src/Tizen.NUI/src/internal/Layouting/AbsoluteLayout.cs

   1 /* Copyright (c) 2019 Samsung Electronics Co., Ltd.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at
   6  *
   7  * http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  *
  15  */
  16 using System;
  17 using Tizen.NUI.BaseComponents;
  18
  19 namespace Tizen.NUI
  20 {
  21     /// <summary>
  22     /// [Draft] This class implements a absolute layout, allowing explicit positioning of children.
  23     ///  Positions are from the top left of the layout and can be set using the Actor::Property::POSITION and alike.
  24     /// </summary>
  25     internal class AbsoluteLayout : LayoutGroup
  26     {
  27         /// <summary>
  28         /// Struct to store Measured states of height and width.
  29         /// </summary>
  30         private struct HeightAndWidthState
  31         {
  32             public MeasuredSize.StateType widthState;
  33             public MeasuredSize.StateType heightState;
  34
  35             public HeightAndWidthState( MeasuredSize.StateType width, MeasuredSize.StateType height)
  36             {
  37                 widthState = width;
  38                 heightState = height;
  39             }
  40         }
  41
  42         /// <summary>
  43         /// [Draft] Constructor
  44         /// </summary>
  45         public AbsoluteLayout()
  46         {
  47         }
  48
  49         protected override void OnMeasure(MeasureSpecification widthMeasureSpec, MeasureSpecification heightMeasureSpec)
  50         {
  51             float totalHeight = 0.0f;
  52             float totalWidth = 0.0f;
  53
  54             HeightAndWidthState childState = new HeightAndWidthState(MeasuredSize.StateType.MeasuredSizeOK,
  55                                                                      MeasuredSize.StateType.MeasuredSizeOK);
  56
  57             float minPositionX = 0.0f;
  58             float minPositionY = 0.0f;
  59             float maxPositionX = 0.0f;
  60             float maxPositionY = 0.0f;
  61
  62             // measure children
  63             foreach( LayoutItem childLayout in _children )
  64             {
  65                 if (childLayout != null)
  66                 {
  67                     // Get size of child
  68                     MeasureChild( childLayout, widthMeasureSpec, heightMeasureSpec );
  69                     float childWidth = childLayout.MeasuredWidth.Size.AsDecimal();
  70                     float childHeight = childLayout.MeasuredHeight.Size.AsDecimal();
  71
  72                     // Determine the width and height needed by the children using their given position and size.
  73                     // Children could overlap so find the left most and right most child.
  74                     Position2D childPosition = childLayout.Owner.Position2D;
  75                     float childLeft = childPosition.X;
  76                     float childTop = childPosition.Y;
  77
  78                     minPositionX = Math.Min( minPositionX, childLeft );
  79                     maxPositionX = Math.Max( maxPositionX, childLeft + childWidth );
  80                     // Children could overlap so find the highest and lowest child.
  81                     minPositionY = Math.Min( minPositionY, childTop );
  82                     maxPositionY = Math.Max( maxPositionY, childTop + childHeight );
  83
  84                     // Store current width and height needed to contain all children.
  85                     totalWidth = maxPositionX - minPositionX;
  86                     totalHeight = maxPositionY - minPositionY;
  87
  88                     if (childLayout.MeasuredWidthAndState.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  89                     {
  90                         childState.widthState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  91                     }
  92                     if (childLayout.MeasuredWidthAndState.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  93                     {
  94                         childState.heightState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  95                     }
  96                 }
  97             }
  98
  99
 100             MeasuredSize widthSizeAndState = ResolveSizeAndState(new LayoutLength(totalWidth), widthMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
 101             MeasuredSize heightSizeAndState = ResolveSizeAndState(new LayoutLength(totalHeight), heightMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
 102             totalWidth = widthSizeAndState.Size.AsDecimal();
 103             totalHeight = heightSizeAndState.Size.AsDecimal();
 104
 105             // Ensure layout respects it's given minimum size
 106             totalWidth = Math.Max( totalWidth, SuggestedMinimumWidth.AsDecimal() );
 107             totalHeight = Math.Max( totalHeight, SuggestedMinimumHeight.AsDecimal() );
 108
 109             widthSizeAndState.State = childState.widthState;
 110             heightSizeAndState.State = childState.heightState;
 111
 112             SetMeasuredDimensions( ResolveSizeAndState( new LayoutLength(totalWidth), widthMeasureSpec, childState.widthState ),
 113                                    ResolveSizeAndState( new LayoutLength(totalHeight), heightMeasureSpec, childState.heightState ) );
 114         }
 115
 116         protected override void OnLayout(bool changed, LayoutLength left, LayoutLength top, LayoutLength right, LayoutLength bottom)
 117         {
 118             // Absolute layout positions it's children at their Actor positions.
 119             // Children could overlap or spill outside the parent, as is the nature of absolute positions.
 120             foreach( LayoutItem childLayout in _children )
 121             {
 122                 if( childLayout != null )
 123                 {
 124                     LayoutLength childWidth = childLayout.MeasuredWidth.Size;
 125                     LayoutLength childHeight = childLayout.MeasuredHeight.Size;
 126
 127                     Position2D childPosition = childLayout.Owner.Position2D;
 128
 129                     LayoutLength childLeft = new LayoutLength(childPosition.X);
 130                     LayoutLength childTop = new LayoutLength(childPosition.Y);
 131
 132                     childLayout.Layout( childLeft, childTop, childLeft + childWidth, childTop + childHeight );
 133                 }
 134             }
 135         }
 136     }
 137
 138 } // namespace