qimage.cpp

qt-x11-opensource-src-4.1.4.tar.gz源码

/****************************************************************************
**
** Copyright (C) 1992-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the QtGui module of the Qt Toolkit.
**
** This file may be used under the terms of the GNU General Public
** License version 2.0 as published by the Free Software Foundation
** and appearing in the file LICENSE.GPL included in the packaging of
** this file.  Please review the following information to ensure GNU
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**
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** review the following information:
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** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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#include "qimage.h"
#include "qdatastream.h"
#include "qbuffer.h"
#include "qmap.h"
#include "qmatrix.h"
#include "qimagereader.h"
#include "qimagewriter.h"
#include "qstringlist.h"
#include "qvariant.h"
#include <ctype.h>
#include <stdlib.h>
#include <limits.h>
#include <math.h>
#include <private/qdrawhelper_p.h>
#include <private/qpixmap_p.h>

#ifdef QT_RASTER_IMAGEENGINE
#include <private/qpaintengine_raster_p.h>
#else
#include <qpaintengine.h>
#endif

#ifdef Q_WS_QWS
#include <qscreen_qws.h> //### for qt_conv...
#endif

#if defined(Q_CC_DEC) && defined(__alpha) && (__DECCXX_VER-0 >= 50190001)
#pragma message disable narrowptr
#endif

typedef void (*_qt_image_cleanup_hook)(int);
Q_GUI_EXPORT _qt_image_cleanup_hook qt_image_cleanup_hook = 0;

struct QImageData {        // internal image data
    QImageData();
    ~QImageData();
    static QImageData *create(const QSize &size, QImage::Format format, int numColors = 0);

    QAtomic ref;

    int width;
    int height;
    int depth;
    int nbytes;               // number of bytes data
    QVector<QRgb> colortable;
    uchar *data;
#ifdef QT3_SUPPORT
    uchar **jumptable;
#endif
    QImage::Format format;
    int bytes_per_line;
    int ser_no;               // serial number
    int detach_no;

    qreal  dpmx;                // dots per meter X (or 0)
    qreal  dpmy;                // dots per meter Y (or 0)
    QPoint  offset;           // offset in pixels
    uint own_data : 1;
    uint has_alpha_clut : 1;

#ifndef QT_NO_IMAGE_TEXT
    QMap<QImageTextKeyLang, QString> text_lang;

    QStringList languages() const
    {
        QStringList r;
        QMap<QImageTextKeyLang,QString>::const_iterator it = text_lang.begin();
        for (; it != text_lang.end(); ++it) {
            r.removeAll(it.key().lang);
            r.append(it.key().lang);
        }
        return r;
    }
    QStringList keys() const
    {
        QStringList r;
        QMap<QImageTextKeyLang,QString>::const_iterator it = text_lang.begin();
        for (; it != text_lang.end(); ++it) {
            r.removeAll(it.key().key);
            r.append(it.key().key);
        }
        return r;
    }

    QMap<QString, QString> text;
#endif
    bool doImageIO(const QImage *image, QImageWriter* io, int quality) const;

    QPaintEngine *paintEngine;
};

Q_GUI_EXPORT qint64 qt_image_id(const QImage &image)
{
    return (((qint64) image.d->ser_no) << 32) | ((qint64) image.d->detach_no);
}

const QVector<QRgb> *qt_image_colortable(const QImage &image)
{
    return (image.d->format <= QImage::Format_Indexed8 && !image.d->colortable.isEmpty()) ? &image.d->colortable : 0;
}

extern int qt_defaultDpi();

QBasicAtomic qimage_serial_number = Q_ATOMIC_INIT(1);
int qimage_next_serial_number()
{
    register int id;
    for (;;) {
        id = qimage_serial_number;
        if (qimage_serial_number.testAndSet(id, id + 1))
            break;
    }
    return id;
}


QImageData::QImageData()
{
    ser_no = qimage_next_serial_number();
    detach_no = 0;
    ref = 0;

    width = height = depth = 0;
    nbytes = 0;
    data = 0;
    own_data = true;
#ifdef QT3_SUPPORT
    jumptable = 0;
#endif
    bytes_per_line = 0;
    format = QImage::Format_ARGB32;

    dpmx = qt_defaultDpi()*100./2.54;
    dpmy = qt_defaultDpi()*100./2.54;
    offset = QPoint(0,0);

    paintEngine = 0;
}

static int depthForFormat(QImage::Format format)
{
    int depth = 0;
    switch(format) {
    case QImage::Format_Invalid:
    case QImage::NImageFormats:
        Q_ASSERT(false);
    case QImage::Format_Mono:
    case QImage::Format_MonoLSB:
        depth = 1;
        break;
    case QImage::Format_Indexed8:
        depth = 8;
        break;
    case QImage::Format_RGB32:
    case QImage::Format_ARGB32:
    case QImage::Format_ARGB32_Premultiplied:
        depth = 32;
        break;
#ifdef Q_WS_QWS
    case QImage::Format_RGB16:
        depth = 16;
        break;
#endif
    }
    return depth;
}

QImageData * QImageData::create(const QSize &size, QImage::Format format, int numColors)
{
    int width = size.width();
    int height = size.height();
    if (width <= 0 || height <= 0 || numColors < 0 || format == QImage::Format_Invalid)
        return 0;                                // invalid parameter(s)

    int depth = 0;
    switch(format) {
    case QImage::NImageFormats:
    case QImage::Format_Invalid:
        Q_ASSERT(false);
    case QImage::Format_Mono:
    case QImage::Format_MonoLSB:
        depth = 1;
        numColors = 2;
        break;
    case QImage::Format_Indexed8:
        depth = 8;
        numColors = qMin(numColors, 256);
        numColors = qMax(0, numColors);
        break;
    case QImage::Format_RGB32:
    case QImage::Format_ARGB32:
    case QImage::Format_ARGB32_Premultiplied:
        depth = 32;
        numColors = 0;
        break;
#ifdef Q_WS_QWS
    case QImage::Format_RGB16:
        depth = 16;
        numColors = 0;
        break;
#endif
    }

    QImageData *d = new QImageData;
    d->colortable.resize(numColors);
    if (depth == 1) {
        d->colortable[0] = QColor(Qt::black).rgba();
        d->colortable[1] = QColor(Qt::white).rgba();
    } else {
        for (int i = 0; i < numColors; ++i)
            d->colortable[i] = 0;
    }

    d->width = width;
    d->height = height;
    d->depth = depth;
    d->format = format;
    d->has_alpha_clut = false;

    d->bytes_per_line = ((width * d->depth + 31) >> 5) << 2; // bytes per scanline (must be multiple of 8)

    d->nbytes = d->bytes_per_line*height;
    d->data  = (uchar *)malloc(d->nbytes);

    if (!d->data) {
        delete d;
        return 0;
    }

    d->ref.ref();
    return d;

}

QImageData::~QImageData()
{
    delete paintEngine;
    if (data && own_data)
        free(data);
#ifdef QT3_SUPPORT
    if (jumptable)
        free(jumptable);
    jumptable = 0;
#endif
    data = 0;
}

/*!
    \class QImage

    \ingroup multimedia
    \ingroup shared
    \mainclass

    \brief The QImage class provides a hardware-independent image
    representation that allows direct access to the pixel data, and
    can be used as a paint device.

    Qt provides four classes for handling image data: QImage, QPixmap,
    QBitmap and QPicture.  QImage is designed and optimized for I/O,
    and for direct pixel access and manipulation, while QPixmap is
    designed and optimized for showing images on screen. QBitmap is
    only a convenience class that inherits QPixmap, ensuring a
    depth of 1. Finally, the QPicture class is a paint device that
    records and replays QPainter commands.

    Because QImage is a QPaintDevice subclass, QPainter can be used to
    draw directly onto images.  When using QPainter on a QImage, the
    painting can be performed in another thread than the current GUI
    thread, that is except rendering text (because QFont is GUI
    dependent). To render text in another thread, the text must first
    be derived as a QPainterPath in the GUI thread.

    The QImage class supports several image formats described by the
    \l Format enum. These include monochrome, 8-bit, 32-bit and
    alpha-blended images which are available in all versions of Qt
    4.x. In addition, QImage supports several formats that are
    specific to \l {Qtopia Core}.

    QImage provides a collection of functions that can be used to
    obtain a variety of information about the image. There are also
    several functions that enables transformation of the image.

    QImage objects can be passed around by value since the QImage
    class uses \l{Implicit Data Sharing}{implicit data
    sharing}. QImage objects can also be streamed and compared.

    \tableofcontents

    \section1 Reading and Writing Image Files

    QImage provides several ways of loading an image file: The file
    can be loaded when constructing the QImage object, or by using the
    load() or loadFromData() functions later on. QImage also provides
    the static fromData() function, constructing a QImage from the
    given data.  When loading an image, the file name can either refer
    to an actual file on disk or to one of the application's embedded
    resources. See \l{The Qt Resource System} overview for details
    on how to embed images and other resource files in the
    application's executable.

    Simply call the save() function to save a QImage object.

    The complete list of supported file formats are available through
    the QImageReader::supportedImageFormats() and
    QImageWriter::supportedImageFormats() functions. New file formats
    can be added as plugins. By default, Qt supports the following
    formats:

    \table
    \header \o Format \o Description                      \o Qt's support
    \row    \o BMP    \o Windows Bitmap                   \o Read/write
    \row    \o GIF    \o Graphic Interchange Format (optional) \o Read
    \row    \o JPG    \o Joint Photographic Experts Group \o Read/write
    \row    \o JPEG   \o Joint Photographic Experts Group \o Read/write
    \row    \o PNG    \o Portable Network Graphics        \o Read/write
    \row    \o PBM    \o Portable Bitmap                  \o Read
    \row    \o PGM    \o Portable Graymap                 \o Read
    \row    \o PPM    \o Portable Pixmap                  \o Read/write
    \row    \o XBM    \o X11 Bitmap                       \o Read/write
    \row    \o XPM    \o X11 Pixmap                       \o Read/write
    \endtable

    (To configure Qt with GIF support, pass \c -qt-gif to the \c
    configure script or check the appropriate option in the graphical
    installer.)

    \section1 Image Information

    QImage provides a collection of functions that can be used to
    obtain a variety of information about the image:

    \table
    \header
    \o \o Available Functions

    \row
    \o Geometry
    \o

    The size(), width(), height(), dotsPerMeterX(), and
    dotsPerMeterY() functions provide information about the image size
    and aspect ratio.

    The rect() function returns the image's enclosing rectangle. The
    valid() function tells if a given pair of coordinates is within
    this rectangle. The offset() function returns the number of pixels
    by which the image is intended to be offset by when positioned
    relative to other images, which also can be manipulated using the
    setOffset() function.

    \row
    \o Colors
    \o

    The color of a pixel can be retrieved by passing its coordinates
    to the pixel() function.  The pixel() function returns the color
    as a QRgb value indepedent of the image's format.

    In case of monochrome and 8-bit images, the numColors() and
    colorTable() functions provide information about the color
    components used to store the image data: The colorTable() function
    returns the image's entire color table. To obtain a single entry,
    use the pixelIndex() function to retrieve the pixel index for a
    given pair of coordinates, then use the color() function to
    retrieve the color.

    The hasAlphaChannel() function tells if the image's format
    respects the alpha channel, or not. The allGray() and
    isGrayscale() functions tell whether an image's colors are all
    shades of gray.

    See also the \l {QImage#Pixel Manipulation}{Pixel Manipulation}
    and \l {QImage#Image Transformations}{Image Transformations}
    sections.

    \row
    \o Text
    \o

    The text() function returns the image text associated with the
    given text key. An image's text keys can be retrieved using the
    textKeys() function. Use the setText() function to alter an
    image's text.

    \row
    \o Low-level information
    \o
    The depth() function returns the depth of the image. The supported
    depths are 1 (monochrome), 8 and 32 (for more information see the
    \l {QImage#Image Formats}{Image Formats} section).

    The format(), bytesPerLine(), and numBytes() functions provide
    low-level information about the data stored in the image.

    The serialNumber() function returns a number that uniquely
    identifies the contents of this QImage object.
    \endtable

    \section1 Pixel Manipulation

    The functions used to manipulate an image's pixels depend on the
    image format. The reason is that monochrome and 8-bit images are
    index-based and use a color lookup table, while 32-bit images
    store ARGB values directly. For more information on image formats,