WPFCanvas画区域

王朝学院·作者佚名  2016-08-27
窄屏简体版  字體: |||超大  

有时候需要实现类似于QQ截图那样的选择区域功能,这里的区域可以是一条线,圆,矩形等等

实现原理就是一个Canvas做蒙板,然后canvas的三个事件,MouseLeftButtonDown,MouseMove,MouseLeftButtonUp。非常easy!

首先,你要有个canvas

<Canvas Name="videocanvas"Height="288"Width="352"Background="Transparent"MouseMove="image_MouseMove"MouseLeftButtonDown="Mask_MouseLeftButtonDown"MouseLeftButtonUp="Mask_MouseLeftButtonUp"/>

然后实现他的事件,在之前我们先决定一下到底是什么形状的区域。

1publicstaticShape CreateShape()2{3//矩形区域4returnnewSystem.Windows.Shapes.Rectangle() { Fill =null, Stroke = System.Windows.Media.Brushes.Red, StrokeThickness =1};5//圆形区域6//return new System.Windows.Shapes.Ellipse() { Fill = null, Stroke = System.Windows.Media.Brushes.Red, StrokeThickness = 1 };78}

然后实现三个事件

booldrawFlag =false;

Shape insertShape;

System.Windows.Point startPosition;PRivatevoidMask_MouseLeftButtonDown(objectsender, MouseButtonEventArgs e)

{

insertShape=CreateShape();if(insertShape !=null)

{

drawFlag=true;

Canvas board= senderasCanvas;

board.Children.Clear();

startPosition=e.GetPosition(board);

insertShape.Opacity=1;

Canvas.SetLeft(insertShape, e.GetPosition(board).X);

Canvas.SetTop(insertShape, e.GetPosition(board).Y);

board.Children.Add(insertShape);

}

}privatevoidimage_MouseMove(objectsender, MouseEventArgs e)

{

Canvas board= senderasCanvas;if(drawFlag && insertShape !=null)

{if(e.GetPosition(board).X >startPosition.X)

{

insertShape.Width= e.GetPosition(board).X -startPosition.X;

}else{

insertShape.Width= startPosition.X -e.GetPosition(board).X;

Canvas.SetLeft(insertShape, e.GetPosition(board).X);

}if(e.GetPosition(board).Y >startPosition.Y)

{

insertShape.Height= e.GetPosition(board).Y -startPosition.Y;

}else{

insertShape.Height= startPosition.Y -e.GetPosition(board).Y;

Canvas.SetTop(insertShape, e.GetPosition(board).Y);

}

}

}privatevoidMask_MouseLeftButtonUp(objectsender, MouseButtonEventArgs e)

{

drawFlag=false;if(insertShape !=null)

{

insertShape.Opacity=1;

System.Windows.Point p= e.GetPosition(senderasCanvas);

Canvas.SetLeft(insertShape, e.GetPosition(board).X);

Canvas.SetTop(insertShape, e.GetPosition(board).Y);

}

}

本来还想做个多边形的例子,水平有限,没达到我想要的效果。研究研究再发。

 
 
 
免责声明:本文为网络用户发布,其观点仅代表作者个人观点,与本站无关,本站仅提供信息存储服务。文中陈述内容未经本站证实,其真实性、完整性、及时性本站不作任何保证或承诺,请读者仅作参考,并请自行核实相关内容。
 
 
© 2005- 王朝網路 版權所有 導航