[matplotlib-devel] Cairo Backend and Subpixel Rendering

[Freddie W. <fr...@wi...>]

Hi all,

As some of you probably know I am working on the GSoC project to  
externalise the Mathtex engine from Matplotlib. Today I have been  
toying around with the renderer using various backends.

One of the interesting things that I discovered was that the Cairo  
backend was making use of subpixel rendering. (Or 'ClearType' as  
Microsoft call it.) This is not surprising -- by default Cairo will  
respect a users fontconfig settings when rendering text. Since I have  
subpixel rendering enabled all text rendered by Cairo is subpixel  
rendered.

While this is fantastic for on screen text -- being significantly more  
pleasing to look at that the text produced by the AGG backend -- it is  
unsuitable for print. Now it is not too difficult to disable this,  
Cairo has an API call: cairo_font_options_set_antialias to deal with  
this.

While I could write a quick patch to always disable subpixel rendering  
it would be something off a loss to those who either view their graphs  
onscreen or export them for the web -- where using subpixel rendering  
is now surprisingly common.

Is it worth looking into adding subpixel rendering as a configuration  
option?

Regards, Freddie.