Handle degenerate 2pt conical center values gracefully

SkMatrix::setPolyToPoly() may fail to map degenerate values.  Handle
this case explicitly, instead of assuming it never fails.

BUG=chromium:738746
TBR=

Change-Id: Ie1049b98f7e07ae5d6bdb706ba7b4a399388e5d8
Reviewed-on: https://skia-review.googlesource.com/21375
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/shaders/gradients/SkTwoPointConicalGradient.cpp b/src/shaders/gradients/SkTwoPointConicalGradient.cpp
index 0f48affc85..f79e78c310 100644
--- a/src/shaders/gradients/SkTwoPointConicalGradient.cpp
+++ b/src/shaders/gradients/SkTwoPointConicalGradient.cpp
@@ -204,7 +204,9 @@ bool SkTwoPointConicalGradient::adjustMatrixAndAppendStages(SkArenaAlloc* alloc,
     SkMatrix map_to_unit_vector;
     const SkPoint centers[2] = { fCenter1, fCenter2 };
     const SkPoint unitvec[2] = { {0, 0}, {1, 0} };
-    SkAssertResult(map_to_unit_vector.setPolyToPoly(centers, unitvec, 2));
+    if (!map_to_unit_vector.setPolyToPoly(centers, unitvec, 2)) {
+        return false;
+    }
     matrix->postConcat(map_to_unit_vector);
 
     // Since we've squashed the centers into a unit vector, we must also scale