Sets the source pattern within cr to source. This pattern
will then be used for any subsequent drawing operation until a new
source pattern is set.
Note: The pattern's transformation matrix will be locked to the
user space in effect at the time of cairo_set_source(). This means
that further modifications of the current transformation matrix
will not affect the source pattern. See cairo_pattern_set_matrix().
The default source pattern is a solid pattern that is opaque black,
(that is, it is equivalent to cairo_set_source_rgb(cr, 0.0, 0.0,
0.0)).
Sets the source pattern within cr to source. This pattern will then be used for any subsequent drawing operation until a new source pattern is set. Note: The pattern's transformation matrix will be locked to the user space in effect at the time of cairo_set_source(). This means that further modifications of the current transformation matrix will not affect the source pattern. See cairo_pattern_set_matrix(). The default source pattern is a solid pattern that is opaque black, (that is, it is equivalent to cairo_set_source_rgb(cr, 0.0, 0.0, 0.0)).