qt-creator/share/qtcreator/qml/qmlpuppet/container/imagecontainer.cpp

/****************************************************************************
**
** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** This file is part of Qt Creator.
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** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
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#include "imagecontainer.h"

#include <QSharedMemory>
#include <QCache>

#include <cstring>

#define QTC_ASSERT_STRINGIFY_HELPER(x) #x
#define QTC_ASSERT_STRINGIFY(x) QTC_ASSERT_STRINGIFY_HELPER(x)
#define QTC_ASSERT_STRING(cond) qDebug("SOFT ASSERT: \"" cond"\" in file " __FILE__ ", line " QTC_ASSERT_STRINGIFY(__LINE__))
#define QTC_ASSERT(cond, action) if (cond) {} else { QTC_ASSERT_STRING(#cond); action; } do {} while (0)

namespace QmlDesigner {

static QCache<qint32, QSharedMemory> globalSharedMemoryCache(10000);

ImageContainer::ImageContainer()
    : m_instanceId(-1),
      m_keyNumber(-2)
{
}

ImageContainer::ImageContainer(qint32 instanceId, const QImage &image, qint32 keyNumber)
    :  m_image(image),
       m_instanceId(instanceId),
       m_keyNumber(keyNumber)
{
}

qint32 ImageContainer::instanceId() const
{
    return m_instanceId;
}

QImage ImageContainer::image() const
{
    return m_image;
}

qint32 ImageContainer::keyNumber() const
{
    return m_keyNumber;
}

void ImageContainer::setImage(const QImage &image)
{
    QTC_ASSERT(m_image.isNull(), /**/);

    m_image = image;
}

void ImageContainer::removeSharedMemorys(const QVector<qint32> &keyNumberVector)
{
    foreach (qint32 keyNumber, keyNumberVector) {
        QSharedMemory *sharedMemory = globalSharedMemoryCache.take(keyNumber);
        delete sharedMemory;
    }
}

static const QLatin1String imageKeyTemplateString("Image-%1");

static QSharedMemory *createSharedMemory(qint32 key, int byteCount)
{
    QSharedMemory *sharedMemory = globalSharedMemoryCache.take(key);

    if (sharedMemory == 0)
        sharedMemory = new QSharedMemory(QString(imageKeyTemplateString).arg(key));

    bool sharedMemoryIsCreated = sharedMemory->isAttached();
    if (!sharedMemoryIsCreated)
        sharedMemoryIsCreated = sharedMemory->attach();

    bool sharedMemorySizeIsSmallerThanByteCount = sharedMemory->size() < byteCount;
    bool sharedMemorySizeIsDoubleBiggerThanByteCount = sharedMemory->size() * 2 > byteCount;

    if (!sharedMemoryIsCreated  || sharedMemorySizeIsSmallerThanByteCount || sharedMemorySizeIsDoubleBiggerThanByteCount) {
        sharedMemory->detach();
        sharedMemoryIsCreated = sharedMemory->create(byteCount);
    }

    if (sharedMemoryIsCreated) {
        globalSharedMemoryCache.insert(key, sharedMemory);
        return sharedMemory;
    }

    return 0;
}

static void writeSharedMemory(QSharedMemory *sharedMemory, const QImage &image)
{
    sharedMemory->lock();

    qint32 headerData[5];
    headerData[0] = image.byteCount();
    headerData[1] = image.bytesPerLine();
    headerData[2] = image.size().width();
    headerData[3] = image.size().height();
    headerData[4] = image.format();

    std::memcpy(sharedMemory->data(), headerData, 20);
    std::memcpy(reinterpret_cast<char*>(sharedMemory->data()) + 20, image.constBits(), image.byteCount());

    sharedMemory->unlock();
}

static void writeStream(QDataStream &out, const QImage &image)
{
    out << qint32(image.bytesPerLine());
    out << image.size();
    out << qint32(image.format());
    out << qint32(image.byteCount());
    out.writeRawData(reinterpret_cast<const char*>(image.constBits()), image.byteCount());
}

QDataStream &operator<<(QDataStream &out, const ImageContainer &container)
{
    const int extraDataSize =  20;
    static const bool dontUseSharedMemory = !qgetenv("DESIGNER_DONT_USE_SHARED_MEMORY").isEmpty();

    out << container.instanceId();
    out << container.keyNumber();

    const QImage image = container.image();

    if (dontUseSharedMemory) {
        out << qint32(0);
        writeStream(out, image);
    } else {
        QSharedMemory *sharedMemory = createSharedMemory(container.keyNumber(), image.byteCount() + extraDataSize);

        out << qint32(sharedMemory != 0); // send if shared memory is used

        if (sharedMemory)
            writeSharedMemory(sharedMemory, image);
        else
            writeStream(out, image);
    }

    return out;
}

static void readSharedMemory(qint32 key, ImageContainer &container)
{
    QSharedMemory sharedMemory(QString(imageKeyTemplateString).arg(key));

    bool canAttach = sharedMemory.attach(QSharedMemory::ReadOnly);

    if (canAttach && sharedMemory.size() >= 20)
    {
        sharedMemory.lock();
        qint32 headerData[5];
        std::memcpy(headerData, sharedMemory.constData(), 20);

        qint32 byteCount = headerData[0];
//        qint32 bytesPerLine = headerData[1];
        qint32 imageWidth = headerData[2];
        qint32 imageHeight = headerData[3];
        qint32 imageFormat = headerData[4];

        QImage image = QImage(imageWidth, imageHeight, QImage::Format(imageFormat));

        std::memcpy(image.bits(), reinterpret_cast<const qint32*>(sharedMemory.constData()) + 5, byteCount);

        container.setImage(image);

        sharedMemory.unlock();
    }
}

static void readStream(QDataStream &in, ImageContainer &container)
{
    qint32 byteCount;
    qint32 bytesPerLine;
    QSize imageSize;
    qint32 imageFormat;

    in >> bytesPerLine;
    in >> imageSize;
    in >> imageFormat;
    in >> byteCount;

    QImage image = QImage(imageSize, QImage::Format(imageFormat));

    in.readRawData(reinterpret_cast<char*>(image.bits()), byteCount);

    container.setImage(image);
}

QDataStream &operator>>(QDataStream &in, ImageContainer &container)
{
    qint32 sharedMemoryIsUsed;

    in >> container.m_instanceId;
    in >> container.m_keyNumber;
    in >> sharedMemoryIsUsed;

    if (sharedMemoryIsUsed) {
        readSharedMemory(container.keyNumber(), container);
    } else
        readStream(in, container);

    return in;
}

} // namespace QmlDesigner