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

   1 /* Copyright (c) 2021 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
  17 namespace Tizen.NUI
  18 {
  19     /// <summary>
  20     /// [Draft] This class implements a absolute layout, allowing explicit positioning of children.
  21     ///  Positions are from the top left of the layout and can be set using the View.Position and alike.
  22     /// </summary>
  23     public class AbsoluteLayout : LayoutGroup
  24     {
  25         /// <summary>
  26         /// [Draft] Constructor
  27         /// </summary>
  28         /// <since_tizen> 6 </since_tizen>
  29         public AbsoluteLayout()
  30         {
  31         }
  32
  33         /// <summary>
  34         /// Measure the layout and its content to determine the measured width and the measured height.<br />
  35         /// </summary>
  36         /// <param name="widthMeasureSpec">horizontal space requirements as imposed by the parent.</param>
  37         /// <param name="heightMeasureSpec">vertical space requirements as imposed by the parent.</param>
  38         /// <since_tizen> 6 </since_tizen>
  39         protected override void OnMeasure(MeasureSpecification widthMeasureSpec, MeasureSpecification heightMeasureSpec)
  40         {
  41             // Ensure layout respects it's given minimum size
  42             float maxWidth = SuggestedMinimumWidth.AsDecimal();
  43             float maxHeight = SuggestedMinimumHeight.AsDecimal();
  44
  45             MeasuredSize.StateType childWidthState = MeasuredSize.StateType.MeasuredSizeOK;
  46             MeasuredSize.StateType childHeightState = MeasuredSize.StateType.MeasuredSizeOK;
  47
  48             foreach (LayoutItem childLayout in IterateLayoutChildren())
  49             {
  50                 // Get size of child with no padding, no margin. we won't support margin, padding for AbsolutLayout.
  51                 MeasureChildWithoutPadding(childLayout, widthMeasureSpec, heightMeasureSpec);
  52
  53                 // Determine the width and height needed by the children using their given position and size.
  54                 // Children could overlap so find the right most child.
  55                 float childRight = childLayout.MeasuredWidth.Size.AsDecimal() + childLayout.Owner.PositionX;
  56                 float childBottom = childLayout.MeasuredHeight.Size.AsDecimal() + childLayout.Owner.PositionY;
  57
  58                 if (maxWidth < childRight)
  59                     maxWidth = childRight;
  60
  61                 if (maxHeight < childBottom)
  62                     maxHeight = childBottom;
  63
  64                 if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  65                 {
  66                     childWidthState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  67                 }
  68                 if (childLayout.MeasuredHeight.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  69                 {
  70                     childHeightState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  71                 }
  72             }
  73
  74             SetMeasuredDimensions(ResolveSizeAndState(new LayoutLength(maxWidth), widthMeasureSpec, childWidthState),
  75                                   ResolveSizeAndState(new LayoutLength(maxHeight), heightMeasureSpec, childHeightState));
  76         }
  77
  78         /// <summary>
  79         /// Assign a size and position to each of its children.<br />
  80         /// </summary>
  81         /// <param name="changed">This is a new size or position for this layout.</param>
  82         /// <param name="left">Left position, relative to parent.</param>
  83         /// <param name="top"> Top position, relative to parent.</param>
  84         /// <param name="right">Right position, relative to parent.</param>
  85         /// <param name="bottom">Bottom position, relative to parent.</param>
  86         /// <since_tizen> 6 </since_tizen>
  87         protected override void OnLayout(bool changed, LayoutLength left, LayoutLength top, LayoutLength right, LayoutLength bottom)
  88         {
  89             // Absolute layout positions it's children at their Actor positions.
  90             // Children could overlap or spill outside the parent, as is the nature of absolute positions.
  91             foreach (LayoutItem childLayout in IterateLayoutChildren())
  92             {
  93                 LayoutLength childWidth = childLayout.MeasuredWidth.Size;
  94                 LayoutLength childHeight = childLayout.MeasuredHeight.Size;
  95
  96                 LayoutLength childLeft = new LayoutLength(childLayout.Owner.PositionX);
  97                 LayoutLength childTop = new LayoutLength(childLayout.Owner.PositionY);
  98
  99                 childLayout.Layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight, true);
 100             }
 101         }
 102     }
 103 } // namespace