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<Window x:Class="TestProject.MainWindow"
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 xmlns:local="clr-namespace:TestProject"
 mc:Ignorable="d"
 Title="MainWindow" Height="450" Width="800">

 <!--The following code snippets go here-->

</Window>

Example 1

<Grid>
 <Grid x:Name="myGrid" Width="200" Height="100" Background="Green">
 <Grid.LayoutTransform>
 <ScaleTransform ScaleX="3" ScaleY="1" CenterX=".5" CenterY=".5"></ScaleTransform>
 </Grid.LayoutTransform>
 </Grid>
</Grid>

Actual:

myGrid.RenderSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200

myGrid.DesiredSize
600,100
    Height: 100
    IsEmpty: false
    Width: 600

Expected:

myGrid.RenderSize
200,100
    Height: 100
    IsEmpty: false
    Width: 600

myGrid.DesiredSize
600,100
    Height: 100
    IsEmpty: false
    Width: 600

Example 2

<Grid>
 <Grid x:Name="myGrid" Width="200" Height="100" Background="Green">
 <Grid.RenderTransform>
 <ScaleTransform ScaleX="3" ScaleY="1" CenterX=".5" CenterY=".5"></ScaleTransform>
 </Grid.RenderTransform>
 </Grid>
</Grid>

Actual:

myGrid.RenderSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200

myGrid.DesiredSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200

Expected:

myGrid.RenderSize
200,100
    Height: 100
    IsEmpty: false
    Width: 600

myGrid.DesiredSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200

Example 3

<Viewbox Stretch="UniformToFill">
 <Grid x:Name="myGrid" Width="200" Height="100" Background="Green"></Grid>
</Viewbox>

Actual:

myGrid.RenderSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200
myGrid.DesiredSize
200,100
    Height: 100
    IsEmpty: false
    Width: 200

Expected:

Not sure, if Viewbox uses RenderTransform then I would expect myGrid.RenderSize.Width to be 600 and myGrid.DesiredSize.Width to be 200, otherwise if Viewbox uses LayoutTransform then I would expect myGrid.RenderSize.Width and myGrid.DesiredSize.Width to be 600.

I am basing my expected results based on the following layout process stages:

1. LayoutTransform


2. Measure - DesiredSize of each element is computer here


3. Arrange - Position of child elements within their parents is determined


4. RenderTransform


5. Render - RenderSize is computer here, elements are rendered to the screen

Questions:

• Does Viewbox apply RenderTransform or LayoutTransform?


• How does RenderTransform change the element such that RenderSize dimensions do not change?


• For example 1, why is Rendered Width is 200, even though LayoutTransform is applied to myGrid and the Desired with is 600?

Thank you in advance.