Add GMs for testing drawArc.
This is in preparation for virtualizing this on SkCanvas/SkDevice.
Tests the following variations:
aa and non-aa
stroke/hairline/fill
cap types
using center point and not
BUG=skia:5227
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2264593002
Review-Url: https://codereview.chromium.org/2264593002
diff --git a/gm/circulararcs.cpp b/gm/circulararcs.cpp
new file mode 100644
index 0000000..7bc40de
--- /dev/null
+++ b/gm/circulararcs.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <functional>
+#include "SkCanvas.h"
+#include "gm.h"
+
+static constexpr SkScalar kStarts[] = {0.f, 10.f, 30.f, 45.f, 90.f, 165.f, 180.f, 270.f};
+static constexpr SkScalar kSweeps[] = {45.f, 90.f, 165.f, 180.f, 220.f, 270.f, 300.f, 315.f};
+static constexpr SkScalar kDiameter = 40.f;
+static constexpr SkRect kRect = {0.f, 0.f, kDiameter, kDiameter};
+static constexpr int kW = 1000;
+static constexpr int kH = 1000;
+static constexpr SkScalar kPad = 20.f;
+
+void draw_arcs(SkCanvas* canvas, std::function<void(SkPaint*)> configureStyle) {
+ // Draws grid of arcs with different start/sweep angles in red and their complement arcs in
+ // blue.
+ auto drawGrid = [canvas, &configureStyle] (SkScalar x, SkScalar y, bool useCenter, bool aa) {
+ SkPaint p0;
+ p0.setColor(SK_ColorRED);
+ p0.setAntiAlias(aa);
+ // Set a reasonable stroke width that configureStyle can override.
+ p0.setStrokeWidth(15.f);
+ // Use alpha so we see magenta on overlap between arc and its complement.
+ p0.setAlpha(100);
+ SkPaint p1 = p0;
+ p1.setColor(SK_ColorBLUE);
+ configureStyle(&p0);
+ configureStyle(&p1);
+
+ canvas->save();
+ canvas->translate(kPad + x, kPad + y);
+ for (auto start : kStarts) {
+ canvas->save();
+ for (auto sweep : kSweeps) {
+ canvas->drawArc(kRect, start, sweep, useCenter, p0);
+ canvas->drawArc(kRect, start, -(360.f - sweep), useCenter, p1);
+ canvas->translate(kRect.width() + kPad, 0.f);
+ }
+ canvas->restore();
+ canvas->translate(0, kRect.height() + kPad);
+ }
+ canvas->restore();
+ };
+ // Draw a grids for combo of enabling/disabling aa and using center.
+ static constexpr SkScalar kGridW = kW / 2.f;
+ static constexpr SkScalar kGridH = kH / 2.f;
+ drawGrid(0.f , 0.f , false, false);
+ drawGrid(kGridW, 0.f , true , false);
+ drawGrid(0.f , kGridH, false, true );
+ drawGrid(kGridW, kGridH, true , true );
+ // Draw separators between the grids.
+ SkPaint linePaint;
+ linePaint.setAntiAlias(true);
+ linePaint.setColor(SK_ColorBLACK);
+ canvas->drawLine(kGridW, 0.f , kGridW, SkIntToScalar(kH), linePaint);
+ canvas->drawLine(0.f , kGridH, SkIntToScalar(kW), kGridH, linePaint);
+}
+
+#define DEF_ARC_GM(name) DEF_SIMPLE_GM(circular_arcs_##name, canvas, kW, kH)
+
+DEF_ARC_GM(circular_arcs_fill) {
+ auto setFill = [] (SkPaint*p) { p->setStyle(SkPaint::kFill_Style); };
+ draw_arcs(canvas, setFill);
+}
+
+DEF_ARC_GM(hairline) {
+ auto setHairline = [] (SkPaint* p) {
+ p->setStyle(SkPaint::kStroke_Style);
+ p->setStrokeWidth(0.f);
+ };
+ draw_arcs(canvas, setHairline);
+}
+
+DEF_ARC_GM(stroke_butt) {
+ auto setStroke = [](SkPaint* p) {
+ p->setStyle(SkPaint::kStroke_Style);
+ p->setStrokeCap(SkPaint::kButt_Cap);
+ };
+ draw_arcs(canvas, setStroke);
+}
+
+DEF_ARC_GM(stroke_square) {
+ auto setStroke = [] (SkPaint* p) {
+ p->setStyle(SkPaint::kStroke_Style);
+ p->setStrokeCap(SkPaint::kSquare_Cap);
+ };
+ draw_arcs(canvas, setStroke);
+}
+
+DEF_ARC_GM(stroke_round) {
+ auto setStroke = [] (SkPaint* p) {
+ p->setStyle(SkPaint::kStroke_Style);
+ p->setStrokeCap(SkPaint::kRound_Cap);
+ };
+ draw_arcs(canvas, setStroke);
+}