diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/core/SkMatrixUtils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/core/SkMatrixUtils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkMatrixUtils_DEFINED
+#define SkMatrixUtils_DEFINED
+
+#include "SkMatrix.h"
+
+/**
+ *  Number of subpixel bits used in skia's bilerp.
+ *  See SkBitmapProcState_procs.h and SkBitmapProcState_filter.h
+ */
+#define kSkSubPixelBitsForBilerp   4
+
+/**
+ *  Given a matrix and width/height, return true if the computed dst-rect would
+ *  align such that there is a 1-to-1 coorspondence between src and dst pixels.
+ *  This can be called by drawing code to see if drawBitmap can be turned into
+ *  drawSprite (which is faster).
+ *
+ *  The src-rect is defined to be { 0, 0, width, height }
+ *
+ *  The "closeness" test is based on the subpixelBits parameter. Pass 0 for
+ *  round-to-nearest behavior (e.g. nearest neighbor sampling). Pass the number
+ *  of subpixel-bits to simulate filtering.
+ */
+bool SkTreatAsSprite(const SkMatrix&, int width, int height,
+                     unsigned subpixelBits);
+
+/**
+ *  Calls SkTreatAsSprite() with default subpixelBits value to match Skia's
+ *  filter-bitmap implementation (i.e. kSkSubPixelBitsForBilerp).
+ */
+static inline bool SkTreatAsSpriteFilter(const SkMatrix& matrix,
+                                         int width, int height) {
+    return SkTreatAsSprite(matrix, width, height, kSkSubPixelBitsForBilerp);
+}
+
+/** Decomposes the upper-left 2x2 of the matrix into a rotation (represented by
+    the cosine and sine of the rotation angle), followed by a non-uniform scale,
+    followed by another rotation. If there is a reflection, one of the scale
+    factors will be negative.
+    Returns true if successful. Returns false if the matrix is degenerate.
+    */
+bool SkDecomposeUpper2x2(const SkMatrix& matrix,
+                         SkPoint* rotation1,
+                         SkPoint* scale,
+                         SkPoint* rotation2);
+
+#endif