Direct2D equivalent of GDI InvertRect

Question

I need to convert GDI methods calls of a relatively complex program into equivalent Direct2D code. For most of the GDI functions I could write equivalent code. But I haven't found any equivalent code for InvertRect. Since the drawing is done dynamically, I can't create (or it will be a performance bottleneck) WICBitmap to get pixels and invert the color.

Can anyone suggest me a good solution, please?

Right, that's exactly why you can't find the equivalent, Direct2D doesn't want to do this expensive thing either. Restructure your drawing code so you can reproduce those pixels, but now with a different set of colors. As a bonus it should be much more pleasing to the eye, given the often awful colors that InvertRect() produces. — Hans Passant

Rick Brewster Rick Brewster · Accepted Answer · 2019-03-14T01:02:21

If you want to invert an area that's already been drawn, I believe you can use CreateEffect(CLSID_D2D1Flood) to create an effect that fills with a solid color, then set the effect's color parameter to white, and then use ID2D1DeviceContext::DrawImage with that effect and use D2D1_COMPOSITE_MODE_XOR for the compositeMode parameter.

(You may also need to use transparent white, now that I think of it ... assuming that XOR also operates on the alpha channel. You may need to experiment. Also, it may not work, I haven't tried it.)

Direct2D equivalent of GDI InvertRect

2 Answers