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-rw-r--r--src/plugins/imageformats/jpeg/qjpeghandler.cpp233
-rw-r--r--src/plugins/imageformats/jpeg/qjpeghandler.h2
2 files changed, 149 insertions, 86 deletions
diff --git a/src/plugins/imageformats/jpeg/qjpeghandler.cpp b/src/plugins/imageformats/jpeg/qjpeghandler.cpp
index 8da6610..7165c38 100644
--- a/src/plugins/imageformats/jpeg/qjpeghandler.cpp
+++ b/src/plugins/imageformats/jpeg/qjpeghandler.cpp
@@ -90,9 +90,6 @@ public:
QImage scale();
-protected:
- int scaledWidth(void) const;
-
private:
QImageSmoothScalerPrivate *d;
virtual QRgb *scanLine(const int line = 0, const QImage *src = 0);
@@ -140,11 +137,6 @@ void QImageSmoothScalerPrivate::setup(const int srcWidth, const int srcHeight,
hasAlpha = hasAlphaChannel;
}
-int QImageSmoothScaler::scaledWidth() const
-{
- return d->cols;
-}
-
QImageSmoothScaler::~QImageSmoothScaler()
{
delete d;
@@ -443,20 +435,18 @@ QImage QImageSmoothScaler::scale()
class jpegSmoothScaler : public QImageSmoothScaler
{
public:
- jpegSmoothScaler(struct jpeg_decompress_struct *info, int dstWidth, int dstHeight)
- : QImageSmoothScaler(info->output_width, info->output_height, dstWidth, dstHeight)
+ jpegSmoothScaler(struct jpeg_decompress_struct *info, const QSize& dstSize, const QRect& clipRect)
+ : QImageSmoothScaler(clipRect.width(), clipRect.height(),
+ dstSize.width(), dstSize.height())
{
- cinfo = info;
- cols24Bit = scaledWidth() * 3;
-
- cacheHeight = 1;
- imageCache = QImage( info->output_width, cacheHeight, QImage::Format_RGB32 );
+ cinfo = info;
+ clip = clipRect;
+ imageCache = QImage(info->output_width, 1, QImage::Format_RGB32);
}
private:
- int cols24Bit;
+ QRect clip;
QImage imageCache;
- int cacheHeight;
struct jpeg_decompress_struct *cinfo;
QRgb *scanLine(const int line = 0, const QImage *src = 0)
@@ -468,33 +458,42 @@ private:
Q_UNUSED(src);
uchar* data = imageCache.bits();
+
+ // Read ahead if we haven't reached the first clipped scanline yet.
+ while (int(cinfo->output_scanline) < clip.y() &&
+ cinfo->output_scanline < cinfo->output_height)
+ jpeg_read_scanlines(cinfo, &data, 1);
+
+ // Read the next scanline. We assume that "line"
+ // will never be >= clip.height().
jpeg_read_scanlines(cinfo, &data, 1);
- out = (QRgb*)imageCache.scanLine(0);
+ if (cinfo->output_scanline == cinfo->output_height)
+ jpeg_finish_decompress(cinfo);
+
+ out = ((QRgb*)data) + clip.x();
//
// The smooth scale algorithm only works on 32-bit images;
// convert from (8|24) bits to 32.
//
if (cinfo->output_components == 1) {
- in = (uchar*)out + scaledWidth();
- for (uint i = scaledWidth(); i--; ) {
- in--;
+ in = data + clip.right();
+ for (int i = clip.width(); i--; ) {
out[i] = qRgb(*in, *in, *in);
+ in--;
}
- } else if (cinfo->out_color_space == JCS_CMYK) {
- int cols32Bit = scaledWidth() * 4;
- in = (uchar*)out + cols32Bit;
- for (uint i = scaledWidth(); i--; ) {
- in -= 4;
- int k = in[3];
- out[i] = qRgb(k * in[0] / 255, k * in[1] / 255, k * in[2] / 255);
- //out[i] = qRgb(in[0], in[1], in[2]);
- }
- } else {
- in = (uchar*)out + cols24Bit;
- for (uint i = scaledWidth(); i--; ) {
- in -= 3;
+ } else if (cinfo->out_color_space == JCS_CMYK) {
+ in = data + clip.right() * 4;
+ for (int i = clip.width(); i--; ) {
+ int k = in[3];
+ out[i] = qRgb(k * in[0] / 255, k * in[1] / 255, k * in[2] / 255);
+ in -= 4;
+ }
+ } else {
+ in = data + clip.right() * 3;
+ for (int i = clip.width(); i--; ) {
out[i] = qRgb(in[0], in[1], in[2]);
+ in -= 3;
}
}
@@ -693,7 +692,7 @@ static bool read_jpeg_format(QIODevice *device, QImage::Format &format)
}
static bool ensureValidImage(QImage *dest, struct jpeg_decompress_struct *info,
- bool dummy = false)
+ const QSize& size)
{
QImage::Format format;
switch (info->output_components) {
@@ -708,13 +707,8 @@ static bool ensureValidImage(QImage *dest, struct jpeg_decompress_struct *info,
return false; // unsupported format
}
- const QSize size(info->output_width, info->output_height);
if (dest->size() != size || dest->format() != format) {
- static uchar dummyImage[1];
- if (dummy) // Create QImage but don't read the pixels
- *dest = QImage(dummyImage, size.width(), size.height(), format);
- else
- *dest = QImage(size, format);
+ *dest = QImage(size, format);
if (format == QImage::Format_Indexed8) {
dest->setColorCount(256);
@@ -727,12 +721,9 @@ static bool ensureValidImage(QImage *dest, struct jpeg_decompress_struct *info,
}
static bool read_jpeg_image(QIODevice *device, QImage *outImage,
- QSize scaledSize, int inQuality )
+ QSize scaledSize, const QRect& clipRect,
+ int inQuality )
{
-#ifdef QT_NO_IMAGE_SMOOTHSCALE
- Q_UNUSED( scaledSize );
-#endif
-
struct jpeg_decompress_struct cinfo;
struct my_jpeg_source_mgr *iod_src = new my_jpeg_source_mgr(device);
@@ -757,10 +748,17 @@ static bool read_jpeg_image(QIODevice *device, QImage *outImage,
if (quality < 0)
quality = 75;
-#ifndef QT_NO_IMAGE_SMOOTHSCALE
+ // Determine the scale factor to pass to libjpeg for quick downscaling.
if (!scaledSize.isEmpty()) {
- cinfo.scale_denom = qMin(cinfo.image_width / scaledSize.width(),
- cinfo.image_height / scaledSize.height());
+ if (clipRect.isEmpty()) {
+ cinfo.scale_denom =
+ qMin(cinfo.image_width / scaledSize.width(),
+ cinfo.image_height / scaledSize.height());
+ } else {
+ cinfo.scale_denom =
+ qMin(clipRect.width() / scaledSize.width(),
+ clipRect.height() / scaledSize.height());
+ }
if (cinfo.scale_denom < 2) {
cinfo.scale_denom = 1;
} else if (cinfo.scale_denom < 4) {
@@ -771,9 +769,19 @@ static bool read_jpeg_image(QIODevice *device, QImage *outImage,
cinfo.scale_denom = 8;
}
cinfo.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 (cinfo.scale_denom > 1 &&
+ ((clipRect.x() % cinfo.scale_denom) != 0 ||
+ (clipRect.y() % cinfo.scale_denom) != 0 ||
+ (clipRect.width() % cinfo.scale_denom) != 0 ||
+ (clipRect.height() % cinfo.scale_denom) != 0)) {
+ cinfo.scale_denom /= 2;
+ }
+ }
}
-#endif
-
// If high quality not required, use fast decompression
if( quality < HIGH_QUALITY_THRESHOLD ) {
@@ -781,54 +789,102 @@ static bool read_jpeg_image(QIODevice *device, QImage *outImage,
cinfo.do_fancy_upsampling = FALSE;
}
+ (void) jpeg_calc_output_dimensions(&cinfo);
- (void) jpeg_start_decompress(&cinfo);
+ // Determine the clip region to extract.
+ QRect imageRect(0, 0, cinfo.output_width, cinfo.output_height);
+ QRect clip;
+ if (clipRect.isEmpty()) {
+ clip = imageRect;
+ } else if (cinfo.scale_denom == 1) {
+ 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(cinfo.scale_denom),
+ clipRect.y() / int(cinfo.scale_denom),
+ clipRect.width() / int(cinfo.scale_denom),
+ clipRect.height() / int(cinfo.scale_denom));
+ clip = clip.intersected(imageRect);
+ }
#ifndef QT_NO_IMAGE_SMOOTHSCALE
- if (scaledSize.isValid() && scaledSize != QSize(cinfo.output_width, cinfo.output_height)
+ if (scaledSize.isValid() && scaledSize != clip.size()
&& quality >= HIGH_QUALITY_THRESHOLD) {
- jpegSmoothScaler scaler(&cinfo, scaledSize.width(), scaledSize.height());
+ (void) jpeg_start_decompress(&cinfo);
+
+ jpegSmoothScaler scaler(&cinfo, scaledSize, clip);
*outImage = scaler.scale();
} else
#endif
{
- if (!ensureValidImage(outImage, &cinfo))
+ // Allocate memory for the clipped QImage.
+ if (!ensureValidImage(outImage, &cinfo, clip.size()))
longjmp(jerr.setjmp_buffer, 1);
- uchar* data = outImage->bits();
- int bpl = outImage->bytesPerLine();
- while (cinfo.output_scanline < cinfo.output_height) {
- uchar *d = data + cinfo.output_scanline * bpl;
- (void) jpeg_read_scanlines(&cinfo,
- &d,
- 1);
- }
- (void) jpeg_finish_decompress(&cinfo);
-
- if (cinfo.output_components == 3) {
- // Expand 24->32 bpp.
- for (uint j=0; j<cinfo.output_height; j++) {
- uchar *in = outImage->scanLine(j) + cinfo.output_width * 3;
- QRgb *out = (QRgb*)outImage->scanLine(j);
-
- for (uint i=cinfo.output_width; i--;) {
- in-=3;
- out[i] = qRgb(in[0], in[1], in[2]);
+ // Avoid memcpy() overhead if grayscale with no clipping.
+ bool quickGray = (cinfo.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 = (cinfo.mem->alloc_sarray)
+ ((j_common_ptr)&cinfo, JPOOL_IMAGE,
+ cinfo.output_width * cinfo.output_components, 1);
+
+ (void) jpeg_start_decompress(&cinfo);
+
+ while (cinfo.output_scanline < cinfo.output_height) {
+ int y = int(cinfo.output_scanline) - clip.y();
+ if (y >= clip.height())
+ break; // We've read the entire clip region, so abort.
+
+ (void) jpeg_read_scanlines(&cinfo, rows, 1);
+
+ if (y < 0)
+ continue; // Haven't reached the starting line yet.
+
+ if (cinfo.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 (cinfo.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 (cinfo.output_components == 1) {
+ // Grayscale.
+ memcpy(outImage->scanLine(y),
+ rows[0] + clip.x(), clip.width());
}
}
- } else if (cinfo.out_color_space == JCS_CMYK) {
- for (uint j = 0; j < cinfo.output_height; ++j) {
- uchar *in = outImage->scanLine(j) + cinfo.output_width * 4;
- QRgb *out = (QRgb*)outImage->scanLine(j);
-
- for (uint i = cinfo.output_width; i--; ) {
- in-=4;
- int k = in[3];
- out[i] = qRgb(k * in[0] / 255, k * in[1] / 255, k * in[2] / 255);
- }
+ } else {
+ // Load unclipped grayscale data directly into the QImage.
+ (void) jpeg_start_decompress(&cinfo);
+ while (cinfo.output_scanline < cinfo.output_height) {
+ uchar *row = outImage->scanLine(cinfo.output_scanline);
+ (void) jpeg_read_scanlines(&cinfo, &row, 1);
}
}
+
+ if (cinfo.output_scanline == cinfo.output_height)
+ (void) jpeg_finish_decompress(&cinfo);
+
if (cinfo.density_unit == 1) {
outImage->setDotsPerMeterX(int(100. * cinfo.X_density / 2.54));
outImage->setDotsPerMeterY(int(100. * cinfo.Y_density / 2.54));
@@ -837,7 +893,7 @@ static bool read_jpeg_image(QIODevice *device, QImage *outImage,
outImage->setDotsPerMeterY(int(100. * cinfo.Y_density));
}
- if (scaledSize.isValid() && scaledSize != QSize(cinfo.output_width, cinfo.output_height))
+ if (scaledSize.isValid() && scaledSize != clip.size())
*outImage = outImage->scaled(scaledSize, Qt::IgnoreAspectRatio, Qt::FastTransformation);
}
}
@@ -1101,7 +1157,7 @@ bool QJpegHandler::read(QImage *image)
{
if (!canRead())
return false;
- return read_jpeg_image(device(), image, scaledSize, quality);
+ return read_jpeg_image(device(), image, scaledSize, clipRect, quality);
}
bool QJpegHandler::write(const QImage &image)
@@ -1115,6 +1171,7 @@ bool QJpegHandler::supportsOption(ImageOption option) const
#ifndef QT_NO_IMAGE_SMOOTHSCALE
|| option == ScaledSize
#endif
+ || option == ClipRect
|| option == Size
|| option == ImageFormat;
}
@@ -1127,6 +1184,8 @@ QVariant QJpegHandler::option(ImageOption option) const
} else if (option == ScaledSize) {
return scaledSize;
#endif
+ } else if (option == ClipRect) {
+ return clipRect;
} else if (option == Size) {
if (canRead() && !device()->isSequential()) {
qint64 pos = device()->pos();
@@ -1157,6 +1216,8 @@ void QJpegHandler::setOption(ImageOption option, const QVariant &value)
else if ( option == ScaledSize )
scaledSize = value.toSize();
#endif
+ else if ( option == ClipRect )
+ clipRect = value.toRect();
}
QByteArray QJpegHandler::name() const
diff --git a/src/plugins/imageformats/jpeg/qjpeghandler.h b/src/plugins/imageformats/jpeg/qjpeghandler.h
index 0a14a88..108b131 100644
--- a/src/plugins/imageformats/jpeg/qjpeghandler.h
+++ b/src/plugins/imageformats/jpeg/qjpeghandler.h
@@ -44,6 +44,7 @@
#include <QtGui/qimageiohandler.h>
#include <QtCore/QSize>
+#include <QtCore/QRect>
QT_BEGIN_NAMESPACE
@@ -67,6 +68,7 @@ public:
private:
int quality;
QSize scaledSize;
+ QRect clipRect;
};
QT_END_NAMESPACE
generated by cgit v0.12 at 2024-11-25 19:34:26 (GMT)