gradients_degenerate.cpp 5.3 KB

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  1. /*
  2. * Copyright 2018 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 "gm/gm.h"
  8. #include "include/core/SkCanvas.h"
  9. #include "include/core/SkColor.h"
  10. #include "include/core/SkFont.h"
  11. #include "include/core/SkPaint.h"
  12. #include "include/core/SkPoint.h"
  13. #include "include/core/SkRect.h"
  14. #include "include/core/SkRefCnt.h"
  15. #include "include/core/SkScalar.h"
  16. #include "include/core/SkShader.h"
  17. #include "include/core/SkSize.h"
  18. #include "include/core/SkString.h"
  19. #include "include/core/SkTileMode.h"
  20. #include "include/core/SkTypes.h"
  21. #include "include/effects/SkGradientShader.h"
  22. // NOTE: The positions define hardstops for the red and green borders. For the repeating degenerate
  23. // gradients, that means the red and green are never visible, so the average color used should only
  24. // be based off of the white, blue, black blend.
  25. static const SkColor COLORS[] = { SK_ColorRED, SK_ColorWHITE, SK_ColorBLUE,
  26. SK_ColorBLACK, SK_ColorGREEN };
  27. static const SkScalar POS[] = { 0.0, 0.0, 0.5, 1.0, 1.0 };
  28. static const int COLOR_CT = SK_ARRAY_COUNT(COLORS);
  29. static const SkTileMode TILE_MODES[] = { SkTileMode::kDecal,
  30. SkTileMode::kRepeat,
  31. SkTileMode::kMirror,
  32. SkTileMode::kClamp };
  33. static const char* TILE_NAMES[] = { "decal", "repeat", "mirror", "clamp" };
  34. static const int TILE_MODE_CT = SK_ARRAY_COUNT(TILE_MODES);
  35. static constexpr int TILE_SIZE = 100;
  36. static constexpr int TILE_GAP = 10;
  37. static const SkPoint CENTER = SkPoint::Make(TILE_SIZE / 2, TILE_SIZE / 2);
  38. typedef sk_sp<SkShader> (*GradientFactory)(SkTileMode tm);
  39. static void draw_tile_header(SkCanvas* canvas) {
  40. canvas->save();
  41. for (int i = 0; i < TILE_MODE_CT; ++i) {
  42. canvas->drawString(TILE_NAMES[i], 0, 0, SkFont(), SkPaint());
  43. canvas->translate(TILE_SIZE + TILE_GAP, 0);
  44. }
  45. canvas->restore();
  46. // Now adjust to start at rows below the header
  47. canvas->translate(0, 2 * TILE_GAP);
  48. }
  49. static void draw_row(SkCanvas* canvas, const char* desc, GradientFactory factory) {
  50. canvas->save();
  51. SkPaint text;
  52. text.setAntiAlias(true);
  53. canvas->translate(0, TILE_GAP);
  54. canvas->drawString(desc, 0, 0, SkFont(), text);
  55. canvas->translate(0, TILE_GAP);
  56. SkPaint paint;
  57. paint.setColor(SK_ColorBLACK);
  58. paint.setStyle(SkPaint::kStrokeAndFill_Style);
  59. paint.setStrokeWidth(2.0f);
  60. for (int i = 0; i < TILE_MODE_CT; ++i) {
  61. paint.setShader(factory(TILE_MODES[i]));
  62. canvas->drawRect(SkRect::MakeWH(TILE_SIZE, TILE_SIZE), paint);
  63. canvas->translate(TILE_SIZE + TILE_GAP, 0);
  64. }
  65. canvas->restore();
  66. // Now adjust to start the next row below this one (1 gap for text and 2 gap for margin)
  67. canvas->translate(0, 3 * TILE_GAP + TILE_SIZE);
  68. }
  69. static sk_sp<SkShader> make_linear(SkTileMode mode) {
  70. // Same position
  71. SkPoint pts[2] = {CENTER, CENTER};
  72. return SkGradientShader::MakeLinear(pts, COLORS, POS, COLOR_CT, mode);
  73. }
  74. static sk_sp<SkShader> make_radial(SkTileMode mode) {
  75. // Radius = 0
  76. return SkGradientShader::MakeRadial(CENTER, 0.0, COLORS, POS, COLOR_CT, mode);
  77. }
  78. static sk_sp<SkShader> make_sweep(SkTileMode mode) {
  79. // Start and end angles at 45
  80. static constexpr SkScalar SWEEP_ANG = 45.0;
  81. return SkGradientShader::MakeSweep(CENTER.fX, CENTER.fY, COLORS, POS, COLOR_CT, mode,
  82. SWEEP_ANG, SWEEP_ANG, 0, nullptr);
  83. }
  84. static sk_sp<SkShader> make_sweep_zero_ang(SkTileMode mode) {
  85. // Start and end angles at 0
  86. return SkGradientShader::MakeSweep(CENTER.fX, CENTER.fY, COLORS, POS, COLOR_CT, mode,
  87. 0.0, 0.0, 0, nullptr);
  88. }
  89. static sk_sp<SkShader> make_2pt_conic(SkTileMode mode) {
  90. // Start and end radius = TILE_SIZE, same position
  91. return SkGradientShader::MakeTwoPointConical(CENTER, TILE_SIZE / 2, CENTER, TILE_SIZE / 2,
  92. COLORS, POS, COLOR_CT, mode);
  93. }
  94. static sk_sp<SkShader> make_2pt_conic_zero_rad(SkTileMode mode) {
  95. // Start and end radius = 0, same position
  96. return SkGradientShader::MakeTwoPointConical(CENTER, 0.0, CENTER, 0.0, COLORS, POS,
  97. COLOR_CT, mode);
  98. }
  99. class DegenerateGradientGM : public skiagm::GM {
  100. public:
  101. DegenerateGradientGM() {
  102. }
  103. protected:
  104. SkString onShortName() override {
  105. return SkString("degenerate_gradients");
  106. }
  107. SkISize onISize() override {
  108. return SkISize::Make(800, 800);
  109. }
  110. void onDraw(SkCanvas* canvas) override {
  111. canvas->translate(3 * TILE_GAP, 3 * TILE_GAP);
  112. draw_tile_header(canvas);
  113. draw_row(canvas, "linear: empty, blue, blue, green", make_linear);
  114. draw_row(canvas, "radial: empty, blue, blue, green", make_radial);
  115. draw_row(canvas, "sweep-0: empty, blue, blue, green", make_sweep_zero_ang);
  116. draw_row(canvas, "sweep-45: empty, blue, blue, red 45 degree sector then green",
  117. make_sweep);
  118. draw_row(canvas, "2pt-conic-0: empty, blue, blue, green", make_2pt_conic_zero_rad);
  119. draw_row(canvas, "2pt-conic-1: empty, blue, blue, full red circle on green",
  120. make_2pt_conic);
  121. }
  122. private:
  123. typedef skiagm::GM INHERITED;
  124. };
  125. DEF_GM(return new DegenerateGradientGM;)