutBidiParameters layoutBidiParameters;
+
+    // Whether the layout is being updated or set from scratch.
+    const bool updateCurrentBuffer = layoutParameters.numberOfGlyphs < totalNumberOfGlyphs;
+
+    Vector2*        glyphPositionsBuffer = nullptr;
+    Vector<Vector2> newGlyphPositions;
+
+    LineRun*        linesBuffer = nullptr;
+    Vector<LineRun> newLines;
+
+    // Estimate the number of lines.
+    Length linesCapacity = std::max(1u, layoutParameters.estimatedNumberOfLines);
+    Length numberOfLines = 0u;
+
+    if(updateCurrentBuffer)
+    {
+      newGlyphPositions.Resize(layoutParameters.numberOfGlyphs);
+      glyphPositionsBuffer = newGlyphPositions.Begin();
+
+      newLines.Resize(linesCapacity);
+      linesBuffer = newLines.Begin();
+    }
+    else
+    {
+      glyphPositionsBuffer = glyphPositions.Begin();
+
+      lines.Resize(linesCapacity);
+      linesBuffer = lines.Begin();
+    }
+
+    float penY = CalculateLineOffset(lines,
+                                     layoutParameters.startLineIndex);
+    for(GlyphIndex index = layoutParameters.startGlyphIndex; index < lastGlyphPlusOne;)
     {
-      case HORIZONTAL_ALIGN_BEGIN:
+      layoutBidiParameters.Clear();
+
+      if(hasBidiParagraphs)
       {
-        line.alignmentOffset = 0.f;
+        const CharacterIndex startCharacterIndex = *(glyphsToCharactersBuffer + index);
 
-        if( isRTL )
+        for(Vector<BidirectionalParagraphInfoRun>::ConstIterator it    = bidirectionalParagraphsInfo.Begin(),
+                                                                 endIt = bidirectionalParagraphsInfo.End();
+            it != endIt;
+            ++it, ++layoutBidiParameters.bidiParagraphIndex)
         {
-          // 'Remove' the white spaces at the end of the line (which are at the beginning in visual order)
-          line.alignmentOffset -= line.extraLength;
+          const BidirectionalParagraphInfoRun& run = *it;
+
+          const CharacterIndex lastCharacterIndex = run.characterRun.characterIndex + run.characterRun.numberOfCharacters;
+
+          if(lastCharacterIndex <= startCharacterIndex)
+          {
+            // Do not process, the paragraph has already been processed.
+            continue;
+          }
+
+          if(startCharacterIndex >= run.characterRun.characterIndex && startCharacterIndex < lastCharacterIndex)
+          {
+            layoutBidiParameters.paragraphDirection = run.direction;
+            layoutBidiParameters.isBidirectional    = true;
+          }
+
+          // Has already been found.
+          break;
+        }
 
-          if( isLastLine )
+        if(layoutBidiParameters.isBidirectional)
+        {
+          for(Vector<BidirectionalLineInfoRun>::ConstIterator it    = bidirectionalLinesInfo.Begin(),
+                                                              endIt = bidirectionalLinesInfo.End();
+              it != endIt;
+              ++it, ++layoutBidiParameters.bidiLineIndex)
           {
-            line.alignmentOffset += std::min( line.extraLength, boxWidth - lineLength );
+            const BidirectionalLineInfoRun& run = *it;
+
+            const CharacterIndex lastCharacterIndex = run.characterRun.characterIndex + run.characterRun.numberOfCharacters;
+
+            if(lastCharacterIndex <= startCharacterIndex)
+            {
+              // skip
+              continue;
+            }
+
+            if(startCharacterIndex < lastCharacterIndex)
+            {
+              // Found where to insert the bidi line info.
+              break;
+            }
           }
         }
+      }
+
+      CharacterDirection currentParagraphDirection = layoutBidiParameters.paragraphDirection;
+
+      // Get the layout for the line.
+      LineLayout layout;
+      layout.direction  = layoutBidiParameters.paragraphDirection;
+      layout.glyphIndex = index;
+      GetLineLayoutForBox(layoutParameters,
+                          layoutBidiParameters,
+                          layout,
+                          false);
+
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "           glyph index %d\n", layout.glyphIndex);
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "       character index %d\n", layout.characterIndex);
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "      number of glyphs %d\n", layout.numberOfGlyphs);
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  number of characters %d\n", layout.numberOfCharacters);
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "                length %f\n", layout.length);
+
+      if(0u == layout.numberOfGlyphs)
+      {
+        // The width is too small and no characters are laid-out.
+        DALI_LOG_INFO(gLogFilter, Debug::Verbose, "<--LayoutText width too small!\n\n");
+
+        lines.Resize(numberOfLines);
+
+        // Rounds upward to avoid a non integer size.
+        layoutSize.height = std::ceil(layoutSize.height);
+
+        return false;
+      }
+
+      // Set the line position. DISCARD if ellipsis is enabled and the position exceeds the boundaries
+      // of the box.
+      penY += layout.ascender;
+
+      DALI_LOG_INFO(gLogFilter, Debug::Verbose, "  pen y %f\n", penY);
+
+      bool ellipsis = false;
+      if(elideTextEnabled)
+      {
+        layoutBidiParameters.paragraphDirection = currentParagraphDirection;
+
+        // Does the ellipsis of the last line.
+        ellipsis = EllipsisLine(layoutParameters,
+                                layoutBidiParameters,
+                                layout,
+                                layoutSize,
+                                linesBuffer,
+                                glyphPositionsBuffer,
+                                numberOfLines,
+                                penY,
+                                isAutoScrollEnabled);
+      }
+
+      if(ellipsis)
+      {
+        //clear hyphen from ellipsis line
+        const Length* hyphenIndices = layoutParameters.textModel->mVisualModel->mHyphen.index.Begin();
+        Length        hyphensCount  = layoutParameters.textModel->mVisualModel->mHyphen.glyph.Size();
+
+        while(hyphenIndices && hyphensCount > 0 && hyphenIndices[hyphensCount - 1] >= layout.glyphIndex)
+        {
+          layoutParameters.textModel->mVisualModel->mHyphen.index.Remove(layoutParameters.textModel->mVisualModel->mHyphen.index.Begin() + hyphensCount - 1);
+          layoutParameters.textModel->mVisualModel->mHyphen.glyph.Remove(layoutParameters.textModel->mVisualModel->mHyphen.glyph.Begin() + hyphensCount - 1);
+          hyphensCount--;
+        }
+
+        // No more lines to layout.
         break;
       }
-      case HORIZONTAL_ALIGN_CENTER:
+      else
       {
-        if( isLastLine && !isRTL )
+        // Whether the last line has been laid-out.
+        const bool isLastLine = index + layout.numberOfGlyphs == totalNumberOfGlyphs;
+
+        if(numberOfLines == linesCapacity)
         {
-          lineLength += line.extraLength;
-          if( lineLength > boxWidth )
-          {
-            lineLength = boxWidth;
-            line.alignmentOffset = 0.f;
-            break;
-          }
+          // Reserve more space for the next lines.
+          linesBuffer = ResizeLinesBuffer(lines,
+                                          newLines,
+                                          linesCapacity,
+                                          updateCurrentBuffer);
         }
 
-        line.alignmentOffset = 0.5f * ( boxWidth - lineLength );
+        // Updates the current text's layout with the line's layout.
+        UpdateTextLayout(layoutParameters,
+                         layout,
+                         layoutSize,
+                         linesBuffer,
+                         index,
+                         numberOfLines,
+                         isLastLine);
 
-        if( isRTL )
+        const GlyphIndex nextIndex = index + layout.numberOfGlyphs;
+
+        if((nextIndex == totalNumberOfGlyphs) &&
+           layoutParameters.isLastNewParagraph &&
+           (mLayout == MULTI_LINE_BOX))
         {
-          line.alignmentOffset -= line.extraLength;
+          // The last character of the text is a new paragraph character.
+          // An extra line with no characters is added to increase the text's height
+          // in order to place the cursor.
 
-          if( isLastLine )
+          if(numberOfLines == linesCapacity)
           {
-            line.alignmentOffset += 0.5f * std::min( line.extraLength, boxWidth - lineLength );
+            // Reserve more space for the next lines.
+            linesBuffer = ResizeLinesBuffer(lines,
+                                            newLines,
+                                            linesCapacity,
+                                            updateCurrentBuffer);
           }
+
+          UpdateTextLayout(layoutParameters,
+                           layout.characterIndex + layout.numberOfCharacters,
+                           index + layout.numberOfGlyphs,
+                           layoutSize,
+                           linesBuffer,
+                           numberOfLines);
+        } // whether to add a last line.
+
+        const GlyphInfo* const glyphsBuffer = layoutParameters.textModel->mVisualModel->mGlyphs.Begin();
+        const float            outlineWidth = static_cast<float>(layoutParameters.textModel->GetOutlineWidth());
+
+        const BidirectionalLineInfoRun* const bidirectionalLineInfo = (layoutBidiParameters.isBidirectional && !bidirectionalLinesInfo.Empty()) ? &bidirectionalLinesInfo[layoutBidiParameters.bidiLineIndex] : nullptr;
+
+        if((nullptr != bidirectionalLineInfo) &&
+           !bidirectionalLineInfo->isIdentity &&
+           (layout.characterIndex == bidirectionalLineInfo->characterRun.characterIndex))
+        {
+          SetGlyphPositions(layoutParameters,
+                            glyphPositionsBuffer,
+                            layoutBidiParameters,
+                            layout);
+        }
+        else
+        {
+          // Sets the positions of the glyphs.
+          SetGlyphPositions(glyphsBuffer + index,
+                            layout.numberOfGlyphs,
+                            outlineWidth,
+                            layoutParameters.interGlyphExtraAdvance,
+                            glyphPositionsBuffer + index - layoutParameters.startGlyphIndex);
         }
 
-        line.alignmentOffset = floorf( line.alignmentOffset ); // try to avoid pixel alignment.
+        // Updates the vertical pen's position.
+        penY += -layout.descender + layout.lineSpacing + mDefaultLineSpacing;
+        // If there is a defaultLineSize, updates the pen's position.
+        if(mDefaultLineSize > 0.f)
+        {
+          float lineSpacing = mDefaultLineSize - (layout.ascender + -layout.descender);
+          lineSpacing       = lineSpacing < 0.f ? 0.f : lineSpacing;
+          penY += lineSpacing;
+        }
+
+        // Increase the glyph index.
+        index = nextIndex;
+      } // no ellipsis
+    }   // end for() traversing glyphs.
+
+    if(updateCurrentBuffer)
+    {
+      glyphPositions.Insert(glyphPositions.Begin() + layoutParameters.startGlyphIndex,
+                            newGlyphPositions.Begin(),
+                            newGlyphPositions.End());
+      glyphPositions.Resize(totalNumberOfGlyphs);
+
+      newLines.Resize(numberOfLines);
+
+      // Current text's layout size adds only the newly laid-out lines.
+      // Updates the layout size with the previously laid-out lines.
+      UpdateLayoutSize(lines,
+                       layoutSize);
+
+      if(0u != newLines.Count())
+      {
+        const LineRun& lastLine = *(newLines.End() - 1u);
+
+        const Length characterOffset = lastLine.characterRun.characterIndex + lastLine.characterRun.numberOfCharacters;
+        const Length glyphOffset     = lastLine.glyphRun.glyphIndex + lastLine.glyphRun.numberOfGlyphs;
+
+        // Update the indices of the runs before the new laid-out lines are inserted.
+        UpdateLineIndexOffsets(layoutParameters,
+                               lines,
+                               characterOffset,
+                               glyphOffset);
+
+        // Insert the lines.
+        lines.Insert(lines.Begin() + layoutParameters.startLineIndex,
+                     newLines.Begin(),
+                     newLines.End());
+      }
+    }
+    else
+    {
+      lines.Resize(numberOfLines);
+    }
+
+    // Rounds upward to avoid a non integer size.
+    layoutSize.height = std::ceil(layoutSize.height);
+
+    DALI_LOG_INFO(gLogFilter, Debug::Verbose, "<--LayoutText\n\n");
+
+    return true;
+  }
+
+  void Align(const Size&                     size,
+             CharacterIndex                  startIndex,
+             Length                          numberOfCharacters,
+             Text::HorizontalAlignment::Type horizontalAlignment,
+             Vector<LineRun>&                lines,
+             float&                          alignmentOffset,
+             Dali::LayoutDirection::Type     layoutDirection,
+             bool                            matchSystemLanguageDirection)
+  {
+    const CharacterIndex lastCharacterPlusOne = startIndex + numberOfCharacters;
+
+    alignmentOffset = MAX_FLOAT;
+    // Traverse all lines and align the glyphs.
+    for(Vector<LineRun>::Iterator it = lines.Begin(), endIt = lines.End();
+        it != endIt;
+        ++it)
+    {
+      LineRun& line = *it;
+
+      if(line.characterRun.characterIndex < startIndex)
+      {
+        // Do not align lines which have already been aligned.
+        continue;
+      }
+
+      if(line.characterRun.characterIndex > lastCharacterPlusOne)
+      {
+        // Do not align lines beyond the last laid-out character.
+        break;
+      }
+
+      if(line.characterRun.characterIndex == lastCharacterPlusOne && !isEmptyLineAtLast(lines, it))
+      {
+        // Do not align lines beyond the last laid-out character unless the line is last and empty.
         break;
       }
-      case HORIZONTAL_ALIGN_END:
+
+      // Calculate the line's alignment offset accordingly with the align option,
+      // the box width, line length, and the paragraph's direction.
+      CalculateHorizontalAlignment(size.width,
+                                   horizontalAlignment,
+                                   line,
+                                   layoutDirection,
+                                   matchSystemLanguageDirection);
+
+      // Updates the alignment offset.
+      alignmentOffset = std::min(alignmentOffset, line.alignmentOffset);
+    }
+  }
+
+  void CalculateHorizontalAlignment(float                       boxWidth,
+                                    HorizontalAlignment::Type   horizontalAlignment,
+                                    LineRun&                    line,
+                                    Dali::LayoutDirection::Type layoutDirection,
+                                    bool                        matchSystemLanguageDirection)
+  {
+    line.alignmentOffset = 0.f;
+    const bool isLineRTL = RTL == line.direction;
+
+    // Whether to swap the alignment.
+    // Swap if the line is RTL and is not required to match the direction of the system's language or if it's required to match the direction of the system's language and it's RTL.
+    bool  isLayoutRTL = isLineRTL;
+    float lineLength  = line.width;
+
+    // match align for system language direction
+    if(matchSystemLanguageDirection)
+    {
+      // Swap the alignment type if the line is right to left.
+      isLayoutRTL = layoutDirection == LayoutDirection::RIGHT_TO_LEFT;
+    }
+    // Calculate the horizontal line offset.
+    switch(horizontalAlignment)
+    {
+      case HorizontalAlignment::BEGIN:
       {
-        if( isLastLine && !isRTL )
+        if(isLayoutRTL)
         {
-          lineLength += line.extraLength;
-          if( lineLength > boxWidth )
+          if(isLineRTL)
           {
-            line.alignmentOffset = 0.f;
-            break;
+            lineLength += line.extraLength;
           }
+
+          line.alignmentOffset = boxWidth - lineLength;
         }
+        else
+        {
+          line.alignmentOffset = 0.f;
 
-        if( isRTL )
+          if(isLineRTL)
+          {
+            // 'Remove' the white spaces at the end of the line (which are at the beginning in visual order)
+            line.alignmentOffset -= line.extraLength;
+          }
+        }
+        break;
+      }
+      case HorizontalAlignment::CENTER:
+      {
+        line.alignmentOffset = 0.5f * (boxWidth - lineLength);
+
+        if(isLineRTL)
         {
-          lineLength += line.extraLength;
+          line.alignmentOffset -= line.extraLength;
         }
 
-        line.alignmentOffset = boxWidth - lineLength;
+        line.alignmentOffset = std::floor(line.alignmentOffset); // floor() avoids pixel alignment issues.
+        break;
+      }
+      case HorizontalAlignment::END:
+      {
+        if(isLayoutRTL)
+        {
+          line.alignmentOffset = 0.f;
+
+          if(isLineRTL)
+          {
+            // 'Remove' the white spaces at the end of the line (which are at the beginning in visual order)
+            line.alignmentOffset -= line.extraLength;
+          }
+        }
+        else
+        {
+          if(isLineRTL)
+          {
+            lineLength += line.extraLength;
+          }
+
+          line.alignmentOffset = boxWidth - lineLength;
+        }
         break;
       }
     }
   }
 
-  LayoutEngine::Layout mLayout;
-  LayoutEngine::HorizontalAlignment mHorizontalAlignment;
-  LayoutEngine::VerticalAlignment mVerticalAlignment;
+  void Initialize(LineRun& line)
+  {
+    line.glyphRun.glyphIndex             = 0u;
+    line.glyphRun.numberOfGlyphs         = 0u;
+    line.characterRun.characterIndex     = 0u;
+    line.characterRun.numberOfCharacters = 0u;
+    line.width                           = 0.f;
+    line.ascender                        = 0.f;
+    line.descender                       = 0.f;
+    line.extraLength                     = 0.f;
+    line.alignmentOffset                 = 0.f;
+    line.direction                       = LTR;
+    line.ellipsis                        = false;
+    line.lineSpacing                     = mDefaultLineSpacing;
+  }
 
-  TextAbstraction::FontClient mFontClient;
+  Type  mLayout;
+  float mCursorWidth;
+  float mDefaultLineSpacing;
+  float mDefaultLineSize;
 
-  bool mEllipsisEnabled:1;
+  IntrusivePtr<Metrics> mMetrics;
 };
 
-LayoutEngine::LayoutEngine()
-: mImpl( NULL )
+Engine::Engine()
+: mImpl{nullptr}
 {
-  mImpl = new LayoutEngine::Impl();
+  mImpl = new Engine::Impl();
 }
 
-LayoutEngine::~LayoutEngine()
+Engine::~Engine()
 {
   delete mImpl;
 }
 
-void LayoutEngine::SetLayout( Layout layout )
+void Engine::SetMetrics(MetricsPtr& metrics)
 {
-  mImpl->mLayout = layout;
+  mImpl->mMetrics = metrics;
 }
 
-unsigned int LayoutEngine::GetLayout() const
+void Engine::SetLayout(Type layout)
 {
-  return mImpl->mLayout;
+  mImpl->mLayout = layout;
 }
 
-void LayoutEngine::SetTextEllipsisEnabled( bool enabled )
+Engine::Type Engine::GetLayout() const
 {
-  mImpl->mEllipsisEnabled = enabled;
+  DALI_LOG_INFO(gLogFilter, Debug::Verbose, "GetLayout[%d]\n", mImpl->mLayout);
+  return mImpl->mLayout;
 }
 
-bool LayoutEngine::GetTextEllipsisEnabled() const
+void Engine::SetCursorWidth(int width)
 {
-  return mImpl->mEllipsisEnabled;
+  mImpl->mCursorWidth = static_cast<float>(width);
 }
 
-void LayoutEngine::SetHorizontalAlignment( HorizontalAlignment alignment )
+int Engine::GetCursorWidth() const
 {
-  mImpl->mHorizontalAlignment = alignment;
+  return static_cast<int>(mImpl->mCursorWidth);
 }
 
-LayoutEngine::HorizontalAlignment LayoutEngine::GetHorizontalAlignment() const
+bool Engine::LayoutText(Parameters& layoutParameters,
+                        Size&       layoutSize,
+                        bool        elideTextEnabled,
+                        bool&       isAutoScrollEnabled)
 {
-  return mImpl->mHorizontalAlignment;
+  return mImpl->LayoutText(layoutParameters,
+                           layoutSize,
+                           elideTextEnabled,
+                           isAutoScrollEnabled);
 }
 
-void LayoutEngine::SetVerticalAlignment( VerticalAlignment alignment )
+void Engine::Align(const Size&                     size,
+                   CharacterIndex                  startIndex,
+                   Length                          numberOfCharacters,
+                   Text::HorizontalAlignment::Type horizontalAlignment,
+                   Vector<LineRun>&                lines,
+                   float&                          alignmentOffset,
+                   Dali::LayoutDirection::Type     layoutDirection,
+                   bool                            matchSystemLanguageDirection)
 {
-  mImpl->mVerticalAlignment = alignment;
+  mImpl->Align(size,
+               startIndex,
+               numberOfCharacters,
+               horizontalAlignment,
+               lines,
+               alignmentOffset,
+               layoutDirection,
+               matchSystemLanguageDirection);
 }
 
-LayoutEngine::VerticalAlignment LayoutEngine::GetVerticalAlignment() const
+void Engine::SetDefaultLineSpacing(float lineSpacing)
 {
-  return mImpl->mVerticalAlignment;
+  mImpl->mDefaultLineSpacing = lineSpacing;
 }
 
-bool LayoutEngine::LayoutText( const LayoutParameters& layoutParameters,
-                               Vector<Vector2>& glyphPositions,
-                               Vector<LineRun>& lines,
-                               Size& actualSize )
+float Engine::GetDefaultLineSpacing() const
 {
-  return mImpl->LayoutText( layoutParameters,
-                            glyphPositions,
-                            lines,
-                            actualSize );
+  return mImpl->mDefaultLineSpacing;
 }
 
-void LayoutEngine::ReLayoutRightToLeftLines( const LayoutParameters& layoutParameters,
-                                             Vector<Vector2>& glyphPositions )
+void Engine::SetDefaultLineSize(float lineSize)
 {
-  mImpl->ReLayoutRightToLeftLines( layoutParameters,
-                                   glyphPositions );
+  mImpl->mDefaultLineSize = lineSize;
 }
 
-void LayoutEngine::Align( const Size& layoutSize,
-                          Vector<LineRun>& lines )
+float Engine::GetDefaultLineSize() const
 {
-  mImpl->Align( layoutSize,
-                lines );
+  return mImpl->mDefaultLineSize;
 }
 
+} // namespace Layout
+
 } // namespace Text
 
 } // namespace Toolkit