[cairo] Cairo Tutorial

[Lawrence D'Oliveiro]

On Thu, 19 Nov 2015 14:02:37 -0600, Michael Urman wrote:

> I'd say your list of concepts is critically lacking coverage of
> *paths* and the *verbs* that use them; perhaps you mean for them to
> be part of what you call the *context*.

Yes, this has to be covered after introducing the idea of a context.

* What does Cairo draw? It primarily draws geometric shapes called
  *paths*. These are made out of straight-line segments and Bézier-curve
  segments.

Also operators need to be mentioned:

* While a pattern provides the values used for updating pixels during
  drawing, the *operator* governs how the new destination pixel values
  are computed from the existing ones and the values supplied by the
  source pattern: besides simple replacement of the destination by the
  source, some more elaborate effects are possible.

Then perhaps a bit about transformations.