gm to test hairlines which fill RenderTarget

BUG=skia:

Review URL: https://codereview.chromium.org/934283002

gm/stlouisarch.cpp

@@ -0,0 +1,97 @@
+/*
+ * 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);
+
+}

gyp/gmslides.gypi

@@ -179,9 +179,10 @@
         '../gm/skbug1719.cpp',
         '../gm/smallarc.cpp',
         '../gm/smallimage.cpp',
-        '../gm/stringart.cpp',
         '../gm/spritebitmap.cpp',
         '../gm/srcmode.cpp',
+        '../gm/stlouisarch.cpp',
+        '../gm/stringart.cpp',
         '../gm/strokefill.cpp',
         '../gm/strokerect.cpp',
         '../gm/strokerects.cpp',

src/gpu/GrAAHairLinePathRenderer.cpp

@@ -184,7 +184,7 @@ int chop_conic(const SkPoint src[3], SkConic dst[4], const SkScalar weight) {
 // returns 0 if quad/conic is degen or close to it
 // in this case approx the path with lines
 // otherwise returns 1
-int is_degen_quad_or_conic(const SkPoint p[3]) {
+int is_degen_quad_or_conic(const SkPoint p[3], SkScalar* dsqd) {
     static const SkScalar gDegenerateToLineTol = SK_Scalar1;
     static const SkScalar gDegenerateToLineTolSqd =
         SkScalarMul(gDegenerateToLineTol, gDegenerateToLineTol);
@@ -194,8 +194,8 @@ int is_degen_quad_or_conic(const SkPoint p[3]) {
         return 1;
     }
 
-    SkScalar dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]);
-    if (dsqd < gDegenerateToLineTolSqd) {
+    *dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]);
+    if (*dsqd < gDegenerateToLineTolSqd) {
         return 1;
     }
 
@@ -205,24 +205,16 @@ int is_degen_quad_or_conic(const SkPoint p[3]) {
     return 0;
 }
 
+int is_degen_quad_or_conic(const SkPoint p[3]) {
+    SkScalar dsqd;
+    return is_degen_quad_or_conic(p, &dsqd);
+}
+
 // we subdivide the quads to avoid huge overfill
 // if it returns -1 then should be drawn as lines
 int num_quad_subdivs(const SkPoint p[3]) {
-    static const SkScalar gDegenerateToLineTol = SK_Scalar1;
-    static const SkScalar gDegenerateToLineTolSqd =
-        SkScalarMul(gDegenerateToLineTol, gDegenerateToLineTol);
-
-    if (p[0].distanceToSqd(p[1]) < gDegenerateToLineTolSqd ||
-        p[1].distanceToSqd(p[2]) < gDegenerateToLineTolSqd) {
-        return -1;
-    }
-
-    SkScalar dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]);
-    if (dsqd < gDegenerateToLineTolSqd) {
-        return -1;
-    }
-
-    if (p[2].distanceToLineBetweenSqd(p[1], p[0]) < gDegenerateToLineTolSqd) {
+    SkScalar dsqd;
+    if (is_degen_quad_or_conic(p, &dsqd)) {
         return -1;
     }