应用ScaleTransform后，如何确定控件大小？

Question

在应用转换后，如何确定控件的实际宽度和实际高度？

例如，我认为遵循XAML代码应该显示类似400x400的大小（例如，在图片。红色矩形，宽度为400），但宽度和高度等于200。

我做错了什么？

<Window
    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"
    x:Class="VisualCad.Components.TempVisualTests.MainWindow"
    mc:Ignorable="d"
    x:Name="MyWin"
    Title="MainWindow" WindowState="Maximized" Height="500" Width="500">

    <Grid>
        <Rectangle Width="400" Height="5" Fill="Red" Margin="0,20,0,0" VerticalAlignment="Top"/>

        <Canvas x:Name="MyCanvas" Width="200" Height="200">
            <Canvas.RenderTransform>
                <ScaleTransform CenterX="100" CenterY="100" ScaleX="2" ScaleY="2" />
            </Canvas.RenderTransform>

            <StackPanel>
                <TextBlock Text="{Binding Path=RenderSize, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Canvas}}, StringFormat='Render size: {0}'}" />
                <TextBlock Text="{Binding Path=ActualWidth, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Canvas}}, StringFormat='ActualWidth: {0}'}" />
                <TextBlock Text="{Binding Path=ActualHeight, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Canvas}}, StringFormat='ActualHeight: {0}'}" />
            </StackPanel>
        </Canvas>
    </Grid>
</Window>

Answer 1

此代码适用于我：

var parent = element.Parent as UIElement;

Point bottomLeft = element.TranslatePoint(new Point(0, 0), parent);
Point topRight = element.TranslatePoint(new Point(element.ActualWidth, element.ActualHeight), parent);

var renderWidth = topRight.X - bottomLeft.X;
var renderHeight = topRight.Y - bottomLeft.Y;

Answer 2

  

在应用转换后，如何确定控件的实际宽度和实际高度？

您需要自己计算宽度和高度。它应该是非常简单的：

double width = MyCanvas.ActualWidth;
double height = MyCanvas.ActualHeight;

ScaleTransform st = MyCanvas.RenderTransform as ScaleTransform;
if(st != null)
{
    width *= st.ScaleX;
    height *= st.ScaleY;
}

没有属性会为您返回此大小。转换不会影响ActualWidth和ActualHeight属性。