blob: 4c38f1e841489aa96631b8067870ef0fce19f8b6 [file] [log] [blame]
* Copyright 2021 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#include "src/shaders/SkTransformShader.h"
#include "include/core/SkMatrix.h"
#include "src/core/SkEffectPriv.h"
#include "src/core/SkRasterPipeline.h"
#include "src/core/SkRasterPipelineOpList.h"
#include <optional>
SkTransformShader::SkTransformShader(const SkShaderBase& shader, bool allowPerspective)
: fShader{shader}, fAllowPerspective{allowPerspective} {
bool SkTransformShader::update(const SkMatrix& matrix) {
if (!fAllowPerspective && matrix.hasPerspective()) {
return false;
return true;
bool SkTransformShader::appendStages(const SkStageRec& rec,
const SkShaders::MatrixRec& mRec) const {
// We have to seed and apply any constant matrices before appending our matrix that may
// mutate. We could try to add one matrix stage and then incorporate the parent matrix
// with the variable matrix in each call to update(). However, in practice our callers
// fold the CTM into the update() matrix and don't wrap the transform shader in local matrix
// shaders so the call to apply below should just seed the coordinates. If this assert fires
// it just indicates an optimization opportunity, not a correctness bug.
std::optional<SkShaders::MatrixRec> childMRec = mRec.apply(rec);
if (!childMRec.has_value()) {
return false;
// The matrix we're about to insert gets updated between uses of the pipeline so our children
// can't know the total transform when they add their stages. We don't even incorporate this
// matrix into the SkShaders::MatrixRec at all.
auto type = fAllowPerspective ? SkRasterPipelineOp::matrix_perspective
: SkRasterPipelineOp::matrix_2x3;
rec.fPipeline->append(type, fMatrixStorage);
fShader.appendStages(rec, *childMRec);
return true;