Bug 348610 - Cairo degenerate path values are in device units. r=tor, sr=roc

layout/svg/base/src/nsSVGPathGeometryFrame.cpp

@@ -431,12 +431,10 @@ nsSVGPathGeometryFrame::UpdateCoveredRegion()
 
   SetupCairoStrokeGeometry(ctx);
   cairo_stroke_extents(ctx, &xmin, &ymin, &xmax, &ymax);
-  if (!IsDegeneratePath(xmin, ymin, xmax, ymax)) {
-    cairo_user_to_device(ctx, &xmin, &ymin);
-    cairo_user_to_device(ctx, &xmax, &ymax);
-
+  cairo_user_to_device(ctx, &xmin, &ymin);
+  cairo_user_to_device(ctx, &xmax, &ymax);
+  if (!IsDegeneratePath(xmin, ymin, xmax, ymax))
     mRect = nsSVGUtils::ToBoundingPixelRect(xmin, ymin, xmax, ymax);
-  }
 
   cairo_destroy(ctx);
 
@@ -502,14 +500,17 @@ nsSVGPathGeometryFrame::GetBBox(nsIDOMSVGRect **_retval)
 
   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_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);
-  }
 
-  cairo_user_to_device(ctx, &xmin, &ymin);
-  cairo_user_to_device(ctx, &xmax, &ymax);
+    cairo_user_to_device(ctx, &xmin, &ymin);
+    cairo_user_to_device(ctx, &xmax, &ymax);
+  }
 
   cairo_destroy(ctx);
 

layout/svg/base/src/nsSVGPathGeometryFrame.h

@@ -135,12 +135,19 @@ private:
 
   /*
    * Check for what cairo returns for the fill extents of a degenerate path
+   *
+   * @param xmin the minimum x value in device units
+   * @param ymin the minimum y value in device units
+   * @param xmax the maximum x value in device units
+   * @param ymax the maximum y value in device units
+   *
+   * @return PR_TRUE if the path is degenerate
    */
   static PRBool
   IsDegeneratePath(double xmin, double ymin, double xmax, double ymax)
   {
-    return (xmin ==  32767 && ymin ==  32767 &&
-            xmax == -32768 && ymax == -32768);
+    return (fabs(xmin - 32767) < 1 && fabs(ymin - 32767) < 1 &&
+            fabs(xmax + 32768) < 1 && fabs(ymax + 32768) < 1);
   }
 
   nsSVGMarkerProperty *GetMarkerProperty();