/*

 * 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 "modules/svg/include/SkSVGMask.h"

#include "include/core/SkCanvas.h"

#include "include/effects/SkLumaColorFilter.h"

#include "modules/svg/include/SkSVGRenderContext.h"

bool SkSVGMask::parseAndSetAttribute(const char* n, const char* v) {

    return INHERITED::parseAndSetAttribute(n, v) ||

           this->setX(SkSVGAttributeParser::parse<SkSVGLength>("x", n, v)) ||

           this->setY(SkSVGAttributeParser::parse<SkSVGLength>("y", n, v)) ||

           this->setWidth(SkSVGAttributeParser::parse<SkSVGLength>("width", n, v)) ||

           this->setHeight(SkSVGAttributeParser::parse<SkSVGLength>("height", n, v)) ||

           this->setMaskUnits(

                SkSVGAttributeParser::parse<SkSVGObjectBoundingBoxUnits>("maskUnits", n, v)) ||

           this->setMaskContentUnits(

                SkSVGAttributeParser::parse<SkSVGObjectBoundingBoxUnits>("maskContentUnits", n, v));

}

SkRect SkSVGMask::bounds(const SkSVGRenderContext& ctx) const {

    return ctx.resolveOBBRect(fX, fY, fWidth, fHeight, fMaskUnits);

}

void SkSVGMask::renderMask(const SkSVGRenderContext& ctx) const {

    // https://www.w3.org/TR/SVG11/masking.html#Masking

    // Propagate any inherited properties that may impact mask effect behavior (e.g.

    // color-interpolation). We call this explicitly here because the SkSVGMask

    // nodes do not participate in the normal onRender path, which is when property

    // propagation currently occurs.

    // The local context also restores the filter layer created below on scope exit.

    SkSVGRenderContext lctx(ctx);

    this->onPrepareToRender(&lctx);

    const auto ci = *lctx.presentationContext().fInherited.fColorInterpolation;

    auto ci_filter = (ci == SkSVGColorspace::kLinearRGB)

            ? SkColorFilters::SRGBToLinearGamma()

            : nullptr;

    SkPaint mask_filter;

    mask_filter.setColorFilter(

                SkColorFilters::Compose(SkLumaColorFilter::Make(), std::move(ci_filter)));

    // Mask color filter layer.

    // Note: We could avoid this extra layer if we invert the stacking order

    // (mask/content -> content/mask, kSrcIn -> kDstIn) and apply the filter

    // via the top (mask) layer paint.  That requires deferring mask rendering

    // until after node content, which introduces extra state/complexity.

    // Something to consider if masking performance ever becomes an issue.

    lctx.canvas()->saveLayer(nullptr, &mask_filter);

    const auto obbt = ctx.transformForCurrentOBB(fMaskContentUnits);

    lctx.canvas()->translate(obbt.offset.x, obbt.offset.y);

    lctx.canvas()->scale(obbt.scale.x, obbt.scale.y);

    for (const auto& child : fChildren) {

        child->render(lctx);

    }

}