Don't draw if SkShader::asNewFragmentProcessor fails.

gm/badpaint.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "gm.h"
+#include "SkCanvas.h"
+#include "SkShader.h"
+
+
+/** This GM draws with invalid paints. It should draw nothing other than the background. */
+class BadPaintGM : public skiagm::GM {
+ public:
+    BadPaintGM() {}
+
+protected:
+    SkString onShortName() override { return SkString("badpaint"); }
+
+    SkISize onISize() override { return SkISize::Make(100, 100); }
+
+    void onOnceBeforeDraw() override {
+        SkBitmap emptyBmp;
+
+        SkBitmap blueBmp;
+        blueBmp.allocN32Pixels(10, 10);
+        blueBmp.eraseColor(SK_ColorBLUE);
+
+        SkMatrix badMatrix;
+        badMatrix.setAll(0, 0, 0, 0, 0, 0, 0, 0, 0);
+
+#if 0 // This crashes pipe!
+        // Empty bitmap.
+        fPaints.push_back().setColor(SK_ColorGREEN);
+        fPaints.back().setShader(SkShader::CreateBitmapShader(emptyBmp, SkShader::kClamp_TileMode,
+                                                              SkShader::kClamp_TileMode))->unref();
+#endif
+
+        // Non-invertible local matrix.
+        fPaints.push_back().setColor(SK_ColorGREEN);
+        fPaints.back().setShader(SkShader::CreateBitmapShader(blueBmp, SkShader::kClamp_TileMode,
+                                                              SkShader::kClamp_TileMode,
+                                                              &badMatrix))->unref();
+    }
+
+    void onDraw(SkCanvas* canvas) override {
+        SkRect rect = SkRect::MakeXYWH(10, 10, 80, 80);
+        for (int i = 0; i < fPaints.count(); ++i) {
+            canvas->drawRect(rect, fPaints[i]);
+        }
+    }
+
+private:
+    SkTArray<SkPaint> fPaints;
+
+    typedef skiagm::GM INHERITED;
+};
+
+/////////////////////////////////////////////////////////////////////////////////////
+
+DEF_GM( return SkNEW(BadPaintGM); )