[cairo] Write ups on Microsoft Avalon

Bill Spitzak spitzak at d2.com
Mon May 17 10:06:13 PDT 2004

On Monday 17 May 2004 09:59 am, Jost Boekemeier wrote:
> Glyphs okay, but I don't understand your suggestion to draw in device
> coordinates; does a common device space exist for all output formats?

Cairo is designed so the default CTM puts integers at predictable locations 
relative to the device coordinates.

I strongly recommend that this be at the corners of the pixels, though I am 
not absolutely certain this is the CTM chosen for Cairo. In theory a 1-unit 
wide horizontal or vertical line drawn at a coordinate of N+.5 will exactly 
fill an integer number of pixels. In the other mail I also recommended that a 
special "0" case be provided that eliminates the need to put .5 in the 
coordinate, the reason is to discourage people from moving the CTM by .5 and 
messing up all the optimized drawing of rectangles.

                   ,~,~,~,~ ~ ~ ~ ~
     /\_       _|_========___         Bill Spitzak
 ~~~/\/\\~~~~~~\____________/~~~~~~~~ spitzak at d2.com

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