SkBlitter* SkRasterPipelineBlitter::Create(const SkPixmap& dst,
                                           const SkPaint& paint,
                                           const SkMatrix& ctm,
                                           SkArenaAlloc* alloc) {
    auto blitter = alloc->make<SkRasterPipelineBlitter>(
            dst,
            paint.getBlendMode(),
            SkPM4f_from_SkColor(paint.getColor(), dst.colorSpace()));


    SkBlendMode*      blend       = &blitter->fBlend;
    SkPM4f*           paintColor  = &blitter->fPaintColor;
    SkRasterPipeline* pipeline    = &blitter->fShader;

    SkShader*      shader      = paint.getShader();
    SkColorFilter* colorFilter = paint.getColorFilter();

    // TODO: all temporary
    if (!supported(dst.info()) || !SkBlendMode_AppendStages(*blend)) {
        return nullptr;
    }

    bool is_opaque   = paintColor->a() == 1.0f,
         is_constant = true;
    if (shader) {
        pipeline->append(SkRasterPipeline::seed_shader, &blitter->fCurrentY);
        if (!shader->appendStages(pipeline, dst.colorSpace(), alloc, ctm, paint)) {
            return nullptr;
        }
        if (!is_opaque) {
            pipeline->append(SkRasterPipeline::scale_1_float,
                             &paintColor->fVec[SkPM4f::A]);
        }

        is_opaque   = is_opaque && shader->isOpaque();
        is_constant = shader->isConstant();
    } else {
        pipeline->append(SkRasterPipeline::constant_color, paintColor);
    }

    if (colorFilter) {
        if (!colorFilter->appendStages(pipeline, dst.colorSpace(), alloc, is_opaque)) {
            return nullptr;
        }
        is_opaque = is_opaque && (colorFilter->getFlags() & SkColorFilter::kAlphaUnchanged_Flag);
    }

    if (is_constant) {
        pipeline->append(SkRasterPipeline::store_f32, &paintColor);
        pipeline->run(0,1);

        *pipeline = SkRasterPipeline();
        pipeline->append(SkRasterPipeline::constant_color, paintColor);

        is_opaque = paintColor->a() == 1.0f;
    }

    if (is_opaque && *blend == SkBlendMode::kSrcOver) {
        *blend = SkBlendMode::kSrc;
    }

    if (is_constant && *blend == SkBlendMode::kSrc) {
        SkRasterPipeline p;
        p.extend(*pipeline);
        blitter->fDstPtr = &blitter->fMemsetColor;
        blitter->append_store(&p);
        p.run(0,1);

        blitter->fCanMemsetInBlitH = true;
    }

    return blitter;
}