b=379436, borders on elements > 2^15px drawn backwards, r=dbaron

gfx/thebes/public/gfxRect.h

@@ -86,6 +86,12 @@ struct THEBES_API gfxRect {
     gfxPoint TopRight() const { return pos + gfxSize(size.width, 0.0); }
     gfxPoint BottomLeft() const { return pos + gfxSize(0.0, size.height); }
     gfxPoint BottomRight() const { return pos + size; }
+
+    /* Conditions this border to Cairo's max coordinate space.
+     * The caller can check IsEmpty() after Condition() -- if it's TRUE,
+     * the caller can possibly avoid doing any extra rendering.
+     */
+    void Condition();
 };
 
 #endif /* GFX_RECT_H */

gfx/thebes/src/gfxRect.cpp

@@ -87,3 +87,48 @@ gfxRect::Round()
     size.width = x1 - x0;
     size.height = y1 - y0;
 }
+
+/* Clamp r to CAIRO_COORD_MIN .. CAIRO_COORD_MAX
+ * these are to be device coordinates.
+ */
+
+#define CAIRO_COORD_MAX (16382.0)
+#define CAIRO_COORD_MIN (-16383.0)
+
+void
+gfxRect::Condition()
+{
+    // if either x or y is way out of bounds;
+    // note that we don't handle negative w/h here
+    if (pos.x > CAIRO_COORD_MAX) {
+        pos.x = CAIRO_COORD_MAX;
+        size.width = 0.0;
+    } 
+
+    if (pos.y > CAIRO_COORD_MAX) {
+        pos.y = CAIRO_COORD_MAX;
+        size.height = 0.0;
+    }
+
+    if (pos.x < CAIRO_COORD_MIN) {
+        size.width += pos.x - CAIRO_COORD_MIN;
+        if (size.width < 0.0)
+            size.width = 0.0;
+        pos.x = CAIRO_COORD_MIN;
+    }
+
+    if (pos.y < CAIRO_COORD_MIN) {
+        size.height += pos.y - CAIRO_COORD_MIN;
+        if (size.height < 0.0)
+            size.height = 0.0;
+        pos.y = CAIRO_COORD_MIN;
+    }
+
+    if (pos.x + size.width > CAIRO_COORD_MAX) {
+        size.width = CAIRO_COORD_MAX - pos.x;
+    }
+
+    if (pos.y + size.height > CAIRO_COORD_MAX) {
+        size.height = CAIRO_COORD_MAX - pos.y;
+    }
+}

layout/base/nsCSSRendering.cpp

@@ -2261,11 +2261,19 @@ nsCSSRendering::PaintBorder(nsPresContext* aPresContext,
                 oRect.size.width - (border.left + border.right) / (2.0 * twipsPerPixel),
                 oRect.size.height - (border.top + border.bottom) / (2.0 * twipsPerPixel));
 
-
   S(" oRect: "), S(oRect), SN();
   S(" iRect: "), S(iRect), SN();
   S(" lRect: "), S(lRect), SN();
 
+  // if conditioning the outside rect failed, then ail -- the outside
+  // rect is supposed to enclose the entire border
+  oRect.Condition();
+  if (oRect.IsEmpty())
+    return;
+
+  iRect.Condition();
+  lRect.Condition();
+
   ctx->Save();
 
 #if 0
@@ -2539,6 +2547,15 @@ nsCSSRendering::PaintOutline(nsPresContext* aPresContext,
                 oRect.size.width - (2*width) / (2.0 * twipsPerPixel),
                 oRect.size.height - (2*width) / (2.0 * twipsPerPixel));
 
+  // if conditioning the outside rect failed, then bail -- the outside
+  // rect is supposed to enclose the entire outline
+  oRect.Condition();
+  if (oRect.IsEmpty())
+    return;
+
+  iRect.Condition();
+  lRect.Condition();
+
   nscolor outlineColor;
 
   // PR_FALSE means use the initial color; PR_TRUE means a color was