add convex and concave polygons GM test

gm/polygons.cpp

+/*
+ * 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 "SkPath.h"
+#include "SkRandom.h"
+#include "SkTArray.h"
+
+namespace skiagm {
+
+// This GM tests a grab-bag of convex and concave polygons. They are triangles,
+// trapezoid, diamond, polygons with lots of edges, several concave polygons...
+// But rectangles are excluded.
+class PolygonsGM: public GM {
+public:
+    PolygonsGM() {}
+
+protected:
+    virtual SkString onShortName() SK_OVERRIDE {
+        return SkString("polygons");
+    }
+
+    virtual SkISize onISize() SK_OVERRIDE {
+        size_t width = kNumPolygons * kCellSize + 40;
+        size_t height = (kNumJoins * kNumStrokeWidths + kNumExtraStyles) * kCellSize + 40;
+        return SkISize::Make(width, height);
+    }
+
+    // Construct all polygons
+    virtual void onOnceBeforeDraw SK_OVERRIDE() {
+        SkPoint p0[] = {{0, 0}, {60, 0}, {90, 40}};  // triangle
+        SkPoint p1[] = {{0, 0}, {0, 40}, {60, 40}, {40, 0}};  // trapezoid
+        SkPoint p2[] = {{0, 0}, {40, 40}, {80, 40}, {40, 0}};  // diamond
+        SkPoint p3[] = {{10, 0}, {50, 0}, {60, 10}, {60, 30}, {50, 40},
+                        {10, 40}, {0, 30}, {0, 10}};  // octagon
+        SkPoint p4[32];  // circle-like polygons with 32-edges.
+        SkPoint p5[] = {{0, 0}, {20, 20}, {0, 40}, {60, 20}};  // concave polygon with 4 edges
+        SkPoint p6[] = {{0, 40}, {0, 30}, {15, 30}, {15, 20}, {30, 20},
+                        {30, 10}, {45, 10}, {45, 0}, {60, 0}, {60, 40}};  // stairs-like polygon
+        SkPoint p7[] = {{0, 20}, {20, 20}, {30, 0}, {40, 20}, {60, 20},
+                        {45, 30}, {55, 50}, {30, 40}, {5, 50}, {15, 30}};  // five-point stars
+
+        for (size_t i = 0; i < SK_ARRAY_COUNT(p4); ++i) {
+            SkScalar angle = 2 * SK_ScalarPI * i / SK_ARRAY_COUNT(p4);
+            p4[i].set(20 * cos(angle) + 20, 20 * sin(angle) + 20);
+        }
+
+        struct Polygons {
+            SkPoint* fPoints;
+            size_t fPointNum;
+        } pgs[] = {
+            { p0, SK_ARRAY_COUNT(p0) },
+            { p1, SK_ARRAY_COUNT(p1) },
+            { p2, SK_ARRAY_COUNT(p2) },
+            { p3, SK_ARRAY_COUNT(p3) },
+            { p4, SK_ARRAY_COUNT(p4) },
+            { p5, SK_ARRAY_COUNT(p5) },
+            { p6, SK_ARRAY_COUNT(p6) },
+            { p7, SK_ARRAY_COUNT(p7) }
+        };
+
+        SkASSERT(SK_ARRAY_COUNT(pgs) == kNumPolygons);

[robertphillips, 2013/11/22 13:27:04]

These two don't seem to be used after the following nested loop so we might as
well move them into the for loops (e.g., "for (size_t pgIndex ...")

+        size_t pgIndex, ptIndex;
+        for (pgIndex = 0; pgIndex < SK_ARRAY_COUNT(pgs); ++pgIndex) {
+            fPolygons.push_back().moveTo(pgs[pgIndex].fPoints[0].fX,
+                                         pgs[pgIndex].fPoints[0].fY);
+            for (ptIndex = 1; ptIndex < pgs[pgIndex].fPointNum; ++ptIndex) {
+                fPolygons.back().lineTo(pgs[pgIndex].fPoints[ptIndex].fX,
+                                        pgs[pgIndex].fPoints[ptIndex].fY);
+            }
+            fPolygons.back().close();
+        }
+    }
+
+    // Set the location for the current test on the canvas
+    static void SetLocation(SkCanvas* canvas, int counter, int lineNum) {
+        SkScalar x = SK_Scalar1 * kCellSize * (counter % lineNum) + 30 + SK_Scalar1 / 4;
+        SkScalar y = SK_Scalar1 * kCellSize * (counter / lineNum) + 30 + 3 * SK_Scalar1 / 4;
+        canvas->translate(x, y);
+    }
+
+    static void SetColorAndAlpha(SkPaint* paint, SkLCGRandom* rand) {
+        SkColor color = rand->nextU();
+        paint->setColor(color);
+        if (color | 0x01) {
+           paint->setAlpha(color >> 24);
+        }
+    }
+
+    virtual void onDraw(SkCanvas* canvas) SK_OVERRIDE {
+        // Stroke widths are:
+        // 0(may use hairline rendering), 10(common case for stroke-style)
+        // 40(>= geometry width/height, make the contour filled in fact)
+        static const int kStrokeWidths[] = {0, 10, 40};
+        SkASSERT(kNumStrokeWidths == SK_ARRAY_COUNT(kStrokeWidths));
+
+        static const SkPaint::Join kJoins[] = {
+            SkPaint::kMiter_Join, SkPaint::kRound_Join, SkPaint::kBevel_Join
+        };
+        SkASSERT(kNumJoins == SK_ARRAY_COUNT(kJoins));
+
+        int counter = 0;
+        SkPaint paint;
+        paint.setAntiAlias(true);
+
+        SkLCGRandom rand;
+        // For stroke style painter
+        paint.setStyle(SkPaint::kStroke_Style);
+        for (int join = 0; join < kNumJoins; ++join) {
+            for (int width = 0; width < kNumStrokeWidths; ++width) {
+                for (int i = 0; i < fPolygons.count(); ++i) {
+                    canvas->save();
+                    SetLocation(canvas, counter, fPolygons.count());
+
+                    SetColorAndAlpha(&paint, &rand);
+                    paint.setStrokeJoin(kJoins[join]);
+                    paint.setStrokeWidth(SkIntToScalar(kStrokeWidths[width]));
+
+                    canvas->drawPath(fPolygons[i], paint);
+                    canvas->restore();
+                    ++counter;
+                }
+            }
+        }
+
+        // For stroke-and-fill style painter and fill style painter
+        static const SkPaint::Style kStyles[] = {
+            SkPaint::kStrokeAndFill_Style, SkPaint::kFill_Style
+        };
+        SkASSERT(kNumExtraStyles == SK_ARRAY_COUNT(kStyles));
+
+        paint.setStrokeJoin(SkPaint::kMiter_Join);
+        for (int style = 0; style < kNumExtraStyles; ++style) {
+            paint.setStyle(kStyles[style]);

[robertphillips, 2013/11/22 13:27:04]

The "setStrokeWidth" call could be pulled out of the loop, right?

+            paint.setStrokeWidth(SkIntToScalar(20));
+            for (int i = 0; i < fPolygons.count(); ++i) {
+                canvas->save();
+                SetLocation(canvas, counter, fPolygons.count());
+                SetColorAndAlpha(&paint, &rand);
+                canvas->drawPath(fPolygons[i], paint);
+                canvas->restore();
+                ++counter;
+            }
+        }
+    }
+
+private:
+    static const int kNumPolygons = 8;
+    static const int kCellSize = 100;
+    static const int kNumExtraStyles = 2;
+    static const int kNumStrokeWidths = 3;
+    static const int kNumJoins = 3;
+
+    SkTArray<SkPath> fPolygons;
+    typedef GM INHERITED;
+};
+
+//////////////////////////////////////////////////////////////////////////////
+
+DEF_GM(return new PolygonsGM;)
+
+}