GDI programming question (from a newbie)

[Jeremy Bradshaw]

I'm trying to paint rectangles using GDI (I'm implementing drag and drop and
want to paint a dashed rectangle as I drag a control to a new position). I
instantiate a Rectangle object ok and handle its painting in the form's
Paint event. This works fine, but the rectangle always appears "underneath"
other objects on the form - I want it to always appear over the top of them.
How can I achieve this ?

 

[Gerben van Loon]

maybe it's better to ask your question in
microsoft.public.dotnet.framework.drawing

greets

 

[Bob Powell [MVP]]

Take a look at ControlPaint.DrawSelectionFrame

--
Bob Powell [MVP]
C#, System.Drawing

Check out the GDI+ FAQ
http://www.bobpowell.net/gdiplus_faq.htm

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New Tips and Tricks include creating transparent controls
and how to do double buffering.

 

[Bob Powell [MVP]]

Probably the easiest is to import the GetDC method, get the desktop DC and
then get a Graphics object for it so you can draw on that using
ControlPaint.

using System.Runtime.InteropServices;


[DllImport("user32.dll")]
static extern System.IntPtr GetDC(System.IntPtr hWnd);

[DllImport("user32.dll")]
static extern int ReleaseDC(System.IntPtr hWnd, System.IntPtr hDC);

//in the draw routine...

System.IntPtr hDCDeskTop=GetDC(System.IntPtr.Zero);

Graphics g1=Graphics.FromHdc(hDCDeskTop);

//draw on the desktop here....

g1.DrawLine(Pens.Red,0,0,1024,768);

g1.DrawLine(Pens.Red,0,768,1024,0);

//clean up

g1.Dispose();

ReleaseDC(System.IntPtr.Zero,hDCDeskTop);

--
Bob Powell [MVP]
C#, System.Drawing

Check out the GDI+ FAQ
http://www.bobpowell.net/gdiplus_faq.htm

Buy quality Windows Forms tools
http://www.bobpowell.net/xray_tools.htm

New Tips and Tricks include creating transparent controls
and how to do double buffering.