SampleDegenerateTwoPtRadials.cpp 2.5 KB

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  1. /*
  2. * Copyright 2011 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. #include "include/core/SkCanvas.h"
  8. #include "include/core/SkFont.h"
  9. #include "include/core/SkString.h"
  10. #include "include/effects/SkGradientShader.h"
  11. #include "samplecode/Sample.h"
  12. static void draw_gradient2(SkCanvas* canvas, const SkRect& rect, SkScalar delta) {
  13. SkColor colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorMAGENTA };
  14. SkScalar pos[] = { 0, 0.25f, 0.75f, SK_Scalar1 };
  15. SkScalar l = rect.fLeft;
  16. SkScalar t = rect.fTop;
  17. SkScalar w = rect.width();
  18. SkScalar h = rect.height();
  19. SkASSERT(0 == SkScalarMod(w, SK_Scalar1 * 5));
  20. SkPoint c0 = { l + 2 * w / 5 + delta, t + h / 2 };
  21. SkPoint c1 = { l + 3 * w / 5, t + h / 2 };
  22. SkScalar r0 = w / 5;
  23. SkScalar r1 = 2 * w / 5;
  24. SkPaint paint;
  25. paint.setShader(SkGradientShader::MakeTwoPointConical(c0, r0, c1, r1, colors,
  26. pos, SK_ARRAY_COUNT(pos),
  27. SkTileMode::kClamp));
  28. canvas->drawRect(rect, paint);
  29. }
  30. class DegenerateTwoPtRadialsView : public Sample {
  31. public:
  32. DegenerateTwoPtRadialsView() {
  33. fTime = 0;
  34. this->setBGColor(0xFFDDDDDD);
  35. }
  36. protected:
  37. SkString name() override { return SkString("DegenerateTwoPtRadials"); }
  38. void onDrawContent(SkCanvas* canvas) override {
  39. SkScalar delta = fTime / 15.f;
  40. int intPart = SkScalarFloorToInt(delta);
  41. delta = delta - SK_Scalar1 * intPart;
  42. if (intPart % 2) {
  43. delta = SK_Scalar1 - delta;
  44. }
  45. delta -= SK_ScalarHalf;
  46. static const int DELTA_SCALE = 500;
  47. delta /= DELTA_SCALE;
  48. SkScalar w = SK_Scalar1 * 500;
  49. SkScalar h = SK_Scalar1 * 500;
  50. SkScalar l = SK_Scalar1 * 100;
  51. SkScalar t = SK_Scalar1 * 100;
  52. draw_gradient2(canvas, SkRect::MakeXYWH(l, t, w, h), delta);
  53. SkString txt;
  54. txt.appendf("gap at \"tangent\" pt = %f", SkScalarToFloat(delta));
  55. canvas->drawString(txt, l + w / 2 + w * DELTA_SCALE * delta, t + h + SK_Scalar1 * 10,
  56. SkFont(), SkPaint());
  57. }
  58. bool onAnimate(double nanos) override {
  59. fTime = SkDoubleToScalar(1e-9 * nanos / 15);
  60. return true;
  61. }
  62. private:
  63. SkScalar fTime;
  64. typedef Sample INHERITED;
  65. };
  66. //////////////////////////////////////////////////////////////////////////////
  67. DEF_SAMPLE( return new DegenerateTwoPtRadialsView(); )