[cairo] How to render 1bpp bitmaps normally & selected (in GTK+ 3)

Mark Leisher mleisher at gmail.com
Tue Jul 12 12:26:38 PDT 2011

On 07/12/2011 12:53 PM, Bill Spitzak wrote:
>>> 1. You mention the XOR operator. I never could get it to work
>>> (OpenSuSE 11.4
>>> 32-bit/Gtk+ 3.0.10/cairo 1.10.2) and never managed to dig up any
>>> examples
>>> that did. The DIFFERENCE operator worked exactly as advertised, but it
>>> wasn't quite what I was looking for. Before I dig into the cairo
>>> sources,
>>> any pointers to XOR examples that work?
> XOR is between the *alpha* of the two surfaces, not the colors or the
> bits of the colors. Probably useless in this case because I would expect
> that at least the destination window has 100% solid alpha. If one of the
> items is solid alpha then XOR is going to be equivalent to some other
> operator.

Thanks. I discovered this perusing the sources this morning. It wasn't 
clear in the documentation. A solid alpha in the destination was likely 
why I wasn't seeing what I expected.
Mark Leisher

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