| /* |
| * Copyright 2019 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 "SkColorFilter.h" |
| #include "SkGradientShader.h" |
| #include "SkLumaColorFilter.h" |
| #include "SkTableColorFilter.h" |
| |
| namespace { |
| |
| class MixerCFGM final : public skiagm::GM { |
| public: |
| MixerCFGM(const SkSize& tileSize, size_t tileCount) |
| : fTileSize(tileSize) |
| , fTileCount(tileCount) {} |
| |
| protected: |
| SkString onShortName() override { |
| return SkString("mixerCF"); |
| } |
| |
| SkISize onISize() override { |
| return SkISize::Make(fTileSize.width() * 1.2f * fTileCount, |
| fTileSize.height() * 1.2f * 3); // 3 rows |
| } |
| |
| void onDraw(SkCanvas* canvas) override { |
| SkPaint paint; |
| |
| const SkColor gradient_colors[] = { SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorRED }; |
| paint.setShader(SkGradientShader::MakeSweep(fTileSize.width() / 2, |
| fTileSize.height() / 2, |
| gradient_colors, nullptr, |
| SK_ARRAY_COUNT(gradient_colors))); |
| |
| auto cf0 = MakeTintColorFilter(0xff300000, 0xffa00000); // red tint |
| auto cf1 = MakeTintColorFilter(0xff003000, 0xff00a000); // green tint |
| |
| this->mixRow(canvas, paint, nullptr, cf1); |
| this->mixRow(canvas, paint, cf0, nullptr); |
| this->mixRow(canvas, paint, cf0, cf1); |
| } |
| |
| private: |
| const SkSize fTileSize; |
| const size_t fTileCount; |
| |
| void mixRow(SkCanvas* canvas, SkPaint& paint, |
| sk_sp<SkColorFilter> cf0, sk_sp<SkColorFilter> cf1) { |
| canvas->translate(0, fTileSize.height() * 0.1f); |
| { |
| SkAutoCanvasRestore arc(canvas, true); |
| for (size_t i = 0; i < fTileCount; ++i) { |
| paint.setColorFilter( |
| SkColorFilter::MakeLerp(cf0, cf1, static_cast<float>(i) / (fTileCount - 1))); |
| canvas->translate(fTileSize.width() * 0.1f, 0); |
| canvas->drawRect(SkRect::MakeWH(fTileSize.width(), fTileSize.height()), paint); |
| canvas->translate(fTileSize.width() * 1.1f, 0); |
| } |
| } |
| canvas->translate(0, fTileSize.height() * 1.1f); |
| } |
| |
| // A tint filter maps colors to a given range (gradient), based on the input luminance: |
| // |
| // c' = lerp(lo, hi, luma(c)) |
| // |
| // TODO: move to public headers/API? |
| // |
| static sk_sp<SkColorFilter> MakeTintColorFilter(SkColor lo, SkColor hi) { |
| const auto r_lo = SkColorGetR(lo), |
| g_lo = SkColorGetG(lo), |
| b_lo = SkColorGetB(lo), |
| a_lo = SkColorGetA(lo), |
| r_hi = SkColorGetR(hi), |
| g_hi = SkColorGetG(hi), |
| b_hi = SkColorGetB(hi), |
| a_hi = SkColorGetA(hi); |
| |
| // We map component-wise: |
| // |
| // r' = lo.r + (hi.r - lo.r) * luma |
| // g' = lo.g + (hi.g - lo.g) * luma |
| // b' = lo.b + (hi.b - lo.b) * luma |
| // a' = lo.a + (hi.a - lo.a) * luma |
| // |
| // The input luminance is stored in the alpha channel |
| // (and RGB are cleared -- see SkLumaColorFilter). Thus: |
| const SkScalar tint_matrix[] = { |
| 0, 0, 0, (r_hi - r_lo) / 255.0f, SkIntToScalar(r_lo), |
| 0, 0, 0, (g_hi - g_lo) / 255.0f, SkIntToScalar(g_lo), |
| 0, 0, 0, (b_hi - b_lo) / 255.0f, SkIntToScalar(b_lo), |
| 0, 0, 0, (a_hi - a_lo) / 255.0f, SkIntToScalar(a_lo), |
| }; |
| |
| return SkColorFilter::MakeMatrixFilterRowMajor255(tint_matrix) |
| ->makeComposed(SkLumaColorFilter::Make()); |
| } |
| |
| using INHERITED = skiagm::GM; |
| }; |
| |
| } // namespace |
| |
| DEF_GM( return new MixerCFGM(SkSize::Make(200, 250), 5); ) |