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 Tizen.NUI.BaseComponents;
  17
  18 namespace Tizen.NUI
  19 {
  20     /// <summary>
  21     /// [Draft] This class implements a absolute layout, allowing explicit positioning of children.
  22     ///  Positions are from the top left of the layout and can be set using the View.Position and alike.
  23     /// </summary>
  24     public class AbsoluteLayout : LayoutGroup
  25     {
  26         /// <summary>
  27         /// [Draft] Constructor
  28         /// </summary>
  29         /// <since_tizen> 6 </since_tizen>
  30         public AbsoluteLayout()
  31         {
  32         }
  33
  34         /// <summary>
  35         /// Measure the layout and its content to determine the measured width and the measured height.<br />
  36         /// </summary>
  37         /// <param name="widthMeasureSpec">horizontal space requirements as imposed by the parent.</param>
  38         /// <param name="heightMeasureSpec">vertical space requirements as imposed by the parent.</param>
  39         /// <since_tizen> 6 </since_tizen>
  40         protected override void OnMeasure(MeasureSpecification widthMeasureSpec, MeasureSpecification heightMeasureSpec)
  41         {
  42             // Ensure layout respects it's given minimum size
  43             float maxWidth = SuggestedMinimumWidth.AsDecimal();
  44             float maxHeight = SuggestedMinimumHeight.AsDecimal();
  45
  46             MeasuredSize.StateType childWidthState = MeasuredSize.StateType.MeasuredSizeOK;
  47             MeasuredSize.StateType childHeightState = MeasuredSize.StateType.MeasuredSizeOK;
  48
  49             for (int i = 0; i < LayoutChildren.Count; i++)
  50             {
  51                 LayoutItem childLayout = LayoutChildren[i];
  52                 if (childLayout != null)
  53                 {
  54                     // Get size of child with no padding, no margin. we won't support margin, padding for AbsolutLayout.
  55                     MeasureChildWithoutPadding(childLayout, widthMeasureSpec, heightMeasureSpec);
  56
  57                     // Determine the width and height needed by the children using their given position and size.
  58                     // Children could overlap so find the right most child.
  59                     Position2D childPosition = childLayout.Owner.Position2D;
  60                     float childRight = childLayout.MeasuredWidth.Size.AsDecimal() + childPosition.X;
  61                     float childBottom = childLayout.MeasuredHeight.Size.AsDecimal() + childPosition.Y;
  62
  63                     if (maxWidth < childRight)
  64                         maxWidth = childRight;
  65
  66                     if (maxHeight < childBottom)
  67                         maxHeight = childBottom;
  68
  69                     if (childLayout.MeasuredWidth.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  70                     {
  71                         childWidthState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  72                     }
  73                     if (childLayout.MeasuredHeight.State == MeasuredSize.StateType.MeasuredSizeTooSmall)
  74                     {
  75                         childHeightState = MeasuredSize.StateType.MeasuredSizeTooSmall;
  76                     }
  77                 }
  78             }
  79
  80             SetMeasuredDimensions(ResolveSizeAndState(new LayoutLength(maxWidth), widthMeasureSpec, childWidthState),
  81                                   ResolveSizeAndState(new LayoutLength(maxHeight), heightMeasureSpec, childHeightState));
  82         }
  83
  84         /// <summary>
  85         /// Assign a size and position to each of its children.<br />
  86         /// </summary>
  87         /// <param name="changed">This is a new size or position for this layout.</param>
  88         /// <param name="left">Left position, relative to parent.</param>
  89         /// <param name="top"> Top position, relative to parent.</param>
  90         /// <param name="right">Right position, relative to parent.</param>
  91         /// <param name="bottom">Bottom position, relative to parent.</param>
  92         /// <since_tizen> 6 </since_tizen>
  93         protected override void OnLayout(bool changed, LayoutLength left, LayoutLength top, LayoutLength right, LayoutLength bottom)
  94         {
  95             // Absolute layout positions it's children at their Actor positions.
  96             // Children could overlap or spill outside the parent, as is the nature of absolute positions.
  97             for (int i = 0; i < LayoutChildren.Count; i++)
  98             {
  99                 LayoutItem childLayout = LayoutChildren[i];
 100                 if ( childLayout != null )
 101                 {
 102                     LayoutLength childWidth = childLayout.MeasuredWidth.Size;
 103                     LayoutLength childHeight = childLayout.MeasuredHeight.Size;
 104
 105                     Position2D childPosition = childLayout.Owner.Position2D;
 106
 107                     LayoutLength childLeft = new LayoutLength(childPosition.X);
 108                     LayoutLength childTop = new LayoutLength(childPosition.Y);
 109
 110                     childLayout.Layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);
 111                 }
 112             }
 113         }
 114
 115         private void MeasureChildWithoutPadding(LayoutItem child, MeasureSpecification parentWidthMeasureSpec, MeasureSpecification parentHeightMeasureSpec)
 116         {
 117             View childOwner = child.Owner;
 118
 119             MeasureSpecification childWidthMeasureSpec = GetChildMeasureSpecification(
 120                         new MeasureSpecification(new LayoutLength(parentWidthMeasureSpec.Size), parentWidthMeasureSpec.Mode),
 121                         new LayoutLength(0),
 122                         new LayoutLength(childOwner.WidthSpecification));
 123
 124             MeasureSpecification childHeightMeasureSpec = GetChildMeasureSpecification(
 125                         new MeasureSpecification(new LayoutLength(parentHeightMeasureSpec.Size), parentHeightMeasureSpec.Mode),
 126                         new LayoutLength(0),
 127                         new LayoutLength(childOwner.HeightSpecification));
 128
 129             child.Measure(childWidthMeasureSpec, childHeightMeasureSpec);
 130         }
 131     }
 132
 133 } // namespace