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      1 /*
      2  * Copyright 2013 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "gm.h"
      9 #include "sk_tool_utils.h"
     10 #include "SkAnimTimer.h"
     11 #include "SkCanvas.h"
     12 #include "SkPath.h"
     13 
     14 // Reproduces https://code.google.com/p/chromium/issues/detail?id=279014
     15 
     16 constexpr int kWidth = 440;
     17 constexpr int kHeight = 440;
     18 constexpr SkScalar kAngle = 0.305f;
     19 constexpr int kMaxNumSteps = 140;
     20 
     21 // Renders a string art shape.
     22 // The particular shape rendered can be controlled by adjusting kAngle, from 0 to 1
     23 
     24 class StringArtGM : public skiagm::GM {
     25 public:
     26     StringArtGM() : fNumSteps(kMaxNumSteps) {}
     27 
     28 protected:
     29 
     30     SkString onShortName() override {
     31         return SkString("stringart");
     32     }
     33 
     34     SkISize onISize() override {
     35         return SkISize::Make(kWidth, kHeight);
     36     }
     37 
     38     void onDraw(SkCanvas* canvas) override {
     39         SkScalar angle = kAngle*SK_ScalarPI + SkScalarHalf(SK_ScalarPI);
     40         SkScalar size = SkIntToScalar(SkMin32(kWidth, kHeight));
     41         SkPoint center = SkPoint::Make(SkScalarHalf(kWidth), SkScalarHalf(kHeight));
     42         SkScalar length = 5;
     43         SkScalar step = angle;
     44 
     45         SkPath path;
     46         path.moveTo(center);
     47 
     48         for (int i = 0; i < fNumSteps && length < (SkScalarHalf(size) - 10.f); ++i) {
     49             SkPoint rp = SkPoint::Make(length*SkScalarCos(step) + center.fX,
     50                                        length*SkScalarSin(step) + center.fY);
     51             path.lineTo(rp);
     52             length += angle / SkScalarHalf(SK_ScalarPI);
     53             step += angle;
     54         }
     55 
     56         SkPaint paint;
     57         paint.setAntiAlias(true);
     58         paint.setStyle(SkPaint::kStroke_Style);
     59         paint.setColor(sk_tool_utils::color_to_565(0xFF007700));
     60 
     61         canvas->drawPath(path, paint);
     62     }
     63 
     64     bool onAnimate(const SkAnimTimer& timer) override {
     65         constexpr SkScalar kDesiredDurationSecs = 3.0f;
     66 
     67         // Make the animation ping-pong back and forth but start in the fully drawn state
     68         SkScalar fraction = 1.0f - timer.scaled(2.0f/kDesiredDurationSecs, 2.0f);
     69         if (fraction <= 0.0f) {
     70             fraction = -fraction;
     71         }
     72 
     73         SkASSERT(fraction >= 0.0f && fraction <= 1.0f);
     74 
     75         fNumSteps = (int) (fraction * kMaxNumSteps);
     76         return true;
     77     }
     78 
     79 private:
     80     int fNumSteps;
     81 
     82     typedef GM INHERITED;
     83 };
     84 
     85 DEF_GM( return new StringArtGM; )
     86