[cairo] Blurriness when drawing from a temporary surface as the source
dogusanh at tr.net
Mon Jun 29 05:59:34 PDT 2009
Adam Richard wrote:
> 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
> 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 may be wrong but, it may be related to:
FAQ: How do I draw a sharp, single-pixel-wide line?
(I ended up adjusting all coordinates for zooming, instead of using
> 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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