From 0815265fb2a3001d78adb2a1dbcc3d198a9a2093 Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Fri, 31 Jan 2014 16:58:26 +1300
Subject: [PATCH] Bug 952011 - Don't restrict Untransform points/rects to the
 child bounds if we're not a projective matrix. r=bjacob

---
 gfx/thebes/gfx3DMatrix.cpp | 15 +++++++++++++++
 gfx/thebes/gfx3DMatrix.h   |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/gfx/thebes/gfx3DMatrix.cpp b/gfx/thebes/gfx3DMatrix.cpp
index e8e62f96c228..11bc0cd80052 100644
--- a/gfx/thebes/gfx3DMatrix.cpp
+++ b/gfx/thebes/gfx3DMatrix.cpp
@@ -721,6 +721,14 @@ gfx3DMatrix::Is2D(gfxMatrix* aMatrix) const
   return true;
 }
 
+bool
+gfx3DMatrix::IsProjective() const
+{
+  return _14 != 0.0f || _24 != 0.0f ||
+         _34 != 0.0f || _44 != 1.0f;
+}
+
+
 bool
 gfx3DMatrix::CanDraw2D(gfxMatrix* aMatrix) const
 {
@@ -810,6 +818,9 @@ gfxRect gfx3DMatrix::ProjectRectBounds(const gfxRect& aRect) const
 
 gfxRect gfx3DMatrix::UntransformBounds(const gfxRect& aRect, const gfxRect& aChildBounds) const
 {
+  if (!IsProjective()) {
+    return Inverse().TransformBounds(aRect);
+  }
   gfxRect bounds = TransformBounds(aChildBounds);
 
   gfxRect rect = aRect.Intersect(bounds);
@@ -819,6 +830,10 @@ gfxRect gfx3DMatrix::UntransformBounds(const gfxRect& aRect, const gfxRect& aChi
 
 bool gfx3DMatrix::UntransformPoint(const gfxPoint& aPoint, const gfxRect& aChildBounds, gfxPoint* aOut) const
 {
+  if (!IsProjective()) {
+    *aOut = Inverse().Transform(aPoint);
+    return true;
+  }
   gfxRect bounds = TransformBounds(aChildBounds);
 
   if (!bounds.Contains(aPoint)) {
diff --git a/gfx/thebes/gfx3DMatrix.h b/gfx/thebes/gfx3DMatrix.h
index 38a3ef96202c..d9d7b959464b 100644
--- a/gfx/thebes/gfx3DMatrix.h
+++ b/gfx/thebes/gfx3DMatrix.h
@@ -81,6 +81,8 @@ public:
   bool Is2D(gfxMatrix* aMatrix) const;
   bool Is2D() const;
 
+  bool IsProjective() const;
+
   /**
    * Returns true if the matrix can be reduced to a 2D affine transformation
    * (i.e. as obtained by From2D). If it is, optionally returns the 2D