gl: Switch to deferred rendering

1) call _cairo_gl_composite_flush() or cairo_surface_flush() where
   needed
2) Destroy texture operands when necessary
3) get rid of _cairo_gl_composite_end()

With this patch, vertices are not flushed immediately anymore, but only
when needed or when a new set of vertices is emitted that requires an
incompatible setup. This improves performance a lot in particular for
text. (gnome-terminal-vim gets 10x faster)

4 files changed, 28 insertions, 32 deletions

diff --git a/src/cairo-gl-composite.c b/src/cairo-gl-composite.c
index c77bd39d..4ced6f90 100644
--- a/src/cairo-gl-composite.c
+++ b/src/cairo-gl-composite.c
@@ -726,6 +726,11 @@ _cairo_gl_context_setup_operand (cairo_gl_context_t *ctx,
                                                  operand,
                                                  vertex_offset);
 
+    if (needs_setup) {
+        _cairo_gl_composite_flush (ctx);
+        _cairo_gl_context_destroy_operand (ctx, tex_unit);
+    }
+
     memcpy (&ctx->operands[tex_unit], operand, sizeof (cairo_gl_operand_t));
     ctx->operands[tex_unit].vertex_offset = vertex_offset;
 
@@ -858,6 +863,9 @@ _cairo_gl_set_operator (cairo_gl_context_t *ctx,
     GLenum src_factor, dst_factor;
 
     assert (op < ARRAY_LENGTH (blend_factors));
+    /* different dst and component_alpha changes cause flushes elsewhere */
+    if (ctx->current_operator != op)
+        _cairo_gl_composite_flush (ctx);
     ctx->current_operator = op;
 
     src_factor = blend_factors[op].src;
@@ -1068,6 +1076,17 @@ _cairo_gl_composite_begin (cairo_gl_composite_t *setup,
     }
 
     _cairo_gl_context_set_destination (ctx, setup->dst);
+
+    if (_cairo_gl_context_is_flushed (ctx)) {
+        glBindBufferARB (GL_ARRAY_BUFFER_ARB, ctx->vbo);
+
+        glVertexPointer (2, GL_FLOAT, ctx->vertex_size, NULL);
+        glEnableClientState (GL_VERTEX_ARRAY);
+    }
+
+    _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, dst_size, shader != NULL);
+    _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, dst_size + src_size, shader != NULL);
+
     _cairo_gl_set_operator (ctx,
                             setup->op,
                             component_alpha);
@@ -1079,16 +1098,11 @@ _cairo_gl_composite_begin (cairo_gl_composite_t *setup,
         }
         _cairo_gl_set_shader (ctx, shader);
         _cairo_gl_composite_bind_to_shader (ctx, setup);
-
-        glBindBufferARB (GL_ARRAY_BUFFER_ARB, ctx->vbo);
-
-        glVertexPointer (2, GL_FLOAT, ctx->vertex_size, NULL);
-        glEnableClientState (GL_VERTEX_ARRAY);
     }
 
-    _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_SOURCE, &setup->src, dst_size, shader != NULL);
-    _cairo_gl_context_setup_operand (ctx, CAIRO_GL_TEX_MASK, &setup->mask, dst_size + src_size, shader != NULL);
-
+    if (! _cairo_gl_context_is_flushed (ctx) &&
+        ! cairo_region_equal (ctx->clip_region, setup->clip_region))
+        _cairo_gl_composite_flush (ctx);
     cairo_region_destroy (ctx->clip_region);
     ctx->clip_region = cairo_region_reference (setup->clip_region);
     if (ctx->clip_region)
@@ -1293,16 +1307,6 @@ _cairo_gl_composite_emit_glyph (cairo_gl_context_t *ctx,
 }
 
 void
-_cairo_gl_composite_end (cairo_gl_context_t *ctx,
-                         cairo_gl_composite_t *setup)
-{
-    _cairo_gl_composite_flush (ctx);
-
-    _cairo_gl_context_destroy_operand (ctx, CAIRO_GL_TEX_SOURCE);
-    _cairo_gl_context_destroy_operand (ctx, CAIRO_GL_TEX_MASK);
-}
-
-void
 _cairo_gl_composite_fini (cairo_gl_composite_t *setup)
 {
     _cairo_gl_operand_destroy (&setup->src);
diff --git a/src/cairo-gl-glyphs.c b/src/cairo-gl-glyphs.c
index 91d3c20d..a19174d3 100644
--- a/src/cairo-gl-glyphs.c
+++ b/src/cairo-gl-glyphs.c
@@ -293,9 +293,6 @@ _render_glyphs (cairo_gl_surface_t	*dst,
 	}
 
 	if (scaled_glyph->surface->format != last_format) {
-            if (last_format != CAIRO_FORMAT_INVALID)
-                _cairo_gl_composite_end (ctx, &setup);
-
 	    cache = cairo_gl_context_get_glyph_cache (ctx,
 						      scaled_glyph->surface->format);
 
@@ -350,7 +347,6 @@ _render_glyphs (cairo_gl_surface_t	*dst,
 
     status = CAIRO_STATUS_SUCCESS;
   FINISH:
-    _cairo_gl_composite_end (ctx, &setup);
     _cairo_scaled_font_thaw_cache (scaled_font);
 
     _cairo_gl_context_release (ctx);
diff --git a/src/cairo-gl-private.h b/src/cairo-gl-private.h
index 07333042..3554c67a 100644
--- a/src/cairo-gl-private.h
+++ b/src/cairo-gl-private.h
@@ -348,10 +348,6 @@ cairo_private void
 _cairo_gl_composite_flush (cairo_gl_context_t *ctx);
 
 cairo_private void
-_cairo_gl_composite_end (cairo_gl_context_t *ctx,
-                         cairo_gl_composite_t *setup);
-
-cairo_private void
 _cairo_gl_context_destroy_operand (cairo_gl_context_t *ctx,
                                    cairo_gl_tex_t tex_unit);
 
diff --git a/src/cairo-gl-surface.c b/src/cairo-gl-surface.c
index 59053a43..f7a16ae9 100644
--- a/src/cairo-gl-surface.c
+++ b/src/cairo-gl-surface.c
@@ -440,6 +440,8 @@ cairo_gl_surface_swapbuffers (cairo_surface_t *abstract_surface)
         if (_cairo_gl_context_acquire (surface->base.device, &ctx))
             return;
 
+        cairo_surface_flush (abstract_surface);
+
 	ctx->swap_buffers (ctx, surface);
 
         _cairo_gl_context_release (ctx);
@@ -553,11 +555,13 @@ _cairo_gl_surface_draw_image (cairo_gl_surface_t *dst,
 	    color.blue = 0.0;
 	    color.alpha = 1.0;
 
+            _cairo_gl_composite_flush (ctx);
 	    glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_TRUE);
 	    _cairo_gl_surface_fill_rectangles (dst,
 					       CAIRO_OPERATOR_SOURCE,
 					       &color,
 					       &rect, 1);
+            _cairo_gl_composite_flush (ctx);
 	    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 	}
     } else {
@@ -652,6 +656,8 @@ _cairo_gl_surface_get_image (cairo_gl_surface_t      *surface,
     status = _cairo_gl_context_acquire (surface->base.device, &ctx);
     if (unlikely (status))
         return status;
+
+    _cairo_gl_composite_flush (ctx);
     _cairo_gl_context_set_destination (ctx, surface);
 
     glPixelStorei (GL_PACK_ALIGNMENT, 1);
@@ -951,7 +957,6 @@ _cairo_gl_surface_composite (cairo_operator_t		  op,
                                        0);
     }
 
-    _cairo_gl_composite_end (ctx, &setup);
     _cairo_gl_context_release (ctx);
 
   CLEANUP:
@@ -1063,7 +1068,6 @@ _cairo_gl_surface_fill_rectangles (void			   *abstract_dst,
                                        0);
     }
 
-    _cairo_gl_composite_end (ctx, &setup);
     _cairo_gl_context_release (ctx);
 
   CLEANUP:
@@ -1166,10 +1170,6 @@ _cairo_gl_surface_span_renderer_destroy (void *abstract_renderer)
 static cairo_status_t
 _cairo_gl_surface_span_renderer_finish (void *abstract_renderer)
 {
-    cairo_gl_surface_span_renderer_t *renderer = abstract_renderer;
-
-    _cairo_gl_composite_end (renderer->ctx, &renderer->setup);
-
     return CAIRO_STATUS_SUCCESS;
 }