获取在画布上鼠标的位置与透明背景

Question

我建立一个简单的应用WPF。我有一个透明最大化Window和Canvas（canvas1）。

我想获取鼠标位置在canvas1或MainWindow（在这种情况下是相同的事情）。

这样做我用这个代码：

Point p = Mouse.GetPosition(canvas1); //and then I have p.X and p.Y 

此代码工作正常的不透明Canvas。问题是，我有一个透明Canvas，而这个代码不工作...（它不给我的错误，但坐标是p.X = 0和p.Y = 0）。

我怎样才能解决这个问题？

Answer 1

一个可能的解决方法是使用GetCursorPos Win32函数：

[DllImport("user32.dll")] 
    [return: MarshalAs(UnmanagedType.Bool)] 
    static extern bool GetCursorPos(out System.Drawing.Point lpPoint); 

你必须坐标从像素转换为点，如果你想在WPF使用它

用法例如：

System.Drawing.Point point; 
if(!GetCursorPos(out point)) 
    throw new InvalidOperationException("GetCursorPos failed"); 
// point contains cursor's position in screen coordinates. 

Answer 2

C＃

using System.Windows; 
    using System.Windows.Input; 
    using System.Diagnostics; 
    using System.Runtime.InteropServices; 
    using System; 
    using System.Windows.Threading; 
    namespace Test 
    { 
     public partial class MainWindow : Window 
     { 
      [DllImport("user32.dll")] 
      [return: MarshalAs(UnmanagedType.Bool)] 
      internal static extern bool GetCursorPos(ref Win32Point pt); 

      [StructLayout(LayoutKind.Sequential)] 
      internal struct Win32Point 
      { 
       public Int32 X; 
       public Int32 Y; 
      }; 
      public static Point GetMousePosition() 
      { 
       Win32Point w32Mouse = new Win32Point(); 
       GetCursorPos(ref w32Mouse); 
       return new Point(w32Mouse.X, w32Mouse.Y); 
      } 

      private double screenWidth; 
      private double screenHeight; 

      public MainWindow() 
      { 
       InitializeComponent(); 
      } 

      private void Window_Loaded(object sender, RoutedEventArgs e) 
      { 
       screenWidth = System.Windows.SystemParameters.PrimaryScreenWidth; 
       screenHeight = System.Windows.SystemParameters.PrimaryScreenHeight; 

       this.Width = screenWidth; 
       this.Height = screenHeight; 
       this.Top = 0; 
       this.Left = 0; 
       DispatcherTimer timer = new DispatcherTimer(); 
       timer.Tick += new EventHandler(timer_Tick); 
       timer.Start(); 
      } 

      void timer_Tick(object sender, EventArgs e) 
      { 
       var mouseLocation = GetMousePosition(); 
       elipse1.Margin = new Thickness(mouseLocation.X, mouseLocation.Y, screenWidth - mouseLocation.X - elipse1.Width, screenHeight - mouseLocation.Y- elipse1.Height); 
      } 
     } 
    } 

XAML

<Window x:Class="Test.MainWindow" 
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
      Title="MainWindow" 
      Height="350" Width="525" 
      WindowStyle="None" 
      Topmost="True" 
      AllowsTransparency="True" 
      Background="Transparent" 
      ShowInTaskbar="False" 
      Loaded="Window_Loaded"> 
     <Grid> 
       <Ellipse Width="20" Height="20" Fill="Red" Name="elipse1"/> 
     </Grid> 
    </Window> 

解决了！但后期:(