[cairo] Cairo Tutorial
Colin William Brown
colinwilliambrown at gmail.com
Sun Nov 22 09:27:05 PST 2015
I think a good teaching document needs to come at the subject from the two
perspectives: the relationships among principle object types and the
mechanism for actually using them. Seeing only one dimension can leave me
On Thu, Nov 19, 2015 at 1:15 AM, Lawrence D'Oliveiro <
ldo at geek-central.gen.nz> wrote:
> Do people find the existing Cairo tutorial
> <http://cairographics.org/tutorial/> useful? I don’t feel it jibes with
> how I learned to understand Cairo. Rather, I made sense of it in terms
> of the interrelationships of the principal object types:
> * a *surface* is the recipient of drawing operations. There are various
> types of surfaces, in particular an *image surface* is a rectangular
> array of pixels, which can be of various formats.
> Other surface types have their uses, for example PDF and SVG
> surfaces allow the direct creation of those file formats with Cairo
> drawing operations, such that the original object geometry (including
> text font outlines) is preserved as far as possible, rather than being
> rendered to pixels at some fixed resolution.
> * a *context* is the holder of state for drawing operations. It keeps
> information needed during drawing, but which is no longer needed once
> the final image has been produced, such as the colour/pattern to use
> for drawing, the font to use for text, and so on.
> * a *pattern* supplies the information for affecting pixel values
> during drawing. It can be as simple as a single uniform colour
> (in this case, Cairo provides convenience routines to set the source
> colour for drawing directly, rather than having to explicitly create a
> pattern object first), or it can be a more elaborate gradient or mesh
> pattern, or it can even consist of the image from another surface.
> * a *font face* is the Cairo object for loading fonts to use for
> rendering text.
> * a *scaled font* is the user-visible part of Cairo’s font-caching
> mechanism. It represents a font with a particular transformation and
> rendering options selected. If you use a number of different
> font settings repeatedly, then obtaining and setting scaled fonts is a
> quicker way of switching among these settings when rendering text than
> specifying the font face and size and other options separately every
> As I see it, those are the most important ones to get straight. Once
> you grasp those concepts, the rest makes a whole lot more sense.
> cairo mailing list
> cairo at cairographics.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the cairo