src/core/SkWriteBuffer.cpp

/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "SkWriteBuffer.h"

#include "SkBitmap.h"
#include "SkData.h"
#include "SkImagePriv.h"
#include "SkPaintPriv.h"
#include "SkPtrRecorder.h"
#include "SkStream.h"
#include "SkTo.h"
#include "SkTypeface.h"

///////////////////////////////////////////////////////////////////////////////////////////////////

SkBinaryWriteBuffer::SkBinaryWriteBuffer()
    : fFactorySet(nullptr)
    , fTFSet(nullptr) {
}

SkBinaryWriteBuffer::SkBinaryWriteBuffer(void* storage, size_t storageSize)
    : fFactorySet(nullptr)
    , fTFSet(nullptr)
    , fWriter(storage, storageSize)
{}

SkBinaryWriteBuffer::~SkBinaryWriteBuffer() {}

bool SkBinaryWriteBuffer::usingInitialStorage() const {
    return fWriter.usingInitialStorage();
}

void SkBinaryWriteBuffer::writeByteArray(const void* data, size_t size) {
    fWriter.write32(SkToU32(size));
    fWriter.writePad(data, size);
}

void SkBinaryWriteBuffer::writeBool(bool value) {
    fWriter.writeBool(value);
}

void SkBinaryWriteBuffer::writeScalar(SkScalar value) {
    fWriter.writeScalar(value);
}

void SkBinaryWriteBuffer::writeScalarArray(const SkScalar* value, uint32_t count) {
    fWriter.write32(count);
    fWriter.write(value, count * sizeof(SkScalar));
}

void SkBinaryWriteBuffer::writeInt(int32_t value) {
    fWriter.write32(value);
}

void SkBinaryWriteBuffer::writeIntArray(const int32_t* value, uint32_t count) {
    fWriter.write32(count);
    fWriter.write(value, count * sizeof(int32_t));
}

void SkBinaryWriteBuffer::writeUInt(uint32_t value) {
    fWriter.write32(value);
}

void SkBinaryWriteBuffer::writeString(const char* value) {
    fWriter.writeString(value);
}

void SkBinaryWriteBuffer::writeColor(SkColor color) {
    fWriter.write32(color);
}

void SkBinaryWriteBuffer::writeColorArray(const SkColor* color, uint32_t count) {
    fWriter.write32(count);
    fWriter.write(color, count * sizeof(SkColor));
}

void SkBinaryWriteBuffer::writeColor4f(const SkColor4f& color) {
    fWriter.write(&color, sizeof(SkColor4f));
}

void SkBinaryWriteBuffer::writeColor4fArray(const SkColor4f* color, uint32_t count) {
    fWriter.write32(count);
    fWriter.write(color, count * sizeof(SkColor4f));
}

void SkBinaryWriteBuffer::writePoint(const SkPoint& point) {
    fWriter.writeScalar(point.fX);
    fWriter.writeScalar(point.fY);
}

void SkBinaryWriteBuffer::writePoint3(const SkPoint3& point) {
    this->writePad32(&point, sizeof(SkPoint3));
}

void SkBinaryWriteBuffer::writePointArray(const SkPoint* point, uint32_t count) {
    fWriter.write32(count);
    fWriter.write(point, count * sizeof(SkPoint));
}

void SkBinaryWriteBuffer::writeMatrix(const SkMatrix& matrix) {
    fWriter.writeMatrix(matrix);
}

void SkBinaryWriteBuffer::writeIRect(const SkIRect& rect) {
    fWriter.write(&rect, sizeof(SkIRect));
}

void SkBinaryWriteBuffer::writeRect(const SkRect& rect) {
    fWriter.writeRect(rect);
}

void SkBinaryWriteBuffer::writeRegion(const SkRegion& region) {
    fWriter.writeRegion(region);
}

void SkBinaryWriteBuffer::writePath(const SkPath& path) {
    fWriter.writePath(path);
}

size_t SkBinaryWriteBuffer::writeStream(SkStream* stream, size_t length) {
    fWriter.write32(SkToU32(length));
    size_t bytesWritten = fWriter.readFromStream(stream, length);
    if (bytesWritten < length) {
        fWriter.reservePad(length - bytesWritten);
    }
    return bytesWritten;
}

bool SkBinaryWriteBuffer::writeToStream(SkWStream* stream) const {
    return fWriter.writeToStream(stream);
}

/*  Format:
 *  (subset) bounds
 *  size (31bits)
 *  data [ encoded, with raw width/height ]
 */
void SkBinaryWriteBuffer::writeImage(const SkImage* image) {
    const SkIRect bounds = SkImage_getSubset(image);
    this->writeIRect(bounds);

    sk_sp<SkData> data;
    if (fProcs.fImageProc) {
        data = fProcs.fImageProc(const_cast<SkImage*>(image), fProcs.fImageCtx);
    }
    if (!data) {
        data = image->encodeToData();
    }

    size_t size = data ? data->size() : 0;
    if (!SkTFitsIn<int32_t>(size)) {
        size = 0;   // too big to store
    }
    this->write32(SkToS32(size));   // writing 0 signals failure
    if (size) {
        this->writePad32(data->data(), size);
    }
}

void SkBinaryWriteBuffer::writeTypeface(SkTypeface* obj) {
    // Write 32 bits (signed)
    //   0 -- default font
    //  >0 -- index
    //  <0 -- custom (serial procs)

    if (obj == nullptr) {
        fWriter.write32(0);
    } else if (fProcs.fTypefaceProc) {
        auto data = fProcs.fTypefaceProc(obj, fProcs.fTypefaceCtx);
        if (data) {
            size_t size = data->size();
            if (!SkTFitsIn<int32_t>(size)) {
                size = 0;               // fall back to default font
            }
            int32_t ssize = SkToS32(size);
            fWriter.write32(-ssize);    // negative to signal custom
            if (size) {
                this->writePad32(data->data(), size);
            }
            return;
        }
        // no data means fall through for std behavior
    }
    fWriter.write32(fTFSet ? fTFSet->add(obj) : 0);
}

void SkBinaryWriteBuffer::writePaint(const SkPaint& paint) {
    SkPaintPriv::Flatten(paint, *this);
}

void SkBinaryWriteBuffer::setFactoryRecorder(sk_sp<SkFactorySet> rec) {
    fFactorySet = std::move(rec);
}

void SkBinaryWriteBuffer::setTypefaceRecorder(sk_sp<SkRefCntSet> rec) {
    fTFSet = std::move(rec);
}

void SkBinaryWriteBuffer::writeFlattenable(const SkFlattenable* flattenable) {
    if (nullptr == flattenable) {
        this->write32(0);
        return;
    }

    /*
     *  We can write 1 of 2 versions of the flattenable:
     *  1.  index into fFactorySet : This assumes the writer will later
     *      resolve the function-ptrs into strings for its reader. SkPicture
     *      does exactly this, by writing a table of names (matching the indices)
     *      up front in its serialized form.
     *  2.  string name of the flattenable or index into fFlattenableDict:  We
     *      store the string to allow the reader to specify its own factories
     *      after write time.  In order to improve compression, if we have
     *      already written the string, we write its index instead.
     */

    SkFlattenable::Factory factory = flattenable->getFactory();
    SkASSERT(factory);

    if (fFactorySet) {
        this->write32(fFactorySet->add(factory));
    } else {

        if (uint32_t* indexPtr = fFlattenableDict.find(factory)) {
            // We will write the index as a 32-bit int.  We want the first byte
            // that we send to be zero - this will act as a sentinel that we
            // have an index (not a string).  This means that we will send the
            // the index shifted left by 8.  The remaining 24-bits should be
            // plenty to store the index.  Note that this strategy depends on
            // being little endian.
            SkASSERT(0 == *indexPtr >> 24);
            this->write32(*indexPtr << 8);
        } else {
            const char* name = flattenable->getTypeName();
            SkASSERT(name);
            // Otherwise write the string.  Clients should not use the empty
            // string as a name, or we will have a problem.
            SkASSERT(0 != strcmp("", name));
            this->writeString(name);

            // Add key to dictionary.
            fFlattenableDict.set(factory, fFlattenableDict.count() + 1);
        }
    }

    // make room for the size of the flattened object
    (void)fWriter.reserve(sizeof(uint32_t));
    // record the current size, so we can subtract after the object writes.
    size_t offset = fWriter.bytesWritten();
    // now flatten the object
    flattenable->flatten(*this);
    size_t objSize = fWriter.bytesWritten() - offset;
    // record the obj's size
    fWriter.overwriteTAt(offset - sizeof(uint32_t), SkToU32(objSize));
}