add a GM case to ensure path effect for big filled/stroked text is correctly rendered

gm/patheffect4bigtext.cpp

+/*
+ * Copyright 2014 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 "Sk2DPathEffect.h"
+#include "SkCanvas.h"
+
+// PathEffect for a text impacts the paths generated for the text. Big text
+// and hairline text are drawn by paths, instead of using scalercontext and
+// caching the glyph. This GM wants to ensure that we draw filled, thick-stroked,
+// and hairline-stroked text with path effect correctly on both sides of the
+// threshold.
+static void draw_text(SkCanvas* canvas, const SkPaint& paint) {
+    SkPaint p(paint);
+
+    SkPoint loc = { 250, 225 };
+    p.setColor(SK_ColorRED);
+
+    canvas->drawText("P", 1, loc.fX - 225, loc.fY, p);
+    canvas->drawPosText("P", 1, &loc, p);
+
+    loc.set(250, 450);
+    p.setColor(SK_ColorGREEN);
+    p.setStyle(SkPaint::kStroke_Style);
+    p.setStrokeWidth(10);
+    canvas->drawText("P", 1, loc.fX - 225, loc.fY, p);
+    canvas->drawPosText("P", 1, &loc, p);
+
+    loc.set(250, 675);
+    p.setColor(SK_ColorBLUE);
+    p.setStrokeWidth(0);
+    canvas->drawText("P", 1, loc.fX - 225, loc.fY, p);
+    canvas->drawPosText("P", 1, &loc, p);
+}
+
+class PathEffect4BigTextGM : public skiagm::GM {
+public:
+    PathEffect4BigTextGM() {}
+
+protected:
+    virtual uint32_t onGetFlags() const SK_OVERRIDE {
+        return kSkipTiled_Flag;
+    }
+
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("patheffect4bigtext");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        return SkISize::Make(900, 700);
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        SkPaint paint;
+        paint.setAntiAlias(true);
+
+        SkMatrix lattice;
+        lattice.setScale(SK_Scalar1, SK_Scalar1 * 6, 0, 0);
+        lattice.postRotate(SkIntToScalar(30), 0, 0);
+        paint.setPathEffect(SkLine2DPathEffect::Create(SK_Scalar1 * 2, lattice))->unref();
+
+        SkScalar textSize[2] = {240, 270};
+        for (size_t i = 0; i < SK_ARRAY_COUNT(textSize); ++i) {
+            paint.setTextSize(textSize[i]);
+            draw_text(canvas, paint);
+            canvas->translate(450, 0);
+        }
+    }
+
+private:
+    typedef skiagm::GM INHERITED;
+};
+
+DEF_GM( return SkNEW(PathEffect4BigTextGM); )