WPF OnRender Z-Order控件

Question

我有一个自定义面板，它实现了一个很好的子面板的自定义布局。我想要添加一些额外的图形到面板上，因此覆盖OnRender来添加额外的矩形等。它工作得很好，除了OnRender似乎只是添加到背景。有没有办法让你的OnRender图画放在孩子们的上面？

示例面板...

public class RenderPanel : WrapPanel
{
    protected override void OnRender(DrawingContext drawingContext)
    {
        base.OnRender(drawingContext);
        drawingContext.DrawRectangle(Brushes.Red, 
                                     new Pen(Brushes.Black, 2), 
                                     new Rect(0, 0, 100, 100));
    }
}

...used以这种方式...

<Grid>
    <my:RenderPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
    </my:RenderPanel>
</Grid>

Answer 1

我将使您的"RenderPanel“继承自canvas，然后将其放在WrapPanel之上，并根据需要指定ZIndex。像这样的东西应该是有效的：

<Grid>
    <WrapPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Canvas.ZIndex="0">
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
        <Button Margin="10" Content="Hello"/>
    </WrapPanel>
    <my:RenderPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Canvas.ZIndex="1" />
</Grid>