PATCH: GL: Create glyph mask surface only once per context, enlarge on demand

From 50e7162186cd92d130879bb2bdccd79d97b43ac9 Mon Sep 17 00:00:00 2001
From: Mikko Strandborg <[email protected]>
Date: Wed, 13 Feb 2013 13:23:13 +0200
Subject: [PATCH] GL: Create glyph mask only once per GL context, enlarge on
 demand

---
 src/cairo-gl-device.c  |    8 ++++++
 src/cairo-gl-glyphs.c  |   73 ++++++++++++++++++++++++++++++++++++++++--------
 src/cairo-gl-private.h |    3 ++
 3 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/src/cairo-gl-device.c b/src/cairo-gl-device.c
index 22297b3..b7e679f 100644
--- a/src/cairo-gl-device.c
+++ b/src/cairo-gl-device.c
@@ -122,6 +122,12 @@ _gl_destroy (void *device)
 
     ctx->acquire (ctx);
 
+    if(ctx->glyph_mask)
+    {
+    	cairo_surface_destroy(ctx->glyph_mask);
+    	ctx->glyph_mask = NULL;
+    }
+
     while (! cairo_list_is_empty (&ctx->fonts)) {
 	cairo_gl_font_t *font;
 
@@ -285,6 +291,8 @@ _cairo_gl_context_init (cairo_gl_context_t *ctx)
     ctx->current_operator = -1;
     ctx->gl_flavor = gl_flavor;
 
+    ctx->glyph_mask = NULL;
+
     status = _cairo_gl_context_init_shaders (ctx);
     if (unlikely (status))
         return status;
diff --git a/src/cairo-gl-glyphs.c b/src/cairo-gl-glyphs.c
index 34b5d72..1cd3e86 100644
--- a/src/cairo-gl-glyphs.c
+++ b/src/cairo-gl-glyphs.c
@@ -219,6 +219,25 @@ cairo_gl_context_get_glyph_cache (cairo_gl_context_t *ctx,
     return CAIRO_STATUS_SUCCESS;
 }
 
+/* Clear a partial surface, assumes context has already been acquired */
+static void _cairo_gl_surface_clear_with_extent( cairo_gl_context_t *ctx,
+                                                 cairo_gl_surface_t * dst,
+                                                 cairo_rectangle_int_t *extent,
+                                                 const cairo_color_t *color,
+                                                 cairo_bool_t use_multisample )
+{
+	_cairo_gl_context_set_destination(ctx, dst, use_multisample);
+	glClearColor(color->red, color->green, color->blue, color->alpha);
+	ctx->states_cache.clear_red = color->red;
+	ctx->states_cache.clear_green = color->green;
+	ctx->states_cache.clear_blue = color->blue;
+	ctx->states_cache.clear_alpha = color->alpha;
+	glEnable(GL_SCISSOR_TEST);
+	glScissor(extent->x, extent->y, extent->width, extent->height);
+	glClear(GL_COLOR_BUFFER_BIT);
+}
+
+
 static cairo_status_t
 render_glyphs (cairo_gl_surface_t *dst,
 	       int dst_x, int dst_y,
@@ -357,18 +376,50 @@ render_glyphs_via_mask (cairo_gl_surface_t *dst,
     cairo_surface_t *mask;
     cairo_status_t status;
     cairo_bool_t has_component_alpha;
+    cairo_gl_context_t *ctx;
 
     TRACE ((stderr, "%s\n", __FUNCTION__));
 
-    /* XXX: For non-CA, this should be CAIRO_CONTENT_ALPHA to save memory */
-    mask = cairo_gl_surface_create (dst->base.device,
-                                    CAIRO_CONTENT_COLOR_ALPHA,
-                                    info->extents.width,
-                                    info->extents.height);
-    if (unlikely (mask->status))
-        return mask->status;
+    status = _cairo_gl_context_acquire (dst->base.device, &ctx);
+    if (unlikely (status))
+    		return status;
+
+    /* Lazily create the glyph mask */
+    /* Delete previous glyph mask if it is too small */
+    if(ctx->glyph_mask &&
+    		(
+    			((cairo_gl_surface_t *)ctx->glyph_mask)->width < info->extents.width ||
+    			((cairo_gl_surface_t *)ctx->glyph_mask)->height < info->extents.height )
+    		)
+    {
+    	cairo_surface_destroy(ctx->glyph_mask);
+    	ctx->glyph_mask = NULL;
+    }
+
+   	/* Create the mask if it has not yet been initialized or it was too small and deleted above. */
+    if(!ctx->glyph_mask)
+    {
+        /* XXX: For non-CA, this should be CAIRO_CONTENT_ALPHA to save memory */
+        ctx->glyph_mask = cairo_gl_surface_create (dst->base.device,
+                                        CAIRO_CONTENT_COLOR_ALPHA,
+                                        info->extents.width,
+                                        info->extents.height);
+        if (unlikely (ctx->glyph_mask->status))
+        {
+        	status = ctx->glyph_mask->status;
+        	status = _cairo_gl_context_release(ctx, status);
+            return status;
+        }
 
-    status = render_glyphs ((cairo_gl_surface_t *) mask,
+    }
+    else
+    {
+    	/* Reusing old glyph mask, clear it */
+    	_cairo_gl_surface_clear_with_extent(ctx, (cairo_gl_surface_t *)ctx->glyph_mask,
+                                            &info->extents, CAIRO_COLOR_TRANSPARENT, FALSE);
+    }
+ 
+    status = render_glyphs ((cairo_gl_surface_t *) ctx->glyph_mask,
 			    info->extents.x, info->extents.y,
 			    CAIRO_OPERATOR_ADD, NULL,
 			    info, &has_component_alpha, NULL);
@@ -377,8 +428,8 @@ render_glyphs_via_mask (cairo_gl_surface_t *dst,
 	cairo_surface_pattern_t source_pattern;
 	cairo_rectangle_int_t clip_extents;
 
-	mask->is_clear = FALSE;
-	_cairo_pattern_init_for_surface (&mask_pattern, mask);
+	ctx->glyph_mask->is_clear = FALSE;
+	_cairo_pattern_init_for_surface (&mask_pattern, ctx->glyph_mask);
 	mask_pattern.base.has_component_alpha = has_component_alpha;
 	mask_pattern.base.filter = CAIRO_FILTER_NEAREST;
 	mask_pattern.base.extend = CAIRO_EXTEND_NONE;
@@ -408,7 +459,7 @@ render_glyphs_via_mask (cairo_gl_surface_t *dst,
 	_cairo_pattern_fini (&source_pattern.base);
     }
 
-    cairo_surface_destroy (mask);
+    status = _cairo_gl_context_release(ctx, status);
 
     return status;
 }
diff --git a/src/cairo-gl-private.h b/src/cairo-gl-private.h
index 5c9193d..077f291 100644
--- a/src/cairo-gl-private.h
+++ b/src/cairo-gl-private.h
@@ -373,6 +373,9 @@ struct _cairo_gl_context {
 
     cairo_bool_t thread_aware;
 
+    /* Intermediate mask surface for glyph rendering. Created on first access, enlarged on demand. */
+    cairo_surface_t *glyph_mask;
+
     void (*acquire) (void *ctx);
     void (*release) (void *ctx);
 
-- 
1.7.9.5