Cliquez et faites glisser la boîte de sélection en WPF

Voici un exemple de code pour une technique simple que j'ai utilisé dans le passé pour dessiner un rectangle de sélection de la boîte.

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;
}
}
}
}

OriginalL'auteur Ashley Davis

MouseDown logique:

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);

OriginalL'auteur user7128900