下面的示例演示如何在基于 Silverlight 的应用程序中拖放对象。出于安全考虑，不能在应用程序之间拖放对象。因此，说成在 Silverlight 插件区域内"滑动"对象更为准确。但是，术语"拖放"更为人知，因此在此处使用。
| XAML |
|
<UserControl x:Class="DragAndDropSimple.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="400" Height="300">
<Canvas x:Name="rootCanvas"
Width="640"
Height="480"
Background="Gray"
>
<!-- You can drag this rectangle around the canvas. -->
<Rectangle
MouseLeftButtonDown="Handle_MouseDown"
MouseMove="Handle_MouseMove"
MouseLeftButtonUp="Handle_MouseUp"
Canvas.Left="30" Canvas.Top="30" Fill="Red"
Width="50" Height="50" />
</Canvas>
</UserControl>
|
| C# |
|
// Global variables used to keep track of the
// mouse position and whether the object is captured
// by the mouse.
bool isMouseCaptured;
double mouseVerticalPosition;
double mouseHorizontalPosition;
public void Handle_MouseDown (object sender, MouseEventArgs args)
{
Rectangle item = sender as Rectangle;
mouseVerticalPosition = args.GetPosition(null).Y;
mouseHorizontalPosition = args.GetPosition(null).X;
isMouseCaptured = true;
item.CaptureMouse();
}
public void Handle_MouseMove(object sender, MouseEventArgs args)
{
Rectangle item = sender as Rectangle;
if (isMouseCaptured)
{
// Calculate the current position of the object.
double deltaV = args.GetPosition(null).Y - mouseVerticalPosition;
double deltaH = args.GetPosition(null).X - mouseHorizontalPosition;
double newTop = deltaV + (double)item.GetValue(Canvas.TopProperty);
double newLeft = deltaH + (double)item.GetValue(Canvas.LeftProperty);
// Set new position of object.
item.SetValue(Canvas.TopProperty, newTop);
item.SetValue(Canvas.LeftProperty, newLeft);
// Update position global variables.
mouseVerticalPosition = args.GetPosition(null).Y;
mouseHorizontalPosition = args.GetPosition(null).X;
}
}
public void Handle_MouseUp(object sender, MouseEventArgs args)
{
Rectangle item = sender as Rectangle;
isMouseCaptured = false;
item.ReleaseMouseCapture();
mouseVerticalPosition = -1;
mouseHorizontalPosition = -1;
}
|
| Visual Basic |
|
' Global variables used to keep track of the
' mouse position and whether the object is captured
' by the mouse.
Dim isMouseCaptured As Boolean
Dim mouseVerticalPosition As Double
Dim mouseHorizontalPosition As Double
Private Sub Handle_MouseDown(ByVal sender As Object, ByVal e As MouseButtonEventArgs)
Dim item As Rectangle = sender
mouseVerticalPosition = e.GetPosition(Nothing).Y
mouseHorizontalPosition = e.GetPosition(Nothing).X
isMouseCaptured = True
item.CaptureMouse()
End Sub
Private Sub Handle_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
Dim item As Rectangle = sender
If (isMouseCaptured) Then
' Calculate the current position of the object.
Dim deltaV As Double = e.GetPosition(Nothing).Y - mouseVerticalPosition
Dim deltaH As Double = e.GetPosition(Nothing).X - mouseHorizontalPosition
Dim newTop As Double = deltaV + item.GetValue(Canvas.TopProperty)
Dim newLeft As Double = deltaH + item.GetValue(Canvas.LeftProperty)
' Set new position of object.
item.SetValue(Canvas.TopProperty, newTop)
item.SetValue(Canvas.LeftProperty, newLeft)
' Update position global variables.
mouseVerticalPosition = e.GetPosition(Nothing).Y
mouseHorizontalPosition = e.GetPosition(Nothing).X
End If
End Sub
Private Sub Handle_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Input.MouseButtonEventArgs)
Dim item As Rectangle = sender
isMouseCaptured = False
item.ReleaseMouseCapture()
mouseVerticalPosition = -1
mouseHorizontalPosition = -1
End Sub
End Class
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