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 "SkDeduper.h"
#include "SkPixelRef.h"
#include "SkPtrRecorder.h"
#include "SkStream.h"
#include "SkTypeface.h"

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

SkBinaryWriteBuffer::SkBinaryWriteBuffer(uint32_t flags)
    : fFlags(flags)
    , fFactorySet(nullptr)
    , fTFSet(nullptr) {
}

SkBinaryWriteBuffer::SkBinaryWriteBuffer(void* storage, size_t storageSize, uint32_t flags)
    : fFlags(flags)
    , fFactorySet(nullptr)
    , fWriter(storage, storageSize)
    , fTFSet(nullptr) {
}

SkBinaryWriteBuffer::~SkBinaryWriteBuffer() {
    SkSafeUnref(fFactorySet);
    SkSafeUnref(fTFSet);
}

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::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) {
    return fWriter.writeToStream(stream);
}

static void write_encoded_bitmap(SkBinaryWriteBuffer* buffer, SkData* data,
                                 const SkIPoint& origin) {
    buffer->writeDataAsByteArray(data);
    buffer->write32(origin.fX);
    buffer->write32(origin.fY);
}

void SkBinaryWriteBuffer::writeBitmap(const SkBitmap& bitmap) {
    // Record the width and height. This way if readBitmap fails a dummy bitmap can be drawn at the
    // right size.
    this->writeInt(bitmap.width());
    this->writeInt(bitmap.height());

    // Record information about the bitmap in one of two ways, in order of priority:
    // 1. If there is a function for encoding bitmaps, use it to write an encoded version of the
    //    bitmap. After writing a boolean value of false, signifying that a heap was not used, write
    //    the size of the encoded data. A non-zero size signifies that encoded data was written.
    // 2. Call SkBitmap::flatten. After writing a boolean value of false, signifying that a heap was
    //    not used, write a zero to signify that the data was not encoded.

    // Write a bool to indicate that we did not use an SkBitmapHeap. That feature is deprecated.
    this->writeBool(false);

    // see if the caller wants to manually encode
    SkAutoPixmapUnlock result;
    if (fPixelSerializer && bitmap.requestLock(&result)) {
        sk_sp<SkData> data(fPixelSerializer->encode(result.pixmap()));
        if (data) {
            // if we have to "encode" the bitmap, then we assume there is no
            // offset to share, since we are effectively creating a new pixelref
            write_encoded_bitmap(this, data.get(), SkIPoint::Make(0, 0));
            return;
        }
    }

    this->writeUInt(0); // signal raw pixels
    SkBitmap::WriteRawPixels(this, bitmap);
}

void SkBinaryWriteBuffer::writeImage(const SkImage* image) {
    if (fDeduper) {
        this->write32(fDeduper->findOrDefineImage(const_cast<SkImage*>(image)));
        return;
    }

    this->writeInt(image->width());
    this->writeInt(image->height());

    sk_sp<SkData> encoded(image->encode(this->getPixelSerializer()));
    if (encoded && encoded->size() > 0) {
        write_encoded_bitmap(this, encoded.get(), SkIPoint::Make(0, 0));
        return;
    }

    SkBitmap bm;
    if (image->asLegacyBitmap(&bm, SkImage::kRO_LegacyBitmapMode)) {
        this->writeUInt(1);  // signal raw pixels.
        SkBitmap::WriteRawPixels(this, bm);
        return;
    }

    this->writeUInt(0); // signal no pixels (in place of the size of the encoded data)
}

void SkBinaryWriteBuffer::writeTypeface(SkTypeface* obj) {
    if (fDeduper) {
        this->write32(fDeduper->findOrDefineTypeface(obj));
        return;
    }

    if (nullptr == obj || nullptr == fTFSet) {
        fWriter.write32(0);
    } else {
        fWriter.write32(fTFSet->add(obj));
    }
}

void SkBinaryWriteBuffer::writePaint(const SkPaint& paint) {
    paint.flatten(*this);
}

SkFactorySet* SkBinaryWriteBuffer::setFactoryRecorder(SkFactorySet* rec) {
    SkRefCnt_SafeAssign(fFactorySet, rec);
    return rec;
}

SkRefCntSet* SkBinaryWriteBuffer::setTypefaceRecorder(SkRefCntSet* rec) {
    SkRefCnt_SafeAssign(fTFSet, rec);
    return rec;
}

void SkBinaryWriteBuffer::setPixelSerializer(sk_sp<SkPixelSerializer> serializer) {
    fPixelSerializer = std::move(serializer);
}

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

    if (fDeduper) {
        this->write32(fDeduper->findOrDefineFactory(const_cast<SkFlattenable*>(flattenable)));
    } else {
        /*
         *  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.
         */
        if (fFactorySet) {
            SkFlattenable::Factory factory = flattenable->getFactory();
            SkASSERT(factory);
            this->write32(fFactorySet->add(factory));
        } else {
            const char* name = flattenable->getTypeName();
            SkASSERT(name);
            SkString key(name);
            if (uint32_t* indexPtr = fFlattenableDict.find(key)) {
                // 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 {
                // Otherwise write the string.  Clients should not use the empty
                // string as a name, or we will have a problem.
                SkASSERT(strcmp("", name));
                this->writeString(name);

                // Add key to dictionary.
                fFlattenableDict.set(key, 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));
}