I need to draw a textbox in a Compact Framework app, but using directly a Graphics object.
I've found the Control.DrawToBitmap method, which I could use for drawing with GDI, but it's not available on Compact Framework.
Any hints?
A:
Well typically you just inherit from : Control, override OnPaint and use the graphics object provided by the arguments. Have you tried this yet?
Quibblesome
2009-12-15 10:40:10
With this I can draw text, lines, polygons, bitmaps, etc. But how I can get the "image" from a textbox that is not in any control?
penyaskito
2009-12-15 10:42:20
Eh? You want to get the image that is drawn by the control? You cannot get this, unless you implement the control yourself and expose it via a property. You could do this by drawing the control on a graphics object created by Graphics.FromImage() then expose that image via a property before finally drawing the control by using Graphics.DrawImage on the "main" graphics object in the event args. You would have to re-implement every single control this way though so it would be a lot of effort.
Quibblesome
2009-12-15 13:23:52
+1
A:
Control.DrawToBitmap() is implemented by sending WM_PRINT to the control to let it draw itself in a memory device context. If you are using non-standard controls, the odds are great that the programmer did not implement this message. I don't think it is implemented by the standard Windows Mobile controls either.
Your only other recourse then is to copy the pixels off the screen. Graphics.CopyFromScreen() is a no-go, you'll have to P/Invoke the BitBlt() API function. Possibly useful sample code is available in this thread. and at pinvoke.net
Hans Passant
2009-12-15 13:02:04
I did the BitBit p/Invoke, but got a black image (I think that's because of the controls not being visible in any form). If I use visible controls it works. Thanks anyway :(
penyaskito
2009-12-15 13:59:22
Well you always make them visible but "off screen". Again not pretty....
Quibblesome
2009-12-15 16:14:27
The problem is that in Windows Mobile I can only have an active screen, so puting the StartLocation out of the bounds of it it's not an option.
penyaskito
2009-12-15 17:02:28
A:
I have no idea if this would work.... but technically you could use reflection to call into the control's OnPaint method and pass in your own graphics object (Graphics.FromImage) in a new set of PaintEventArgs.
It's ugly as hell..... but it might work.
Quibblesome
2009-12-15 13:30:14