Fix degenerate and near-degenerate hairlines on the gpu
R=robertphillips@google.com, bsalomon@google.com
Author: bsalomon@google.com
Review URL: https://chromiumcodereview.appspot.com/16035002
git-svn-id: http://skia.googlecode.com/svn/trunk@9279 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gm/hairlines.cpp b/gm/hairlines.cpp
new file mode 100644
index 0000000..e73cc6d
--- /dev/null
+++ b/gm/hairlines.cpp
@@ -0,0 +1,143 @@
+/*
+ * Copyright 2013 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 {
+
+class HairlinesGM : public GM {
+protected:
+
+ virtual SkString onShortName() SK_OVERRIDE {
+ return SkString("hairlines");
+ }
+
+ virtual SkISize onISize() { return make_isize(800, 600); }
+
+ virtual void onOnceBeforeDraw() SK_OVERRIDE {
+ {
+ SkPath* lineAnglesPath = &fPaths.push_back();
+ enum {
+ kNumAngles = 15,
+ kRadius = 40,
+ };
+ for (int i = 0; i < kNumAngles; ++i) {
+ SkScalar angle = SK_ScalarPI * SkIntToScalar(i) / kNumAngles;
+ SkScalar x = kRadius * SkScalarCos(angle);
+ SkScalar y = kRadius * SkScalarSin(angle);
+ lineAnglesPath->moveTo(x, y);
+ lineAnglesPath->lineTo(-x, -y);
+ }
+ }
+
+ {
+ SkPath* kindaTightQuad = &fPaths.push_back();
+ kindaTightQuad->moveTo(0, -10 * SK_Scalar1);
+ kindaTightQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), -10 * SK_Scalar1, 0);
+ }
+
+ {
+ SkPath* tightQuad = &fPaths.push_back();
+ tightQuad->moveTo(0, -5 * SK_Scalar1);
+ tightQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), -5 * SK_Scalar1, 0);
+ }
+
+ {
+ SkPath* tighterQuad = &fPaths.push_back();
+ tighterQuad->moveTo(0, -2 * SK_Scalar1);
+ tighterQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), -2 * SK_Scalar1, 0);
+ }
+
+ {
+ SkPath* unevenTighterQuad = &fPaths.push_back();
+ unevenTighterQuad->moveTo(0, -1 * SK_Scalar1);
+ SkPoint p;
+ p.set(-2 * SK_Scalar1 + 3 * SkIntToScalar(102) / 4, SkIntToScalar(75));
+ unevenTighterQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), p.fX, p.fY);
+ }
+
+ {
+ SkPath* reallyTightQuad = &fPaths.push_back();
+ reallyTightQuad->moveTo(0, -1 * SK_Scalar1);
+ reallyTightQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), -1 * SK_Scalar1, 0);
+ }
+
+ {
+ SkPath* closedQuad = &fPaths.push_back();
+ closedQuad->moveTo(0, -0);
+ closedQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100), 0, 0);
+ }
+
+ {
+ SkPath* unevenClosedQuad = &fPaths.push_back();
+ unevenClosedQuad->moveTo(0, -0);
+ unevenClosedQuad->quadTo(SkIntToScalar(100), SkIntToScalar(100),
+ SkIntToScalar(75), SkIntToScalar(75));
+ }
+ }
+
+ virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+ static const SkAlpha kAlphaValue[] = { 0xFF, 0x40 };
+
+ enum {
+ kMargin = 5,
+ };
+ int wrapX = canvas->getDeviceSize().fWidth - kMargin;
+
+ SkScalar maxH = 0;
+ canvas->translate(SkIntToScalar(kMargin), SkIntToScalar(kMargin));
+ canvas->save();
+
+ SkScalar x = SkIntToScalar(kMargin);
+ for (int p = 0; p < fPaths.count(); ++p) {
+ for (size_t a = 0; a < SK_ARRAY_COUNT(kAlphaValue); ++a) {
+ for (int aa = 0; aa < 2; ++aa) {
+ const SkRect& bounds = fPaths[p].getBounds();
+
+ if (x + bounds.width() > wrapX) {
+ canvas->restore();
+ canvas->translate(0, maxH + SkIntToScalar(kMargin));
+ canvas->save();
+ maxH = 0;
+ x = SkIntToScalar(kMargin);
+ }
+
+ SkPaint paint;
+ paint.setARGB(kAlphaValue[a], 0, 0, 0);
+ paint.setAntiAlias(SkToBool(aa));
+ paint.setStyle(SkPaint::kStroke_Style);
+ paint.setStrokeWidth(0);
+
+ canvas->save();
+ canvas->translate(-bounds.fLeft, -bounds.fTop);
+ canvas->drawPath(fPaths[p], paint);
+ canvas->restore();
+
+ maxH = SkMaxScalar(maxH, bounds.height());
+
+ SkScalar dx = bounds.width() + SkIntToScalar(kMargin);
+ x += dx;
+ canvas->translate(dx, 0);
+ }
+ }
+ }
+ canvas->restore();
+ }
+
+private:
+ SkTArray<SkPath> fPaths;
+ typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+static GM* MyFactory(void*) { return new HairlinesGM; }
+static GMRegistry reg(MyFactory);
+
+}