[cairo] BUG: CAIRO_FORMAT_ARGB32, image_surface transparency = CAIRO_IMAGE_IS_OPAQUE after write_png()

Lawrence D'Oliveiro ldo at geek-central.gen.nz
Tue Jun 7 07:29:18 UTC 2016

On Tue, 7 Jun 2016 08:19:47 +0930, Adrian Johnson wrote:

> Cairo analyses image transparency to ensure it uses the most
> efficient format when writing out images to
> PNG, PDF, and PS.

I don’t mind PDF and PostScript, they’re quite complicated formats. But
I thought the PNG reading/writing capability built into Cairo was
supposed to be, and I quote, “a toy API”

Optimizing out the alpha channel would have to count as an “advanced”
feature, not a “toy” one, I would have thought.

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