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Drawing problem with list box [.NET]


Question

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

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13 answers to this question

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  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.

  • 0
  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.

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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

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  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?

  • 0
  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

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