Test and document extents of degenerate "dots"

It's a common idiom to stroke degenerate sub-paths made with
cairo_move_to(x,y);cairo_rel_line_to(0,0) to draw dots. Test
that we get the desired extents from cairo_fill_extents,
cairo_stroke_extents, and cairo_path_extents for these cases.

Also document that the cairo_path_extents result is equivalent
to the limit of stroking with CAIRO_LINE_CAP_ROUND, (so that
these "dot" points are included), as the line width
approaches 0.0 .

1 files changed, 3 insertions, 3 deletions

diff --git a/src/cairo.c b/src/cairo.c
index f5b92a77..3011125f 100644
--- a/src/cairo.c
+++ b/src/cairo.c
@@ -1887,9 +1887,9 @@ slim_hidden_def(cairo_close_path);
  * the corresponding drawing operations.
  *
  * The result of cairo_path_extents() is defined as equivalent to the
- * limit of cairo_stroke_extents() as the line width approaches 0.0,
- * (but never reaching the empty-rectangle returned by
- * cairo_stroke_extents() for a line width of 0.0).
+ * limit of cairo_stroke_extents() with CAIRO_LINE_CAP_ROUND as the
+ * line width approaches 0.0, (but never reaching the empty-rectangle
+ * returned by cairo_stroke_extents() for a line width of 0.0).
  *
  * Specifically, this means that zero-area sub-paths such as
  * cairo_move_to();cairo_line_to() segments, (even degenerate cases