bool SkPNGImageDecoder::getBitmapConfig(png_structp png_ptr, png_infop info_ptr,
SkBitmap::Config *configp, bool *hasAlphap, bool *doDitherp,
SkPMColor *theTranspColorp) {
png_uint_32 origWidth, origHeight;
int bit_depth, color_type, interlace_type;
png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bit_depth,
&color_type, &interlace_type, int_p_NULL, int_p_NULL);
// check for sBIT chunk data, in case we should disable dithering because
// our data is not truely 8bits per component
if (*doDitherp) {
#if 0
SkDebugf("----- sBIT %d %d %d %d\n", info_ptr->sig_bit.red,
info_ptr->sig_bit.green, info_ptr->sig_bit.blue,
info_ptr->sig_bit.alpha);
#endif
// 0 seems to indicate no information available
if (pos_le(info_ptr->sig_bit.red, SK_R16_BITS) &&
pos_le(info_ptr->sig_bit.green, SK_G16_BITS) &&
pos_le(info_ptr->sig_bit.blue, SK_B16_BITS)) {
*doDitherp = false;
}
}
if (color_type == PNG_COLOR_TYPE_PALETTE) {
bool paletteHasAlpha = hasTransparencyInPalette(png_ptr, info_ptr);
*configp = this->getPrefConfig(kIndex_SrcDepth, paletteHasAlpha);
// now see if we can upscale to their requested config
if (!canUpscalePaletteToConfig(*configp, paletteHasAlpha)) {
*configp = SkBitmap::kIndex8_Config;
}
} else {
png_color_16p transpColor = NULL;
int numTransp = 0;
png_get_tRNS(png_ptr, info_ptr, NULL, &numTransp, &transpColor);
bool valid = png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS);
if (valid && numTransp == 1 && transpColor != NULL) {
/* Compute our transparent color, which we'll match against later.
We don't really handle 16bit components properly here, since we
do our compare *after* the values have been knocked down to 8bit
which means we will find more matches than we should. The real
fix seems to be to see the actual 16bit components, do the
compare, and then knock it down to 8bits ourselves.
*/
if (color_type & PNG_COLOR_MASK_COLOR) {
if (16 == bit_depth) {
*theTranspColorp = SkPackARGB32(0xFF, transpColor->red >> 8,
transpColor->green >> 8, transpColor->blue >> 8);
} else {
*theTranspColorp = SkPackARGB32(0xFF, transpColor->red,
transpColor->green, transpColor->blue);
}
} else { // gray
if (16 == bit_depth) {
void
down_heap(void *vroot, unsigned size)
{
struct position **root = vroot;
struct position *el;
unsigned j;
/* Handle common case: removing the only remaining heap element */
if (size == 0)
return;
el = root[size];
root[size] = root[0];
j = 0;
while (left(j) < size) {
unsigned child = left(j);
if (child + 1 < size && pos_lt(*root[child + 1], *root[child]))
child++;
if (pos_le(*el, *root[child]))
break;
root[j] = root[child];
j = child;
}
root[j] = el;
}
bool SkPNGImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* decodedBitmap,
Mode mode) {
// SkAutoTrace apr("SkPNGImageDecoder::onDecode");
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also supply the
* the compiler header file version, so that we know if the application
* was compiled with a compatible version of the library. */
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, sk_error_fn, NULL);
// png_voidp user_error_ptr, user_error_fn, user_warning_fn);
if (png_ptr == NULL) {
return false;
}
/* Allocate/initialize the memory for image information. */
png_infop info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL) {
png_destroy_read_struct(&png_ptr, NULL, NULL);
return false;
}
PNGAutoClean autoClean(png_ptr, info_ptr);
/* Set error handling if you are using the setjmp/longjmp method (this is
* the normal method of doing things with libpng). REQUIRED unless you
* set up your own error handlers in the png_create_read_struct() earlier.
*/
if (setjmp(png_jmpbuf(png_ptr))) {
return false;
}
/* If you are using replacement read functions, instead of calling
* png_init_io() here you would call:
*/
png_set_read_fn(png_ptr, (void *)sk_stream, sk_read_fn);
/* where user_io_ptr is a structure you want available to the callbacks */
/* If we have already read some of the signature */
// png_set_sig_bytes(png_ptr, 0 /* sig_read */ );
// hookup our peeker so we can see any user-chunks the caller may be interested in
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0);
if (this->getPeeker()) {
png_set_read_user_chunk_fn(png_ptr, (png_voidp)this->getPeeker(), sk_read_user_chunk);
}
/* The call to png_read_info() gives us all of the information from the
* PNG file before the first IDAT (image data chunk). */
png_read_info(png_ptr, info_ptr);
png_uint_32 origWidth, origHeight;
int bit_depth, color_type, interlace_type;
png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bit_depth, &color_type,
&interlace_type, NULL, NULL);
/* tell libpng to strip 16 bit/color files down to 8 bits/color */
if (bit_depth == 16) {
png_set_strip_16(png_ptr);
}
/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
* byte into separate bytes (useful for paletted and grayscale images). */
if (bit_depth < 8) {
png_set_packing(png_ptr);
}
/* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
png_set_expand_gray_1_2_4_to_8(png_ptr);
}
/* Make a grayscale image into RGB. */
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
png_set_gray_to_rgb(png_ptr);
}
SkBitmap::Config config;
bool hasAlpha = false;
bool doDither = this->getDitherImage();
SkPMColor theTranspColor = 0; // 0 tells us not to try to match
// check for sBIT chunk data, in case we should disable dithering because
// our data is not truely 8bits per component
if (doDither) {
png_color_8p sig_bit = NULL;
bool has_sbit = PNG_INFO_sBIT == png_get_sBIT(png_ptr, info_ptr,
&sig_bit);
#if 0
if (has_sbit) {
SkDebugf("----- sBIT %d %d %d %d\n", sig_bit->red, sig_bit->green,
sig_bit->blue, sig_bit->alpha);
}
#endif
// 0 seems to indicate no information available
if (has_sbit && pos_le(sig_bit->red, SK_R16_BITS) &&
pos_le(sig_bit->green, SK_G16_BITS) &&
pos_le(sig_bit->blue, SK_B16_BITS)) {
doDither = false;
}
}
if (color_type == PNG_COLOR_TYPE_PALETTE) {
bool paletteHasAlpha = hasTransparencyInPalette(png_ptr, info_ptr);
config = this->getPrefConfig(kIndex_SrcDepth, paletteHasAlpha);
// now see if we can upscale to their requested config
if (!canUpscalePaletteToConfig(config, paletteHasAlpha)) {
config = SkBitmap::kIndex8_Config;
}
} else {
png_color_16p transpColor = NULL;
int numTransp = 0;
png_get_tRNS(png_ptr, info_ptr, NULL, &numTransp, &transpColor);
bool valid = png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS);
if (valid && numTransp == 1 && transpColor != NULL) {
/* Compute our transparent color, which we'll match against later.
We don't really handle 16bit components properly here, since we
do our compare *after* the values have been knocked down to 8bit
which means we will find more matches than we should. The real
fix seems to be to see the actual 16bit components, do the
compare, and then knock it down to 8bits ourselves.
*/
if (color_type & PNG_COLOR_MASK_COLOR) {
if (16 == bit_depth) {
theTranspColor = SkPackARGB32(0xFF, transpColor->red >> 8,
transpColor->green >> 8, transpColor->blue >> 8);
} else {
theTranspColor = SkPackARGB32(0xFF, transpColor->red,
transpColor->green, transpColor->blue);
}
} else { // gray
if (16 == bit_depth) {
bool SkPNGImageDecoder::onDecode(SkStream* sk_stream, SkBitmap* decodedBitmap,
SkBitmap::Config prefConfig, Mode mode) {
// SkAutoTrace apr("SkPNGImageDecoder::onDecode");
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also supply the
* the compiler header file version, so that we know if the application
* was compiled with a compatible version of the library. */
png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, sk_error_fn, NULL);
// png_voidp user_error_ptr, user_error_fn, user_warning_fn);
if (png_ptr == NULL) {
return false;
}
/* Allocate/initialize the memory for image information. */
png_infop info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL) {
png_destroy_read_struct(&png_ptr, png_infopp_NULL, png_infopp_NULL);
return false;
}
PNGAutoClean autoClean(png_ptr, info_ptr);
/* Set error handling if you are using the setjmp/longjmp method (this is
* the normal method of doing things with libpng). REQUIRED unless you
* set up your own error handlers in the png_create_read_struct() earlier.
*/
if (setjmp(png_jmpbuf(png_ptr))) {
return false;
}
/* If you are using replacement read functions, instead of calling
* png_init_io() here you would call:
*/
png_set_read_fn(png_ptr, (void *)sk_stream, sk_read_fn);
/* where user_io_ptr is a structure you want available to the callbacks */
/* If we have already read some of the signature */
// png_set_sig_bytes(png_ptr, 0 /* sig_read */ );
// hookup our peeker so we can see any user-chunks the caller may be interested in
png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_ALWAYS, (png_byte*)"", 0);
if (this->getPeeker()) {
png_set_read_user_chunk_fn(png_ptr, (png_voidp)this->getPeeker(), sk_read_user_chunk);
}
/* The call to png_read_info() gives us all of the information from the
* PNG file before the first IDAT (image data chunk). */
png_read_info(png_ptr, info_ptr);
png_uint_32 origWidth, origHeight;
int bit_depth, color_type, interlace_type;
png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bit_depth, &color_type,
&interlace_type, int_p_NULL, int_p_NULL);
SkBitmap::Config config;
bool hasAlpha = false;
bool doDither = this->getDitherImage();
// check for sBIT chunk data, in case we should disable dithering because
// our data is not truely 8bits per component
if (doDither) {
#if 0
SkDebugf("----- sBIT %d %d %d %d\n", info_ptr->sig_bit.red,
info_ptr->sig_bit.green, info_ptr->sig_bit.blue,
info_ptr->sig_bit.alpha);
#endif
// 0 seems to indicate no information available
if (pos_le(info_ptr->sig_bit.red, SK_R16_BITS) &&
pos_le(info_ptr->sig_bit.green, SK_G16_BITS) &&
pos_le(info_ptr->sig_bit.blue, SK_B16_BITS)) {
doDither = false;
}
}
if (color_type == PNG_COLOR_TYPE_PALETTE) {
config = SkBitmap::kIndex8_Config; // defer sniffing for hasAlpha
} else {
png_color_16p transColor;
png_get_tRNS(png_ptr, info_ptr, NULL, NULL, &transColor);
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ||
PNG_COLOR_TYPE_RGB_ALPHA == color_type ||
PNG_COLOR_TYPE_GRAY_ALPHA == color_type) {
hasAlpha = true;
config = SkBitmap::kARGB_8888_Config;
} else { // we get to choose the config
config = prefConfig;
if (config == SkBitmap::kNo_Config) {
config = SkImageDecoder::GetDeviceConfig();
}
if (config != SkBitmap::kRGB_565_Config &&
config != SkBitmap::kARGB_4444_Config) {
config = SkBitmap::kARGB_8888_Config;
}
}
}
if (!this->chooseFromOneChoice(config, origWidth, origHeight)) {
return false;
}
const int sampleSize = this->getSampleSize();
SkScaledBitmapSampler sampler(origWidth, origHeight, sampleSize);
decodedBitmap->setConfig(config, sampler.scaledWidth(),
sampler.scaledHeight(), 0);
if (SkImageDecoder::kDecodeBounds_Mode == mode) {
return true;
}
// from here down we are concerned with colortables and pixels
/* tell libpng to strip 16 bit/color files down to 8 bits/color */
if (bit_depth == 16) {
png_set_strip_16(png_ptr);
}
/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
* byte into separate bytes (useful for paletted and grayscale images). */
if (bit_depth < 8) {
png_set_packing(png_ptr);
}
/* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
png_set_gray_1_2_4_to_8(png_ptr);
}
/* Make a grayscale image into RGB. */
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
png_set_gray_to_rgb(png_ptr);
}
// we track if we actually see a non-opaque pixels, since sometimes a PNG sets its colortype
// to |= PNG_COLOR_MASK_ALPHA, but all of its pixels are in fact opaque. We care, since we
// draw lots faster if we can flag the bitmap has being opaque
bool reallyHasAlpha = false;
SkColorTable* colorTable = NULL;
if (color_type == PNG_COLOR_TYPE_PALETTE) {
int num_palette;
png_colorp palette;
png_bytep trans;
int num_trans;
png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette);
/* BUGGY IMAGE WORKAROUND
We hit some images (e.g. fruit_.png) who contain bytes that are == colortable_count
which is a problem since we use the byte as an index. To work around this we grow
the colortable by 1 (if its < 256) and duplicate the last color into that slot.
*/
int colorCount = num_palette + (num_palette < 256);
colorTable = SkNEW_ARGS(SkColorTable, (colorCount));
SkPMColor* colorPtr = colorTable->lockColors();
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, NULL);
hasAlpha = (num_trans > 0);
} else {
num_trans = 0;
colorTable->setFlags(colorTable->getFlags() | SkColorTable::kColorsAreOpaque_Flag);
}
// check for bad images that might make us crash
if (num_trans > num_palette) {
num_trans = num_palette;
}
int index = 0;
int transLessThanFF = 0;
for (; index < num_trans; index++) {
transLessThanFF |= (int)*trans - 0xFF;
*colorPtr++ = SkPreMultiplyARGB(*trans++, palette->red, palette->green, palette->blue);
palette++;
}
reallyHasAlpha |= (transLessThanFF < 0);
for (; index < num_palette; index++) {
*colorPtr++ = SkPackARGB32(0xFF, palette->red, palette->green, palette->blue);
palette++;
}
// see BUGGY IMAGE WORKAROUND comment above
if (num_palette < 256) {
*colorPtr = colorPtr[-1];
}
colorTable->unlockColors(true);
}
SkAutoUnref aur(colorTable);
if (!this->allocPixelRef(decodedBitmap, colorTable)) {
delete colorTable;
return false;
}
SkAutoLockPixels alp(*decodedBitmap);
/* swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
// if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
// ; // png_set_swap_alpha(png_ptr);
/* swap bytes of 16 bit files to least significant byte first */
// png_set_swap(png_ptr);
/* Add filler (or alpha) byte (before/after each RGB triplet) */
if (color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_GRAY) {
png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
}
/* Turn on interlace handling. REQUIRED if you are not using
* png_read_image(). To see how to handle interlacing passes,
* see the png_read_row() method below:
*/
const int number_passes = interlace_type != PNG_INTERLACE_NONE ?
png_set_interlace_handling(png_ptr) : 1;
/* Optional call to gamma correct and add the background to the palette
* and update info structure. REQUIRED if you are expecting libpng to
* update the palette for you (ie you selected such a transform above).
*/
png_read_update_info(png_ptr, info_ptr);
if (SkBitmap::kIndex8_Config == config && 1 == sampleSize) {
for (int i = 0; i < number_passes; i++) {
for (png_uint_32 y = 0; y < origHeight; y++) {
uint8_t* bmRow = decodedBitmap->getAddr8(0, y);
png_read_rows(png_ptr, &bmRow, png_bytepp_NULL, 1);
}
}
} else {
SkScaledBitmapSampler::SrcConfig sc;
int srcBytesPerPixel = 4;
if (SkBitmap::kIndex8_Config == config) {
sc = SkScaledBitmapSampler::kIndex;
srcBytesPerPixel = 1;
} else if (hasAlpha) {
sc = SkScaledBitmapSampler::kRGBA;
} else {
sc = SkScaledBitmapSampler::kRGBX;
}
SkAutoMalloc storage(origWidth * srcBytesPerPixel);
const int height = decodedBitmap->height();
for (int i = 0; i < number_passes; i++) {
if (!sampler.begin(decodedBitmap, sc, doDither)) {
return false;
}
uint8_t* srcRow = (uint8_t*)storage.get();
skip_src_rows(png_ptr, srcRow, sampler.srcY0());
for (int y = 0; y < height; y++) {
uint8_t* tmp = srcRow;
png_read_rows(png_ptr, &tmp, png_bytepp_NULL, 1);
reallyHasAlpha |= sampler.next(srcRow);
if (y < height - 1) {
skip_src_rows(png_ptr, srcRow, sampler.srcDY() - 1);
}
}
// skip the rest of the rows (if any)
png_uint_32 read = (height - 1) * sampler.srcDY() +
sampler.srcY0() + 1;
SkASSERT(read <= origHeight);
skip_src_rows(png_ptr, srcRow, origHeight - read);
}
if (hasAlpha && !reallyHasAlpha) {
SkDEBUGF(("Image doesn't really have alpha [%d %d]\n",
origWidth, origHeight));
}
}
/* read rest of file, and get additional chunks in info_ptr - REQUIRED */
png_read_end(png_ptr, info_ptr);
decodedBitmap->setIsOpaque(!reallyHasAlpha);
return true;
}
