Bug 1224433 - Part 2: Clamp the invalidation rect to values that fit within nscoord. r=roc

gfx/2d/BaseRect.h

@@ -545,6 +545,22 @@ struct BaseRect {
     return rect;
   }
 
+  // Returns the largest rectangle that can be represented with 32-bit
+  // signed integers, centered around a point at 0,0.  As BaseRect's represent
+  // the dimensions as a top-left point with a width and height, the width
+  // and height will be the largest positive 32-bit value.  The top-left
+  // position coordinate is divided by two to center the rectangle around a
+  // point at 0,0.
+  static Sub MaxIntRect()
+  {
+    return Sub(
+      -std::numeric_limits<int32_t>::max() * 0.5,
+      -std::numeric_limits<int32_t>::max() * 0.5,
+      std::numeric_limits<int32_t>::max(),
+      std::numeric_limits<int32_t>::max()
+    );
+  };
+
   friend std::ostream& operator<<(std::ostream& stream,
       const BaseRect<T, Sub, Point, SizeT, MarginT>& aRect) {
     return stream << '(' << aRect.x << ',' << aRect.y << ','

gfx/2d/Rect.h

@@ -156,22 +156,6 @@ struct RectTyped :
         Super(F(rect.x), F(rect.y),
               F(rect.width), F(rect.height)) {}
 
-    // Returns the largest rectangle that can be represented with 32-bit
-    // signed integers, centered around a point at 0,0.  As BaseRect's represent
-    // the dimensions as a top-left point with a width and height, the width
-    // and height will be the largest positive 32-bit value.  The top-left
-    // position coordinate is divided by two to center the rectangle around a
-    // point at 0,0.
-    static RectTyped<units, F> MaxIntRect()
-    {
-      return RectTyped<units, F>(
-        -std::numeric_limits<int32_t>::max() * 0.5,
-        -std::numeric_limits<int32_t>::max() * 0.5,
-        std::numeric_limits<int32_t>::max(),
-        std::numeric_limits<int32_t>::max()
-      );
-    };
-
     void NudgeToIntegers()
     {
       NudgeToInteger(&(this->x));

layout/base/nsPresContext.cpp

@@ -2452,10 +2452,21 @@ nsPresContext::NotifyInvalidation(uint32_t aFlags)
 void
 nsPresContext::NotifyInvalidation(const nsIntRect& aRect, uint32_t aFlags)
 {
-  nsRect rect(DevPixelsToAppUnits(aRect.x),
-              DevPixelsToAppUnits(aRect.y),
-              DevPixelsToAppUnits(aRect.width),
-              DevPixelsToAppUnits(aRect.height));
+  // Prevent values from overflow after DevPixelsToAppUnits().
+  //
+  // DevPixelsTopAppUnits() will multiple a factor (60) to the value,
+  // it may make the result value over the edge (overflow) of max or
+  // min value of int32_t. Compute the max sized dev pixel rect that
+  // we can support and intersect with it.
+  nsIntRect clampedRect = nsIntRect::MaxIntRect();
+  clampedRect.ScaleInverseRoundIn(AppUnitsPerDevPixel());
+
+  clampedRect = clampedRect.Intersect(aRect);
+
+  nsRect rect(DevPixelsToAppUnits(clampedRect.x),
+              DevPixelsToAppUnits(clampedRect.y),
+              DevPixelsToAppUnits(clampedRect.width),
+              DevPixelsToAppUnits(clampedRect.height));
   NotifyInvalidation(rect, aFlags);
 }