Klicken und ziehen Sie die Auswahl-box in WPF

Hier ein Beispielcode für eine einfache Technik, die ich in der Vergangenheit verwendet haben zu zeichnen, ziehen Sie die Auswahl-box.

XAML:

<Window x:Class="DragSelectionBox.Window1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Window1" Height="300" Width="300"
    >
    <Grid
        x:Name="theGrid"
        MouseDown="Grid_MouseDown"
        MouseUp="Grid_MouseUp"
        MouseMove="Grid_MouseMove"
        Background="Transparent"
        >
        <Canvas>
            <!-- This canvas contains elements that are to be selected -->
        </Canvas>

        <Canvas>
            <!-- This canvas is overlaid over the previous canvas and is used to 
                place the rectangle that implements the drag selection box. -->
            <Rectangle
                x:Name="selectionBox"
                Visibility="Collapsed"
                Stroke="Black"
                StrokeThickness="1"
                />
        </Canvas>
    </Grid>
</Window>

C#:

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();
    }

    bool mouseDown = false; //Set to 'true' when mouse is held down.
    Point mouseDownPos; //The point where the mouse button was clicked down.

    private void Grid_MouseDown(object sender, MouseButtonEventArgs e)
    {
        //Capture and track the mouse.
        mouseDown = true;
        mouseDownPos = e.GetPosition(theGrid);
        theGrid.CaptureMouse();

        //Initial placement of the drag selection box.         
        Canvas.SetLeft(selectionBox, mouseDownPos.X);
        Canvas.SetTop(selectionBox, mouseDownPos.Y);
        selectionBox.Width = 0;
        selectionBox.Height = 0;

        //Make the drag selection box visible.
        selectionBox.Visibility = Visibility.Visible;
    }

    private void Grid_MouseUp(object sender, MouseButtonEventArgs e)
    {
        //Release the mouse capture and stop tracking it.
        mouseDown = false;
        theGrid.ReleaseMouseCapture();

        //Hide the drag selection box.
        selectionBox.Visibility = Visibility.Collapsed;

        Point mouseUpPos = e.GetPosition(theGrid);

        //TODO: 
        //
        //The mouse has been released, check to see if any of the items 
        //in the other canvas are contained within mouseDownPos and 
        //mouseUpPos, for any that are, select them!
        //
    }

    private void Grid_MouseMove(object sender, MouseEventArgs e)
    {
        if (mouseDown)
        {
            //When the mouse is held down, reposition the drag selection box.

            Point mousePos = e.GetPosition(theGrid);

            if (mouseDownPos.X < mousePos.X)
            {
                Canvas.SetLeft(selectionBox, mouseDownPos.X);
                selectionBox.Width = mousePos.X - mouseDownPos.X;
            }
            else
            {
                Canvas.SetLeft(selectionBox, mousePos.X);
                selectionBox.Width = mouseDownPos.X - mousePos.X;
            }

            if (mouseDownPos.Y < mousePos.Y)
            {
                Canvas.SetTop(selectionBox, mouseDownPos.Y);
                selectionBox.Height = mousePos.Y - mouseDownPos.Y;
            }
            else
            {
                Canvas.SetTop(selectionBox, mousePos.Y);
                selectionBox.Height = mouseDownPos.Y - mousePos.Y;
            }
        }
    }
}

InformationsquelleAutor der Antwort Ashley Davis

MouseDown-Logik:

MouseRect.X = mousePos.X >= MouseStart.X ? MouseStart.X : mousePos.X;
MouseRect.Y = mousePos.Y >= MouseStart.Y ? MouseStart.Y : mousePos.Y;
MouseRect.Width = Math.Abs(mousePos.X - MouseStart.X);
MouseRect.Height = Math.Abs(mousePos.Y - MouseStart.Y);

InformationsquelleAutor der Antwort user7128900