Drawing problem with list box [.NET]

[Winston]

Ok, this might be hard to understand but anyways:

i'm currently inheriting from the ListBox control and providing my own drawing code.

I'm drawing a gradient background on each listbox item. All fine, however the gradient i'm drawing is a little away from the edge of the actual rectangle so youll see some white space around the actual rectangle.

All fine till when you run it and when u resize the listbox, only the first item gets refreshed and draw appropriately.

If i drew the gradient so that it covered the whole rectangle up with no spaces between the edges, and if i resize it during runtime, all the items become drawn correctly.

Here's a screenshot of the issue when it's resized

http://www.ug.it.usyd.edu.au/~wpan6331/ss/ss.JPG

Has anyone experienced the same situation before?

Thanks

[lexecutil]

You could try setting the ControlStyles.ResizeRedraw flag.. I'm pretty sure that will fix your problem..

this.SetStyle(ControlStyles.ResizeRedraw, true);

By the way very nice looking listbox you've got there. :)

Dan

[Winston]

  dannyres said:

You could try setting the ControlStyles.ResizeRedraw flag.. I'm pretty sure that will fix your problem..

this.SetStyle(ControlStyles.ResizeRedraw, true);

By the way very nice looking listbox you've got there. :)

Dan

585278752[/snapback]

Thanks, i've tried al the SetStyle options.

Doesn't help, try it yourself actually, if u dont mind

draw a gradient inside a listbox item, and make it so that its off the edges of the rectangle and resize and ullsee it happen too.

[lexecutil]

Ah ok, I don't have time to try it myself right now, but you could try filling the bounds with white (Graphics.Chear(Color.White);) then drawing ontop of that.. Hopfully that will solve your problem.. :)

Dan

[Ianmac45]

can you give us the code, winston?

[azcodemonkey]

Are you invalidating the listbox's ClientRectangle, or just the rect you're drawing in?

[Winston]

I call invalidate on resize of the actual listbox, but this causes the entire control to flicker like crazy, having double buffer turned on too.

[Winston]

  dannyres said:

Ah ok, I don't have time to try it myself right now, but you could try filling the bounds with white (Graphics.Chear(Color.White);) then drawing ontop of that.. Hopfully that will solve your problem.. :)

Dan

585281362[/snapback]

lol that doesn't really work, it then causes only one listbox item to be drawn.

[lexecutil]

Hmm try using Graphics.FillRectangle on the Bounds of the listbox item them. :)

Dan

[Winston]

Ok update guys, i overrided OnResize, so i have to invoke mybase's resize method, added ResizeRedraw for the styles that fixed it up, now i'm left with a listbox that flickers really badly, has anyoen got any other tips they can share to avoid this flickering, i've used double buffer, doesn't work, it also said to truly enable double buffer u have to set the AllWmPaint one and the UserPaint styles, however UserPaint stuffs up the drawing.

Any other suggestions guys?

Thanks

[lexecutil]

You could try doing the double buffering yourself by creating a temporary Bitmap object which you will draw ontop, then paint that to the screen.. :)

Dan

[azcodemonkey]

  dannyres said:

You could try doing the double buffering yourself by creating a temporary Bitmap object which you will draw ontop, then paint that to the screen.. :)

Dan

585284364[/snapback]

I did that in some test code and it didn't help for me, although the SetStyle with DoubleBuffer worked for me.

What kind of paint trouble do you get when you use SetStyle?

[Winston]

  weenur said:

I did that in some test code and it didn't help for me, although the SetStyle with DoubleBuffer worked for me.

What kind of paint trouble do you get when you use SetStyle?

585284643[/snapback]

Hmmm i'm gonna have to show you, sometime when you're free and when you're on msn lol

[azcodemonkey]

  Winston said:

Hmmm i'm gonna have to show you, sometime when you're free and when you're on msn lol

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:D I've been World of Warcraft-ing every night. I'll pop on to MSN tonight when I get home.