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/*
* Copyright 2021 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkColor.h"
#include "include/core/SkColorFilter.h"
#include "include/core/SkImage.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkScalar.h"
#include "include/core/SkShader.h"
#include "include/core/SkSize.h"
#include "include/core/SkString.h"
#include "include/core/SkTileMode.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkGradientShader.h"
#include "include/effects/SkImageFilters.h"
#include "include/effects/SkLumaColorFilter.h"
#include "include/effects/SkPerlinNoiseShader.h"
#include "include/effects/SkRuntimeEffect.h"
#include "src/core/SkRuntimeEffectPriv.h"
#include "tools/Resources.h"
#include <math.h>
// A tint filter maps colors to a given range (gradient), based on the input luminance:
//
// c' = lerp(lo, hi, luma(c))
static sk_sp<SkColorFilter> MakeTintColorFilter(SkColor lo, SkColor hi, bool useSkSL) {
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 float tint_matrix[] = {
0, 0, 0, (r_hi - r_lo) / 255.0f, SkIntToScalar(r_lo) / 255.0f,
0, 0, 0, (g_hi - g_lo) / 255.0f, SkIntToScalar(g_lo) / 255.0f,
0, 0, 0, (b_hi - b_lo) / 255.0f, SkIntToScalar(b_lo) / 255.0f,
0, 0, 0, (a_hi - a_lo) / 255.0f, SkIntToScalar(a_lo) / 255.0f,
};
sk_sp<SkColorFilter> inner = SkLumaColorFilter::Make(),
outer = SkColorFilters::Matrix(tint_matrix);
// Prove that we can implement compose-color-filter using runtime effects
if (useSkSL) {
auto [effect, error] = SkRuntimeEffect::MakeForColorFilter(SkString(R"(
uniform colorFilter inner;
uniform colorFilter outer;
half4 main(half4 c) { return outer.eval(inner.eval(c)); }
)"));
SkASSERT(effect);
sk_sp<SkColorFilter> children[] = { inner, outer };
return effect->makeColorFilter(nullptr, children, std::size(children));
} else {
return outer->makeComposed(inner);
}
}
DEF_SIMPLE_GM(composeCF, canvas, 200, 200) {
// This GM draws a simple color-filter network, using the existing "makeComposed" API, and also
// using a runtime color filter that does the same thing.
SkPaint paint;
const SkColor gradient_colors[] = {SK_ColorRED, SK_ColorGREEN, SK_ColorBLUE, SK_ColorRED};
paint.setShader(SkGradientShader::MakeSweep(
50, 50, gradient_colors, nullptr, std::size(gradient_colors)));
canvas->save();
for (bool useSkSL : {false, true}) {
auto cf0 = MakeTintColorFilter(0xff300000, 0xffa00000, useSkSL); // red tint
auto cf1 = MakeTintColorFilter(0xff003000, 0xff00a000, useSkSL); // green tint
paint.setColorFilter(cf0);
canvas->drawRect({0, 0, 100, 100}, paint);
canvas->translate(100, 0);
paint.setColorFilter(cf1);
canvas->drawRect({0, 0, 100, 100}, paint);
canvas->restore();
canvas->translate(0, 100);
}
}
DEF_SIMPLE_GM(composeCFIF, canvas, 604, 200) {
// This GM draws a ::Shader image filter composed with a ::ColorFilter image filter in two
// ways (direct and via ::Compose). This ensures the use (or non-use in this case) of the source
// image is the same across both means of composition.
auto cf = MakeTintColorFilter(0xff300000, 0xffa00000, /*useSkSL=*/false);
auto shader = SkShaders::MakeTurbulence(0.01f, 0.01f, 2, 0.f);
auto shaderIF = SkImageFilters::Shader(shader, SkImageFilters::Dither::kNo);
auto directCompose = SkImageFilters::ColorFilter(cf, shaderIF);
auto indirectCompose = SkImageFilters::Compose(
/*outer=*/SkImageFilters::ColorFilter(cf, nullptr),
/*inner=*/shaderIF);
{ // Directly draw the shader composed with the color filter
canvas->save();
canvas->clipRect({0, 0, 200, 200});
SkPaint p;
p.setShader(shader);
p.setColorFilter(cf);
canvas->drawPaint(p);
canvas->restore();
}
canvas->translate(202, 0);
{ // Draw with the directly composed image filter
canvas->save();
canvas->clipRect({0, 0, 200, 200});
SkPaint p;
p.setImageFilter(directCompose);
canvas->drawPaint(p);
canvas->restore();
}
canvas->translate(202, 0);
{
// Draw with the indirectly composed image filter
canvas->save();
canvas->clipRect({0, 0, 200, 200});
SkPaint p;
p.setImageFilter(indirectCompose);
canvas->drawPaint(p);
canvas->restore();
}
}