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gecko-dev/image/decoders/nsPNGDecoder.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "ImageLogging.h" // Must appear first
#include "gfxColor.h"
#include "gfxPlatform.h"
#include "nsColor.h"
#include "nsIInputStream.h"
#include "nsMemory.h"
#include "nsPNGDecoder.h"
#include "nsRect.h"
#include "nspr.h"
#include "png.h"
#include "RasterImage.h"
#include "mozilla/Telemetry.h"
#include <algorithm>
using namespace mozilla::gfx;
namespace mozilla {
namespace image {
static LazyLogModule sPNGLog("PNGDecoder");
static LazyLogModule sPNGDecoderAccountingLog("PNGDecoderAccounting");
// Limit image dimensions (bug #251381, #591822, and #967656)
#ifndef MOZ_PNG_MAX_DIMENSION
# define MOZ_PNG_MAX_DIMENSION 32767
#endif
nsPNGDecoder::AnimFrameInfo::AnimFrameInfo()
: mDispose(DisposalMethod::KEEP)
, mBlend(BlendMethod::OVER)
, mTimeout(0)
{ }
#ifdef PNG_APNG_SUPPORTED
int32_t GetNextFrameDelay(png_structp aPNG, png_infop aInfo)
{
// Delay, in seconds, is delayNum / delayDen.
png_uint_16 delayNum = png_get_next_frame_delay_num(aPNG, aInfo);
png_uint_16 delayDen = png_get_next_frame_delay_den(aPNG, aInfo);
if (delayNum == 0) {
return 0; // SetFrameTimeout() will set to a minimum.
}
if (delayDen == 0) {
delayDen = 100; // So says the APNG spec.
}
// Need to cast delay_num to float to have a proper division and
// the result to int to avoid a compiler warning.
return static_cast<int32_t>(static_cast<double>(delayNum) * 1000 / delayDen);
}
nsPNGDecoder::AnimFrameInfo::AnimFrameInfo(png_structp aPNG, png_infop aInfo)
: mDispose(DisposalMethod::KEEP)
, mBlend(BlendMethod::OVER)
, mTimeout(0)
{
png_byte dispose_op = png_get_next_frame_dispose_op(aPNG, aInfo);
png_byte blend_op = png_get_next_frame_blend_op(aPNG, aInfo);
if (dispose_op == PNG_DISPOSE_OP_PREVIOUS) {
mDispose = DisposalMethod::RESTORE_PREVIOUS;
} else if (dispose_op == PNG_DISPOSE_OP_BACKGROUND) {
mDispose = DisposalMethod::CLEAR;
} else {
mDispose = DisposalMethod::KEEP;
}
if (blend_op == PNG_BLEND_OP_SOURCE) {
mBlend = BlendMethod::SOURCE;
} else {
mBlend = BlendMethod::OVER;
}
mTimeout = GetNextFrameDelay(aPNG, aInfo);
}
#endif
// First 8 bytes of a PNG file
const uint8_t
nsPNGDecoder::pngSignatureBytes[] = { 137, 80, 78, 71, 13, 10, 26, 10 };
nsPNGDecoder::nsPNGDecoder(RasterImage* aImage)
: Decoder(aImage),
mPNG(nullptr), mInfo(nullptr),
mCMSLine(nullptr), interlacebuf(nullptr),
mInProfile(nullptr), mTransform(nullptr),
format(gfx::SurfaceFormat::UNKNOWN),
mHeaderBytesRead(0), mCMSMode(0),
mChannels(0), mFrameIsHidden(false),
mDisablePremultipliedAlpha(false),
mSuccessfulEarlyFinish(false),
mNumFrames(0)
{
}
nsPNGDecoder::~nsPNGDecoder()
{
if (mPNG) {
png_destroy_read_struct(&mPNG, mInfo ? &mInfo : nullptr, nullptr);
}
if (mCMSLine) {
free(mCMSLine);
}
if (interlacebuf) {
free(interlacebuf);
}
if (mInProfile) {
qcms_profile_release(mInProfile);
// mTransform belongs to us only if mInProfile is non-null
if (mTransform) {
qcms_transform_release(mTransform);
}
}
}
void
nsPNGDecoder::CheckForTransparency(SurfaceFormat aFormat,
const IntRect& aFrameRect)
{
// Check if the image has a transparent color in its palette.
if (aFormat == SurfaceFormat::B8G8R8A8) {
PostHasTransparency();
}
// PNGs shouldn't have first-frame padding.
MOZ_ASSERT_IF(mNumFrames == 0,
IntRect(IntPoint(), GetSize()).IsEqualEdges(aFrameRect));
}
// CreateFrame() is used for both simple and animated images
nsresult
nsPNGDecoder::CreateFrame(png_uint_32 aXOffset, png_uint_32 aYOffset,
int32_t aWidth, int32_t aHeight,
gfx::SurfaceFormat aFormat)
{
MOZ_ASSERT(HasSize());
MOZ_ASSERT(!IsMetadataDecode());
IntRect frameRect(aXOffset, aYOffset, aWidth, aHeight);
CheckForTransparency(aFormat, frameRect);
// XXX(seth): Some tests depend on the first frame of PNGs being B8G8R8A8.
// This is something we should fix.
gfx::SurfaceFormat format = aFormat;
if (mNumFrames == 0) {
format = gfx::SurfaceFormat::B8G8R8A8;
}
// Make sure there's no animation or padding if we're downscaling.
MOZ_ASSERT_IF(mDownscaler, !GetImageMetadata().HasAnimation());
MOZ_ASSERT_IF(mDownscaler,
IntRect(IntPoint(), GetSize()).IsEqualEdges(frameRect));
IntSize targetSize = mDownscaler ? mDownscaler->TargetSize()
: GetSize();
IntRect targetFrameRect = mDownscaler ? IntRect(IntPoint(), targetSize)
: frameRect;
nsresult rv = AllocateFrame(mNumFrames, targetSize, targetFrameRect, format);
if (NS_FAILED(rv)) {
return rv;
}
mFrameRect = frameRect;
MOZ_LOG(sPNGDecoderAccountingLog, LogLevel::Debug,
("PNGDecoderAccounting: nsPNGDecoder::CreateFrame -- created "
"image frame with %dx%d pixels for decoder %p",
aWidth, aHeight, this));
#ifdef PNG_APNG_SUPPORTED
if (png_get_valid(mPNG, mInfo, PNG_INFO_acTL)) {
mAnimInfo = AnimFrameInfo(mPNG, mInfo);
if (mAnimInfo.mDispose == DisposalMethod::CLEAR) {
// We may have to display the background under this image during
// animation playback, so we regard it as transparent.
PostHasTransparency();
}
}
#endif
if (mDownscaler) {
bool hasAlpha = aFormat != SurfaceFormat::B8G8R8X8;
rv = mDownscaler->BeginFrame(frameRect.Size(), Nothing(),
mImageData, hasAlpha);
if (NS_FAILED(rv)) {
return rv;
}
}
return NS_OK;
}
// set timeout and frame disposal method for the current frame
void
nsPNGDecoder::EndImageFrame()
{
if (mFrameIsHidden) {
return;
}
mNumFrames++;
Opacity opacity = Opacity::SOME_TRANSPARENCY;
if (format == gfx::SurfaceFormat::B8G8R8X8) {
opacity = Opacity::OPAQUE;
}
PostFrameStop(opacity, mAnimInfo.mDispose, mAnimInfo.mTimeout,
mAnimInfo.mBlend);
}
void
nsPNGDecoder::InitInternal()
{
mCMSMode = gfxPlatform::GetCMSMode();
if (GetSurfaceFlags() & SurfaceFlags::NO_COLORSPACE_CONVERSION) {
mCMSMode = eCMSMode_Off;
}
mDisablePremultipliedAlpha =
bool(GetSurfaceFlags() & SurfaceFlags::NO_PREMULTIPLY_ALPHA);
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
static png_byte color_chunks[]=
{ 99, 72, 82, 77, '\0', // cHRM
105, 67, 67, 80, '\0'}; // iCCP
static png_byte unused_chunks[]=
{ 98, 75, 71, 68, '\0', // bKGD
104, 73, 83, 84, '\0', // hIST
105, 84, 88, 116, '\0', // iTXt
111, 70, 70, 115, '\0', // oFFs
112, 67, 65, 76, '\0', // pCAL
115, 67, 65, 76, '\0', // sCAL
112, 72, 89, 115, '\0', // pHYs
115, 66, 73, 84, '\0', // sBIT
115, 80, 76, 84, '\0', // sPLT
116, 69, 88, 116, '\0', // tEXt
116, 73, 77, 69, '\0', // tIME
122, 84, 88, 116, '\0'}; // zTXt
#endif
// Initialize the container's source image header
// Always decode to 24 bit pixdepth
mPNG = png_create_read_struct(PNG_LIBPNG_VER_STRING,
nullptr, nsPNGDecoder::error_callback,
nsPNGDecoder::warning_callback);
if (!mPNG) {
PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
return;
}
mInfo = png_create_info_struct(mPNG);
if (!mInfo) {
PostDecoderError(NS_ERROR_OUT_OF_MEMORY);
png_destroy_read_struct(&mPNG, nullptr, nullptr);
return;
}
#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
// Ignore unused chunks
if (mCMSMode == eCMSMode_Off || IsMetadataDecode()) {
png_set_keep_unknown_chunks(mPNG, 1, color_chunks, 2);
}
png_set_keep_unknown_chunks(mPNG, 1, unused_chunks,
(int)sizeof(unused_chunks)/5);
#endif
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (mCMSMode != eCMSMode_Off) {
png_set_chunk_malloc_max(mPNG, 4000000L);
}
#endif
#ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
// Disallow palette-index checking, for speed; we would ignore the warning
// anyhow. This feature was added at libpng version 1.5.10 and is disabled
// in the embedded libpng but enabled by default in the system libpng. This
// call also disables it in the system libpng, for decoding speed.
// Bug #745202.
png_set_check_for_invalid_index(mPNG, 0);
#endif
#if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_sRGB_PROFILE_CHECKS) && \
PNG_sRGB_PROFILE_CHECKS >= 0
// Skip checking of sRGB ICC profiles
png_set_option(mPNG, PNG_SKIP_sRGB_CHECK_PROFILE, PNG_OPTION_ON);
#endif
// use this as libpng "progressive pointer" (retrieve in callbacks)
png_set_progressive_read_fn(mPNG, static_cast<png_voidp>(this),
nsPNGDecoder::info_callback,
nsPNGDecoder::row_callback,
nsPNGDecoder::end_callback);
}
void
nsPNGDecoder::WriteInternal(const char* aBuffer, uint32_t aCount)
{
MOZ_ASSERT(!HasError(), "Shouldn't call WriteInternal after error!");
// libpng uses setjmp/longjmp for error handling. Set it up.
if (setjmp(png_jmpbuf(mPNG))) {
// We exited early. If mSuccessfulEarlyFinish isn't true, then we
// encountered an error. We might not really know what caused it, but it
// makes more sense to blame the data.
if (!mSuccessfulEarlyFinish && !HasError()) {
PostDataError();
}
png_destroy_read_struct(&mPNG, &mInfo, nullptr);
return;
}
// Pass the data off to libpng.
png_process_data(mPNG, mInfo,
reinterpret_cast<unsigned char*>(const_cast<char*>((aBuffer))),
aCount);
}
// Sets up gamma pre-correction in libpng before our callback gets called.
// We need to do this if we don't end up with a CMS profile.
static void
PNGDoGammaCorrection(png_structp png_ptr, png_infop info_ptr)
{
double aGamma;
if (png_get_gAMA(png_ptr, info_ptr, &aGamma)) {
if ((aGamma <= 0.0) || (aGamma > 21474.83)) {
aGamma = 0.45455;
png_set_gAMA(png_ptr, info_ptr, aGamma);
}
png_set_gamma(png_ptr, 2.2, aGamma);
} else {
png_set_gamma(png_ptr, 2.2, 0.45455);
}
}
// Adapted from http://www.littlecms.com/pngchrm.c example code
static qcms_profile*
PNGGetColorProfile(png_structp png_ptr, png_infop info_ptr,
int color_type, qcms_data_type* inType, uint32_t* intent)
{
qcms_profile* profile = nullptr;
*intent = QCMS_INTENT_PERCEPTUAL; // Our default
// First try to see if iCCP chunk is present
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_iCCP)) {
png_uint_32 profileLen;
png_bytep profileData;
png_charp profileName;
int compression;
png_get_iCCP(png_ptr, info_ptr, &profileName, &compression,
&profileData, &profileLen);
profile = qcms_profile_from_memory((char*)profileData, profileLen);
if (profile) {
uint32_t profileSpace = qcms_profile_get_color_space(profile);
bool mismatch = false;
if (color_type & PNG_COLOR_MASK_COLOR) {
if (profileSpace != icSigRgbData) {
mismatch = true;
}
} else {
if (profileSpace == icSigRgbData) {
png_set_gray_to_rgb(png_ptr);
} else if (profileSpace != icSigGrayData) {
mismatch = true;
}
}
if (mismatch) {
qcms_profile_release(profile);
profile = nullptr;
} else {
*intent = qcms_profile_get_rendering_intent(profile);
}
}
}
// Check sRGB chunk
if (!profile && png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB)) {
profile = qcms_profile_sRGB();
if (profile) {
int fileIntent;
png_set_gray_to_rgb(png_ptr);
png_get_sRGB(png_ptr, info_ptr, &fileIntent);
uint32_t map[] = { QCMS_INTENT_PERCEPTUAL,
QCMS_INTENT_RELATIVE_COLORIMETRIC,
QCMS_INTENT_SATURATION,
QCMS_INTENT_ABSOLUTE_COLORIMETRIC };
*intent = map[fileIntent];
}
}
// Check gAMA/cHRM chunks
if (!profile &&
png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) &&
png_get_valid(png_ptr, info_ptr, PNG_INFO_cHRM)) {
qcms_CIE_xyYTRIPLE primaries;
qcms_CIE_xyY whitePoint;
png_get_cHRM(png_ptr, info_ptr,
&whitePoint.x, &whitePoint.y,
&primaries.red.x, &primaries.red.y,
&primaries.green.x, &primaries.green.y,
&primaries.blue.x, &primaries.blue.y);
whitePoint.Y =
primaries.red.Y = primaries.green.Y = primaries.blue.Y = 1.0;
double gammaOfFile;
png_get_gAMA(png_ptr, info_ptr, &gammaOfFile);
profile = qcms_profile_create_rgb_with_gamma(whitePoint, primaries,
1.0/gammaOfFile);
if (profile) {
png_set_gray_to_rgb(png_ptr);
}
}
if (profile) {
uint32_t profileSpace = qcms_profile_get_color_space(profile);
if (profileSpace == icSigGrayData) {
if (color_type & PNG_COLOR_MASK_ALPHA) {
*inType = QCMS_DATA_GRAYA_8;
} else {
*inType = QCMS_DATA_GRAY_8;
}
} else {
if (color_type & PNG_COLOR_MASK_ALPHA ||
png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
*inType = QCMS_DATA_RGBA_8;
} else {
*inType = QCMS_DATA_RGB_8;
}
}
}
return profile;
}
void
nsPNGDecoder::info_callback(png_structp png_ptr, png_infop info_ptr)
{
// int number_passes; NOT USED
png_uint_32 width, height;
int bit_depth, color_type, interlace_type, compression_type, filter_type;
unsigned int channels;
png_bytep trans = nullptr;
int num_trans = 0;
nsPNGDecoder* decoder =
static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));
// Always decode to 24-bit RGB or 32-bit RGBA
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
&interlace_type, &compression_type, &filter_type);
// Are we too big?
if (width > MOZ_PNG_MAX_DIMENSION || height > MOZ_PNG_MAX_DIMENSION) {
png_longjmp(decoder->mPNG, 1);
}
// Post our size to the superclass
decoder->PostSize(width, height);
if (decoder->HasError()) {
// Setting the size led to an error.
png_longjmp(decoder->mPNG, 1);
}
if (color_type == PNG_COLOR_TYPE_PALETTE) {
png_set_expand(png_ptr);
}
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
png_set_expand(png_ptr);
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
png_color_16p trans_values;
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &trans_values);
// libpng doesn't reject a tRNS chunk with out-of-range samples
// so we check it here to avoid setting up a useless opacity
// channel or producing unexpected transparent pixels (bug #428045)
if (bit_depth < 16) {
png_uint_16 sample_max = (1 << bit_depth) - 1;
if ((color_type == PNG_COLOR_TYPE_GRAY &&
trans_values->gray > sample_max) ||
(color_type == PNG_COLOR_TYPE_RGB &&
(trans_values->red > sample_max ||
trans_values->green > sample_max ||
trans_values->blue > sample_max))) {
// clear the tRNS valid flag and release tRNS memory
png_free_data(png_ptr, info_ptr, PNG_FREE_TRNS, 0);
num_trans = 0;
}
}
if (num_trans != 0) {
png_set_expand(png_ptr);
}
}
if (bit_depth == 16) {
png_set_scale_16(png_ptr);
}
qcms_data_type inType = QCMS_DATA_RGBA_8;
uint32_t intent = -1;
uint32_t pIntent;
if (decoder->mCMSMode != eCMSMode_Off) {
intent = gfxPlatform::GetRenderingIntent();
decoder->mInProfile = PNGGetColorProfile(png_ptr, info_ptr,
color_type, &inType, &pIntent);
// If we're not mandating an intent, use the one from the image.
if (intent == uint32_t(-1)) {
intent = pIntent;
}
}
if (decoder->mInProfile && gfxPlatform::GetCMSOutputProfile()) {
qcms_data_type outType;
if (color_type & PNG_COLOR_MASK_ALPHA || num_trans) {
outType = QCMS_DATA_RGBA_8;
} else {
outType = QCMS_DATA_RGB_8;
}
decoder->mTransform = qcms_transform_create(decoder->mInProfile,
inType,
gfxPlatform::GetCMSOutputProfile(),
outType,
(qcms_intent)intent);
} else {
png_set_gray_to_rgb(png_ptr);
// only do gamma correction if CMS isn't entirely disabled
if (decoder->mCMSMode != eCMSMode_Off) {
PNGDoGammaCorrection(png_ptr, info_ptr);
}
if (decoder->mCMSMode == eCMSMode_All) {
if (color_type & PNG_COLOR_MASK_ALPHA || num_trans) {
decoder->mTransform = gfxPlatform::GetCMSRGBATransform();
} else {
decoder->mTransform = gfxPlatform::GetCMSRGBTransform();
}
}
}
// let libpng expand interlaced images
if (interlace_type == PNG_INTERLACE_ADAM7) {
// number_passes =
png_set_interlace_handling(png_ptr);
}
// now all of those things we set above are used to update various struct
// members and whatnot, after which we can get channels, rowbytes, etc.
png_read_update_info(png_ptr, info_ptr);
decoder->mChannels = channels = png_get_channels(png_ptr, info_ptr);
//---------------------------------------------------------------//
// copy PNG info into imagelib structs (formerly png_set_dims()) //
//---------------------------------------------------------------//
if (channels == 1 || channels == 3) {
decoder->format = gfx::SurfaceFormat::B8G8R8X8;
} else if (channels == 2 || channels == 4) {
decoder->format = gfx::SurfaceFormat::B8G8R8A8;
} else {
png_longjmp(decoder->mPNG, 1); // invalid number of channels
}
#ifdef PNG_APNG_SUPPORTED
bool isAnimated = png_get_valid(png_ptr, info_ptr, PNG_INFO_acTL);
if (isAnimated) {
decoder->PostIsAnimated(GetNextFrameDelay(png_ptr, info_ptr));
if (decoder->mDownscaler && !decoder->IsFirstFrameDecode()) {
MOZ_ASSERT_UNREACHABLE("Doing downscale-during-decode "
"for an animated image?");
decoder->mDownscaler.reset();
}
}
#endif
if (decoder->IsMetadataDecode()) {
decoder->CheckForTransparency(decoder->format,
IntRect(0, 0, width, height));
// We have the metadata we're looking for, so we don't need to decode any
// further.
decoder->mSuccessfulEarlyFinish = true;
png_longjmp(decoder->mPNG, 1);
}
#ifdef PNG_APNG_SUPPORTED
if (isAnimated) {
png_set_progressive_frame_fn(png_ptr, nsPNGDecoder::frame_info_callback,
nullptr);
}
if (png_get_first_frame_is_hidden(png_ptr, info_ptr)) {
decoder->mFrameIsHidden = true;
} else {
#endif
nsresult rv = decoder->CreateFrame(0, 0, width, height, decoder->format);
if (NS_FAILED(rv)) {
png_longjmp(decoder->mPNG, 5); // NS_ERROR_OUT_OF_MEMORY
}
MOZ_ASSERT(decoder->mImageData, "Should have a buffer now");
#ifdef PNG_APNG_SUPPORTED
}
#endif
if (decoder->mTransform &&
(channels <= 2 || interlace_type == PNG_INTERLACE_ADAM7)) {
uint32_t bpp[] = { 0, 3, 4, 3, 4 };
decoder->mCMSLine =
(uint8_t*)malloc(bpp[channels] * width);
if (!decoder->mCMSLine) {
png_longjmp(decoder->mPNG, 5); // NS_ERROR_OUT_OF_MEMORY
}
}
if (interlace_type == PNG_INTERLACE_ADAM7) {
if (height < INT32_MAX / (width * channels)) {
decoder->interlacebuf = (uint8_t*)malloc(channels * width * height);
}
if (!decoder->interlacebuf) {
png_longjmp(decoder->mPNG, 5); // NS_ERROR_OUT_OF_MEMORY
}
}
}
void
nsPNGDecoder::PostPartialInvalidation(const IntRect& aInvalidRegion)
{
if (!mDownscaler) {
PostInvalidation(aInvalidRegion);
return;
}
if (!mDownscaler->HasInvalidation()) {
return;
}
DownscalerInvalidRect invalidRect = mDownscaler->TakeInvalidRect();
PostInvalidation(invalidRect.mOriginalSizeRect,
Some(invalidRect.mTargetSizeRect));
}
void
nsPNGDecoder::PostFullInvalidation()
{
PostInvalidation(mFrameRect);
if (mDownscaler) {
mDownscaler->ResetForNextProgressivePass();
}
}
static void
InterpolateInterlacedPNG(const int aPass, const bool aHasAlpha,
const uint32_t aWidth, const uint32_t aHeight,
uint8_t* aImageData)
{
// At this point we have a completed pass of an interlaced image in
// imageData as an array of uint8_t ARGB or XRGB pixels, optionally
// premultiplied, 4 bytes per pixel. If there are leftover partial
// blocks at the right edge or bottom of the image, we just use the
// uninterpolated pixels that libpng gave us.
//
// See Bug #75077, Interpolation of interlaced PNG
// See https://en.wikipedia.org/wiki/Bilinear_interpolation
//
// Note: this doesn't work when downscaling so we simply show
// the uninterpolated blocks that libpng gives us.
//
// Don't try to interpolate images that are less than 8 columns wide
// or 8 rows high; do only square passes (0, 2, 4)
if ((aPass != 0 && aPass != 2 && aPass != 4) || aWidth < 8 || aHeight < 8) {
return;
}
/* Block dimensions are defined by the PNG specification */
uint32_t block_width[] = { 8, 4, 4, 2, 2 };
uint32_t bw = block_width[aPass];
uint32_t bh = bw;
bool first_component = aHasAlpha ? 0: 1;
// Reduced version of the PNG_PASS_ROW_SHIFT(pass) macro in libpng/png.h
// Only works with square passes 0, 2, and 4
uint32_t divisor_shift = 3 - (aPass >> 1);
// Loop over blocks
for (uint32_t y = 0; y < aHeight - bh; y += bh) {
for (uint32_t x = 0; x < aWidth - bw; x += bw) {
// (x,y) is the top left corner of the block
// topleft is the first component of the top left pixel of the block
uint8_t* topleft = aImageData + 4 * (x + aWidth * y);
// Loop over component=[A,]R,G,B
for (uint32_t component = first_component; component < 4; component++) {
if (x == 0) {
// Interpolate ARGB along the left side of the block
uint32_t top = *(topleft + component);
uint32_t bottom = *(topleft + component + (bh * 4 * aWidth));
for (uint32_t j = 1; j < bh; j++) {
*(topleft + component + j * 4 * aWidth) =
((top * (bh - j) + bottom * j) >> divisor_shift) & 0xff;
}
}
// Interpolate ARGB along the right side of the block
uint32_t top = *(topleft + component + 4 * bw);
uint32_t bottom = *(topleft + component + 4 * (bw + (bh * aWidth)));
for (uint32_t j = 1; j < bh; j++) {
*(topleft + component + 4 * (bw + j * aWidth)) =
((top * (bh - j) + bottom * j) >> divisor_shift) & 0xff;
}
// Interpolate ARGB in the X-direction along the top edge
// and within the block
for (uint32_t j = 0; j < bh; j++) {
uint32_t left = *(topleft + component + 4 * j * aWidth);
uint32_t right = *(topleft + component + 4 * (bw + j * aWidth));
for (uint32_t i = 1; i < bw; i++) {
*(topleft + component + 4 * (i + j * aWidth)) =
((left * (bw - i) + right * i) >> divisor_shift) & 0xff;
} // i
} // j
} // component
} // x
} // y
}
void
nsPNGDecoder::row_callback(png_structp png_ptr, png_bytep new_row,
png_uint_32 row_num, int pass)
{
/* libpng comments:
*
* This function is called for every row in the image. If the
* image is interlacing, and you turned on the interlace handler,
* this function will be called for every row in every pass.
* Some of these rows will not be changed from the previous pass.
* When the row is not changed, the new_row variable will be
* nullptr. The rows and passes are called in order, so you don't
* really need the row_num and pass, but I'm supplying them
* because it may make your life easier.
*
* For the non-nullptr rows of interlaced images, you must call
* png_progressive_combine_row() passing in the row and the
* old row. You can call this function for nullptr rows (it will
* just return) and for non-interlaced images (it just does the
* memcpy for you) if it will make the code easier. Thus, you
* can just do this for all cases:
*
* png_progressive_combine_row(png_ptr, old_row, new_row);
*
* where old_row is what was displayed for previous rows. Note
* that the first pass (pass == 0 really) will completely cover
* the old row, so the rows do not have to be initialized. After
* the first pass (and only for interlaced images), you will have
* to pass the current row, and the function will combine the
* old row and the new row.
*/
nsPNGDecoder* decoder =
static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));
// skip this frame
if (decoder->mFrameIsHidden) {
return;
}
if (row_num >= static_cast<png_uint_32>(decoder->mFrameRect.height)) {
return;
}
bool lastRow =
row_num == static_cast<png_uint_32>(decoder->mFrameRect.height) - 1;
if (!new_row && !decoder->mDownscaler && !lastRow) {
// If |new_row| is null, that indicates that this is an interlaced image
// and |row_callback| is being called for a row that hasn't changed.
// Ordinarily we don't need to do anything in this case, but if we're
// downscaling, the downscaler doesn't store the rows from previous passes,
// so we still need to process the row. If |lastRow| is true we need
// to finish the interlace pass.
return;
}
int32_t width = decoder->mFrameRect.width;
uint32_t iwidth = decoder->mFrameRect.width;
png_bytep line = new_row;
if (decoder->interlacebuf) {
line = decoder->interlacebuf + (row_num * decoder->mChannels * width);
png_progressive_combine_row(png_ptr, line, new_row);
}
uint32_t bpr = width * sizeof(uint32_t);
uint32_t* cptr32 = decoder->mDownscaler
? reinterpret_cast<uint32_t*>(decoder->mDownscaler->RowBuffer())
: reinterpret_cast<uint32_t*>(decoder->mImageData + (row_num*bpr));
if (decoder->mTransform) {
if (decoder->mCMSLine) {
qcms_transform_data(decoder->mTransform, line, decoder->mCMSLine,
iwidth);
// copy alpha over
uint32_t channels = decoder->mChannels;
if (channels == 2 || channels == 4) {
for (uint32_t i = 0; i < iwidth; i++)
decoder->mCMSLine[4 * i + 3] = line[channels * i + channels - 1];
}
line = decoder->mCMSLine;
} else {
qcms_transform_data(decoder->mTransform, line, line, iwidth);
}
}
switch (decoder->format) {
case gfx::SurfaceFormat::B8G8R8X8: {
// counter for while() loops below
uint32_t idx = iwidth;
// copy as bytes until source pointer is 32-bit-aligned
for (; (NS_PTR_TO_UINT32(line) & 0x3) && idx; --idx) {
*cptr32++ = gfxPackedPixel(0xFF, line[0], line[1], line[2]);
line += 3;
}
// copy pixels in blocks of 4
while (idx >= 4) {
GFX_BLOCK_RGB_TO_FRGB(line, cptr32);
idx -= 4;
line += 12;
cptr32 += 4;
}
// copy remaining pixel(s)
while (idx--) {
// 32-bit read of final pixel will exceed buffer, so read bytes
*cptr32++ = gfxPackedPixel(0xFF, line[0], line[1], line[2]);
line += 3;
}
}
break;
case gfx::SurfaceFormat::B8G8R8A8: {
if (!decoder->mDisablePremultipliedAlpha) {
for (uint32_t x=width; x>0; --x) {
*cptr32++ = gfxPackedPixel(line[3], line[0], line[1], line[2]);
line += 4;
}
} else {
for (uint32_t x=width; x>0; --x) {
*cptr32++ = gfxPackedPixelNoPreMultiply(line[3], line[0], line[1],
line[2]);
line += 4;
}
}
}
break;
default:
png_longjmp(decoder->mPNG, 1);
}
if (decoder->mDownscaler) {
decoder->mDownscaler->CommitRow();
}
if (!decoder->interlacebuf) {
// Do line-by-line partial invalidations for non-interlaced images.
decoder->PostPartialInvalidation(IntRect(0, row_num, width, 1));
} else if (lastRow) {
// Do only one full image invalidation for each even pass. (Bug 1187569)
if (decoder->mDownscaler) {
decoder->PostFullInvalidation();
} else if (pass % 2 == 0) {
const bool hasAlpha = decoder->format != SurfaceFormat::B8G8R8X8;
InterpolateInterlacedPNG(pass, hasAlpha,
static_cast<uint32_t>(width),
decoder->mFrameRect.height,
decoder->mImageData);
decoder->PostFullInvalidation();
}
}
}
#ifdef PNG_APNG_SUPPORTED
// got the header of a new frame that's coming
void
nsPNGDecoder::frame_info_callback(png_structp png_ptr, png_uint_32 frame_num)
{
png_uint_32 x_offset, y_offset;
int32_t width, height;
nsPNGDecoder* decoder =
static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));
// old frame is done
decoder->EndImageFrame();
if (!decoder->mFrameIsHidden && decoder->IsFirstFrameDecode()) {
// We're about to get a second non-hidden frame, but we only want the first.
// Stop decoding now.
decoder->PostDecodeDone();
decoder->mSuccessfulEarlyFinish = true;
png_longjmp(decoder->mPNG, 1);
}
// Only the first frame can be hidden, so unhide unconditionally here.
decoder->mFrameIsHidden = false;
x_offset = png_get_next_frame_x_offset(png_ptr, decoder->mInfo);
y_offset = png_get_next_frame_y_offset(png_ptr, decoder->mInfo);
width = png_get_next_frame_width(png_ptr, decoder->mInfo);
height = png_get_next_frame_height(png_ptr, decoder->mInfo);
nsresult rv =
decoder->CreateFrame(x_offset, y_offset, width, height, decoder->format);
if (NS_FAILED(rv)) {
png_longjmp(decoder->mPNG, 5); // NS_ERROR_OUT_OF_MEMORY
}
MOZ_ASSERT(decoder->mImageData, "Should have a buffer now");
}
#endif
void
nsPNGDecoder::end_callback(png_structp png_ptr, png_infop info_ptr)
{
/* libpng comments:
*
* this function is called when the whole image has been read,
* including any chunks after the image (up to and including
* the IEND). You will usually have the same info chunk as you
* had in the header, although some data may have been added
* to the comments and time fields.
*
* Most people won't do much here, perhaps setting a flag that
* marks the image as finished.
*/
nsPNGDecoder* decoder =
static_cast<nsPNGDecoder*>(png_get_progressive_ptr(png_ptr));
// We shouldn't get here if we've hit an error
MOZ_ASSERT(!decoder->HasError(), "Finishing up PNG but hit error!");
int32_t loop_count = 0;
#ifdef PNG_APNG_SUPPORTED
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_acTL)) {
int32_t num_plays = png_get_num_plays(png_ptr, info_ptr);
loop_count = num_plays - 1;
}
#endif
// Send final notifications
decoder->EndImageFrame();
decoder->PostDecodeDone(loop_count);
}
void
nsPNGDecoder::error_callback(png_structp png_ptr, png_const_charp error_msg)
{
MOZ_LOG(sPNGLog, LogLevel::Error, ("libpng error: %s\n", error_msg));
png_longjmp(png_ptr, 1);
}
void
nsPNGDecoder::warning_callback(png_structp png_ptr, png_const_charp warning_msg)
{
MOZ_LOG(sPNGLog, LogLevel::Warning, ("libpng warning: %s\n", warning_msg));
}
Telemetry::ID
nsPNGDecoder::SpeedHistogram()
{
return Telemetry::IMAGE_DECODE_SPEED_PNG;
}
} // namespace image
} // namespace mozilla
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