WPF使用TransformToAncestor获取元素的相对坐标

刺骨的言语ヽ痛彻心扉 2023-12-03 06:23 184阅读 0赞

原理：WPF的界面元素是由Visual元素构成的。在可视元素树Visual中，获取某个元素相对于它的父级元素（Ancestor）的坐标，可以使用TransformToAncestor与Transform方法。

**指定中心点，获取相对坐标**

例子一：确定TextBlock相对于窗体的位置

// Return the general transform for the specified visual object.
    GeneralTransform generalTransform1 = myTextBlock.TransformToAncestor(this);
    
    // Retrieve the point value relative to the parent.
    Point currentPoint = generalTransform1.Transform(new Point(0, 0));//窗体位置为（0,0）

例子二：获取Button的中心点，相对于Canvas的位置

private void MyButton_Click(object sender, RoutedEventArgs e)
            {
                Point current = new Point();
                current=  this.myButton.TransformToAncestor(this.myCanvas)
    .Transform(new Point(myButton.Width/2, myButton.Height/2));//获取中心点的位置
                MessageBox.Show(current.X.ToString() +  "  "+ current.Y.ToString ());
            }

**获取相对于屏幕的坐标**

Point controlPoint = new Point(0, 0);
                controlPoint = ((TextBox)sender).PointToScreen(controlPoint);//获取控件相对于屏幕的位置
                mkeyBoard.Top = controlPoint.Y + ((TextBox)sender).ActualHeight;
                mkeyBoard.Left = controlPoint.X-20;

**获得子元素相对于父元素位置和宽高**

<Canvas x:Name="cv">
            <Rectangle x:Name="rct" Width="100" Height="80" Fill="#FFD62525" Canvas.Left="309" Canvas.Top="181" />
     </Canvas>
    
    后台C#
    
    
            private void MainWindow_Loaded(object sender, RoutedEventArgs e)
            {
                Rect itemRect = VisualTreeHelper.GetDescendantBounds(rct);//itemRect是0,0,100,80
                Rect itemBounds = rct.TransformToAncestor(cv).TransformBounds(itemRect);// itemBounds是309,181,100,80
                Console.WriteLine(itemRect);
                Console.WriteLine(itemBounds);
            }

参考

[http://www.ayjs.net/post/757.html][http_www.ayjs.net_post_757.html]

[https://docs.microsoft.com/zh-cn/dotnet/api/system.windows.media.visual.transformtoancestor?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev15.query%3FappId%3DDev15IDEF1%26l%3DZH-CN%26k%3Dk(System.Windows.Media.Visual.TransformToAncestor);k(SolutionItemsProject);k(TargetFrameworkMoniker-.NETFramework,Version%3Dv4.0);k(DevLang-csharp)%26rd%3Dtrue&view=netframework-4.8][https_docs.microsoft.com_zh-cn_dotnet_api_system.windows.media.visual.transformtoancestor_f1url_https_3A_2F_2Fmsdn.microsoft.com_2Fquery_2Fdev15.query_3FappId_3DDev15IDEF1_26l_3DZH-CN_26k_3Dk_System.Windows.Media.Visual.TransformToAncestor_k_SolutionItemsProject_k_TargetFrameworkMoniker-.NETFramework_Version_3Dv4.0_k_DevLang-csharp_26rd_3Dtrue_view_netframework-4.8]

[http_www.ayjs.net_post_757.html]: http://www.ayjs.net/post/757.html
[https_docs.microsoft.com_zh-cn_dotnet_api_system.windows.media.visual.transformtoancestor_f1url_https_3A_2F_2Fmsdn.microsoft.com_2Fquery_2Fdev15.query_3FappId_3DDev15IDEF1_26l_3DZH-CN_26k_3Dk_System.Windows.Media.Visual.TransformToAncestor_k_SolutionItemsProject_k_TargetFrameworkMoniker-.NETFramework_Version_3Dv4.0_k_DevLang-csharp_26rd_3Dtrue_view_netframework-4.8]: https://docs.microsoft.com/zh-cn/dotnet/api/system.windows.media.visual.transformtoancestor?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev15.query%3FappId%3DDev15IDEF1%26l%3DZH-CN%26k%3Dk%28System.Windows.Media.Visual.TransformToAncestor%29;k%28SolutionItemsProject%29;k%28TargetFrameworkMoniker-.NETFramework,Version%3Dv4.0%29;k%28DevLang-csharp%29%26rd%3Dtrue&view=netframework-4.8