XAML:当子对象的ScaleTransform变大时，使ScrollViewer显示滚动条 [英] XAML: make a ScrollViewer show scrollbars when the ScaleTransform of a child object gets big

问题描述

我正在Silverlight 3应用程序中对某些文档进行打印预览"控件.我在ScrollViewer内有一个Canvas(用于显示文档)，并且具有放大/缩小"按钮，用于控制Canvas.RenderTransform属性的ScaleTransform的X和Y Scale属性.我希望当我放大"足够以使画布不再在ScrollViewer区域中可见时显示ScrollViewer的滚动条，但是似乎它们仅根据Canvas本身的宽度/高度显示.是否放大.

I am making a sort of "print preview" control for some documents in my Silverlight 3 application. I have a Canvas (for showing the document) inside of a ScrollViewer, and I have zoom in / zoom out buttons that control the X and Y Scale properties of the ScaleTransform for the Canvas.RenderTransform property. I want the scrollbars of the ScrollViewer to show up when I "zoom in" enough such that the canvas is no longer visible in the ScrollViewer area, but it seems that they only show up depending on the Width/Height of the Canvas itself, regardless of whether it is zoomed in or not.

任何人都可以帮忙吗?

推荐答案

是的，问题在于Silverlight中没有LayoutTransform. 此处列出了一些解决此问题的方法.

Yeah, the problem is that there is no LayoutTransform in Silverlight. There are some workarounds to this problem listed here.

这里的想法是提供一个调整大小的中间画布，从而调整可滚动区域的大小.例如，如果我具有以下XAML:

The idea here is to provide an intermediate canvas that gets resized and as a result, resizes the scrollable area. For example, if I have the following XAML:

<Grid x:Name="LayoutRoot">
    <Grid.RowDefinitions>
        <RowDefinition Height="200" />
        <RowDefinition Height="25" />
    </Grid.RowDefinitions>
        <ScrollViewer Grid.Row="0" x:Name="sc" VerticalScrollBarVisibility="Auto" 
                      HorizontalScrollBarVisibility="Auto" Width="200" Height="200" >
        <Canvas x:Name="sizer" Width="200" Height="200">
            <Rectangle x:Name="gradientRect" Width="200" Height="200">
            <Rectangle.RenderTransform>
                <ScaleTransform ScaleX="1" ScaleY="1"/>
            </Rectangle.RenderTransform>
                <Rectangle.Fill>
                    <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
                        <GradientStop Color="Red" Offset="0.1"/>
                        <GradientStop Color="Yellow" Offset="0.5"/>
                        <GradientStop Color="Red" Offset="0.9"/>
                    </LinearGradientBrush>
                </Rectangle.Fill>
            </Rectangle>
        </Canvas>
    </ScrollViewer>
    <Button Grid.Row="1" Content="Multiply by Two" Click="ScaleRect" Width="100" Height="25"></Button>
</Grid>

您会注意到，我将<Canvas x:Name="sizer"/>放在了<ScrollViewer/>和<Rectangle/>之间，并且将ScaleRect的单击事件放在了<Button/>中.

You'll notice that I put the <Canvas x:Name="sizer"/> between the <ScrollViewer/> and <Rectangle/> and the click event of ScaleRect in the <Button/>.

ScaleRect子项仅将矩形缩放2.然后使用该值更改sizer，Width和Height，从而更新ScrollViewer的滚动条.这是ScaleRect的子项:

The ScaleRect sub simply scales the rectangle by 2. That value is then used to change the sizer Width and Height, thus updating the ScrollViewer's scrollbars. Here's the sub for ScaleRect:

Private Sub ScaleRect(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim zoom As Double = 2.0
    Dim scaleX = gradientRect.RenderTransform.GetValue(ScaleTransform.ScaleXProperty)
    Dim scaleY = gradientRect.RenderTransform.GetValue(ScaleTransform.ScaleYProperty)
    gradientRect.RenderTransform.SetValue(ScaleTransform.ScaleXProperty, scaleX * zoom)
    gradientRect.RenderTransform.SetValue(ScaleTransform.ScaleYProperty, scaleY * zoom)
    sizer.Height *= zoom
    sizer.Width *= zoom
End Sub

这篇关于XAML:当子对象的ScaleTransform变大时，使ScrollViewer显示滚动条的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！