qpnghandler.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
** General Public Licensing requirements will be met:
** http://www.trolltech.com/products/qt/opensource.html
**
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://www.trolltech.com/products/qt/licensing.html or contact the
** sales department at [e-mail].
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "private/qpnghandler_p.h"

#ifndef QT_NO_IMAGEFORMAT_PNG
#include <qcoreapplication.h>
#include <qiodevice.h>
#include <qimage.h>
#include <qlist.h>
#include <qtextcodec.h>
#include <qvariant.h>
#include <qvector.h>

#include <png.h>

#ifdef Q_OS_TEMP
#define CALLBACK_CALL_TYPE        __cdecl
#else
#define CALLBACK_CALL_TYPE
#endif


/*
  All PNG files load to the minimal QImage equivalent.

  All QImage formats output to reasonably efficient PNG equivalents.
  Never to grayscale.
*/

#if defined(Q_C_CALLBACKS)
extern "C" {
#endif

class QPNGImageWriter {
public:
    explicit QPNGImageWriter(QIODevice*);
    ~QPNGImageWriter();

    enum DisposalMethod { Unspecified, NoDisposal, RestoreBackground, RestoreImage };
    void setDisposalMethod(DisposalMethod);
    void setLooping(int loops=0); // 0 == infinity
    void setFrameDelay(int msecs);
    void setGamma(float);

    bool writeImage(const QImage& img, int x, int y);
    bool writeImage(const QImage& img, int quality, const QString &description, int x, int y);
    bool writeImage(const QImage& img)
        { return writeImage(img, 0, 0); }
    bool writeImage(const QImage& img, int quality, const QString &description)
        { return writeImage(img, quality, description, 0, 0); }

    QIODevice* device() { return dev; }

private:
    QIODevice* dev;
    int frames_written;
    DisposalMethod disposal;
    int looping;
    int ms_delay;
    float gamma;
};

static
void CALLBACK_CALL_TYPE iod_read_fn(png_structp png_ptr, png_bytep data, png_size_t length)
{
    QIODevice *in = (QIODevice *)png_get_io_ptr(png_ptr);

    while (length) {
        int nr = in->read((char*)data, length);
        if (nr <= 0) {
            png_error(png_ptr, "Read Error");
            return;
        }
        length -= nr;
    }
}


static
void CALLBACK_CALL_TYPE qpiw_write_fn(png_structp png_ptr, png_bytep data, png_size_t length)
{
    QPNGImageWriter* qpiw = (QPNGImageWriter*)png_get_io_ptr(png_ptr);
    QIODevice* out = qpiw->device();

    uint nr = out->write((char*)data, length);
    if (nr != length) {
        png_error(png_ptr, "Write Error");
        return;
    }
}


static
void CALLBACK_CALL_TYPE qpiw_flush_fn(png_structp /* png_ptr */)
{
}

#if defined(Q_C_CALLBACKS)
}
#endif

static
void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0)
{
    if (screen_gamma != 0.0 && png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA)) {
        double file_gamma;
        png_get_gAMA(png_ptr, info_ptr, &file_gamma);
        png_set_gamma(png_ptr, screen_gamma, file_gamma);
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);

    if (color_type == PNG_COLOR_TYPE_GRAY) {
        // Black & White or 8-bit grayscale
        if (bit_depth == 1 && info_ptr->channels == 1) {
            png_set_invert_mono(png_ptr);
            png_read_update_info(png_ptr, info_ptr);
            image = QImage(width, height, QImage::Format_Mono);
            if (image.isNull())
                return;
            image.setNumColors(2);
            image.setColor(1, qRgb(0,0,0));
            image.setColor(0, qRgb(255,255,255));
        } else if (bit_depth == 16 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
            png_set_expand(png_ptr);
            png_set_strip_16(png_ptr);
            png_set_gray_to_rgb(png_ptr);
            image = QImage(width, height, QImage::Format_ARGB32);
            if (image.isNull())
                return;
            if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
                png_set_swap_alpha(png_ptr);

            png_read_update_info(png_ptr, info_ptr);
        } else {
            if (bit_depth == 16)
                png_set_strip_16(png_ptr);
            else if (bit_depth < 8)
                png_set_packing(png_ptr);
            int ncols = bit_depth < 8 ? 1 << bit_depth : 256;
            png_read_update_info(png_ptr, info_ptr);
            image = QImage(width, height, QImage::Format_Indexed8);
            if (image.isNull())
                return;
            image.setNumColors(ncols);
            for (int i=0; i<ncols; i++) {
                int c = i*255/(ncols-1);
                image.setColor(i, qRgba(c,c,c,0xff));
            }
            if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
                const int g = info_ptr->trans_values.gray;
                if (g < ncols) {
                    image.setColor(g, 0);
                }
            }
        }
    } else if (color_type == PNG_COLOR_TYPE_PALETTE
               && png_get_valid(png_ptr, info_ptr, PNG_INFO_PLTE)
               && info_ptr->num_palette <= 256)
    {
        // 1-bit and 8-bit color
        if (bit_depth != 1)
            png_set_packing(png_ptr);
        png_read_update_info(png_ptr, info_ptr);
        png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
        image = QImage(width, height, bit_depth == 1 ? QImage::Format_Mono : QImage::Format_Indexed8);
        if (image.isNull())
            return;
        image.setNumColors(info_ptr->num_palette);
        int i = 0;
        if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
            while (i < info_ptr->num_trans) {
                image.setColor(i, qRgba(
                    info_ptr->palette[i].red,
                    info_ptr->palette[i].green,
                    info_ptr->palette[i].blue,
                    info_ptr->trans[i]
                   )
               );
                i++;
            }
        }
        while (i < info_ptr->num_palette) {
            image.setColor(i, qRgba(
                info_ptr->palette[i].red,
                info_ptr->palette[i].green,
                info_ptr->palette[i].blue,
                0xff
               )
           );
            i++;
        }
    } else {
        // 32-bit
        if (bit_depth == 16)
            png_set_strip_16(png_ptr);

        png_set_expand(png_ptr);

        if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
            png_set_gray_to_rgb(png_ptr);

        QImage::Format format = QImage::Format_ARGB32;
        // Only add filler if no alpha, or we can get 5 channel data.
        if (!(color_type & PNG_COLOR_MASK_ALPHA)
            && !png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
            png_set_filler(png_ptr, 0xff, QSysInfo::ByteOrder == QSysInfo::BigEndian ?
                           PNG_FILLER_BEFORE : PNG_FILLER_AFTER);
            // We want 4 bytes, but it isn't an alpha channel
            format = QImage::Format_RGB32;
        }
        image = QImage(width, height, format);
        if (image.isNull())
            return;

        if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
            png_set_swap_alpha(png_ptr);

        png_read_update_info(png_ptr, info_ptr);
    }

    // Qt==ARGB==Big(ARGB)==Little(BGRA)
    if (QSysInfo::ByteOrder == QSysInfo::LittleEndian) {
        png_set_bgr(png_ptr);
    }
}


#if defined(Q_C_CALLBACKS)
extern "C" {
#endif
static void CALLBACK_CALL_TYPE qt_png_warning(png_structp /*png_ptr*/, png_const_charp message)
{
    qWarning("libpng warning: %s", message);
}

#if defined(Q_C_CALLBACKS)
}
#endif

class QPngHandlerPrivate
{
public:
    enum State {
        Ready,
        ReadHeader,
        Error
    };

    QPngHandlerPrivate(QPngHandler *qq)
        : gamma(0.0), quality(2), png_ptr(0), info_ptr(0),
          end_info(0), row_pointers(0), state(Ready), q(qq)
    { }

    float gamma;
    int quality;
    QString description;

    png_struct *png_ptr;
    png_info *info_ptr;
    png_info *end_info;
    png_byte **row_pointers;

    bool readPngHeader();
    bool readPngImage(QImage *image);

    State state;

    QPngHandler *q;
};

/*!
    \internal
*/
bool QPngHandlerPrivate::readPngHeader()
{
    state = Error;
    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
    if (!png_ptr)
        return false;

    png_set_error_fn(png_ptr, 0, 0, qt_png_warning);

    info_ptr = png_create_info_struct(png_ptr);
    if (!info_ptr) {
        png_destroy_read_struct(&png_ptr, 0, 0);
        png_ptr = 0;
        return false;
    }

    end_info = png_create_info_struct(png_ptr);
    if (!end_info) {
        png_destroy_read_struct(&png_ptr, &info_ptr, 0);
        png_ptr = 0;
        return false;
    }

    if (setjmp(png_ptr->jmpbuf)) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        png_ptr = 0;
        return false;
    }

    png_set_read_fn(png_ptr, q->device(), iod_read_fn);
    png_read_info(png_ptr, info_ptr);

#ifndef QT_NO_IMAGE_TEXT
    png_textp text_ptr;
    int num_text=0;
    png_get_text(png_ptr,info_ptr,&text_ptr,&num_text);

    while (num_text--) {
        QString key, value;
#if defined(PNG_iTXt_SUPPORTED)
        if (text_ptr->lang) {
            QTextCodec *textCodec = QTextCodec::codecForName(text_ptr->lang);
            if (textCodec) {
                key = codec->toUnicode(text_ptr->lang_key);
                value = codec->toUnicode(QByteArray(text_ptr->text, text_ptr->itxt_length));
            } else {
                key = QString::fromLatin1(text_ptr->key);
                value = QString::fromLatin1(QByteArray(text_ptr->text, text_ptr->text_length));
            }
        } else
#endif
        {
            key = QString::fromLatin1(text_ptr->key);
            value = QString::fromLatin1(QByteArray(text_ptr->text, text_ptr->text_length));
        }
        if (!description.isEmpty())
            description += QLatin1String("\n\n");
        description += key + QLatin1String(": ") + value.simplified();
        text_ptr++;
    }
#endif

    state = ReadHeader;
    return true;
}

/*!
    \internal
*/
bool QPngHandlerPrivate::readPngImage(QImage *outImage)
{
    if (state == Error)
        return false;

    if (state == Ready && !readPngHeader()) {
        state = Error;
        return false;
    }

    if (setjmp(png_ptr->jmpbuf)) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        png_ptr = 0;
        state = Error;
        return false;
    }

    QImage image;
    setup_qt(image, png_ptr, info_ptr, gamma);

    if (image.isNull()) {
        png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
        png_ptr = 0;
        state = Error;
        return false;
    }

    png_uint_32 width;
    png_uint_32 height;
    int bit_depth;
    int color_type;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
                 0, 0, 0);

    uchar *data = image.bits();
    int bpl = image.bytesPerLine();
    row_pointers=new png_bytep[height];

    for (uint y = 0; y < height; y++)
        row_pointers[y] = data + y * bpl;

    png_read_image(png_ptr, row_pointers);

#if 0 // libpng takes care of this.
    png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)
        if (image.depth()==32 && png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
            QRgb trans = 0xFF000000 | qRgb(
                (info_ptr->trans_values.red << 8 >> bit_depth)&0xff,
                (info_ptr->trans_values.green << 8 >> bit_depth)&0xff,
                (info_ptr->trans_values.blue << 8 >> bit_depth)&0xff);
            for (uint y=0; y<height; y++) {
                for (uint x=0; x<info_ptr->width; x++) {
                    if (((uint**)jt)[y][x] == trans) {
                        ((uint**)jt)[y][x] &= 0x00FFFFFF;
                    } else {
                    }
                }
            }
        }
#endif

    image.setDotsPerMeterX(png_get_x_pixels_per_meter(png_ptr,info_ptr));
    image.setDotsPerMeterY(png_get_y_pixels_per_meter(png_ptr,info_ptr));