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authoraavit <qt_aavit@ovi.com>2012-04-18 15:02:21 +0200
committerQt by Nokia <qt-info@nokia.com>2012-04-27 10:37:02 +0200
commit878a01b2d1ca819e24cda04c9baa2417c53a1215 (patch)
tree08ff13218984de78f17678fb4294b95bb7bc7dfa /src
parentbc5e82ad99e5213a470ebbeb85a9c9c1f70b83e1 (diff)
Implement inline downscaling in png reader, to save memory
Instead of allocating and reading the entire image and then scaling it down, this code reads only one line at a time and scales it on the fly. Change-Id: I61fde307146c11dcd90ca617cc2e7f85dd3b66c4 Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Diffstat (limited to 'src')
-rw-r--r--src/gui/image/qpnghandler.cpp213
1 files changed, 153 insertions, 60 deletions
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index b2f4c4b151..ec7e7d25d0 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -116,19 +116,18 @@ public:
};
QPngHandlerPrivate(QPngHandler *qq)
- : gamma(0.0), quality(2), png_ptr(0), info_ptr(0),
- end_info(0), row_pointers(0), state(Ready), q(qq)
+ : gamma(0.0), quality(2), png_ptr(0), info_ptr(0), end_info(0), state(Ready), q(qq)
{ }
float gamma;
int quality;
QString description;
+ QSize scaledSize;
QStringList readTexts;
png_struct *png_ptr;
png_info *info_ptr;
png_info *end_info;
- png_byte **row_pointers;
bool readPngHeader();
bool readPngImage(QImage *image);
@@ -136,6 +135,30 @@ public:
QImage::Format readImageFormat();
+ struct AllocatedMemoryPointers {
+ AllocatedMemoryPointers()
+ : row_pointers(0), accRow(0), inRow(0), outRow(0)
+ { }
+ void deallocate()
+ {
+ delete [] row_pointers;
+ row_pointers = 0;
+ delete [] accRow;
+ accRow = 0;
+ delete [] inRow;
+ inRow = 0;
+ delete [] outRow;
+ outRow = 0;
+ }
+
+ png_byte **row_pointers;
+ quint32 *accRow;
+ png_byte *inRow;
+ uchar *outRow;
+ };
+
+ AllocatedMemoryPointers amp;
+
State state;
QPngHandler *q;
@@ -224,7 +247,7 @@ void CALLBACK_CALL_TYPE qpiw_flush_fn(png_structp /* png_ptr */)
#endif
static
-void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float screen_gamma=0.0)
+void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, QSize scaledSize, bool *doScaledRead, float screen_gamma=0.0)
{
if (screen_gamma != 0.0 && png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA)) {
double file_gamma;
@@ -241,7 +264,8 @@ void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float scre
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);
+ int interlace_method;
+ png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_method, 0, 0);
png_set_interlace_handling(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY) {
@@ -353,8 +377,16 @@ void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float scre
// 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);
+ QSize outSize(width,height);
+ if (!scaledSize.isEmpty() && quint32(scaledSize.width()) <= width &&
+ quint32(scaledSize.height()) <= height && interlace_method == PNG_INTERLACE_NONE) {
+ // Do inline downscaling
+ outSize = scaledSize;
+ if (doScaledRead)
+ *doScaledRead = true;
+ }
+ if (image.size() != outSize || image.format() != format) {
+ image = QImage(outSize, format);
if (image.isNull())
return;
}
@@ -371,6 +403,75 @@ void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, float scre
}
}
+static void read_image_scaled(QImage *outImage, png_structp png_ptr, png_infop info_ptr,
+ QPngHandlerPrivate::AllocatedMemoryPointers &amp, QSize scaledSize)
+{
+
+ 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 = outImage->bits();
+ int bpl = outImage->bytesPerLine();
+
+ if (scaledSize.isEmpty() || !width || !height)
+ return;
+
+ const quint32 iysz = height;
+ const quint32 ixsz = width;
+ const quint32 oysz = scaledSize.height();
+ const quint32 oxsz = scaledSize.width();
+ const quint32 ibw = 4*width;
+ amp.accRow = new quint32[ibw];
+ qMemSet(amp.accRow, 0, ibw*sizeof(quint32));
+ amp.inRow = new png_byte[ibw];
+ qMemSet(amp.inRow, 0, ibw*sizeof(png_byte));
+ amp.outRow = new uchar[ibw];
+ qMemSet(amp.outRow, 0, ibw*sizeof(uchar));
+ qint32 rval = 0;
+ for (quint32 oy=0; oy<oysz; oy++) {
+ // Store the rest of the previous input row, if any
+ for (quint32 i=0; i < ibw; i++)
+ amp.accRow[i] = rval*amp.inRow[i];
+ // Accumulate the next input rows
+ for (rval = iysz-rval; rval > 0; rval-=oysz) {
+ png_read_row(png_ptr, amp.inRow, NULL);
+ quint32 fact = qMin(oysz, quint32(rval));
+ for (quint32 i=0; i < ibw; i++)
+ amp.accRow[i] += fact*amp.inRow[i];
+ }
+ rval *= -1;
+
+ // We have a full output row, store it
+ for (quint32 i=0; i < ibw; i++)
+ amp.outRow[i] = uchar(amp.accRow[i]/iysz);
+
+ quint32 a[4] = {0, 0, 0, 0};
+ qint32 cval = oxsz;
+ quint32 ix = 0;
+ for (quint32 ox=0; ox<oxsz; ox++) {
+ for (quint32 i=0; i < 4; i++)
+ a[i] = cval * amp.outRow[ix+i];
+ for (cval = ixsz - cval; cval > 0; cval-=oxsz) {
+ ix += 4;
+ if (ix >= ibw)
+ break; // Safety belt, should not happen
+ quint32 fact = qMin(oxsz, quint32(cval));
+ for (quint32 i=0; i < 4; i++)
+ a[i] += fact * amp.outRow[ix+i];
+ }
+ cval *= -1;
+ for (quint32 i=0; i < 4; i++)
+ data[(4*ox)+i] = uchar(a[i]/ixsz);
+ }
+ data += bpl;
+ }
+ amp.deallocate();
+
+ outImage->setDotsPerMeterX((png_get_x_pixels_per_meter(png_ptr,info_ptr)*oxsz)/ixsz);
+ outImage->setDotsPerMeterY((png_get_y_pixels_per_meter(png_ptr,info_ptr)*oysz)/iysz);
+}
#if defined(Q_C_CALLBACKS)
extern "C" {
@@ -469,61 +570,60 @@ bool Q_INTERNAL_WIN_NO_THROW QPngHandlerPrivate::readPngImage(QImage *outImage)
return false;
}
- row_pointers = 0;
if (setjmp(png_jmpbuf(png_ptr))) {
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
- delete [] row_pointers;
png_ptr = 0;
+ amp.deallocate();
state = Error;
return false;
}
- setup_qt(*outImage, png_ptr, info_ptr, gamma);
+ bool doScaledRead = false;
+ setup_qt(*outImage, png_ptr, info_ptr, scaledSize, &doScaledRead, gamma);
if (outImage->isNull()) {
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
- delete [] row_pointers;
png_ptr = 0;
+ amp.deallocate();
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 = outImage->bits();
- int bpl = outImage->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 (outImage->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 {
- }
+ if (doScaledRead) {
+ read_image_scaled(outImage, png_ptr, info_ptr, amp, scaledSize);
+ } else {
+ 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 = outImage->bits();
+ int bpl = outImage->bytesPerLine();
+ amp.row_pointers = new png_bytep[height];
+
+ for (uint y = 0; y < height; y++)
+ amp.row_pointers[y] = data + y * bpl;
+
+ png_read_image(png_ptr, amp.row_pointers);
+ amp.deallocate();
+
+ outImage->setDotsPerMeterX(png_get_x_pixels_per_meter(png_ptr,info_ptr));
+ outImage->setDotsPerMeterY(png_get_y_pixels_per_meter(png_ptr,info_ptr));
+
+ // sanity check palette entries
+ if (color_type == PNG_COLOR_TYPE_PALETTE && outImage->format() == QImage::Format_Indexed8) {
+ int color_table_size = outImage->colorCount();
+ for (int y=0; y<(int)height; ++y) {
+ uchar *p = FAST_SCAN_LINE(data, bpl, y);
+ uchar *end = p + width;
+ while (p < end) {
+ if (*p >= color_table_size)
+ *p = 0;
+ ++p;
}
}
}
-#endif
-
- outImage->setDotsPerMeterX(png_get_x_pixels_per_meter(png_ptr,info_ptr));
- outImage->setDotsPerMeterY(png_get_y_pixels_per_meter(png_ptr,info_ptr));
+ }
state = ReadingEnd;
png_read_end(png_ptr, end_info);
@@ -533,24 +633,12 @@ bool Q_INTERNAL_WIN_NO_THROW QPngHandlerPrivate::readPngImage(QImage *outImage)
outImage->setText(readTexts.at(i), readTexts.at(i+1));
png_destroy_read_struct(&png_ptr, &info_ptr, &end_info);
- delete [] row_pointers;
png_ptr = 0;
+ amp.deallocate();
state = Ready;
- // sanity check palette entries
- if (color_type == PNG_COLOR_TYPE_PALETTE
- && outImage->format() == QImage::Format_Indexed8) {
- int color_table_size = outImage->colorCount();
- for (int y=0; y<(int)height; ++y) {
- uchar *p = FAST_SCAN_LINE(data, bpl, y);
- uchar *end = p + width;
- while (p < end) {
- if (*p >= color_table_size)
- *p = 0;
- ++p;
- }
- }
- }
+ if (scaledSize.isValid() && outImage->size() != scaledSize)
+ *outImage = outImage->scaled(scaledSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
return true;
}
@@ -959,7 +1047,8 @@ bool QPngHandler::supportsOption(ImageOption option) const
|| option == Description
|| option == ImageFormat
|| option == Quality
- || option == Size;
+ || option == Size
+ || option == ScaledSize;
}
QVariant QPngHandler::option(ImageOption option) const
@@ -978,6 +1067,8 @@ QVariant QPngHandler::option(ImageOption option) const
else if (option == Size)
return QSize(png_get_image_width(d->png_ptr, d->info_ptr),
png_get_image_height(d->png_ptr, d->info_ptr));
+ else if (option == ScaledSize)
+ return d->scaledSize;
else if (option == ImageFormat)
return d->readImageFormat();
return QVariant();
@@ -991,6 +1082,8 @@ void QPngHandler::setOption(ImageOption option, const QVariant &value)
d->quality = value.toInt();
else if (option == Description)
d->description = value.toString();
+ else if (option == ScaledSize)
+ d->scaledSize = value.toSize();
}
QByteArray QPngHandler::name() const