Bug 344887 - ASSERTION: Don't try to move the root widget to something non-zero. r=tor, sr=roc

layout/svg/base/src/nsSVGPathGeometryFrame.cpp

@@ -433,12 +433,13 @@ nsSVGPathGeometryFrame::UpdateCoveredRegion()
     } else
       cairo_fill_extents(ctx, &xmin, &ymin, &xmax, &ymax);
 
-    cairo_user_to_device(ctx, &xmin, &ymin);
-    cairo_user_to_device(ctx, &xmax, &ymax);
+    if (!IsDegeneratePath(xmin, ymin, xmax, ymax)) {
+      cairo_user_to_device(ctx, &xmin, &ymin);
+      cairo_user_to_device(ctx, &xmax, &ymax);
 
+      mRect = nsSVGUtils::ToBoundingPixelRect(xmin, ymin, xmax, ymax);
+    }
     cairo_destroy(ctx);
-
-    mRect = nsSVGUtils::ToBoundingPixelRect(xmin, ymin, xmax, ymax);
   }
 
   // Add in markers
@@ -503,11 +504,7 @@ nsSVGPathGeometryFrame::GetBBox(nsIDOMSVGRect **_retval)
 
   cairo_fill_extents(ctx, &xmin, &ymin, &xmax, &ymax);
 
-  /* cairo_fill_extents doesn't work on degenerate paths */
-  if (xmin ==  32767 &&
-      ymin ==  32767 &&
-      xmax == -32768 &&
-      ymax == -32768) {
+  if (IsDegeneratePath(xmin, ymin, xmax, ymax)) {
     /* cairo_stroke_extents doesn't work with stroke width zero, fudge */
     cairo_set_line_width(ctx, 0.0001);
     cairo_stroke_extents(ctx, &xmin, &ymin, &xmax, &ymax);

layout/svg/base/src/nsSVGPathGeometryFrame.h

@@ -133,6 +133,16 @@ private:
   void Render(nsISVGRendererCanvas *aCanvas);
   void GeneratePath(cairo_t *ctx, nsISVGCairoCanvas* aCanvas);
 
+  /*
+   * Check for what cairo returns for the fill extents of a degenerate path
+   */
+  static PRBool
+  IsDegeneratePath(double xmin, double ymin, double xmax, double ymax)
+  {
+    return (xmin ==  32767 && ymin ==  32767 &&
+            xmax == -32768 && ymax == -32768);
+  }
+
   nsSVGMarkerProperty *GetMarkerProperty();
   void GetMarkerFromStyle(nsSVGMarkerFrame   **aResult,
                           nsSVGMarkerProperty *property,