C# Signature:
[DllImport("user32.dll")]
static extern bool ReleaseCapture();
VB.NET Signature:
<DllImport("user32.dll")> _
Private Shared Function ReleaseCapture() As Boolean
End Function
User-Defined Types:
None.
Notes:
None.
ReleaseCapture will delegate mousedown events to underlying controls.
Tips & Tricks:
Please add some!
Sample Code:
You can use the ReleaseCapture() function to provide drag functionality. for example the following code will allow the user to drag a control around a form (you'll have to assign this code to the mousedown event):
[DllImport("User32.dll")]
private static extern int SendMessage(IntPtr hWnd, int msg , int wParam , ref int lParam);
[DllImport("user32")]
public static extern int ReleaseCapture(IntPtr hwnd);
private const int WM_SYSCOMMAND = 0x112;
private const int MOUSE_MOVE = 0xF012;
private void control_MouseDown(object sender, MouseEventArgs e)
{
Control ctrl = sender as Control;
ReleaseCapture(ctrl.Handle);
int nul =0;
SendMessage(ctrl.Handle, WM_SYSCOMMAND, MOUSE_MOVE, ref nul);
}
Alternative Managed API:
Capture property on System.Windows.Forms.Control
Do you know one? Please contribute it!
Public Class Form1
Private MouseDown1 As Boolean
Private PosDiff As Point
Private Sub Form1_Load(ByVal sender As Object, _
ByVal e As System.EventArgs) Handles Me.Load
Me.TopMost = True
End Sub
Private Sub PictureBox3_MouseMove(ByVal sender As Object, ByVal e As _
System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseMove
If Not MouseDown1 Then Exit Sub
If Not System.Windows.Forms.SystemInformation.MouseButtonsSwapped() Then
If Not e.Button = Windows.Forms.MouseButtons.Left Then Exit Sub
Else
If Not e.Button = Windows.Forms.MouseButtons.Right Then Exit Sub
End If
Me.Location = New Point(Cursor.Position().X - PosDiff.X, Cursor.Position().Y - PosDiff.Y)
End Sub
Private Sub PictureBox3_MouseUp(ByVal sender As Object, ByVal e As _
System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseUp
MouseDown1 = False
End Sub
Private Sub PictureBox3_MouseDown(ByVal sender As Object, ByVal e As _
System.Windows.Forms.MouseEventArgs) Handles PictureBox3.MouseDown
MouseDown1 = True
PosDiff = New Point(Cursor.Position().X - Me.Location.X, Cursor.Position().Y - Me.Location.Y)
End Sub
End Class
