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Re: Transparent Background - Image control [message #42328 is a reply to message #42327]

Fri, 07 March 2014 16:03

Didier
Messages: 680
Registered: November 2008
Location: France

Contributor

Looks like DrawPainter is missing initialization of an image buffer.

I also stumbled on this kind of issue some time ago when using ImageBuffer and didn't initialize it : if there is no init of the whole buffer then alpha management does not work ==> and you get those black corners

Here is sample code showing the initialization of the ImageBuffer :

RGBA bckgColor;   bckgColor.r = 0; bckgColor.g = 0; bckgColor.b = 0; bckgColor.a = 0;
ImageBuffer ib(_plotRect.Size());
Upp::Fill( ib.Begin(), bckgColor, ib.GetLength() );
BufferPainter bp(ib, _drawMode);
PaintPlotData(bp, scale);
dw.DrawImage(0, 0, ib);

NB : using painter to draw images is useless (and slower), so if you don't draw anything else : do not use Painter

[Updated on: Fri, 07 March 2014 16:07]

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