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PreviewMouseMove shoots twice

I have a problem with simple code. I was looking for several hours of solution, but no effects. I have a canvas and a rectangle. I move the Rectangle if the cursor is outside, the pMouseMove delegate only fires once for each pixel. Conversely, if the cursor is in a rectangle, delagate fires twice for each pixel. I want to run it only once, as if it was outside the Rectangle, how to do it?

XAML:

<Window x:Class="WpfApplication1.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">
  <Canvas x:Name="Can" Height="257" Width="503" Background="Gray">
    <TextBox Name="tb" Width="77" Height="20" Canvas.Left="0" Canvas.Top="-21"/>
  </Canvas>
</Window>

Code for:

public partial class MainWindow : Window
{
    Rectangle rect = new Rectangle();
    private static int i;
    private static string s;

    public MainWindow()
    {
        InitializeComponent();

        rect.Height = 50;
        rect.Width = 50;
        rect.Fill = Brushes.Black;
        Can.Children.Add(rect);
        Can.PreviewMouseMove += pMouseMove;
    }

    private void pMouseMove(object sender, MouseEventArgs e)
    {
        //cursor over Rectangle
        Canvas.SetTop(rect, e.GetPosition(Can).Y + 10);
        Canvas.SetLeft(rect, e.GetPosition(Can).X + 10);

        //cursor outside Rectangle
        //Canvas.SetTop(rect, e.GetPosition(Can).Y - 10);
        //Canvas.SetLeft(rect, e.GetPosition(Can).X - 10);

        //Counter
        i++;
        tb.Text = i.ToString();

        //e.Handled = true;
    }
}

Sorry for my bad english

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1 answer

WPF , , Canvas . , Canvas PreviewMouseMove Canvas Rectangle.

[] , e.OriginalSource, , . :

private void pMouseMove(object sender, MouseEventArgs e)
{
    // print out e.OriginalSource just for learning purposes
    Console.WriteLine("OriginalSource:" + e.OriginalSource.ToString());
}

, e.OriginalSource, , . , : e.OriginalSource Rectangle, PreviewMouseMove , e.OriginalSource Canvas. - Rectangle, ( , Reflector, . , .

rect.IsHitTestVisible = false;, Rectangle e.OriginalSource - PreviewMouseMove Canvas. VisualTreeHelper.HitTest, , Rectangle.

, , , .

:

rect.Fill = Brushes.Black;
rect.IsHitTestVisible = false;
Can.Children.Add(rect);

PreviewMouseMove:

private void pMouseMove(object sender, MouseEventArgs e)
{
    // Debug.WriteLine(e.OriginalSource.ToString());

    HitTestResult result = VisualTreeHelper.HitTest(rect, e.GetPosition(sender as UIElement));

    if (result != null) {
        Debug.WriteLine("Mouse inside rect")
    }
    else {
        Debug.WriteLine("Mouse outside rect");
    }
}
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