skia2/experimental/svg/model/SkSVGLinearGradient.cpp

145 lines
5.0 KiB
C++

/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkGradientShader.h"
#include "SkSVGLinearGradient.h"
#include "SkSVGRenderContext.h"
#include "SkSVGStop.h"
#include "SkSVGValue.h"
SkSVGLinearGradient::SkSVGLinearGradient() : INHERITED(SkSVGTag::kLinearGradient) {}
void SkSVGLinearGradient::setHref(const SkSVGStringType& href) {
fHref = std::move(href);
}
void SkSVGLinearGradient::setGradientTransform(const SkSVGTransformType& t) {
fGradientTransform = t;
}
void SkSVGLinearGradient::setSpreadMethod(const SkSVGSpreadMethod& spread) {
fSpreadMethod = spread;
}
void SkSVGLinearGradient::setX1(const SkSVGLength& x1) {
fX1 = x1;
}
void SkSVGLinearGradient::setY1(const SkSVGLength& y1) {
fY1 = y1;
}
void SkSVGLinearGradient::setX2(const SkSVGLength& x2) {
fX2 = x2;
}
void SkSVGLinearGradient::setY2(const SkSVGLength& y2) {
fY2 = y2;
}
void SkSVGLinearGradient::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
switch (attr) {
case SkSVGAttribute::kGradientTransform:
if (const auto* t = v.as<SkSVGTransformValue>()) {
this->setGradientTransform(*t);
}
break;
case SkSVGAttribute::kHref:
if (const auto* href = v.as<SkSVGStringValue>()) {
this->setHref(*href);
}
break;
case SkSVGAttribute::kSpreadMethod:
if (const auto* spread = v.as<SkSVGSpreadMethodValue>()) {
this->setSpreadMethod(*spread);
}
break;
case SkSVGAttribute::kX1:
if (const auto* x1 = v.as<SkSVGLengthValue>()) {
this->setX1(*x1);
}
break;
case SkSVGAttribute::kY1:
if (const auto* y1 = v.as<SkSVGLengthValue>()) {
this->setY1(*y1);
}
break;
case SkSVGAttribute::kX2:
if (const auto* x2 = v.as<SkSVGLengthValue>()) {
this->setX2(*x2);
}
break;
case SkSVGAttribute::kY2:
if (const auto* y2 = v.as<SkSVGLengthValue>()) {
this->setY2(*y2);
}
break;
default:
this->INHERITED::onSetAttribute(attr, v);
}
}
// https://www.w3.org/TR/SVG/pservers.html#LinearGradientElementHrefAttribute
void SkSVGLinearGradient::collectColorStops(const SkSVGRenderContext& ctx,
SkSTArray<2, SkScalar, true>* pos,
SkSTArray<2, SkColor, true>* colors) const {
// Used to resolve percentage offsets.
const SkSVGLengthContext ltx(SkSize::Make(1, 1));
for (const auto& child : fChildren) {
if (child->tag() != SkSVGTag::kStop) {
continue;
}
const auto& stop = static_cast<const SkSVGStop&>(*child);
colors->push_back(SkColorSetA(stop.stopColor(),
SkScalarRoundToInt(stop.stopOpacity() * 255)));
pos->push_back(SkTPin(ltx.resolve(stop.offset(), SkSVGLengthContext::LengthType::kOther),
0.f, 1.f));
}
SkASSERT(colors->count() == pos->count());
if (pos->empty() && !fHref.value().isEmpty()) {
const auto* ref = ctx.findNodeById(fHref);
if (ref && ref->tag() == SkSVGTag::kLinearGradient) {
static_cast<const SkSVGLinearGradient*>(ref)->collectColorStops(ctx, pos, colors);
}
}
}
bool SkSVGLinearGradient::onAsPaint(const SkSVGRenderContext& ctx, SkPaint* paint) const {
const auto& lctx = ctx.lengthContext();
const auto x1 = lctx.resolve(fX1, SkSVGLengthContext::LengthType::kHorizontal);
const auto y1 = lctx.resolve(fY1, SkSVGLengthContext::LengthType::kVertical);
const auto x2 = lctx.resolve(fX2, SkSVGLengthContext::LengthType::kHorizontal);
const auto y2 = lctx.resolve(fY2, SkSVGLengthContext::LengthType::kVertical);
const SkPoint pts[2] = { {x1, y1}, {x2, y2}};
SkSTArray<2, SkColor , true> colors;
SkSTArray<2, SkScalar, true> pos;
this->collectColorStops(ctx, &pos, &colors);
// TODO:
// * stop (lazy?) sorting
// * href loop detection
// * href attribute inheritance (not just color stops)
// * objectBoundingBox units support
static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kPad) ==
SkShader::kClamp_TileMode, "SkSVGSpreadMethod::Type is out of sync");
static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kRepeat) ==
SkShader::kRepeat_TileMode, "SkSVGSpreadMethod::Type is out of sync");
static_assert(static_cast<SkShader::TileMode>(SkSVGSpreadMethod::Type::kReflect) ==
SkShader::kMirror_TileMode, "SkSVGSpreadMethod::Type is out of sync");
const auto tileMode = static_cast<SkShader::TileMode>(fSpreadMethod.type());
paint->setShader(SkGradientShader::MakeLinear(pts, colors.begin(), pos.begin(), colors.count(),
tileMode, 0, &fGradientTransform.value()));
return true;
}