qpnghandler.cpp File Reference

#include "private/qpnghandler_p.h"
#include <qcoreapplication.h>
#include <qiodevice.h>
#include <qimage.h>
#include <qlist.h>
#include <qtextcodec.h>
#include <qvariant.h>
#include <qvector.h>
#include <png.h>
#include <pngconf.h>

Go to the source code of this file.

Classes
class	QPngHandlerPrivate
class	QPNGImageWriter

Macros
#define	CALLBACK_CALL_TYPE   __cdecl
#define	FAST_SCAN_LINE(data, bpl, y)   (data + (y) * bpl)
#define	Q_INTERNAL_WIN_NO_THROW

Functions
static void CALLBACK_CALL_TYPE	iod_read_fn (png_structp png_ptr, png_bytep data, png_size_t length)
static void CALLBACK_CALL_TYPE	qpiw_flush_fn (png_structp)
static void CALLBACK_CALL_TYPE	qpiw_write_fn (png_structp png_ptr, png_bytep data, png_size_t length)
static void CALLBACK_CALL_TYPE	qt_png_warning (png_structp, png_const_charp message)
static void	set_text (const QImage &image, png_structp png_ptr, png_infop info_ptr, const QString &description)
static void	setup_qt (QImage &image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0)
static bool	write_png_image (const QImage &image, QIODevice *device, int quality, float gamma, const QString &description)

Macro Definition Documentation

CALLBACK_CALL_TYPE

#define CALLBACK_CALL_TYPE   __cdecl

Definition at line 85 of file qpnghandler.cpp.

FAST_SCAN_LINE

#define FAST_SCAN_LINE	(		data,
			bpl,
			y
	)		(data + (y) * bpl)

Definition at line 99 of file qpnghandler.cpp.

Referenced by QPngHandlerPrivate::readPngImage().

Q_INTERNAL_WIN_NO_THROW

#define Q_INTERNAL_WIN_NO_THROW

Definition at line 95 of file qpnghandler.cpp.

Function Documentation

iod_read_fn()

static void CALLBACK_CALL_TYPE iod_read_fn ( png_structp  png_ptr, png_bytep  data, png_size_t  length  )

static

Definition at line 179 of file qpnghandler.cpp.

Referenced by QPngHandlerPrivate::readPngHeader().

{
    QPngHandlerPrivate *d = (QPngHandlerPrivate *)png_get_io_ptr(png_ptr);
    QIODevice *in = d->q->device();

    if (d->state == QPngHandlerPrivate::ReadingEnd && !in->isSequential() && (in->size() - in->pos()) < 4 && length == 4) {
        // Workaround for certain malformed PNGs that lack the final crc bytes
        uchar endcrc[4] = { 0xae, 0x42, 0x60, 0x82 };
        qMemCopy(data, endcrc, 4);
        in->seek(in->size());
        return;
    }

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

qpiw_flush_fn()

static void CALLBACK_CALL_TYPE qpiw_flush_fn ( png_structp  )

static

Definition at line 218 of file qpnghandler.cpp.

Referenced by QPNGImageWriter::writeImage().

{
}

qpiw_write_fn()

static void CALLBACK_CALL_TYPE qpiw_write_fn ( png_structp  png_ptr, png_bytep  data, png_size_t  length  )

static

Definition at line 204 of file qpnghandler.cpp.

Referenced by QPNGImageWriter::writeImage().

{
    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;
    }
}

qt_png_warning()

static void CALLBACK_CALL_TYPE qt_png_warning ( png_structp  , png_const_charp  message  )

static

Definition at line 378 of file qpnghandler.cpp.

Referenced by QPngHandlerPrivate::readPngHeader(), and QPNGImageWriter::writeImage().

{
    qWarning("libpng warning: %s", message);
}

set_text()

static void set_text ( const QImage &  image, png_structp  png_ptr, png_infop  info_ptr, const QString &  description  )

static

Definition at line 649 of file qpnghandler.cpp.

Referenced by QPNGImageWriter::writeImage().

{
    QMap<QString, QString> text;
    foreach (const QString &key, image.textKeys()) {
        if (!key.isEmpty())
            text.insert(key, image.text(key));
    }
    foreach (const QString &pair, description.split(QLatin1String("\n\n"))) {
        int index = pair.indexOf(QLatin1Char(':'));
        if (index >= 0 && pair.indexOf(QLatin1Char(' ')) < index) {
            QString s = pair.simplified();
            if (!s.isEmpty())
                text.insert(QLatin1String("Description"), s);
        } else {
            QString key = pair.left(index);
            if (!key.simplified().isEmpty())
                text.insert(key, pair.mid(index + 2).simplified());
        }
    }

    if (text.isEmpty())
        return;

    png_textp text_ptr = new png_text[text.size()];
    qMemSet(text_ptr, 0, text.size() * sizeof(png_text));

    QMap<QString, QString>::ConstIterator it = text.constBegin();
    int i = 0;
    while (it != text.constEnd()) {
        text_ptr[i].key = qstrdup(it.key().left(79).toLatin1().constData());
        bool noCompress = (it.value().length() < 40);

#ifdef PNG_iTXt_SUPPORTED
        bool needsItxt = false;
        foreach(const QChar c, it.value()) {
            uchar ch = c.cell();
            if (c.row() || (ch < 0x20 && ch != '\n') || (ch > 0x7e && ch < 0xa0)) {
                needsItxt = true;
                break;
            }
        }

        if (needsItxt) {
            text_ptr[i].compression = noCompress ? PNG_ITXT_COMPRESSION_NONE : PNG_ITXT_COMPRESSION_zTXt;
            QByteArray value = it.value().toUtf8();
            text_ptr[i].text = qstrdup(value.constData());
            text_ptr[i].itxt_length = value.size();
            text_ptr[i].lang = const_cast<char*>("UTF-8");
            text_ptr[i].lang_key = qstrdup(it.key().toUtf8().constData());
        }
        else
#endif
        {
            text_ptr[i].compression = noCompress ? PNG_TEXT_COMPRESSION_NONE : PNG_TEXT_COMPRESSION_zTXt;
            QByteArray value = it.value().toLatin1();
            text_ptr[i].text = qstrdup(value.constData());
            text_ptr[i].text_length = value.size();
        }
        ++i;
        ++it;
    }

    png_set_text(png_ptr, info_ptr, text_ptr, i);
    for (i = 0; i < text.size(); ++i) {
        delete [] text_ptr[i].key;
        delete [] text_ptr[i].text;
#ifdef PNG_iTXt_SUPPORTED
        delete [] text_ptr[i].lang_key;
#endif
    }
    delete [] text_ptr;
}

setup_qt()

static void setup_qt ( QImage &  image, png_structp  png_ptr, png_infop  info_ptr, float  screen_gamma = 0.0  )

static

Definition at line 227 of file qpnghandler.cpp.

Referenced by QPngHandlerPrivate::readPngImage().

{
    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_bytep trans_alpha = 0;
    png_color_16p trans_color_p = 0;
    int num_trans;
    png_colorp palette = 0;
    int num_palette;
    png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
    png_set_interlace_handling(png_ptr);

    if (color_type == PNG_COLOR_TYPE_GRAY) {
        // Black & White or 8-bit grayscale
        if (bit_depth == 1 && png_get_channels(png_ptr, info_ptr) == 1) {
            png_set_invert_mono(png_ptr);
            png_read_update_info(png_ptr, info_ptr);
            if (image.size() != QSize(width, height) || image.format() != QImage::Format_Mono) {
                image = QImage(width, height, QImage::Format_Mono);
                if (image.isNull())
                    return;
            }
            image.setColorCount(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);
            if (image.size() != QSize(width, height) || image.format() != QImage::Format_ARGB32) {
                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);
            if (image.size() != QSize(width, height) || image.format() != QImage::Format_Indexed8) {
                image = QImage(width, height, QImage::Format_Indexed8);
                if (image.isNull())
                    return;
            }
            image.setColorCount(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_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans, &trans_color_p) && trans_color_p) {
                const int g = trans_color_p->gray;
                if (g < ncols) {
                    image.setColor(g, 0);
                }
            }
        }
    } else if (color_type == PNG_COLOR_TYPE_PALETTE
               && png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)
               && 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);
        QImage::Format format = bit_depth == 1 ? QImage::Format_Mono : QImage::Format_Indexed8;
        if (image.size() != QSize(width, height) || image.format() != format) {
            image = QImage(width, height, format);
            if (image.isNull())
                return;
        }
        png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette);
        image.setColorCount(num_palette);
        int i = 0;
        if (png_get_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans, &trans_color_p) && trans_alpha) {
            while (i < num_trans) {
                image.setColor(i, qRgba(
                    palette[i].red,
                    palette[i].green,
                    palette[i].blue,
                    trans_alpha[i]
                   )
               );
                i++;
            }
        }
        while (i < num_palette) {
            image.setColor(i, qRgba(
                palette[i].red,
                palette[i].green,
                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;
        }
        if (image.size() != QSize(width, height) || image.format() != format) {
            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);
    }
}

write_png_image()

static bool write_png_image ( const QImage &  image, QIODevice *  device, int  quality, float  gamma, const QString &  description  )

static

Definition at line 915 of file qpnghandler.cpp.

Referenced by QPngHandler::write().

{
    QPNGImageWriter writer(device);
    if (quality >= 0) {
        quality = qMin(quality, 100);
        quality = (100-quality) * 9 / 91; // map [0,100] -> [9,0]
    }
    writer.setGamma(gamma);
    return writer.writeImage(image, quality, description);
}