如何在 WPF Canvas 上绘制滚动条
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How to draw scrollbars on WPF Canvas
提问by Scooby
I am trying to create a canvas with scroll bars. Can anyone help me give some ideas on how to do this? I have already tried using grid of 1 row and 1 column but due to certain constraints I want to use canvas.
我正在尝试创建一个带有滚动条的画布。谁能帮我就如何做到这一点提出一些想法？我已经尝试过使用 1 行 1 列的网格，但由于某些限制，我想使用画布。
Thanks in advance!
提前致谢！
回答by Ben Collier
You could put the canvas inside of a scrollviewer. I tried this quick test and it allowed me to scroll through the contents of the canvas.
您可以将画布放在滚动查看器中。我尝试了这个快速测试，它允许我滚动画布的内容。
<ScrollViewer Height="100" Width="200">
<Canvas Height="400" Width="400">
//Content here
</Canvas>
</ScrollViewer>
edit: Here is an example where the scroll-bars show up only when needed, and it changes dynamically as the canvas size changes.
编辑：这是一个示例，其中滚动条仅在需要时显示，并且随着画布大小的变化而动态变化。
<Button Content="Change Canvas Size" Click="ChangeCanvasSize_Click"/>
<ScrollViewer Height="100" Width="200" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto">
<Canvas x:Name="TestCanvas">
<TextBlock Text="Test Test"/>
</Canvas>
</ScrollViewer>
Changing canvas size with button click:
单击按钮更改画布大小：
private void ChangeCanvasSize_Click(object sender, RoutedEventArgs e)
{
TestCanvas.Width = 600;
TestCanvas.Height = 600;
}
In this example, I start out with no scroll-bars and when I click the button to expand the canvas, scroll-bars appear.
在本例中，我开始时没有滚动条，当我单击按钮展开画布时，会出现滚动条。
回答by Scooby
Ok after working with it for sometime I figured out a way. Create a XAML like this
好的，在使用它一段时间后，我想出了一种方法。创建这样的 XAML
<ScrollViewer>
<Grid x:Name="drawingGrid" SizeChanged="drawingGrid_SizeChanged">
<Canvas Name="drawingCanvas"> /<Canvas>
</Grid>
</ScrollViewer>
On windowLoad function set the canvas height/width equal to grid height/width. Update the canvas ht/wd:
在 windowLoad 函数上设置画布高度/宽度等于网格高度/宽度。更新画布 ht/wd：
- when grid size changes, due to mininmize/maximize.
dragging an element beyond the boundaries of canvas or creating a new element too close the edge of canvas
double dHeight = 220; if (drawingCanvas.Height < CurrentPosition.Y + dHeight) { // increase canvas height drawingCanvas.Height += (2 * dHeight); }
- 当网格大小发生变化时，由于最小化/最大化。
将元素拖出画布边界或创建新元素太靠近画布边缘
double dHeight = 220; if (drawingCanvas.Height < CurrentPosition.Y + dHeight) { // increase canvas height drawingCanvas.Height += (2 * dHeight); }
Hope this is of some help. Please share if anyone has any better idea or suggestions to improve this.
希望这个对你有帮助。如果有人有更好的想法或建议来改进这一点，请分享。
回答by ArchAngel
By combining Mario-sannum's answer and your question then I've made a solution that should work fine in most cases..
通过将 Mario-sannum 的回答和您的问题结合起来，我制定了一个在大多数情况下应该可以正常工作的解决方案。
<ScrollViewer>
<Grid x:Name="drawingGrid" SizeChanged="drawingGrid_SizeChanged">
<Canvas Name="c">
<TextBlock x:Name="draw_Text" Text="Test Test"/>
</<Canvas>
</Grid>
</ScrollViewer>
void drawingGrid_SizeChanged(object sender, SizeChangedEventArgs e)
{
try { c.Height = draw_Text.ActualHeight; } catch { }
try { c.Width = draw_Text.ActualWidth; } catch { }
}
That should resize the Canvas so the scrollviewer can scroll...
这应该调整画布的大小，以便滚动查看器可以滚动...
