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Diffstat (limited to 'src/gui/image/qjpeghandler.cpp')
| -rw-r--r-- | src/gui/image/qjpeghandler.cpp | 901 |
1 files changed, 901 insertions, 0 deletions
diff --git a/src/gui/image/qjpeghandler.cpp b/src/gui/image/qjpeghandler.cpp new file mode 100644 index 0000000..972dd65 --- /dev/null +++ b/src/gui/image/qjpeghandler.cpp @@ -0,0 +1,901 @@ +/**************************************************************************** +** +** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the plugins of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qjpeghandler_p.h" + +#include <qimage.h> +#include <qvariant.h> +#include <qvector.h> +#include <qbuffer.h> + +#include <stdio.h> // jpeglib needs this to be pre-included +#include <setjmp.h> + +#ifdef FAR +#undef FAR +#endif + +// including jpeglib.h seems to be a little messy +extern "C" { +// mingw includes rpcndr.h but does not define boolean +#if defined(Q_OS_WIN) && defined(Q_CC_GNU) +# if defined(__RPCNDR_H__) && !defined(boolean) + typedef unsigned char boolean; +# define HAVE_BOOLEAN +# endif +#endif + +#define XMD_H // shut JPEGlib up +#if defined(Q_OS_UNIXWARE) +# define HAVE_BOOLEAN // libjpeg under Unixware seems to need this +#endif +#include <jpeglib.h> +#ifdef const +# undef const // remove crazy C hackery in jconfig.h +#endif +} + +QT_BEGIN_NAMESPACE + +struct my_error_mgr : public jpeg_error_mgr { + jmp_buf setjmp_buffer; +}; + +#if defined(Q_C_CALLBACKS) +extern "C" { +#endif + +static void my_error_exit (j_common_ptr cinfo) +{ + my_error_mgr* myerr = (my_error_mgr*) cinfo->err; + char buffer[JMSG_LENGTH_MAX]; + (*cinfo->err->format_message)(cinfo, buffer); + qWarning("%s", buffer); + longjmp(myerr->setjmp_buffer, 1); +} + +#if defined(Q_C_CALLBACKS) +} +#endif + + +static const int max_buf = 4096; + +struct my_jpeg_source_mgr : public jpeg_source_mgr { + // Nothing dynamic - cannot rely on destruction over longjump + QIODevice *device; + JOCTET buffer[max_buf]; + const QBuffer *memDevice; + +public: + my_jpeg_source_mgr(QIODevice *device); +}; + +#if defined(Q_C_CALLBACKS) +extern "C" { +#endif + +static void qt_init_source(j_decompress_ptr) +{ +} + +static boolean qt_fill_input_buffer(j_decompress_ptr cinfo) +{ + my_jpeg_source_mgr* src = (my_jpeg_source_mgr*)cinfo->src; + if (src->memDevice) { + src->next_input_byte = (const JOCTET *)(src->memDevice->data().constData() + src->memDevice->pos()); + src->bytes_in_buffer = (size_t)(src->memDevice->data().size() - src->memDevice->pos()); + return true; + } + src->next_input_byte = src->buffer; + int num_read = src->device->read((char*)src->buffer, max_buf); + if (num_read <= 0) { + // Insert a fake EOI marker - as per jpeglib recommendation + src->buffer[0] = (JOCTET) 0xFF; + src->buffer[1] = (JOCTET) JPEG_EOI; + src->bytes_in_buffer = 2; + } else { + src->bytes_in_buffer = num_read; + } +#if defined(Q_OS_UNIXWARE) + return B_TRUE; +#else + return true; +#endif +} + +static void qt_skip_input_data(j_decompress_ptr cinfo, long num_bytes) +{ + my_jpeg_source_mgr* src = (my_jpeg_source_mgr*)cinfo->src; + + // `dumb' implementation from jpeglib + + /* Just a dumb implementation for now. Could use fseek() except + * it doesn't work on pipes. Not clear that being smart is worth + * any trouble anyway --- large skips are infrequent. + */ + if (num_bytes > 0) { + while (num_bytes > (long) src->bytes_in_buffer) { // Should not happen in case of memDevice + num_bytes -= (long) src->bytes_in_buffer; + (void) qt_fill_input_buffer(cinfo); + /* note we assume that qt_fill_input_buffer will never return false, + * so suspension need not be handled. + */ + } + src->next_input_byte += (size_t) num_bytes; + src->bytes_in_buffer -= (size_t) num_bytes; + } +} + +static void qt_term_source(j_decompress_ptr cinfo) +{ + my_jpeg_source_mgr* src = (my_jpeg_source_mgr*)cinfo->src; + if (!src->device->isSequential()) + { + // read() isn't used for memDevice, so seek past everything that was used + if (src->memDevice) + src->device->seek(src->device->pos() + (src->memDevice->data().size() - src->memDevice->pos() - src->bytes_in_buffer)); + else + src->device->seek(src->device->pos() - src->bytes_in_buffer); + } +} + +#if defined(Q_C_CALLBACKS) +} +#endif + +inline my_jpeg_source_mgr::my_jpeg_source_mgr(QIODevice *device) +{ + jpeg_source_mgr::init_source = qt_init_source; + jpeg_source_mgr::fill_input_buffer = qt_fill_input_buffer; + jpeg_source_mgr::skip_input_data = qt_skip_input_data; + jpeg_source_mgr::resync_to_restart = jpeg_resync_to_restart; + jpeg_source_mgr::term_source = qt_term_source; + this->device = device; + memDevice = qobject_cast<QBuffer *>(device); + bytes_in_buffer = 0; + next_input_byte = buffer; +} + + +inline static bool read_jpeg_size(int &w, int &h, j_decompress_ptr cinfo) +{ + (void) jpeg_calc_output_dimensions(cinfo); + + w = cinfo->output_width; + h = cinfo->output_height; + return true; +} + +#define HIGH_QUALITY_THRESHOLD 50 + +inline static bool read_jpeg_format(QImage::Format &format, j_decompress_ptr cinfo) +{ + + bool result = true; + switch (cinfo->output_components) { + case 1: + format = QImage::Format_Indexed8; + break; + case 3: + case 4: + format = QImage::Format_RGB32; + break; + default: + result = false; + break; + } + cinfo->output_scanline = cinfo->output_height; + return result; +} + +static bool ensureValidImage(QImage *dest, struct jpeg_decompress_struct *info, + const QSize& size) +{ + QImage::Format format; + switch (info->output_components) { + case 1: + format = QImage::Format_Indexed8; + break; + case 3: + case 4: + format = QImage::Format_RGB32; + break; + default: + return false; // unsupported format + } + + if (dest->size() != size || dest->format() != format) { + *dest = QImage(size, format); + + if (format == QImage::Format_Indexed8) { + dest->setColorCount(256); + for (int i = 0; i < 256; i++) + dest->setColor(i, qRgb(i,i,i)); + } + } + + return !dest->isNull(); +} + +static bool read_jpeg_image(QImage *outImage, + QSize scaledSize, QRect scaledClipRect, + QRect clipRect, int inQuality, j_decompress_ptr info, struct my_error_mgr* err ) +{ + if (!setjmp(err->setjmp_buffer)) { + // -1 means default quality. + int quality = inQuality; + if (quality < 0) + quality = 75; + + // If possible, merge the scaledClipRect into either scaledSize + // or clipRect to avoid doing a separate scaled clipping pass. + // Best results are achieved by clipping before scaling, not after. + if (!scaledClipRect.isEmpty()) { + if (scaledSize.isEmpty() && clipRect.isEmpty()) { + // No clipping or scaling before final clip. + clipRect = scaledClipRect; + scaledClipRect = QRect(); + } else if (scaledSize.isEmpty()) { + // Clipping, but no scaling: combine the clip regions. + scaledClipRect.translate(clipRect.topLeft()); + clipRect = scaledClipRect.intersected(clipRect); + scaledClipRect = QRect(); + } else if (clipRect.isEmpty()) { + // No clipping, but scaling: if we can map back to an + // integer pixel boundary, then clip before scaling. + if ((info->image_width % scaledSize.width()) == 0 && + (info->image_height % scaledSize.height()) == 0) { + int x = scaledClipRect.x() * info->image_width / + scaledSize.width(); + int y = scaledClipRect.y() * info->image_height / + scaledSize.height(); + int width = (scaledClipRect.right() + 1) * + info->image_width / scaledSize.width() - x; + int height = (scaledClipRect.bottom() + 1) * + info->image_height / scaledSize.height() - y; + clipRect = QRect(x, y, width, height); + scaledSize = scaledClipRect.size(); + scaledClipRect = QRect(); + } + } else { + // Clipping and scaling: too difficult to figure out, + // and not a likely use case, so do it the long way. + } + } + + // Determine the scale factor to pass to libjpeg for quick downscaling. + if (!scaledSize.isEmpty()) { + if (clipRect.isEmpty()) { + info->scale_denom = + qMin(info->image_width / scaledSize.width(), + info->image_height / scaledSize.height()); + } else { + info->scale_denom = + qMin(clipRect.width() / scaledSize.width(), + clipRect.height() / scaledSize.height()); + } + if (info->scale_denom < 2) { + info->scale_denom = 1; + } else if (info->scale_denom < 4) { + info->scale_denom = 2; + } else if (info->scale_denom < 8) { + info->scale_denom = 4; + } else { + info->scale_denom = 8; + } + info->scale_num = 1; + if (!clipRect.isEmpty()) { + // Correct the scale factor so that we clip accurately. + // It is recommended that the clip rectangle be aligned + // on an 8-pixel boundary for best performance. + while (info->scale_denom > 1 && + ((clipRect.x() % info->scale_denom) != 0 || + (clipRect.y() % info->scale_denom) != 0 || + (clipRect.width() % info->scale_denom) != 0 || + (clipRect.height() % info->scale_denom) != 0)) { + info->scale_denom /= 2; + } + } + } + + // If high quality not required, use fast decompression + if( quality < HIGH_QUALITY_THRESHOLD ) { + info->dct_method = JDCT_IFAST; + info->do_fancy_upsampling = FALSE; + } + + (void) jpeg_calc_output_dimensions(info); + + // Determine the clip region to extract. + QRect imageRect(0, 0, info->output_width, info->output_height); + QRect clip; + if (clipRect.isEmpty()) { + clip = imageRect; + } else if (info->scale_denom == info->scale_num) { + clip = clipRect.intersected(imageRect); + } else { + // The scale factor was corrected above to ensure that + // we don't miss pixels when we scale the clip rectangle. + clip = QRect(clipRect.x() / int(info->scale_denom), + clipRect.y() / int(info->scale_denom), + clipRect.width() / int(info->scale_denom), + clipRect.height() / int(info->scale_denom)); + clip = clip.intersected(imageRect); + } + + // Allocate memory for the clipped QImage. + if (!ensureValidImage(outImage, info, clip.size())) + longjmp(err->setjmp_buffer, 1); + + // Avoid memcpy() overhead if grayscale with no clipping. + bool quickGray = (info->output_components == 1 && + clip == imageRect); + if (!quickGray) { + // Ask the jpeg library to allocate a temporary row. + // The library will automatically delete it for us later. + // The libjpeg docs say we should do this before calling + // jpeg_start_decompress(). We can't use "new" here + // because we are inside the setjmp() block and an error + // in the jpeg input stream would cause a memory leak. + JSAMPARRAY rows = (info->mem->alloc_sarray) + ((j_common_ptr)info, JPOOL_IMAGE, + info->output_width * info->output_components, 1); + + (void) jpeg_start_decompress(info); + + while (info->output_scanline < info->output_height) { + int y = int(info->output_scanline) - clip.y(); + if (y >= clip.height()) + break; // We've read the entire clip region, so abort. + + (void) jpeg_read_scanlines(info, rows, 1); + + if (y < 0) + continue; // Haven't reached the starting line yet. + + if (info->output_components == 3) { + // Expand 24->32 bpp. + uchar *in = rows[0] + clip.x() * 3; + QRgb *out = (QRgb*)outImage->scanLine(y); + for (int i = 0; i < clip.width(); ++i) { + *out++ = qRgb(in[0], in[1], in[2]); + in += 3; + } + } else if (info->out_color_space == JCS_CMYK) { + // Convert CMYK->RGB. + uchar *in = rows[0] + clip.x() * 4; + QRgb *out = (QRgb*)outImage->scanLine(y); + for (int i = 0; i < clip.width(); ++i) { + int k = in[3]; + *out++ = qRgb(k * in[0] / 255, k * in[1] / 255, + k * in[2] / 255); + in += 4; + } + } else if (info->output_components == 1) { + // Grayscale. + memcpy(outImage->scanLine(y), + rows[0] + clip.x(), clip.width()); + } + } + } else { + // Load unclipped grayscale data directly into the QImage. + (void) jpeg_start_decompress(info); + while (info->output_scanline < info->output_height) { + uchar *row = outImage->scanLine(info->output_scanline); + (void) jpeg_read_scanlines(info, &row, 1); + } + } + + if (info->output_scanline == info->output_height) + (void) jpeg_finish_decompress(info); + + if (info->density_unit == 1) { + outImage->setDotsPerMeterX(int(100. * info->X_density / 2.54)); + outImage->setDotsPerMeterY(int(100. * info->Y_density / 2.54)); + } else if (info->density_unit == 2) { + outImage->setDotsPerMeterX(int(100. * info->X_density)); + outImage->setDotsPerMeterY(int(100. * info->Y_density)); + } + + if (scaledSize.isValid() && scaledSize != clip.size()) { + *outImage = outImage->scaled(scaledSize, Qt::IgnoreAspectRatio, quality >= HIGH_QUALITY_THRESHOLD ? Qt::SmoothTransformation : Qt::FastTransformation); + } + + if (!scaledClipRect.isEmpty()) + *outImage = outImage->copy(scaledClipRect); + return !outImage->isNull(); + } + else + return false; +} + +struct my_jpeg_destination_mgr : public jpeg_destination_mgr { + // Nothing dynamic - cannot rely on destruction over longjump + QIODevice *device; + JOCTET buffer[max_buf]; + +public: + my_jpeg_destination_mgr(QIODevice *); +}; + + +#if defined(Q_C_CALLBACKS) +extern "C" { +#endif + +static void qt_init_destination(j_compress_ptr) +{ +} + +static boolean qt_empty_output_buffer(j_compress_ptr cinfo) +{ + my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest; + + int written = dest->device->write((char*)dest->buffer, max_buf); + if (written == -1) + (*cinfo->err->error_exit)((j_common_ptr)cinfo); + + dest->next_output_byte = dest->buffer; + dest->free_in_buffer = max_buf; + +#if defined(Q_OS_UNIXWARE) + return B_TRUE; +#else + return true; +#endif +} + +static void qt_term_destination(j_compress_ptr cinfo) +{ + my_jpeg_destination_mgr* dest = (my_jpeg_destination_mgr*)cinfo->dest; + qint64 n = max_buf - dest->free_in_buffer; + + qint64 written = dest->device->write((char*)dest->buffer, n); + if (written == -1) + (*cinfo->err->error_exit)((j_common_ptr)cinfo); +} + +#if defined(Q_C_CALLBACKS) +} +#endif + +inline my_jpeg_destination_mgr::my_jpeg_destination_mgr(QIODevice *device) +{ + jpeg_destination_mgr::init_destination = qt_init_destination; + jpeg_destination_mgr::empty_output_buffer = qt_empty_output_buffer; + jpeg_destination_mgr::term_destination = qt_term_destination; + this->device = device; + next_output_byte = buffer; + free_in_buffer = max_buf; +} + +static bool can_write_format(QImage::Format fmt) +{ + switch (fmt) { + case QImage::Format_Mono: + case QImage::Format_MonoLSB: + case QImage::Format_Indexed8: + case QImage::Format_RGB888: + case QImage::Format_RGB32: + case QImage::Format_ARGB32: + case QImage::Format_ARGB32_Premultiplied: + return true; + break; + default: + break; + } + return false; +} + +static bool write_jpeg_image(const QImage &sourceImage, QIODevice *device, int sourceQuality) +{ + bool success = false; + const QImage image = can_write_format(sourceImage.format()) ? + sourceImage : sourceImage.convertToFormat(QImage::Format_RGB888); + const QVector<QRgb> cmap = image.colorTable(); + + struct jpeg_compress_struct cinfo; + JSAMPROW row_pointer[1]; + row_pointer[0] = 0; + + struct my_jpeg_destination_mgr *iod_dest = new my_jpeg_destination_mgr(device); + struct my_error_mgr jerr; + + cinfo.err = jpeg_std_error(&jerr); + jerr.error_exit = my_error_exit; + + if (!setjmp(jerr.setjmp_buffer)) { + // WARNING: + // this if loop is inside a setjmp/longjmp branch + // do not create C++ temporaries here because the destructor may never be called + // if you allocate memory, make sure that you can free it (row_pointer[0]) + jpeg_create_compress(&cinfo); + + cinfo.dest = iod_dest; + + cinfo.image_width = image.width(); + cinfo.image_height = image.height(); + + bool gray=false; + switch (image.format()) { + case QImage::Format_Mono: + case QImage::Format_MonoLSB: + case QImage::Format_Indexed8: + gray = true; + for (int i = image.colorCount(); gray && i--;) { + gray = gray & (qRed(cmap[i]) == qGreen(cmap[i]) && + qRed(cmap[i]) == qBlue(cmap[i])); + } + cinfo.input_components = gray ? 1 : 3; + cinfo.in_color_space = gray ? JCS_GRAYSCALE : JCS_RGB; + break; + default: + cinfo.input_components = 3; + cinfo.in_color_space = JCS_RGB; + } + + jpeg_set_defaults(&cinfo); + + qreal diffInch = qAbs(image.dotsPerMeterX()*2.54/100. - qRound(image.dotsPerMeterX()*2.54/100.)) + + qAbs(image.dotsPerMeterY()*2.54/100. - qRound(image.dotsPerMeterY()*2.54/100.)); + qreal diffCm = (qAbs(image.dotsPerMeterX()/100. - qRound(image.dotsPerMeterX()/100.)) + + qAbs(image.dotsPerMeterY()/100. - qRound(image.dotsPerMeterY()/100.)))*2.54; + if (diffInch < diffCm) { + cinfo.density_unit = 1; // dots/inch + cinfo.X_density = qRound(image.dotsPerMeterX()*2.54/100.); + cinfo.Y_density = qRound(image.dotsPerMeterY()*2.54/100.); + } else { + cinfo.density_unit = 2; // dots/cm + cinfo.X_density = (image.dotsPerMeterX()+50) / 100; + cinfo.Y_density = (image.dotsPerMeterY()+50) / 100; + } + + + int quality = sourceQuality >= 0 ? qMin(sourceQuality,100) : 75; +#if defined(Q_OS_UNIXWARE) + jpeg_set_quality(&cinfo, quality, B_TRUE /* limit to baseline-JPEG values */); + jpeg_start_compress(&cinfo, B_TRUE); +#else + jpeg_set_quality(&cinfo, quality, true /* limit to baseline-JPEG values */); + jpeg_start_compress(&cinfo, true); +#endif + + row_pointer[0] = new uchar[cinfo.image_width*cinfo.input_components]; + int w = cinfo.image_width; + while (cinfo.next_scanline < cinfo.image_height) { + uchar *row = row_pointer[0]; + switch (image.format()) { + case QImage::Format_Mono: + case QImage::Format_MonoLSB: + if (gray) { + const uchar* data = image.scanLine(cinfo.next_scanline); + if (image.format() == QImage::Format_MonoLSB) { + for (int i=0; i<w; i++) { + bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7))); + row[i] = qRed(cmap[bit]); + } + } else { + for (int i=0; i<w; i++) { + bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7)))); + row[i] = qRed(cmap[bit]); + } + } + } else { + const uchar* data = image.scanLine(cinfo.next_scanline); + if (image.format() == QImage::Format_MonoLSB) { + for (int i=0; i<w; i++) { + bool bit = !!(*(data + (i >> 3)) & (1 << (i & 7))); + *row++ = qRed(cmap[bit]); + *row++ = qGreen(cmap[bit]); + *row++ = qBlue(cmap[bit]); + } + } else { + for (int i=0; i<w; i++) { + bool bit = !!(*(data + (i >> 3)) & (1 << (7 -(i & 7)))); + *row++ = qRed(cmap[bit]); + *row++ = qGreen(cmap[bit]); + *row++ = qBlue(cmap[bit]); + } + } + } + break; + case QImage::Format_Indexed8: + if (gray) { + const uchar* pix = image.scanLine(cinfo.next_scanline); + for (int i=0; i<w; i++) { + *row = qRed(cmap[*pix]); + ++row; ++pix; + } + } else { + const uchar* pix = image.scanLine(cinfo.next_scanline); + for (int i=0; i<w; i++) { + *row++ = qRed(cmap[*pix]); + *row++ = qGreen(cmap[*pix]); + *row++ = qBlue(cmap[*pix]); + ++pix; + } + } + break; + case QImage::Format_RGB888: + memcpy(row, image.scanLine(cinfo.next_scanline), w * 3); + break; + case QImage::Format_RGB32: + case QImage::Format_ARGB32: + case QImage::Format_ARGB32_Premultiplied: { + QRgb* rgb = (QRgb*)image.scanLine(cinfo.next_scanline); + for (int i=0; i<w; i++) { + *row++ = qRed(*rgb); + *row++ = qGreen(*rgb); + *row++ = qBlue(*rgb); + ++rgb; + } + break; + } + default: + qWarning("QJpegHandler: unable to write image of format %i", + image.format()); + break; + } + jpeg_write_scanlines(&cinfo, row_pointer, 1); + } + + jpeg_finish_compress(&cinfo); + jpeg_destroy_compress(&cinfo); + success = true; + } else { + jpeg_destroy_compress(&cinfo); + success = false; + } + + delete iod_dest; + delete [] row_pointer[0]; + return success; +} + +class QJpegHandlerPrivate +{ +public: + enum State { + Ready, + ReadHeader, + Error + }; + + QJpegHandlerPrivate(QJpegHandler *qq) + : quality(75), iod_src(0), state(Ready), q(qq) + {} + + ~QJpegHandlerPrivate() + { + if(iod_src) + { + jpeg_destroy_decompress(&info); + delete iod_src; + iod_src = 0; + } + } + + bool readJpegHeader(QIODevice*); + bool read(QImage *image); + + int quality; + QVariant size; + QImage::Format format; + QSize scaledSize; + QRect scaledClipRect; + QRect clipRect; + struct jpeg_decompress_struct info; + struct my_jpeg_source_mgr * iod_src; + struct my_error_mgr err; + + State state; + + QJpegHandler *q; +}; + +/*! + \internal +*/ +bool QJpegHandlerPrivate::readJpegHeader(QIODevice *device) +{ + if(state == Ready) + { + state = Error; + iod_src = new my_jpeg_source_mgr(device); + + jpeg_create_decompress(&info); + info.src = iod_src; + info.err = jpeg_std_error(&err); + err.error_exit = my_error_exit; + + if (!setjmp(err.setjmp_buffer)) { + #if defined(Q_OS_UNIXWARE) + (void) jpeg_read_header(&info, B_TRUE); + #else + (void) jpeg_read_header(&info, true); + #endif + + int width = 0; + int height = 0; + read_jpeg_size(width, height, &info); + size = QSize(width, height); + + format = QImage::Format_Invalid; + read_jpeg_format(format, &info); + state = ReadHeader; + return true; + } + else + { + return false; + } + } + else if(state == Error) + return false; + return true; +} + +bool QJpegHandlerPrivate::read(QImage *image) +{ + if(state == Ready) + readJpegHeader(q->device()); + + if(state == ReadHeader) + { + bool success = read_jpeg_image(image, scaledSize, scaledClipRect, clipRect, quality, &info, &err); + state = success ? Ready : Error; + return success; + } + + return false; + +} + +QJpegHandler::QJpegHandler() + : d(new QJpegHandlerPrivate(this)) +{ +} + +QJpegHandler::~QJpegHandler() +{ + delete d; +} + +bool QJpegHandler::canRead() const +{ + if(d->state == QJpegHandlerPrivate::Ready && !canRead(device())) + return false; + + if (d->state != QJpegHandlerPrivate::Error) { + setFormat("jpeg"); + return true; + } + + return false; +} + +bool QJpegHandler::canRead(QIODevice *device) +{ + if (!device) { + qWarning("QJpegHandler::canRead() called with no device"); + return false; + } + + char buffer[2]; + if (device->peek(buffer, 2) != 2) + return false; + return uchar(buffer[0]) == 0xff && uchar(buffer[1]) == 0xd8; +} + +bool QJpegHandler::read(QImage *image) +{ + if (!canRead()) + return false; + return d->read(image); +} + +bool QJpegHandler::write(const QImage &image) +{ + return write_jpeg_image(image, device(), d->quality); +} + +bool QJpegHandler::supportsOption(ImageOption option) const +{ + return option == Quality + || option == ScaledSize + || option == ScaledClipRect + || option == ClipRect + || option == Size + || option == ImageFormat; +} + +QVariant QJpegHandler::option(ImageOption option) const +{ + switch(option) { + case Quality: + return d->quality; + case ScaledSize: + return d->scaledSize; + case ScaledClipRect: + return d->scaledClipRect; + case ClipRect: + return d->clipRect; + case Size: + d->readJpegHeader(device()); + return d->size; + case ImageFormat: + d->readJpegHeader(device()); + return d->format; + default: + return QVariant(); + } +} + +void QJpegHandler::setOption(ImageOption option, const QVariant &value) +{ + switch(option) { + case Quality: + d->quality = value.toInt(); + break; + case ScaledSize: + d->scaledSize = value.toSize(); + break; + case ScaledClipRect: + d->scaledClipRect = value.toRect(); + break; + case ClipRect: + d->clipRect = value.toRect(); + break; + default: + break; + } +} + +QByteArray QJpegHandler::name() const +{ + return "jpeg"; +} + + + + +QT_END_NAMESPACE |