src/Tizen.NUI/src/public/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     public 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         /// <since_tizen> 6 </since_tizen>
  46         public AbsoluteLayout()
  47         {
  48         }
  49
  50         /// <summary>
  51         /// Measure the layout and its content to determine the measured width and the measured height.<br />
  52         /// </summary>
  53         /// <param name="widthMeasureSpec">horizontal space requirements as imposed by the parent.</param>
  54         /// <param name="heightMeasureSpec">vertical space requirements as imposed by the parent.</param>
  55         /// <since_tizen> 6 </since_tizen>
  56         protected override void OnMeasure(MeasureSpecification widthMeasureSpec, MeasureSpecification heightMeasureSpec)
  57         {
  58             float totalHeight = 0.0f;
  59             float totalWidth = 0.0f;
  60
  61             HeightAndWidthState childState = new HeightAndWidthState(MeasuredSize.StateType.MeasuredSizeOK,
  62                                                                      MeasuredSize.StateType.MeasuredSizeOK);
  63
  64             float minPositionX = 0.0f;
  65             float minPositionY = 0.0f;
  66             float maxPositionX = 0.0f;
  67             float maxPositionY = 0.0f;
  68
  69             // measure children
  70             foreach( LayoutItem childLayout in LayoutChildren )
  71             {
  72                 if (childLayout != null)
  73                 {
  74                     // Get size of child
  75                     MeasureChild( childLayout, widthMeasureSpec, heightMeasureSpec );
  76                     float childWidth = childLayout.MeasuredWidth.Size.AsDecimal();
  77                     float childHeight = childLayout.MeasuredHeight.Size.AsDecimal();
  78
  79                     // Determine the width and height needed by the children using their given position and size.
  80                     // Children could overlap so find the left most and right most child.
  81                     Position2D childPosition = childLayout.Owner.Position2D;
  82                     float childLeft = childPosition.X;
  83                     float childTop = childPosition.Y;
  84
  85                     minPositionX = Math.Min( minPositionX, childLeft );
  86                     maxPositionX = Math.Max( maxPositionX, childLeft + childWidth );
  87                     // Children could overlap so find the highest and lowest child.
  88                     minPositionY = Math.Min( minPositionY, childTop );
  89                     maxPositionY = Math.Max( maxPositionY, childTop + childHeight );
  90
  91                     // Store current width and height needed to contain all children.
  92                     totalWidth = maxPositionX - minPositionX;
  93                     totalHeight = maxPositionY - minPositionY;
  94
  95                     if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  96                     {
  97                         childState.widthState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  98                     }
  99                     if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
 100                     {
 101                         childState.heightState = MeasuredSize.StateType.MeasuredSizeTooSmall;
 102                     }
 103                 }
 104             }
 105
 106
 107             MeasuredSize widthSizeAndState = ResolveSizeAndState(new LayoutLength(totalWidth), widthMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
 108             MeasuredSize heightSizeAndState = ResolveSizeAndState(new LayoutLength(totalHeight), heightMeasureSpec, MeasuredSize.StateType.MeasuredSizeOK);
 109             totalWidth = widthSizeAndState.Size.AsDecimal();
 110             totalHeight = heightSizeAndState.Size.AsDecimal();
 111
 112             // Ensure layout respects it's given minimum size
 113             totalWidth = Math.Max( totalWidth, SuggestedMinimumWidth.AsDecimal() );
 114             totalHeight = Math.Max( totalHeight, SuggestedMinimumHeight.AsDecimal() );
 115
 116             widthSizeAndState.State = childState.widthState;
 117             heightSizeAndState.State = childState.heightState;
 118
 119             SetMeasuredDimensions( ResolveSizeAndState( new LayoutLength(totalWidth), widthMeasureSpec, childState.widthState ),
 120                                    ResolveSizeAndState( new LayoutLength(totalHeight), heightMeasureSpec, childState.heightState ) );
 121         }
 122
 123         /// <summary>
 124         /// Assign a size and position to each of its children.<br />
 125         /// </summary>
 126         /// <param name="changed">This is a new size or position for this layout.</param>
 127         /// <param name="left">Left position, relative to parent.</param>
 128         /// <param name="top"> Top position, relative to parent.</param>
 129         /// <param name="right">Right position, relative to parent.</param>
 130         /// <param name="bottom">Bottom position, relative to parent.</param>
 131         /// <since_tizen> 6 </since_tizen>
 132         protected override void OnLayout(bool changed, LayoutLength left, LayoutLength top, LayoutLength right, LayoutLength bottom)
 133         {
 134             // Absolute layout positions it's children at their Actor positions.
 135             // Children could overlap or spill outside the parent, as is the nature of absolute positions.
 136             foreach( LayoutItem childLayout in LayoutChildren )
 137             {
 138                 if( childLayout != null )
 139                 {
 140                     LayoutLength childWidth = childLayout.MeasuredWidth.Size;
 141                     LayoutLength childHeight = childLayout.MeasuredHeight.Size;
 142
 143                     Position2D childPosition = childLayout.Owner.Position2D;
 144
 145                     LayoutLength childLeft = new LayoutLength(childPosition.X);
 146                     LayoutLength childTop = new LayoutLength(childPosition.Y);
 147
 148                     childLayout.Layout( childLeft, childTop, childLeft + childWidth, childTop + childHeight );
 149                 }
 150             }
 151         }
 152     }
 153
 154 } // namespace