src/core/SkPicture.cpp

/*
 * Copyright 2007 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkPicture.h"

#include "include/core/SkBBHFactory.h"
#include "include/core/SkData.h"
#include "include/core/SkPictureRecorder.h"
#include "include/core/SkSerialProcs.h"
#include "include/core/SkStream.h"
#include "include/private/SkTFitsIn.h"
#include "include/private/SkTo.h"
#include "src/core/SkCanvasPriv.h"
#include "src/core/SkMathPriv.h"
#include "src/core/SkPictureData.h"
#include "src/core/SkPicturePlayback.h"
#include "src/core/SkPicturePriv.h"
#include "src/core/SkPictureRecord.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkRecord.h"
#include "src/core/SkRecordDraw.h"
#include "src/core/SkRecords.h"
#include "src/core/SkResourceCache.h"
#include "src/core/SkStreamPriv.h"
#include "src/core/SkWriteBuffer.h"

#include <atomic>
#include <cstring>
#include <memory>

// When we read/write the SkPictInfo via a stream, we have a sentinel byte right after the info.
// Note: in the read/write buffer versions, we have a slightly different convention:
//      We have a sentinel int32_t:
//          0 : failure
//          1 : PictureData
//         <0 : -size of the custom data
enum {
    kFailure_TrailingStreamByteAfterPictInfo     = 0,   // nothing follows
    kPictureData_TrailingStreamByteAfterPictInfo = 1,   // SkPictureData follows
    kCustom_TrailingStreamByteAfterPictInfo      = 2,   // -size32 follows
};

/* This handles generating unique IDs */
static uint32_t next_picture_id() {
    static std::atomic<uint32_t> nextID{1};
    uint32_t id;
    do {
        id = nextID.fetch_add(+1, std::memory_order_relaxed);
    } while (id == 0);
    return id;
}

SkPicture::SkPicture(const SkRect& cull,
                     sk_sp<const SkRecord> record,
                     std::unique_ptr<const SkSnapshotArray> drawablePicts,
                     sk_sp<const SkBBoxHierarchy> bbh,
                     size_t approxBytesUsedBySubPictures)
        : fUniqueID(next_picture_id())
        , fCullRect(cull)
        , fApproxBytesUsedBySubPictures(approxBytesUsedBySubPictures)
        , fRecord(std::move(record))
        , fDrawablePicts(std::move(drawablePicts))
        , fBBH(std::move(bbh)) {}

SkPicture::~SkPicture() {
    if (fAddedToCache.load()) {
        SkResourceCache::PostPurgeSharedID(SkPicturePriv::MakeSharedID(fUniqueID));
    }
}

static const char kMagic[] = { 's', 'k', 'i', 'a', 'p', 'i', 'c', 't' };

SkPictInfo SkPicture::createHeader() const {
    SkPictInfo info;
    // Copy magic bytes at the beginning of the header
    static_assert(sizeof(kMagic) == 8, "");
    static_assert(sizeof(kMagic) == sizeof(info.fMagic), "");
    memcpy(info.fMagic, kMagic, sizeof(kMagic));

    // Set picture info after magic bytes in the header
    info.setVersion(SkPicturePriv::kCurrent_Version);
    info.fCullRect = this->cullRect();
    return info;
}

bool SkPicture::IsValidPictInfo(const SkPictInfo& info) {
    if (0 != memcmp(info.fMagic, kMagic, sizeof(kMagic))) {
        return false;
    }
    if (info.getVersion() < SkPicturePriv::kMin_Version ||
        info.getVersion() > SkPicturePriv::kCurrent_Version) {
        return false;
    }
    return true;
}

bool SkPicture::StreamIsSKP(SkStream* stream, SkPictInfo* pInfo) {
    if (!stream) {
        return false;
    }

    SkPictInfo info;
    SkASSERT(sizeof(kMagic) == sizeof(info.fMagic));
    if (stream->read(&info.fMagic, sizeof(kMagic)) != sizeof(kMagic)) {
        return false;
    }

    uint32_t version;
    if (!stream->readU32(&version)) { return false; }
    info.setVersion(version);
    if (!stream->readScalar(&info.fCullRect.fLeft  )) { return false; }
    if (!stream->readScalar(&info.fCullRect.fTop   )) { return false; }
    if (!stream->readScalar(&info.fCullRect.fRight )) { return false; }
    if (!stream->readScalar(&info.fCullRect.fBottom)) { return false; }

    if (pInfo) {
        *pInfo = info;
    }
    return IsValidPictInfo(info);
}

bool SkPicture_StreamIsSKP(SkStream* stream, SkPictInfo* pInfo) {
    return SkPicture::StreamIsSKP(stream, pInfo);
}

bool SkPicture::BufferIsSKP(SkReadBuffer* buffer, SkPictInfo* pInfo) {
    SkPictInfo info;
    SkASSERT(sizeof(kMagic) == sizeof(info.fMagic));
    if (!buffer->readByteArray(&info.fMagic, sizeof(kMagic))) {
        return false;
    }

    info.setVersion(buffer->readUInt());
    buffer->readRect(&info.fCullRect);

    if (IsValidPictInfo(info)) {
        if (pInfo) { *pInfo = info; }
        return true;
    }
    return false;
}

sk_sp<SkPicture> SkPicture::Forwardport(const SkPictInfo& info,
                                        const SkPictureData* data,
                                        SkReadBuffer* buffer) {
    if (!data) {
        return nullptr;
    }
    if (!data->opData()) {
        return nullptr;
    }
    SkPicturePlayback playback(data);
    SkPictureRecorder r;
    playback.draw(r.beginRecording(info.fCullRect), nullptr/*no callback*/, buffer);
    return r.finishRecordingAsPicture();
}

sk_sp<SkPicture> SkPicture::MakeFromStream(SkStream* stream, const SkDeserialProcs* procs) {
    return MakeFromStreamPriv(stream, procs, nullptr, SkPicturePriv::kDefaultRecursionLimit);
}

sk_sp<SkPicture> SkPicture::MakeFromData(const void* data, size_t size,
                                         const SkDeserialProcs* procs) {
    if (!data) {
        return nullptr;
    }
    SkMemoryStream stream(data, size);
    return MakeFromStreamPriv(&stream, procs, nullptr, SkPicturePriv::kDefaultRecursionLimit);
}

sk_sp<SkPicture> SkPicture::MakeFromData(const SkData* data, const SkDeserialProcs* procs) {
    if (!data) {
        return nullptr;
    }
    SkMemoryStream stream(data->data(), data->size());
    return MakeFromStreamPriv(&stream, procs, nullptr, SkPicturePriv::kDefaultRecursionLimit);
}

sk_sp<SkPicture> SkPicture::MakeFromStreamPriv(SkStream* stream, const SkDeserialProcs* procsPtr,
                                               SkTypefacePlayback* typefaces, int recursionLimit) {
    if (recursionLimit <= 0) {
        return nullptr;
    }
    SkPictInfo info;
    if (!StreamIsSKP(stream, &info)) {
        return nullptr;
    }

    SkDeserialProcs procs;
    if (procsPtr) {
        procs = *procsPtr;
    }

    uint8_t trailingStreamByteAfterPictInfo;
    if (!stream->readU8(&trailingStreamByteAfterPictInfo)) { return nullptr; }
    switch (trailingStreamByteAfterPictInfo) {
        case kPictureData_TrailingStreamByteAfterPictInfo: {
            std::unique_ptr<SkPictureData> data(
                    SkPictureData::CreateFromStream(stream, info, procs, typefaces,
                                                    recursionLimit));
            return Forwardport(info, data.get(), nullptr);
        }
        case kCustom_TrailingStreamByteAfterPictInfo: {
            int32_t ssize;
            if (!stream->readS32(&ssize) || ssize >= 0 || !procs.fPictureProc) {
                return nullptr;
            }
            size_t size = sk_negate_to_size_t(ssize);
            if (SkStreamPriv::RemainingLengthIsBelow(stream, size)) {
                return nullptr;
            }
            auto data = SkData::MakeUninitialized(size);
            if (stream->read(data->writable_data(), size) != size) {
                return nullptr;
            }
            return procs.fPictureProc(data->data(), size, procs.fPictureCtx);
        }
        default:    // fall out to error return
            break;
    }
    return nullptr;
}

sk_sp<SkPicture> SkPicturePriv::MakeFromBuffer(SkReadBuffer& buffer) {
    if (!buffer.isValid()) {
        return nullptr;
    }
    SkPictInfo info;
    if (!SkPicture::BufferIsSKP(&buffer, &info)) {
        return nullptr;
    }
    // size should be 0, 1, or negative
    int32_t ssize = buffer.read32();
    if (ssize < 0) {
        const SkDeserialProcs& procs = buffer.getDeserialProcs();
        if (!procs.fPictureProc) {
            return nullptr;
        }
        size_t size = sk_negate_to_size_t(ssize);
        return procs.fPictureProc(buffer.skip(size), size, procs.fPictureCtx);
    }
    if (ssize != 1) {
        // 1 is the magic 'size' that means SkPictureData follows
        return nullptr;
    }
    std::unique_ptr<SkPictureData> data(SkPictureData::CreateFromBuffer(buffer, info));
    return SkPicture::Forwardport(info, data.get(), &buffer);
}

SkPictureData* SkPicture::backport() const {
    SkPictInfo info = this->createHeader();
    SkPictureRecord rec(info.fCullRect.roundOut(), 0/*flags*/);
    rec.beginRecording();
        this->playback(&rec);
    rec.endRecording();
    return new SkPictureData(rec, info);
}

void SkPicture::serialize(SkWStream* stream, const SkSerialProcs* procs) const {
    this->serialize(stream, procs, nullptr);
}

sk_sp<SkData> SkPicture::serialize(const SkSerialProcs* procs) const {
    SkDynamicMemoryWStream stream;
    this->serialize(&stream, procs, nullptr);
    return stream.detachAsData();
}

static sk_sp<const SkData> custom_serialize(const SkPicture* picture, const SkSerialProcs& procs) {
    if (procs.fPictureProc) {
        auto data = procs.fPictureProc(const_cast<SkPicture*>(picture), procs.fPictureCtx);
        if (data) {
            size_t size = data->size();
            if (!SkTFitsIn<int32_t>(size) || size <= 1) {
                return SkData::MakeEmpty();
            }
            return data;
        }
    }
    return nullptr;
}

static bool write_pad32(SkWStream* stream, const void* data, size_t size) {
    if (!stream->write(data, size)) {
        return false;
    }
    if (size & 3) {
        uint32_t zero = 0;
        return stream->write(&zero, 4 - (size & 3));
    }
    return true;
}

// Private serialize.
// SkPictureData::serialize makes a first pass on all subpictures, indicated by textBlobsOnly=true,
// to fill typefaceSet.
void SkPicture::serialize(SkWStream* stream, const SkSerialProcs* procsPtr,
                          SkRefCntSet* typefaceSet, bool textBlobsOnly) const {
    SkSerialProcs procs;
    if (procsPtr) {
        procs = *procsPtr;
    }

    SkPictInfo info = this->createHeader();
    stream->write(&info, sizeof(info));

    if (auto custom = custom_serialize(this, procs)) {
        int32_t size = SkToS32(custom->size());
        if (size == 0) {
            stream->write8(kFailure_TrailingStreamByteAfterPictInfo);
            return;
        }
        stream->write8(kCustom_TrailingStreamByteAfterPictInfo);
        stream->write32(-size);    // negative for custom format
        write_pad32(stream, custom->data(), size);
        return;
    }

    std::unique_ptr<SkPictureData> data(this->backport());
    if (data) {
        stream->write8(kPictureData_TrailingStreamByteAfterPictInfo);
        data->serialize(stream, procs, typefaceSet, textBlobsOnly);
    } else {
        stream->write8(kFailure_TrailingStreamByteAfterPictInfo);
    }
}

void SkPicturePriv::Flatten(const sk_sp<const SkPicture> picture, SkWriteBuffer& buffer) {
    SkPictInfo info = picture->createHeader();
    std::unique_ptr<SkPictureData> data(picture->backport());

    buffer.writeByteArray(&info.fMagic, sizeof(info.fMagic));
    buffer.writeUInt(info.getVersion());
    buffer.writeRect(info.fCullRect);

    if (auto custom = custom_serialize(picture.get(), buffer.serialProcs())) {
        int32_t size = SkToS32(custom->size());
        buffer.write32(-size);    // negative for custom format
        buffer.writePad32(custom->data(), size);
        return;
    }

    if (data) {
        buffer.write32(1); // special size meaning SkPictureData
        data->flatten(buffer);
    } else {
        buffer.write32(0); // signal no content
    }
}

sk_sp<SkPicture> SkPicturePriv::MakeEmptyPicture() {
    return SkPicturePriv::MakePicture(
            SkRect::MakeEmpty(), sk_make_sp<SkRecord>(), nullptr, nullptr, 0);
}

sk_sp<SkPicture> SkPicturePriv::MakePicture(const SkRect& cull,
                                            sk_sp<const SkRecord> record,
                                            std::unique_ptr<const SkSnapshotArray> drawablePicts,
                                            sk_sp<const SkBBoxHierarchy> bbh,
                                            size_t approxBytesUsedBySubPictures) {
    return sk_sp<SkPicture>(new SkPicture(cull,
                                          std::move(record),
                                          std::move(drawablePicts),
                                          std::move(bbh),
                                          approxBytesUsedBySubPictures));
}

void SkPicture::playback(SkCanvas* canvas, AbortCallback* callback) const {
    SkASSERT(canvas);
    if (this->isPlaceholder()) {
        return;
    }
    const bool useBBH = !canvas->getLocalClipBounds().contains(this->cullRect());
    SkRecordDraw(*fRecord,
                 canvas,
                 fDrawablePicts ? fDrawablePicts->begin() : nullptr,
                 nullptr,
                 fDrawablePicts ? fDrawablePicts->count() : 0,
                 useBBH ? fBBH.get() : nullptr,
                 callback);
}

struct NestedApproxOpCounter {
    int fCount = 0;
    int fDepth = 0;
    const SkSnapshotArray* fDrawablePicts;

    NestedApproxOpCounter(const SkSnapshotArray* drawablePicts, int depth)
            : fDepth(depth), fDrawablePicts(drawablePicts) {}

    template <typename T> void operator()(const T& op) { fCount++; }

    void operator()(const SkRecords::DrawPicture& op) {
        fCount += 1 + SkPicturePriv::ApproximateOpCount(op.picture.get(), fDepth + 1, true);
    }

    void operator()(const SkRecords::DrawDrawable& op) {
        // Adding one for the DrawDrawable itself at the beginning
        fCount++;

        if (!fDrawablePicts) return;

        if (0 <= op.index && op.index < fDrawablePicts->count()) {
            fCount += SkPicturePriv::ApproximateOpCount(
                    fDrawablePicts->at(op.index), fDepth + 1, true);
        }
    }
};

int SkPicturePriv::ApproximateOpCount(const SkPicture* pic, int depth, bool nested) {
    if (!pic || depth > SkPicturePriv::kDefaultRecursionLimit) {
        return 0;
    }

    if (pic->isPlaceholder()) {
        // approximateOpCount() needs to be greater than kMaxPictureOpsToUnrollInsteadOfRef
        // (SkCanvasPriv.h) to avoid unrolling this into a parent picture.
        return kMaxPictureOpsToUnrollInsteadOfRef + 1;
    }

    if (!nested) {
        return pic->fRecord->count();
    }

    NestedApproxOpCounter visitor(pic->fDrawablePicts.get(), depth);
    for (int i = 0; i < pic->fRecord->count(); i++) {
        pic->fRecord->visit(i, visitor);
    }
    return visitor.fCount;
}

int SkPicture::approximateOpCount(bool nested) const {
    return SkPicturePriv::ApproximateOpCount(this, 0, nested);
}

size_t SkPicture::approximateBytesUsed() const {
    if (this->isPlaceholder()) {
        return sizeof(*this);
    }
    size_t bytes = sizeof(*this) + fRecord->bytesUsed() + fApproxBytesUsedBySubPictures;
    if (fBBH) {
        bytes += fBBH->bytesUsed();
    }
    return bytes;
}

sk_sp<SkPicture> SkPicture::MakePlaceholder(SkRect cull) {
    return SkPicturePriv::MakePicture(cull, nullptr, nullptr, nullptr, 0);
}