background: Don't render with blending when we don't need to

If we have an opaque background image, then we shouldn't need to blend
against anything for it to work. Turn off blending in this case.
This commit is contained in:
Jasper St. Pierre 2014-08-07 12:38:42 -04:00
parent d72bf0cd5d
commit 2d6954186e

View File

@ -288,6 +288,26 @@ get_wrap_mode (MetaBackground *self)
} }
} }
static gboolean
texture_has_alpha (CoglTexture *texture)
{
if (!texture)
return FALSE;
switch (cogl_texture_get_components (texture))
{
case COGL_TEXTURE_COMPONENTS_A:
case COGL_TEXTURE_COMPONENTS_RGBA:
return TRUE;
case COGL_TEXTURE_COMPONENTS_RG:
case COGL_TEXTURE_COMPONENTS_RGB:
case COGL_TEXTURE_COMPONENTS_DEPTH:
return FALSE;
default:
g_assert_not_reached ();
}
}
static ClutterPaintNode * static ClutterPaintNode *
meta_background_paint_node_new (MetaBackground *self, meta_background_paint_node_new (MetaBackground *self,
ClutterActor *actor) ClutterActor *actor)
@ -296,6 +316,7 @@ meta_background_paint_node_new (MetaBackground *self,
ClutterPaintNode *node; ClutterPaintNode *node;
guint8 opacity; guint8 opacity;
guint8 color_component; guint8 color_component;
gboolean needs_blending;
opacity = clutter_actor_get_paint_opacity (actor); opacity = clutter_actor_get_paint_opacity (actor);
color_component = (guint8) (0.5 + opacity * priv->brightness); color_component = (guint8) (0.5 + opacity * priv->brightness);
@ -308,6 +329,13 @@ meta_background_paint_node_new (MetaBackground *self,
node = clutter_pipeline_node_new (priv->pipeline); node = clutter_pipeline_node_new (priv->pipeline);
needs_blending = (opacity < 255) || (texture_has_alpha (priv->texture));
if (needs_blending)
cogl_pipeline_set_blend (priv->pipeline, "RGBA = ADD (SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))", NULL);
else
cogl_pipeline_set_blend (priv->pipeline, "RGBA = ADD (SRC_COLOR, 0)", NULL);
return node; return node;
} }