SkScalerContextRec::computeMatrices to return status.

src/core/SkScalerContext.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkScalerContext_DEFINED
 #define SkScalerContext_DEFINED
 
@@ skipping 128 matching lines @@
      *  underlying library will not be used, often when working directly with font data.
      *
      *  The parameters 'scale' and 'remaining' are required, the other pointers may be nullptr.
      *
      *  @param preMatrixScale the kind of scale to extract from the total matrix.
      *  @param scale the scale extracted from the total matrix (both values positive).
      *  @param remaining apply after scale to apply the total matrix.
      *  @param remainingWithoutRotation apply after scale to apply the total matrix sans rotation.
      *  @param remainingRotation apply after remainingWithoutRotation to apply the total matrix.
      *  @param total the total matrix.
+     *  @return false if the matrix was singular. The output will be valid but not invertable.
      */
-    void computeMatrices(PreMatrixScale preMatrixScale,
+    bool computeMatrices(PreMatrixScale preMatrixScale,
                          SkVector* scale, SkMatrix* remaining,
                          SkMatrix* remainingWithoutRotation = nullptr,
                          SkMatrix* remainingRotation = nullptr,
                          SkMatrix* total = nullptr);
 
     inline SkPaint::Hinting getHinting() const;
     inline void setHinting(SkPaint::Hinting);
 
     SkMask::Format getFormat() const {
         return static_cast<SkMask::Format>(fMaskFormat);
@@ skipping 219 matching lines @@
     return static_cast<SkPaint::Hinting>(hint);
 }
 
 void SkScalerContextRec::setHinting(SkPaint::Hinting hinting) {
     fFlags = (fFlags & ~SkScalerContext::kHinting_Mask) |
                                 (hinting << SkScalerContext::kHinting_Shift);
 }
 
 
 #endif