Remove clip handling from generic surface layer.

Handling clip as part of the surface state, as opposed to being part of
the operation state, is cumbersome and a hindrance to providing true proxy
surface support. For example, the clip must be copied from the surface
onto the fallback image, but this was forgotten causing undue hassle in
each backend. Another example is the contortion the meta surface
endures to ensure the clip is correctly recorded. By contrast passing the
clip along with the operation is quite simple and enables us to write
generic handlers for providing surface wrappers. (And in the future, we
should be able to write more esoteric wrappers, e.g. automatic 2x FSAA,
trivially.)

In brief, instead of the surface automatically applying the clip before
calling the backend, the backend can call into a generic helper to apply
clipping. For raster surfaces, clip regions are handled automatically as
part of the composite interface. For vector surfaces, a clip helper is
introduced to replay and callback into an intersect_clip_path() function
as necessary.

Whilst this is not primarily a performance related change (the change
should just move the computation of the clip from the moment it is applied
by the user to the moment it is required by the backend), it is important
to track any potential regression:

ppc:
Speedups
========
image-rgba         evolution-20090607-0    1026085.22 0.18% -> 672972.07 0.77%:  1.52x speedup
▌
image-rgba         evolution-20090618-0    680579.98 0.12% -> 573237.66  0.16%:  1.19x speedup
▎
image-rgba      swfdec-fill-rate-4xaa-0    460296.92 0.36% -> 407464.63  0.42%:  1.13x speedup
▏
image-rgba      swfdec-fill-rate-2xaa-0    128431.95 0.47% -> 115051.86  0.42%:  1.12x speedup
▏
Slowdowns
=========
image-rgba     firefox-periodic-table-0    56837.61 0.78% -> 66055.17    3.20%:  1.09x slowdown
▏

1 files changed, 14 insertions, 7 deletions

diff --git a/src/cairo-surface-fallback-private.h b/src/cairo-surface-fallback-private.h
index cd1817809..236b74590 100644
--- a/src/cairo-surface-fallback-private.h
+++ b/src/cairo-surface-fallback-private.h
@@ -44,13 +44,15 @@
 cairo_private cairo_status_t
 _cairo_surface_fallback_paint (cairo_surface_t		*surface,
 			       cairo_operator_t		 op,
-			       const cairo_pattern_t	*source);
+			       const cairo_pattern_t	*source,
+			       cairo_clip_t		*clip);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_mask (cairo_surface_t		*surface,
 			      cairo_operator_t		 op,
 			      const cairo_pattern_t	*source,
-			      const cairo_pattern_t	*mask);
+			      const cairo_pattern_t	*mask,
+			      cairo_clip_t		*clip);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_stroke (cairo_surface_t		*surface,
@@ -61,7 +63,8 @@ _cairo_surface_fallback_stroke (cairo_surface_t		*surface,
 				cairo_matrix_t		*ctm,
 				cairo_matrix_t		*ctm_inverse,
 				double			 tolerance,
-				cairo_antialias_t	 antialias);
+				cairo_antialias_t	 antialias,
+				cairo_clip_t		*clip);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_fill (cairo_surface_t		*surface,
@@ -70,7 +73,8 @@ _cairo_surface_fallback_fill (cairo_surface_t		*surface,
 			      cairo_path_fixed_t	*path,
 			      cairo_fill_rule_t		 fill_rule,
 			      double			 tolerance,
-			      cairo_antialias_t		 antialias);
+			      cairo_antialias_t		 antialias,
+			      cairo_clip_t		*clip);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_show_glyphs (cairo_surface_t		*surface,
@@ -78,7 +82,8 @@ _cairo_surface_fallback_show_glyphs (cairo_surface_t		*surface,
 				     const cairo_pattern_t	*source,
 				     cairo_glyph_t		*glyphs,
 				     int			 num_glyphs,
-				     cairo_scaled_font_t	*scaled_font);
+				     cairo_scaled_font_t	*scaled_font,
+				     cairo_clip_t		*clip);
 
 cairo_private cairo_surface_t *
 _cairo_surface_fallback_snapshot (cairo_surface_t *surface);
@@ -95,7 +100,8 @@ _cairo_surface_fallback_composite (cairo_operator_t		 op,
 				   int				 dst_x,
 				   int				 dst_y,
 				   unsigned int			 width,
-				   unsigned int			 height);
+				   unsigned int			 height,
+				   cairo_region_t		*clip_region);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_fill_rectangles (cairo_surface_t         *surface,
@@ -116,7 +122,8 @@ _cairo_surface_fallback_composite_trapezoids (cairo_operator_t		op,
 					      unsigned int		width,
 					      unsigned int		height,
 					      cairo_trapezoid_t	       *traps,
-					      int			num_traps);
+					      int			num_traps,
+					      cairo_region_t		*clip_region);
 
 cairo_private cairo_status_t
 _cairo_surface_fallback_clone_similar (cairo_surface_t  *surface,