Handle more cases by assuming no-super-luminescent colors.

2 files changed, 15 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 160dcc8c..be559920 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2005-05-11  Owen Taylor  <otaylor@redhat.com>
+
+	* src/cairo-win32-surface.c (categorize_solid_dest_operator):
+	Handle more cases by assuming no-super-luminescent colors.
+
 2005-05-11  T Rowley  <tim.rowley@gmail.com>
 
 	* src/cairo-atsui-font.c:
diff --git a/src/cairo-win32-surface.c b/src/cairo-win32-surface.c
index 7d544e49..9df86380 100644
--- a/src/cairo-win32-surface.c
+++ b/src/cairo-win32-surface.c
@@ -604,12 +604,15 @@ _cairo_win32_surface_composite (cairo_operator_t	operator,
 
 /* This big function tells us how to optimize operators for the
  * case of solid destination and constant-alpha source
+ *
+ * NOTE: This function needs revisiting if we add support for
+ *       super-luminescent colors (a == 0, r,g,b > 0)
  */
 static enum { DO_CLEAR, DO_SOURCE, DO_NOTHING, DO_UNSUPPORTED }
 categorize_solid_dest_operator (cairo_operator_t operator,
 				unsigned short   alpha)
 {
-    enum { SOURCE_TRANSPARENT, SOURCE_SOLID, SOURCE_OTHER } source;
+    enum { SOURCE_TRANSPARENT, SOURCE_LIGHT, SOURCE_SOLID, SOURCE_OTHER } source;
 
     if (alpha >= 0xff00)
 	source = SOURCE_SOLID;
@@ -633,6 +636,8 @@ categorize_solid_dest_operator (cairo_operator_t operator,
     case CAIRO_OPERATOR_ATOP:     /* Ab           1 - Aa */
 	if (source == SOURCE_SOLID)
 	    return DO_SOURCE;
+	else if (source == SOURCE_TRANSPARENT)
+	    return DO_NOTHING;
 	else
 	    return DO_UNSUPPORTED;
 	break;
@@ -664,7 +669,10 @@ categorize_solid_dest_operator (cairo_operator_t operator,
 	break;
 	
     case CAIRO_OPERATOR_ADD:	  /* 1                1 */
-	return DO_UNSUPPORTED;
+	if (source == SOURCE_TRANSPARENT)
+	    return DO_NOTHING;
+	else
+	    return DO_UNSUPPORTED;
 	break;
     }	
 }