| /* |
| * Copyright 2012 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "include/private/SkFloatingPoint.h" |
| #include "src/core/SkRasterPipeline.h" |
| #include "src/core/SkReadBuffer.h" |
| #include "src/core/SkWriteBuffer.h" |
| #include "src/shaders/gradients/SkTwoPointConicalGradient.h" |
| |
| #include <utility> |
| |
| // Please see https://skia.org/dev/design/conical for how our shader works. |
| |
| bool SkTwoPointConicalGradient::FocalData::set(SkScalar r0, SkScalar r1, SkMatrix* matrix) { |
| fIsSwapped = false; |
| fFocalX = sk_ieee_float_divide(r0, (r0 - r1)); |
| if (SkScalarNearlyZero(fFocalX - 1)) { |
| // swap r0, r1 |
| matrix->postTranslate(-1, 0); |
| matrix->postScale(-1, 1); |
| std::swap(r0, r1); |
| fFocalX = 0; // because r0 is now 0 |
| fIsSwapped = true; |
| } |
| |
| // Map {focal point, (1, 0)} to {(0, 0), (1, 0)} |
| const SkPoint from[2] = { {fFocalX, 0}, {1, 0} }; |
| const SkPoint to[2] = { {0, 0}, {1, 0} }; |
| SkMatrix focalMatrix; |
| if (!focalMatrix.setPolyToPoly(from, to, 2)) { |
| return false; |
| } |
| matrix->postConcat(focalMatrix); |
| fR1 = r1 / SkScalarAbs(1 - fFocalX); // focalMatrix has a scale of 1/(1-f) |
| |
| // The following transformations are just to accelerate the shader computation by saving |
| // some arithmatic operations. |
| if (this->isFocalOnCircle()) { |
| matrix->postScale(0.5, 0.5); |
| } else { |
| matrix->postScale(fR1 / (fR1 * fR1 - 1), 1 / sqrt(SkScalarAbs(fR1 * fR1 - 1))); |
| } |
| matrix->postScale(SkScalarAbs(1 - fFocalX), SkScalarAbs(1 - fFocalX)); // scale |1 - f| |
| return true; |
| } |
| |
| sk_sp<SkShader> SkTwoPointConicalGradient::Create(const SkPoint& c0, SkScalar r0, |
| const SkPoint& c1, SkScalar r1, |
| const Descriptor& desc) { |
| SkMatrix gradientMatrix; |
| Type gradientType; |
| |
| if (SkScalarNearlyZero((c0 - c1).length())) { |
| if (SkScalarNearlyZero(SkTMax(r0, r1)) || SkScalarNearlyEqual(r0, r1)) { |
| // Degenerate case; avoid dividing by zero. Should have been caught by caller but |
| // just in case, recheck here. |
| return nullptr; |
| } |
| // Concentric case: we can pretend we're radial (with a tiny twist). |
| const SkScalar scale = sk_ieee_float_divide(1, SkTMax(r0, r1)); |
| gradientMatrix = SkMatrix::MakeTrans(-c1.x(), -c1.y()); |
| gradientMatrix.postScale(scale, scale); |
| |
| gradientType = Type::kRadial; |
| } else { |
| const SkPoint centers[2] = { c0 , c1 }; |
| const SkPoint unitvec[2] = { {0, 0}, {1, 0} }; |
| |
| if (!gradientMatrix.setPolyToPoly(centers, unitvec, 2)) { |
| // Degenerate case. |
| return nullptr; |
| } |
| |
| gradientType = SkScalarNearlyZero(r1 - r0) ? Type::kStrip : Type::kFocal; |
| } |
| |
| FocalData focalData; |
| if (gradientType == Type::kFocal) { |
| const auto dCenter = (c0 - c1).length(); |
| if (!focalData.set(r0 / dCenter, r1 / dCenter, &gradientMatrix)) { |
| return nullptr; |
| } |
| } |
| return sk_sp<SkShader>(new SkTwoPointConicalGradient(c0, r0, c1, r1, desc, |
| gradientType, gradientMatrix, focalData)); |
| } |
| |
| SkTwoPointConicalGradient::SkTwoPointConicalGradient( |
| const SkPoint& start, SkScalar startRadius, |
| const SkPoint& end, SkScalar endRadius, |
| const Descriptor& desc, Type type, const SkMatrix& gradientMatrix, const FocalData& data) |
| : SkGradientShaderBase(desc, gradientMatrix) |
| , fCenter1(start) |
| , fCenter2(end) |
| , fRadius1(startRadius) |
| , fRadius2(endRadius) |
| , fType(type) |
| { |
| // this is degenerate, and should be caught by our caller |
| SkASSERT(fCenter1 != fCenter2 || fRadius1 != fRadius2); |
| if (type == Type::kFocal) { |
| fFocalData = data; |
| } |
| } |
| |
| bool SkTwoPointConicalGradient::isOpaque() const { |
| // Because areas outside the cone are left untouched, we cannot treat the |
| // shader as opaque even if the gradient itself is opaque. |
| // TODO(junov): Compute whether the cone fills the plane crbug.com/222380 |
| return false; |
| } |
| |
| // Returns the original non-sorted version of the gradient |
| SkShader::GradientType SkTwoPointConicalGradient::asAGradient(GradientInfo* info) const { |
| if (info) { |
| commonAsAGradient(info); |
| info->fPoint[0] = fCenter1; |
| info->fPoint[1] = fCenter2; |
| info->fRadius[0] = fRadius1; |
| info->fRadius[1] = fRadius2; |
| } |
| return kConical_GradientType; |
| } |
| |
| sk_sp<SkFlattenable> SkTwoPointConicalGradient::CreateProc(SkReadBuffer& buffer) { |
| DescriptorScope desc; |
| if (!desc.unflatten(buffer)) { |
| return nullptr; |
| } |
| SkPoint c1 = buffer.readPoint(); |
| SkPoint c2 = buffer.readPoint(); |
| SkScalar r1 = buffer.readScalar(); |
| SkScalar r2 = buffer.readScalar(); |
| |
| if (buffer.isVersionLT(SkPicturePriv::k2PtConicalNoFlip_Version) && buffer.readBool()) { |
| using std::swap; |
| // legacy flipped gradient |
| swap(c1, c2); |
| swap(r1, r2); |
| |
| SkColor4f* colors = desc.mutableColors(); |
| SkScalar* pos = desc.mutablePos(); |
| const int last = desc.fCount - 1; |
| const int half = desc.fCount >> 1; |
| for (int i = 0; i < half; ++i) { |
| swap(colors[i], colors[last - i]); |
| if (pos) { |
| SkScalar tmp = pos[i]; |
| pos[i] = SK_Scalar1 - pos[last - i]; |
| pos[last - i] = SK_Scalar1 - tmp; |
| } |
| } |
| if (pos) { |
| if (desc.fCount & 1) { |
| pos[half] = SK_Scalar1 - pos[half]; |
| } |
| } |
| } |
| if (!buffer.isValid()) { |
| return nullptr; |
| } |
| return SkGradientShader::MakeTwoPointConical(c1, r1, c2, r2, desc.fColors, |
| std::move(desc.fColorSpace), desc.fPos, |
| desc.fCount, desc.fTileMode, desc.fGradFlags, |
| desc.fLocalMatrix); |
| } |
| |
| void SkTwoPointConicalGradient::flatten(SkWriteBuffer& buffer) const { |
| this->INHERITED::flatten(buffer); |
| buffer.writePoint(fCenter1); |
| buffer.writePoint(fCenter2); |
| buffer.writeScalar(fRadius1); |
| buffer.writeScalar(fRadius2); |
| } |
| |
| void SkTwoPointConicalGradient::appendGradientStages(SkArenaAlloc* alloc, SkRasterPipeline* p, |
| SkRasterPipeline* postPipeline) const { |
| const auto dRadius = fRadius2 - fRadius1; |
| |
| if (fType == Type::kRadial) { |
| p->append(SkRasterPipeline::xy_to_radius); |
| |
| // Tiny twist: radial computes a t for [0, r2], but we want a t for [r1, r2]. |
| auto scale = SkTMax(fRadius1, fRadius2) / dRadius; |
| auto bias = -fRadius1 / dRadius; |
| |
| p->append_matrix(alloc, SkMatrix::Concat(SkMatrix::MakeTrans(bias, 0), |
| SkMatrix::MakeScale(scale, 1))); |
| return; |
| } |
| |
| if (fType == Type::kStrip) { |
| auto* ctx = alloc->make<SkRasterPipeline_2PtConicalCtx>(); |
| SkScalar scaledR0 = fRadius1 / this->getCenterX1(); |
| ctx->fP0 = scaledR0 * scaledR0; |
| p->append(SkRasterPipeline::xy_to_2pt_conical_strip, ctx); |
| p->append(SkRasterPipeline::mask_2pt_conical_nan, ctx); |
| postPipeline->append(SkRasterPipeline::apply_vector_mask, &ctx->fMask); |
| return; |
| } |
| |
| auto* ctx = alloc->make<SkRasterPipeline_2PtConicalCtx>(); |
| ctx->fP0 = 1/fFocalData.fR1; |
| ctx->fP1 = fFocalData.fFocalX; |
| |
| if (fFocalData.isFocalOnCircle()) { |
| p->append(SkRasterPipeline::xy_to_2pt_conical_focal_on_circle); |
| } else if (fFocalData.isWellBehaved()) { |
| p->append(SkRasterPipeline::xy_to_2pt_conical_well_behaved, ctx); |
| } else if (fFocalData.isSwapped() || 1 - fFocalData.fFocalX < 0) { |
| p->append(SkRasterPipeline::xy_to_2pt_conical_smaller, ctx); |
| } else { |
| p->append(SkRasterPipeline::xy_to_2pt_conical_greater, ctx); |
| } |
| |
| if (!fFocalData.isWellBehaved()) { |
| p->append(SkRasterPipeline::mask_2pt_conical_degenerates, ctx); |
| } |
| if (1 - fFocalData.fFocalX < 0) { |
| p->append(SkRasterPipeline::negate_x); |
| } |
| if (!fFocalData.isNativelyFocal()) { |
| p->append(SkRasterPipeline::alter_2pt_conical_compensate_focal, ctx); |
| } |
| if (fFocalData.isSwapped()) { |
| p->append(SkRasterPipeline::alter_2pt_conical_unswap); |
| } |
| if (!fFocalData.isWellBehaved()) { |
| postPipeline->append(SkRasterPipeline::apply_vector_mask, &ctx->fMask); |
| } |
| } |
| |
| ///////////////////////////////////////////////////////////////////// |
| |
| #if SK_SUPPORT_GPU |
| |
| #include "src/gpu/gradients/GrGradientShader.h" |
| |
| std::unique_ptr<GrFragmentProcessor> SkTwoPointConicalGradient::asFragmentProcessor( |
| const GrFPArgs& args) const { |
| return GrGradientShader::MakeConical(*this, args); |
| } |
| |
| #endif |