[GRASS-dev] Cairo monitor driver

Lars Ahlzen lars at ahlzen.com
Sun Oct 14 14:59:04 EDT 2007

Glynn Clements wrote:
> Dylan Beaudette wrote:
>>> Since the Cairo graphics library (http://www.cairographics.org, LGPL
>>> licensed) provides very high-quality graphics output in several vector
>>> and raster formats, I thought it would make sense to create a "pseudo"
>>> monitor driver for it (similar to the PNG and PS drivers). So I did.
>>> Cairo does all of the hard work, so it's really mostly simple "glue" code.
>> Indeed. I have been using it for all of my R work lately. I don't know why 
>> this hasn't come up before, but something like Cairo actually solves a lot of 
>> the problems we are facing: high quality on-screen display, output to PDF...
>> This would also solve the translucency problem, as Cairo can deal with that 
>> quite nicely. 
> The problem with translucency is that not all rendering systems
> support it. The core X11 protocol doesn't, so you either need the
> Render extension or to perform the rendering client-side.

I believe that Cairo does this client-side for X surfaces, so one 
wouldn't really need to worry about it.

> PostScript doesn't support it, as most printers only have one bit per component.

True. Not much do do about this case (other than perhaps use PDF, and a 
printer driver that does the compositing in software before it's sent to 
the printer).

/ Lars

Lars Ahlzen
lars at ahlzen.com

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