[cairo] Re: New API: cairo_surface_get_width/height

Carl Worth cworth at cworth.org
Thu Jun 8 22:42:39 PDT 2006


On Fri, 09 Jun 2006 14:35:54 +1000, Russell Shaw wrote:
> Owen Taylor wrote:
> > 
> > I don't think the argument about pattern sources is very compelling,
> > because using a window as a repeating pattern source is pretty much
> > nonsensical, for X, for Windows, or for any system.
> 
> In a CAD, drawing, or graphing program, the effect of a graph-paper
> background consisting of major/minor lines or dots is most efficiently
> created by the repetition of tiles that contain atleast one major line/dot,
> and a set of minor lines/dots. It also minimizes the size of any backing
> pixmap stored in the server.

Yes, that's useful, and that's why we have the CAIRO_EXTEND_REPEAT
stuff.

Owen was making the distinction that if you were to do that kind of
repeated drawing (in X, say) that you would use a cairo surface
created from a "Pixmap", (an offscreen object), as the source for the
pattern. You would not use a "Window", (an onscreen object), as the
source since reading from a Window isn't reliable, (X doesn't provide
the window contents for regions that are obscured by other windows).

Presumably there's a similar distinction in win32 with possibly
different names.

-Carl

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