wrapper: intersect with target extents

Treat the target extents as an implicit clip for computing the maximal
operation extents.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 30 insertions, 19 deletions

diff --git a/src/cairo-surface-wrapper.c b/src/cairo-surface-wrapper.c
index d2d971dec..48bd30a55 100644
--- a/src/cairo-surface-wrapper.c
+++ b/src/cairo-surface-wrapper.c
@@ -621,35 +621,46 @@ cairo_bool_t
 _cairo_surface_wrapper_get_target_extents (cairo_surface_wrapper_t *wrapper,
 					   cairo_rectangle_int_t *extents)
 {
-    cairo_rectangle_int_t tmp;
+    cairo_rectangle_int_t clip;
+    cairo_bool_t has_clip;
 
+    has_clip = _cairo_surface_get_extents (wrapper->target, &clip);
     if (wrapper->clip) {
-	const cairo_rectangle_int_t *r = _cairo_clip_get_extents (wrapper->clip);
-	if (wrapper->needs_transform) {
-	    cairo_matrix_t m;
-	    double x1, y1, x2, y2;
+	if (has_clip) {
+	    if (! _cairo_rectangle_intersect (&clip,
+					      _cairo_clip_get_extents (wrapper->clip)))
+		return FALSE;
+	} else {
+	    has_clip = TRUE;
+	    clip = *_cairo_clip_get_extents (wrapper->clip);
+	}
+    }
 
-	    _cairo_surface_wrapper_get_inverse_transform (wrapper, &m);
+    if (has_clip && wrapper->needs_transform) {
+	cairo_matrix_t m;
+	double x1, y1, x2, y2;
 
-	    x1 = r->x;
-	    y1 = r->y;
-	    x2 = r->x + r->width;
-	    y2 = r->y + r->height;
+	_cairo_surface_wrapper_get_inverse_transform (wrapper, &m);
 
-	    _cairo_matrix_transform_bounding_box (&m, &x1, &y1, &x2, &y2, NULL);
+	x1 = clip.x;
+	y1 = clip.y;
+	x2 = clip.x + clip.width;
+	y2 = clip.y + clip.height;
 
-	    tmp.x = floor (x1);
-	    tmp.y = floor (y1);
-	    tmp.width  = ceil (x2) - tmp.x;
-	    tmp.height = ceil (y2) - tmp.y;
-	    r = &tmp;
-	}
+	_cairo_matrix_transform_bounding_box (&m, &x1, &y1, &x2, &y2, NULL);
+
+	clip.x = floor (x1);
+	clip.y = floor (y1);
+	clip.width  = ceil (x2) - clip.x;
+	clip.height = ceil (y2) - clip.y;
+    }
 
+    if (has_clip) {
 	if (wrapper->has_extents) {
 	    *extents = wrapper->extents;
-	    return _cairo_rectangle_intersect (extents, r);
+	    return _cairo_rectangle_intersect (extents, &clip);
 	} else {
-	    *extents = *r;
+	    *extents = clip;
 	    return TRUE;
 	}
     } else if (wrapper->has_extents) {