[AGG] Beginner - how to draw text together with shapes with opacity

[Ken R. <res...@sp...>]

I have a procedure 'text' based on the TrueType example that
uses agg::pixfmt_bgr24_gamma<gamma_type> and procedures rect,
circle etc that use pixfmt_bgra32 pixf(rbuf). These procedures put data
into a rendering buffer, which is bitblted onto the screen as a last
and separate step.

My application puts shapes annotated by text in a single=20
rendering buffer with pixel width 4 bytes (opacity needed),=20
but the text procedure does not work.The texts do not go=20
where I want them, there are stripes and the colors are wrong.
I think the pixfmt in the text procedure needs to be=20
replaced by a 32 bit format with gamma, such as=20
agg::pixfmt_bgra32_gamma<gamma_type>, but I have not been=20
able to find that. I have no knowledge about gamma, so cannot
write it myself (if indeed this is the way to solve it).

How can I make text coexist with shapes (with opacity) in a single=20
rendering buffer?