fragment_new_region(); fragment_subtract()

2 files changed, 65 insertions, 19 deletions

diff --git a/fimage.h b/fimage.h
index a44b1b4..cc357d2 100644
--- a/fimage.h
+++ b/fimage.h
@@ -3,26 +3,39 @@ typedef struct fragment_t fragment_t;
 #define TRUE 1
 #define FALSE 0
 
-fragment_t *fragment_new_blank (int width, int height);
-fragment_t *fragment_new_white (int width, int height);
-fragment_t *fragment_new_traps (int width, int height,
-				int		   n_traps,
-				pixman_trapezoid_t *traps);
-fragment_t *fragment_new_glyphs (int width, int height,
+fragment_t *fragment_new_blank  (int                   width,
+				 int                   height);
+fragment_t *fragment_new_white  (int                   width,
+				 int                   height);
+fragment_t *fragment_new_traps  (int                   width,
+				 int                   height,
+				 int                   n_traps,
+				 pixman_trapezoid_t   *traps);
+fragment_t *fragment_new_glyphs (int                   width,
+				 int                   height,
 				 pixman_glyph_cache_t *cache,
-				 int		   n_glyphs,
-				 pixman_glyph_t *glyphs);
-fragment_t *fragment_new_image (int width, int height,
-				pixman_image_t *image);
+				 int                   n_glyphs,
+				 pixman_glyph_t       *glyphs);
+fragment_t *fragment_new_image  (int                   width,
+				 int                   height,
+				 pixman_image_t       *image);
+fragment_t *fragment_new_region (pixman_region32_t    *region);
 
-/* Compute intersection of dest and source with state corresponding
- * to compositing source with dest. Then subtract the region of
- * intersection from dest and return the intersection fragment.
- * Both intersection and dest may end up empty or broken.
+/* Creates a new fragment corresponding to the intersection of
+ * source with destination. The content of this fragment is
+ * (dest OP source).
+ *
+ * The intersection is subtracted from dest. The source is not changed
  */
-fragment_t *fragment_composite (fragment_t *dest,
-				pixman_op_t op,
-				fragment_t *source);
+fragment_t *  fragment_composite (fragment_t     *dest,
+				  pixman_op_t     op,
+				  fragment_t     *source);
+/* A new fragment is create that is the same as dest with the
+ * region of other subtracted. @dest is freed (or, more likely, recycled)
+ */
+fragment_t *  fragment_subtract  (fragment_t     *dest,
+				  fragment_t     *other);
+pixman_bool_t fragment_apply     (fragment_t     *fragment,
+				  pixman_image_t *image);
 
-pixman_bool_t fragment_apply     (fragment_t *fragment,
-				pixman_image_t *image);
+void fragment_free (fragment_t *fragment);
diff --git a/fragment.c b/fragment.c
index ae01e9a..832cbb3 100644
--- a/fragment.c
+++ b/fragment.c
@@ -208,6 +208,24 @@ fragment_new_traps (int width, int height,
 }
 
 fragment_t *
+fragment_new_region (pixman_region32_t *region)
+{
+    fragment_t *fragment;
+
+    fragment = fragment_alloc (1, 1, STATE_WHITE);
+    if (fragment->broken)
+	return fragment;
+
+    if (!pixman_region32_copy (&fragment->region, region))
+    {
+	fragment_free (fragment);
+	return (fragment_t *)&broken_fragment;
+    }
+
+    return fragment;
+}
+
+fragment_t *
 fragment_new_glyphs (int width, int height,
 		     pixman_glyph_cache_t *cache,
 		     int		   n_glyphs,
@@ -226,6 +244,21 @@ fragment_new_glyphs (int width, int height,
     return fragment;
 }
 
+fragment_t *
+fragment_subtract (fragment_t *dest, fragment_t *other)
+{
+    if (dest->broken || other->broken ||
+	!pixman_region32_subtract (
+	    &dest->region, &dest->region, &(other->region)))
+    {
+	fragment_free (dest);
+
+	return (fragment_t *)&broken_fragment;
+    }
+
+    return dest;
+}
+
 static fragment_t *
 fragment_intersect (fragment_t *dest, fragment_t *source)
 {