New GM to test SkDrawFilter

gm/drawfilter.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 "SkBlurMask.h"
+#include "SkBlurMaskFilter.h"
+#include "SkCanvas.h"
+#include "SkDrawFilter.h"
+#include "SkPaint.h"
+
+/**
+ * Initial test coverage for SkDrawFilter.
+ * Draws two rectangles; if draw filters are broken, they will match.
+ * If draw filters are working correctly, the first will be blue and blurred,
+ * the second red and sharp.
+ */
+
+class TestFilter : public SkDrawFilter {
+public:
+    bool filter(SkPaint* p, Type) SK_OVERRIDE {
+        p->setColor(SK_ColorRED);
+        p->setMaskFilter(NULL);
+        return true;
+    }
+};
+
+class DrawFilterGM : public skiagm::GM {
+    SkAutoTUnref<SkMaskFilter> fBlur;
+
+protected:
+    SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(320, 240);
+    }
+
+    SkString onShortName() SK_OVERRIDE {
+        return SkString("drawfilter");
+    }
+
+    void onOnceBeforeDraw() SK_OVERRIDE {
+        fBlur.reset(SkBlurMaskFilter::Create(kNormal_SkBlurStyle,
+                    SkBlurMask::ConvertRadiusToSigma(10.0f),
+                    kLow_SkBlurQuality));
+    }
+
+    void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkPaint p;
+        p.setColor(SK_ColorBLUE);
+        p.setMaskFilter(fBlur.get());
+        SkRect r = { 20, 20, 100, 100 };
+        canvas->setDrawFilter(NULL);
+        canvas->drawRect(r, p);
+        TestFilter redNoBlur;
+        canvas->setDrawFilter(&redNoBlur);
+        canvas->translate(120.0f, 40.0f);
+        canvas->drawRect(r, p);
+
+        // Must unset if the DrawFilter is from the stack to avoid refcount errors!
+        canvas->setDrawFilter(NULL);
+    }
+
+private:
+    typedef GM INHERITED;
+};
+
+static skiagm::GM* MyFactory(void*) { return new DrawFilterGM; }
+static skiagm::GMRegistry reg(MyFactory);
+