src/shaders/SkTriColorShader.cpp

/*
 * Copyright 2023 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/shaders/SkTriColorShader.h"

#include "include/core/SkMatrix.h"
#include "include/core/SkPoint.h"
#include "include/core/SkTypes.h"
#include "src/core/SkColorData.h"
#include "src/core/SkEffectPriv.h"
#include "src/core/SkRasterPipeline.h"
#include "src/core/SkRasterPipelineOpList.h"
#include "src/core/SkVx.h"

bool SkTriColorShader::appendStages(const SkStageRec& rec, const SkShaders::MatrixRec&) const {
    rec.fPipeline->append(SkRasterPipelineOp::seed_shader);
    if (fUsePersp) {
        rec.fPipeline->append(SkRasterPipelineOp::matrix_perspective, &fM33);
    }
    rec.fPipeline->append(SkRasterPipelineOp::matrix_4x3, &fM43);
    return true;
}

bool SkTriColorShader::update(const SkMatrix& ctmInv,
                              const SkPoint pts[],
                              const SkPMColor4f colors[],
                              int index0,
                              int index1,
                              int index2) {
    SkMatrix m, im;
    m.reset();
    m.set(0, pts[index1].fX - pts[index0].fX);
    m.set(1, pts[index2].fX - pts[index0].fX);
    m.set(2, pts[index0].fX);
    m.set(3, pts[index1].fY - pts[index0].fY);
    m.set(4, pts[index2].fY - pts[index0].fY);
    m.set(5, pts[index0].fY);
    if (!m.invert(&im)) {
        return false;
    }

    fM33.setConcat(im, ctmInv);

    auto c0 = skvx::float4::Load(colors[index0].vec()),
         c1 = skvx::float4::Load(colors[index1].vec()),
         c2 = skvx::float4::Load(colors[index2].vec());

    (c1 - c0).store(&fM43.fMat[0]);
    (c2 - c0).store(&fM43.fMat[4]);
    c0.store(&fM43.fMat[8]);

    if (!fUsePersp) {
        fM43.setConcat(fM43, fM33);
    }
    return true;
}