[cairo] Blurriness when drawing from a temporary surface as the source
Adam Richard
adam.richard at caris.com
Mon Jun 29 05:22:58 PDT 2009
Hi,
When I draw a shape normally, it works fine. However, when I create a
temporary surface, draw that same shape on it, then draw using the
temporary surface with cairo_set_source, the image is sometimes more
blurry (of lower quality) than the one drawn directly. It is especially
noticeable when drawing small shapes; not as much when drawing larger
shapes.
I've only noticed this blurriness in a png file resulting from
write_to_png; when I write to a postscript instead it is not
noticeable. I also only notice it when I have matrix transformations
set up so that the units of the shape I'm drawing are much different
than device units.
I've tried disabling antialiasing with cairo_set_antialias, and it does
get disabled, but the 2 images are still different.
Does anyone have any ideas as to what could cause an effect like this?
I'm new to Cairo so I'm not sure whether it's using some approximation
algorithm that could result in unavoidable blurriness in some cases, or
whether perhaps I'm doing something suboptimal in setting up my
temporary surface to pass to cairo_set_source.
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