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/*
* 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 "SkTwoPointConicalGradient.h"
#include "SkRasterPipeline.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#include "../../jumper/SkJumper.h"
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())) {
// Concentric case: we can pretend we're radial (with a tiny twist).
const SkScalar scale = 1.0f / 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;
}
// General two-point case.
gradientType = Type::kTwoPoint;
}
return sk_sp<SkShader>(new SkTwoPointConicalGradient(c0, r0, c1, r1, desc,
gradientType, gradientMatrix));
}
SkTwoPointConicalGradient::SkTwoPointConicalGradient(
const SkPoint& start, SkScalar startRadius,
const SkPoint& end, SkScalar endRadius,
const Descriptor& desc, Type type, const SkMatrix& gradientMatrix)
: 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);
}
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(SkReadBuffer::k2PtConicalNoFlip_Version) && buffer.readBool()) {
// legacy flipped gradient
SkTSwap(c1, c2);
SkTSwap(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) {
SkTSwap(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];
}
}
}
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);
}
#if SK_SUPPORT_GPU
#include "SkGr.h"
#include "SkTwoPointConicalGradient_gpu.h"
std::unique_ptr<GrFragmentProcessor> SkTwoPointConicalGradient::asFragmentProcessor(
const AsFPArgs& args) const {
SkASSERT(args.fContext);
return Gr2PtConicalGradientEffect::Make(
GrGradientEffect::CreateArgs(args.fContext, this, args.fLocalMatrix, fTileMode,
args.fDstColorSpaceInfo->colorSpace()));
}
#endif
sk_sp<SkShader> SkTwoPointConicalGradient::onMakeColorSpace(SkColorSpaceXformer* xformer) const {
const AutoXformColors xformedColors(*this, xformer);
return SkGradientShader::MakeTwoPointConical(fCenter1, fRadius1, fCenter2, fRadius2,
xformedColors.fColors.get(), fOrigPos, fColorCount,
fTileMode, fGradFlags, &this->getLocalMatrix());
}
#ifndef SK_IGNORE_TO_STRING
void SkTwoPointConicalGradient::toString(SkString* str) const {
str->append("SkTwoPointConicalGradient: (");
str->append("center1: (");
str->appendScalar(fCenter1.fX);
str->append(", ");
str->appendScalar(fCenter1.fY);
str->append(") radius1: ");
str->appendScalar(fRadius1);
str->append(" ");
str->append("center2: (");
str->appendScalar(fCenter2.fX);
str->append(", ");
str->appendScalar(fCenter2.fY);
str->append(") radius2: ");
str->appendScalar(fRadius2);
str->append(" ");
this->INHERITED::toString(str);
str->append(")");
}
#endif
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;
}
const auto dCenter = (fCenter1 - fCenter2).length();
// Since we've squashed the centers into a unit vector, we must also scale
// all the coefficient variables by (1 / dCenter).
const auto coeffA = 1 - dRadius * dRadius / (dCenter * dCenter);
auto* ctx = alloc->make<SkJumper_2PtConicalCtx>();
ctx->fCoeffA = coeffA;
ctx->fInvCoeffA = 1 / coeffA;
ctx->fR0 = fRadius1 / dCenter;
ctx->fDR = dRadius / dCenter;
// Is the solver guaranteed to not produce degenerates?
bool isWellBehaved = true;
if (SkScalarNearlyZero(coeffA)) {
// The focal point is on the edge of the end circle.
p->append(SkRasterPipeline::xy_to_2pt_conical_linear, ctx);
isWellBehaved = false;
} else {
isWellBehaved = SkScalarAbs(dRadius) >= dCenter;
bool isFlipped = isWellBehaved && dRadius < 0;
bool isFirst = (coeffA > 0) != isFlipped;
// We want the larger root, per spec:
// "For all values of ω where r(ω) > 0, starting with the value of ω nearest
// to positive infinity and ending with the value of ω nearest to negative
// infinity, draw the circumference of the circle with radius r(ω) at position
// (x(ω), y(ω)), with the color at ω, but only painting on the parts of the
// bitmap that have not yet been painted on by earlier circles in this step for
// this rendering of the gradient."
// (https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-createradialgradient)
//
// ... except when the gradient is flipped.
//
// The first root (-b + sqrt(...)) / 2a is larger if a (i.e. coeffA) > 0 and the second
// root (-b - sqrt(...)) / 2a is larger if a < 0.
p->append(isFirst ? SkRasterPipeline::xy_to_2pt_conical_quadratic_first
: SkRasterPipeline::xy_to_2pt_conical_quadratic_second, ctx);
}
if (!isWellBehaved) {
p->append(SkRasterPipeline::mask_2pt_conical_degenerates, ctx);
postPipeline->append(SkRasterPipeline::apply_vector_mask, &ctx->fMask);
}
}
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