[英]WPF Programatically scrolling a canvas in a items control
I have an ItemsControl
that contains a canvas within a ScrollViewer
. 我有一个
ItemsControl
,其中包含ScrollViewer
中的画布。 The canvas is large and only a portion of it displays at a time. 画布很大,一次只能显示一部分。 I want to programatically scroll it (the user clicks and drags the canvas to scroll).
我想以编程方式滚动它(用户单击并拖动画布进行滚动)。 I looked through the ScrollViewer methods and tried the following in the mouse event handlers:
我浏览了ScrollViewer方法,并在鼠标事件处理程序中尝试了以下方法:
var scrollViewer = (sender) as ScrollViewer;
scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + deltaX);
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + deltaY);
However, this does nothing. 但是,这没有任何作用。 I checked the values of deltaX and deltaY and they are valid values (like 3, 5 etc.).
我检查了deltaX和deltaY的值,它们是有效值(例如3、5等)。 The
HorizontalOffset
and VerticalOffset
remain 0 at all times, even after executing the above lines. 即使执行了上述几行后,
HorizontalOffset
和VerticalOffset
始终保持为0。
Here is my XAML: 这是我的XAML:
<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"
MouseUp="ScrollViewer_MouseUp" MouseMove="ScrollViewer_MouseMove"
PreviewMouseLeftButtonDown="ScrollViewer_PreviewMouseLeftButtonDown" Background="Transparent">
<ItemsControl ItemsSource="{Binding BubbleVMCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<!-- My template here -->
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Left" Value="{Binding AbsoluteLeft}" />
<Setter Property="Canvas.Top" Value="{Binding AbsoluteTop}" />
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>
</ScrollViewer>
Any help/suggestions is appreciated! 任何帮助/建议表示赞赏!
It works fine (ScrollViewer scrolls) in my test application: 在我的测试应用程序中,它工作正常(ScrollViewer滚动):
<ScrollViewer Name="scrollViewer"
VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto"
MouseUp="ScrollViewer_MouseUp" MouseMove="ScrollViewer_MouseMove"
PreviewMouseLeftButtonDown="ScrollViewer_PreviewMouseLeftButtonDown" Background="Transparent">
<ItemsControl ItemsSource="{Binding BubbleVMCollection}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas Width="5000" Height="5000"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<!-- My template here -->
</DataTemplate>
</ItemsControl.ItemTemplate>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Left" Value="{Binding AbsoluteLeft}" />
<Setter Property="Canvas.Top" Value="{Binding AbsoluteTop}" />
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>
</ScrollViewer>
and the code behind of: 以及以下代码:
Point capturePoint { get; set; }
private void ScrollViewer_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e) {
scrollViewer.CaptureMouse();
capturePoint = e.MouseDevice.GetPosition(scrollViewer);
}
private void ScrollViewer_MouseUp(object sender, MouseButtonEventArgs e) {
scrollViewer.ReleaseMouseCapture();
}
private void ScrollViewer_MouseMove(object sender, MouseEventArgs e) {
if (!scrollViewer.IsMouseCaptured) return;
Point currentPoint = e.MouseDevice.GetPosition(scrollViewer);
var deltaX = capturePoint.X - currentPoint.X;
var deltaY = capturePoint.Y - currentPoint.Y;
scrollViewer.ScrollToHorizontalOffset(scrollViewer.HorizontalOffset + deltaX);
scrollViewer.ScrollToVerticalOffset(scrollViewer.VerticalOffset + deltaY);
}
Could you post some more details of the problem you are experiencing? 您能否发布您遇到的问题的更多详细信息?
Another potential solution...used for a TreeView, however don't see why the code should not work in your case: 另一个可能的解决方案...用于TreeView,但是看不到为什么代码在您的情况下不起作用:
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