C# 在图像上绘制叠加层
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Draw overlay on an image
提问by Yuval Peled
I have an image that the user can zoom/scroll. I want to draw some rectangles/circles on a different layer (for example: drawing a circle for each person's face that was identified in the picture).
我有一个用户可以缩放/滚动的图像。我想在不同的图层上绘制一些矩形/圆圈（例如：为图片中识别的每个人的脸绘制一个圆圈）。
The rectangle position is relative to the image.
矩形位置是相对于图像的。
How do I create such an overlay?
如何创建这样的叠加层？
采纳答案by idursun
I have managed to do something similar:
我已经设法做类似的事情：
- Set image as background
- Put a transparent
ItemsControlon top of it - Set
ItemsControl.ItemsPaneltoCanvas - wrote handlers for dragging operations
- 将图像设置为背景
ItemsControl在上面放一个透明的- 设置
ItemsControl.ItemsPanel为Canvas - 为拖动操作编写了处理程序
Code Snippet:
代码片段：
<ItemsControl x:Name="overlayItemsControl"
Background="Transparent"
ItemsSource="{Binding Path=Blocks}"
Width="{Binding ElementName=imageControl, Path=Width}"
Height="{Binding ElementName=imageControl, Path=Height}"
ItemContainerStyle="{StaticResource rectStyle}"
PreviewMouseMove="ItemsControl_PreviewMouseMove"
PreviewMouseDown="ItemsControl_PreviewMouseDown"
PreviewMouseUp="ItemsControl_PreviewMouseUp"
PreviewKeyDown="ItemsControl_PreviewKeyDown">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas IsItemsHost="True" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
....
</ItemsControl>
回答by Rob
An easy way is to just use a Canvas and set the canvas' background property to your photo, and then place your circles or rectangles on top of that and position them with the Canvas.Left and .Top properties.
一个简单的方法是只使用 Canvas 并将画布的背景属性设置为您的照片，然后将您的圆形或矩形放在它上面，并使用 Canvas.Left 和 .Top 属性定位它们。
<Canvas x:Name="myCanvas">
<Canvas.Background>
<ImageBrush ImageSource="c:\photo.bmp"/>
</Canvas.Background>
<Image Canvas.Top="20" Canvas.Left="20" Height="20" Width="20" Source="c:\circle.bmp"/>
</Canvas>
