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- /*
- * Copyright 2018 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include "src/gpu/gradients/GrGradientShader.h"
- #include "src/gpu/gradients/generated/GrClampedGradientEffect.h"
- #include "src/gpu/gradients/generated/GrTiledGradientEffect.h"
- #include "src/gpu/gradients/generated/GrLinearGradientLayout.h"
- #include "src/gpu/gradients/generated/GrRadialGradientLayout.h"
- #include "src/gpu/gradients/generated/GrSweepGradientLayout.h"
- #include "src/gpu/gradients/generated/GrTwoPointConicalGradientLayout.h"
- #include "src/gpu/gradients/GrGradientBitmapCache.h"
- #include "src/gpu/gradients/generated/GrDualIntervalGradientColorizer.h"
- #include "src/gpu/gradients/generated/GrSingleIntervalGradientColorizer.h"
- #include "src/gpu/gradients/generated/GrTextureGradientColorizer.h"
- #include "src/gpu/gradients/generated/GrUnrolledBinaryGradientColorizer.h"
- #include "include/private/GrRecordingContext.h"
- #include "src/gpu/GrCaps.h"
- #include "src/gpu/GrColor.h"
- #include "src/gpu/GrColorSpaceInfo.h"
- #include "src/gpu/GrRecordingContextPriv.h"
- #include "src/gpu/SkGr.h"
- // Intervals smaller than this (that aren't hard stops) on low-precision-only devices force us to
- // use the textured gradient
- static const SkScalar kLowPrecisionIntervalLimit = 0.01f;
- // Each cache entry costs 1K or 2K of RAM. Each bitmap will be 1x256 at either 32bpp or 64bpp.
- static const int kMaxNumCachedGradientBitmaps = 32;
- static const int kGradientTextureSize = 256;
- // NOTE: signature takes raw pointers to the color/pos arrays and a count to make it easy for
- // MakeColorizer to transparently take care of hard stops at the end points of the gradient.
- static std::unique_ptr<GrFragmentProcessor> make_textured_colorizer(const SkPMColor4f* colors,
- const SkScalar* positions, int count, bool premul, const GrFPArgs& args) {
- static GrGradientBitmapCache gCache(kMaxNumCachedGradientBitmaps, kGradientTextureSize);
- // Use 8888 or F16, depending on the destination config.
- // TODO: Use 1010102 for opaque gradients, at least if destination is 1010102?
- SkColorType colorType = kRGBA_8888_SkColorType;
- if (GrColorTypeIsWiderThan(args.fDstColorSpaceInfo->colorType(), 8) &&
- args.fContext->priv().caps()->isConfigTexturable(kRGBA_half_GrPixelConfig)) {
- colorType = kRGBA_F16_SkColorType;
- }
- SkAlphaType alphaType = premul ? kPremul_SkAlphaType : kUnpremul_SkAlphaType;
- SkBitmap bitmap;
- gCache.getGradient(colors, positions, count, colorType, alphaType, &bitmap);
- SkASSERT(1 == bitmap.height() && SkIsPow2(bitmap.width()));
- SkASSERT(bitmap.isImmutable());
- sk_sp<GrTextureProxy> proxy = GrMakeCachedBitmapProxy(
- args.fContext->priv().proxyProvider(), bitmap);
- if (proxy == nullptr) {
- SkDebugf("Gradient won't draw. Could not create texture.");
- return nullptr;
- }
- return GrTextureGradientColorizer::Make(std::move(proxy));
- }
- // Analyze the shader's color stops and positions and chooses an appropriate colorizer to represent
- // the gradient.
- static std::unique_ptr<GrFragmentProcessor> make_colorizer(const SkPMColor4f* colors,
- const SkScalar* positions, int count, bool premul, const GrFPArgs& args) {
- // If there are hard stops at the beginning or end, the first and/or last color should be
- // ignored by the colorizer since it should only be used in a clamped border color. By detecting
- // and removing these stops at the beginning, it makes optimizing the remaining color stops
- // simpler.
- // SkGradientShaderBase guarantees that pos[0] == 0 by adding a dummy
- bool bottomHardStop = SkScalarNearlyEqual(positions[0], positions[1]);
- // The same is true for pos[end] == 1
- bool topHardStop = SkScalarNearlyEqual(positions[count - 2], positions[count - 1]);
- int offset = 0;
- if (bottomHardStop) {
- offset += 1;
- count--;
- }
- if (topHardStop) {
- count--;
- }
- // Two remaining colors means a single interval from 0 to 1
- // (but it may have originally been a 3 or 4 color gradient with 1-2 hard stops at the ends)
- if (count == 2) {
- return GrSingleIntervalGradientColorizer::Make(colors[offset], colors[offset + 1]);
- }
- // Do an early test for the texture fallback to skip all of the other tests for specific
- // analytic support of the gradient (and compatibility with the hardware), when it's definitely
- // impossible to use an analytic solution.
- bool tryAnalyticColorizer = count <= GrUnrolledBinaryGradientColorizer::kMaxColorCount;
- // The remaining analytic colorizers use scale*t+bias, and the scale/bias values can become
- // quite large when thresholds are close (but still outside the hardstop limit). If float isn't
- // 32-bit, output can be incorrect if the thresholds are too close together. However, the
- // analytic shaders are higher quality, so they can be used with lower precision hardware when
- // the thresholds are not ill-conditioned.
- const GrShaderCaps* caps = args.fContext->priv().caps()->shaderCaps();
- if (!caps->floatIs32Bits() && tryAnalyticColorizer) {
- // Could run into problems, check if thresholds are close together (with a limit of .01, so
- // that scales will be less than 100, which leaves 4 decimals of precision on 16-bit).
- for (int i = offset; i < count - 1; i++) {
- SkScalar dt = SkScalarAbs(positions[i] - positions[i + 1]);
- if (dt <= kLowPrecisionIntervalLimit && dt > SK_ScalarNearlyZero) {
- tryAnalyticColorizer = false;
- break;
- }
- }
- }
- if (tryAnalyticColorizer) {
- if (count == 3) {
- // Must be a dual interval gradient, where the middle point is at offset+1 and the two
- // intervals share the middle color stop.
- return GrDualIntervalGradientColorizer::Make(colors[offset], colors[offset + 1],
- colors[offset + 1], colors[offset + 2],
- positions[offset + 1]);
- } else if (count == 4 && SkScalarNearlyEqual(positions[offset + 1],
- positions[offset + 2])) {
- // Two separate intervals that join at the same threshold position
- return GrDualIntervalGradientColorizer::Make(colors[offset], colors[offset + 1],
- colors[offset + 2], colors[offset + 3],
- positions[offset + 1]);
- }
- // The single and dual intervals are a specialized case of the unrolled binary search
- // colorizer which can analytically render gradients of up to 8 intervals (up to 9 or 16
- // colors depending on how many hard stops are inserted).
- std::unique_ptr<GrFragmentProcessor> unrolled = GrUnrolledBinaryGradientColorizer::Make(
- colors + offset, positions + offset, count);
- if (unrolled) {
- return unrolled;
- }
- }
- // Otherwise fall back to a rasterized gradient sampled by a texture, which can handle
- // arbitrary gradients (the only downside being sampling resolution).
- return make_textured_colorizer(colors + offset, positions + offset, count, premul, args);
- }
- // Combines the colorizer and layout with an appropriately configured master effect based on the
- // gradient's tile mode
- static std::unique_ptr<GrFragmentProcessor> make_gradient(const SkGradientShaderBase& shader,
- const GrFPArgs& args, std::unique_ptr<GrFragmentProcessor> layout) {
- // No shader is possible if a layout couldn't be created, e.g. a layout-specific Make() returned
- // null.
- if (layout == nullptr) {
- return nullptr;
- }
- // Convert all colors into destination space and into SkPMColor4fs, and handle
- // premul issues depending on the interpolation mode
- bool inputPremul = shader.getGradFlags() & SkGradientShader::kInterpolateColorsInPremul_Flag;
- bool allOpaque = true;
- SkAutoSTMalloc<4, SkPMColor4f> colors(shader.fColorCount);
- SkColor4fXformer xformedColors(shader.fOrigColors4f, shader.fColorCount,
- shader.fColorSpace.get(), args.fDstColorSpaceInfo->colorSpace());
- for (int i = 0; i < shader.fColorCount; i++) {
- const SkColor4f& upmColor = xformedColors.fColors[i];
- colors[i] = inputPremul ? upmColor.premul()
- : SkPMColor4f{ upmColor.fR, upmColor.fG, upmColor.fB, upmColor.fA };
- if (allOpaque && !SkScalarNearlyEqual(colors[i].fA, 1.0)) {
- allOpaque = false;
- }
- }
- // SkGradientShader stores positions implicitly when they are evenly spaced, but the getPos()
- // implementation performs a branch for every position index. Since the shader conversion
- // requires lots of position tests, calculate all of the positions up front if needed.
- SkTArray<SkScalar, true> implicitPos;
- SkScalar* positions;
- if (shader.fOrigPos) {
- positions = shader.fOrigPos;
- } else {
- implicitPos.reserve(shader.fColorCount);
- SkScalar posScale = SK_Scalar1 / (shader.fColorCount - 1);
- for (int i = 0 ; i < shader.fColorCount; i++) {
- implicitPos.push_back(SkIntToScalar(i) * posScale);
- }
- positions = implicitPos.begin();
- }
- // All gradients are colorized the same way, regardless of layout
- std::unique_ptr<GrFragmentProcessor> colorizer = make_colorizer(
- colors.get(), positions, shader.fColorCount, inputPremul, args);
- if (colorizer == nullptr) {
- return nullptr;
- }
- // The master effect has to export premul colors, but under certain conditions it doesn't need
- // to do anything to achieve that: i.e. its interpolating already premul colors (inputPremul)
- // or all the colors have a = 1, in which case premul is a no op. Note that this allOpaque
- // check is more permissive than SkGradientShaderBase's isOpaque(), since we can optimize away
- // the make-premul op for two point conical gradients (which report false for isOpaque).
- bool makePremul = !inputPremul && !allOpaque;
- // All tile modes are supported (unless something was added to SkShader)
- std::unique_ptr<GrFragmentProcessor> master;
- switch(shader.getTileMode()) {
- case SkTileMode::kRepeat:
- master = GrTiledGradientEffect::Make(std::move(colorizer), std::move(layout),
- /* mirror */ false, makePremul, allOpaque);
- break;
- case SkTileMode::kMirror:
- master = GrTiledGradientEffect::Make(std::move(colorizer), std::move(layout),
- /* mirror */ true, makePremul, allOpaque);
- break;
- case SkTileMode::kClamp:
- // For the clamped mode, the border colors are the first and last colors, corresponding
- // to t=0 and t=1, because SkGradientShaderBase enforces that by adding color stops as
- // appropriate. If there is a hard stop, this grabs the expected outer colors for the
- // border.
- master = GrClampedGradientEffect::Make(std::move(colorizer), std::move(layout),
- colors[0], colors[shader.fColorCount - 1], makePremul, allOpaque);
- break;
- case SkTileMode::kDecal:
- // Even if the gradient colors are opaque, the decal borders are transparent so
- // disable that optimization
- master = GrClampedGradientEffect::Make(std::move(colorizer), std::move(layout),
- SK_PMColor4fTRANSPARENT, SK_PMColor4fTRANSPARENT,
- makePremul, /* colorsAreOpaque */ false);
- break;
- }
- if (master == nullptr) {
- // Unexpected tile mode
- return nullptr;
- }
- if (args.fInputColorIsOpaque) {
- return GrFragmentProcessor::OverrideInput(std::move(master), SK_PMColor4fWHITE, false);
- }
- return GrFragmentProcessor::MulChildByInputAlpha(std::move(master));
- }
- namespace GrGradientShader {
- std::unique_ptr<GrFragmentProcessor> MakeLinear(const SkLinearGradient& shader,
- const GrFPArgs& args) {
- return make_gradient(shader, args, GrLinearGradientLayout::Make(shader, args));
- }
- std::unique_ptr<GrFragmentProcessor> MakeRadial(const SkRadialGradient& shader,
- const GrFPArgs& args) {
- return make_gradient(shader,args, GrRadialGradientLayout::Make(shader, args));
- }
- std::unique_ptr<GrFragmentProcessor> MakeSweep(const SkSweepGradient& shader,
- const GrFPArgs& args) {
- return make_gradient(shader,args, GrSweepGradientLayout::Make(shader, args));
- }
- std::unique_ptr<GrFragmentProcessor> MakeConical(const SkTwoPointConicalGradient& shader,
- const GrFPArgs& args) {
- return make_gradient(shader, args, GrTwoPointConicalGradientLayout::Make(shader, args));
- }
- #if GR_TEST_UTILS
- RandomParams::RandomParams(SkRandom* random) {
- // Set color count to min of 2 so that we don't trigger the const color optimization and make
- // a non-gradient processor.
- fColorCount = random->nextRangeU(2, kMaxRandomGradientColors);
- fUseColors4f = random->nextBool();
- // if one color, omit stops, otherwise randomly decide whether or not to
- if (fColorCount == 1 || (fColorCount >= 2 && random->nextBool())) {
- fStops = nullptr;
- } else {
- fStops = fStopStorage;
- }
- // if using SkColor4f, attach a random (possibly null) color space (with linear gamma)
- if (fUseColors4f) {
- fColorSpace = GrTest::TestColorSpace(random);
- }
- SkScalar stop = 0.f;
- for (int i = 0; i < fColorCount; ++i) {
- if (fUseColors4f) {
- fColors4f[i].fR = random->nextUScalar1();
- fColors4f[i].fG = random->nextUScalar1();
- fColors4f[i].fB = random->nextUScalar1();
- fColors4f[i].fA = random->nextUScalar1();
- } else {
- fColors[i] = random->nextU();
- }
- if (fStops) {
- fStops[i] = stop;
- stop = i < fColorCount - 1 ? stop + random->nextUScalar1() * (1.f - stop) : 1.f;
- }
- }
- fTileMode = static_cast<SkTileMode>(random->nextULessThan(kSkTileModeCount));
- }
- #endif
- }
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