[Qt-interest] how to paint monochrome QImage colorised(black=>arbitrary color, white=>transparent)?

[Ross Bencina]

Sorry to answer my own question. Google got me this:

QColor c = // color of image we want
QImage image0 = QImage( 
":/ImageName.png" ).convertToFormat(QImage::Format_Indexed8);
image0.setColor(0, c.rgb());
image0.setColor(1, Qt::transparent);

(cache image 0)

painter.drawImage( x, y, image0 );

That works.

I'm not sure if this is the most efficient though. Is it worth caching the 
image converted to the native screen color depth?

Ross.

> Can anyone recommend the best (most efficient) way to paint a monochrome
> QImage such that the white pixels are transparent and the black pixels 
> take
> on a specified color?
>
> Thanks!
>
> Ross
>
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