gm to test hairlines which fill RenderTarget

gm/stlouisarch.cpp

Index: gm/stlouisarch.cpp
diff --git a/gm/stlouisarch.cpp b/gm/stlouisarch.cpp
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+++ b/gm/stlouisarch.cpp
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+/*
+ * 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 "SkTArray.h"
+
+namespace skiagm {
+
+// this GM tests hairlines which fill nearly the entire render target
+class StLouisArchGM : public GM {
+protected:
+    SkString onShortName() SK_OVERRIDE {
+        return SkString("stlouisarch");
+    }
+
+    SkISize onISize() SK_OVERRIDE { return SkISize::Make((int)kWidth, (int)kHeight); }
+
+    void onOnceBeforeDraw() SK_OVERRIDE {
+        {
+            SkPath* bigQuad = &fPaths.push_back();
+            bigQuad->moveTo(0, 0);
+            bigQuad->quadTo(kWidth/2, kHeight, kWidth, 0);
+        }
+
+        {
+            SkPath* degenBigQuad = &fPaths.push_back();
+            SkScalar yPos = kHeight / 2 + 10;
+            degenBigQuad->moveTo(0, yPos);
+            degenBigQuad->quadTo(0, yPos, kWidth, yPos);
+        }
+
+
+        {
+            SkPath* bigCubic = &fPaths.push_back();
+            bigCubic->moveTo(0, 0);
+            bigCubic->cubicTo(0, kHeight,
+                              kWidth, kHeight,
+                              kWidth, 0);
+        }
+
+        {
+            SkPath* degenBigCubic = &fPaths.push_back();
+            SkScalar yPos = kHeight / 2;
+            degenBigCubic->moveTo(0, yPos);
+            degenBigCubic->cubicTo(0, yPos,
+                                   0, yPos,
+                                   kWidth, yPos);
+        }
+
+        {
+            SkPath* bigConic = &fPaths.push_back();
+            bigConic->moveTo(0, 0);
+            bigConic->conicTo(kWidth/2, kHeight, kWidth, 0, .5);
+        }
+
+        {
+            SkPath* degenBigConic = &fPaths.push_back();
+            SkScalar yPos = kHeight / 2 - 10;
+            degenBigConic->moveTo(0, yPos);
+            degenBigConic->conicTo(0, yPos, kWidth, yPos, .5);
+        }
+    }
+
+    void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        canvas->save();
+        canvas->scale(1, -1);
+        canvas->translate(0, -kHeight);
+        for (int p = 0; p < fPaths.count(); ++p) {
+            SkPaint paint;
+            paint.setARGB(0xff, 0, 0, 0);
+            paint.setAntiAlias(true);
+            paint.setStyle(SkPaint::kStroke_Style);
+            paint.setStrokeWidth(0);
+            canvas->drawPath(fPaths[p], paint);
+        }
+        canvas->restore();
+    }
+
+    const SkScalar kWidth = 256;
+    const SkScalar kHeight = 256;
+
+private:
+    SkTArray<SkPath> fPaths;
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new StLouisArchGM; }
+static GMRegistry reg(MyFactory);
+
+}