b=358115, expose cairo transform_bounding_box, r=stuart

gfx/cairo/cairo/src/cairo-gstate.c

@@ -718,7 +718,7 @@ _cairo_gstate_backend_to_user_rectangle (cairo_gstate_t *gstate,
 
     cairo_matrix_multiply (&matrix_inverse, &gstate->ctm_inverse,
                            &gstate->target->device_transform_inverse);
-    _cairo_matrix_transform_bounding_box (
+    cairo_matrix_transform_bounding_box (
         &matrix_inverse, x1, y1, &width, &height, is_tight);
 
     *x2 = *x1 + width;

gfx/cairo/cairo/src/cairo-matrix.c

@@ -356,10 +356,10 @@ cairo_matrix_transform_point (const cairo_matrix_t *matrix, double *x, double *y
 slim_hidden_def(cairo_matrix_transform_point);
 
 void
-_cairo_matrix_transform_bounding_box (const cairo_matrix_t *matrix,
-				      double *x, double *y,
-				      double *width, double *height,
-				      cairo_bool_t *is_tight)
+cairo_matrix_transform_bounding_box (const cairo_matrix_t *matrix,
+                                     double *x, double *y,
+                                     double *width, double *height,
+                                     cairo_bool_t *is_tight)
 {
     int i;
     double quad_x[4], quad_y[4];
@@ -422,6 +422,7 @@ _cairo_matrix_transform_bounding_box (const cairo_matrix_t *matrix,
              quad_x[2] == quad_x[0] && quad_y[2] == quad_y[3]);
     }
 }
+slim_hidden_def(cairo_matrix_transform_bounding_box);
 
 static void
 _cairo_matrix_scalar_multiply (cairo_matrix_t *matrix, double scalar)

gfx/cairo/cairo/src/cairo.h

@@ -1670,6 +1670,12 @@ cairo_public void
 cairo_matrix_transform_point (const cairo_matrix_t *matrix,
 			      double *x, double *y);
 
+cairo_public void
+cairo_matrix_transform_bounding_box (const cairo_matrix_t *matrix,
+                                     double *x, double *y,
+                                     double *width, double *height,
+                                     cairo_bool_t *is_tight);
+
 /* Functions to be used while debugging (not intended for use in production code) */
 cairo_public void
 cairo_debug_reset_static_data (void);

gfx/cairo/cairo/src/cairoint.h

@@ -2383,6 +2383,7 @@ slim_hidden_proto (cairo_matrix_multiply);
 slim_hidden_proto (cairo_matrix_scale);
 slim_hidden_proto (cairo_matrix_transform_distance);
 slim_hidden_proto (cairo_matrix_transform_point);
+slim_hidden_proto (cairo_matrix_transform_bounding_box);
 slim_hidden_proto (cairo_matrix_translate);
 slim_hidden_proto (cairo_move_to);
 slim_hidden_proto (cairo_new_path);

gfx/thebes/public/gfxMatrix.h

@@ -213,7 +213,7 @@ public:
     /**
      * Transforms a point according to this matrix.
      */
-    gfxPoint Transform(const gfxPoint point) const {
+    gfxPoint Transform(const gfxPoint& point) const {
         gfxPoint ret = point;
         cairo_matrix_transform_point(&mat, &ret.x, &ret.y);
         return ret;
@@ -223,7 +223,7 @@ public:
      * Transform a distance according to this matrix. This does not apply
      * any translation components.
      */
-    gfxSize Transform(const gfxSize size) const {
+    gfxSize Transform(const gfxSize& size) const {
         gfxSize ret = size;
         cairo_matrix_transform_distance(&mat, &ret.width, &ret.height);
         return ret;
@@ -232,11 +232,22 @@ public:
     /**
      * Transforms both the point and distance according to this matrix.
      */
-    gfxRect Transform(const gfxRect rect) const {
+    gfxRect Transform(const gfxRect& rect) const {
         gfxRect ret(Transform(rect.pos), Transform(rect.size));
         return ret;
     }
 
+    gfxRect TransformBounds(const gfxRect& rect) const {
+        double x = rect.pos.x;
+        double y = rect.pos.y;
+        double width = rect.size.width;
+        double height = rect.size.height;
+
+        cairo_matrix_transform_bounding_box (&mat, &x, &y, &width, &height, NULL);
+
+        return gfxRect(x, y, width, height);
+    }
+
     /**
      * Returns the translation component of this matrix.
      */