src/text/gpu/GlyphVector.cpp

/*
 * Copyright 2022 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "src/text/gpu/GlyphVector.h"

#include "include/private/chromium/SkChromeRemoteGlyphCache.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkStrikeCache.h"
#include "src/core/SkStrikeSpec.h"
#include "src/core/SkWriteBuffer.h"
#if SK_SUPPORT_GPU
#include "src/gpu/ganesh/text/GrAtlasManager.h"
#endif

using MaskFormat = skgpu::MaskFormat;

namespace sktext::gpu {

GlyphVector::GlyphVector(sk_sp<SkStrike>&& strike, SkSpan<Variant> glyphs)
        : fSkStrike{std::move(strike)}
        , fGlyphs{glyphs} {
    SkASSERT(fSkStrike != nullptr);
    SkASSERT(fGlyphs.size() > 0);
}

GlyphVector GlyphVector::Make(
        sk_sp<SkStrike>&& strike, SkSpan<SkGlyphVariant> glyphs, SubRunAllocator* alloc) {
    SkASSERT(strike != nullptr);
    SkASSERT(glyphs.size() > 0);
    Variant* variants = alloc->makePODArray<Variant>(glyphs.size());
    for (auto [i, gv] : SkMakeEnumerate(glyphs)) {
        variants[i] = gv.glyph()->getPackedID();
    }

    return GlyphVector{std::move(strike), SkMakeSpan(variants, glyphs.size())};
}

std::optional<GlyphVector> GlyphVector::MakeFromBuffer(SkReadBuffer& buffer,
                                                       const SkStrikeClient* client,
                                                       SubRunAllocator* alloc) {
    auto descriptor = SkAutoDescriptor::MakeFromBuffer(buffer);
    if (!buffer.validate(descriptor.has_value())) { return {}; }

    if (client != nullptr) {
        if (!client->translateTypefaceID(&descriptor.value())) { return {}; }
    }

    sk_sp<SkStrike> strike = SkStrikeCache::GlobalStrikeCache()->findStrike(*descriptor->getDesc());
    if (!buffer.validate(strike != nullptr)) { return {}; }

    int32_t glyphCount = buffer.read32();
    // Since the glyph count can never be zero. There was a buffer reading problem.
    if (!buffer.validate(glyphCount > 0)) { return {}; }

    // Make sure we can multiply without overflow in the check below.
    static constexpr int kMaxCount = (int)(INT_MAX / sizeof(uint32_t));
    if (!buffer.validate(glyphCount <= kMaxCount)) { return {}; }

    // Check for enough bytes to populate the packedGlyphID array. If not enough something has
    // gone wrong.
    if (!buffer.validate(glyphCount * sizeof(uint32_t) <= buffer.available())) { return {}; }

    Variant* variants = alloc->makePODArray<Variant>(glyphCount);
    for (int i = 0; i < glyphCount; i++) {
        variants[i].packedGlyphID = SkPackedGlyphID(buffer.readUInt());
    }
    return {GlyphVector{std::move(strike), SkMakeSpan(variants, glyphCount)}};
}

void GlyphVector::flatten(SkWriteBuffer& buffer) {
    // There should never be a glyph vector with zero glyphs.
    SkASSERT(fGlyphs.size() != 0);
    if (!fSkStrike) { SK_ABORT("Can't flatten with already drawn."); }

    fSkStrike->getDescriptor().flatten(buffer);

    // Write out the span of packedGlyphIDs.
    buffer.write32(SkTo<int32_t>(fGlyphs.size()));
    for (auto variant : fGlyphs) {
        buffer.writeUInt(variant.packedGlyphID.value());
    }
}

SkSpan<const Glyph*> GlyphVector::glyphs() const {
    return SkMakeSpan(reinterpret_cast<const Glyph**>(fGlyphs.data()), fGlyphs.size());
}

// packedGlyphIDToGlyph must be run in single-threaded mode.
// If fSkStrike != nullptr then the conversion to Glyph* has not happened.
void GlyphVector::packedGlyphIDToGlyph(StrikeCache* cache) {
    if (fSkStrike != nullptr) {
        fTextStrike = cache->findOrCreateStrike(fSkStrike->strikeSpec());

        for (auto& variant : fGlyphs) {
            variant.glyph = fTextStrike->getGlyph(variant.packedGlyphID);
        }

        // This must be pinned for the Atlas filling to work.
        // TODO(herb): re-enable after the cut on 20220414
        // fSkStrike->verifyPinnedStrike();

        // Drop the ref on the strike that was taken in the SkGlyphRunPainter process* methods.
        fSkStrike = nullptr;
    }
}

#if SK_SUPPORT_GPU
std::tuple<bool, int> GlyphVector::regenerateAtlas(int begin, int end,
                                                   MaskFormat maskFormat,
                                                   int srcPadding,
                                                   GrMeshDrawTarget* target) {
    GrAtlasManager* atlasManager = target->atlasManager();
    GrDeferredUploadTarget* uploadTarget = target->deferredUploadTarget();

    uint64_t currentAtlasGen = atlasManager->atlasGeneration(maskFormat);

    this->packedGlyphIDToGlyph(target->strikeCache());

    if (fAtlasGeneration != currentAtlasGen) {
        // Calculate the texture coordinates for the vertexes during first use (fAtlasGeneration
        // is set to kInvalidAtlasGeneration) or the atlas has changed in subsequent calls..
        fBulkUseToken.reset();

        SkBulkGlyphMetricsAndImages metricsAndImages{fTextStrike->strikeSpec()};

        // Update the atlas information in the GrStrike.
        auto tokenTracker = uploadTarget->tokenTracker();
        auto glyphs = fGlyphs.subspan(begin, end - begin);
        int glyphsPlacedInAtlas = 0;
        bool success = true;
        for (const Variant& variant : glyphs) {
            Glyph* gpuGlyph = variant.glyph;
            SkASSERT(gpuGlyph != nullptr);

            if (!atlasManager->hasGlyph(maskFormat, gpuGlyph)) {
                const SkGlyph& skGlyph = *metricsAndImages.glyph(gpuGlyph->fPackedID);
                auto code = atlasManager->addGlyphToAtlas(
                        skGlyph, gpuGlyph, srcPadding, target->resourceProvider(), uploadTarget);
                if (code != GrDrawOpAtlas::ErrorCode::kSucceeded) {
                    success = code != GrDrawOpAtlas::ErrorCode::kError;
                    break;
                }
            }
            atlasManager->addGlyphToBulkAndSetUseToken(
                    &fBulkUseToken, maskFormat, gpuGlyph,
                    tokenTracker->nextDrawToken());
            glyphsPlacedInAtlas++;
        }

        // Update atlas generation if there are no more glyphs to put in the atlas.
        if (success && begin + glyphsPlacedInAtlas == SkCount(fGlyphs)) {
            // Need to get the freshest value of the atlas' generation because
            // updateTextureCoordinates may have changed it.
            fAtlasGeneration = atlasManager->atlasGeneration(maskFormat);
        }

        return {success, glyphsPlacedInAtlas};
    } else {
        // The atlas hasn't changed, so our texture coordinates are still valid.
        if (end == SkCount(fGlyphs)) {
            // The atlas hasn't changed and the texture coordinates are all still valid. Update
            // all the plots used to the new use token.
            atlasManager->setUseTokenBulk(fBulkUseToken,
                                          uploadTarget->tokenTracker()->nextDrawToken(),
                                          maskFormat);
        }
        return {true, end - begin};
    }
}
#endif

}  // namespace sktext::gpu