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ladybird/Userland/Libraries/LibGfx/ImageFormats/PNGLoader.cpp

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <AK/Endian.h>
#include <AK/Vector.h>
#include <LibCompress/Zlib.h>
#include <LibGfx/ImageFormats/PNGLoader.h>
#include <LibGfx/ImageFormats/PNGShared.h>
#include <LibGfx/Painter.h>
namespace Gfx {
struct PNG_IHDR {
NetworkOrdered<u32> width;
NetworkOrdered<u32> height;
u8 bit_depth { 0 };
PNG::ColorType color_type { 0 };
u8 compression_method { 0 };
u8 filter_method { 0 };
u8 interlace_method { 0 };
};
static_assert(AssertSize<PNG_IHDR, 13>());
struct acTL_Chunk {
NetworkOrdered<u32> num_frames;
NetworkOrdered<u32> num_plays;
};
static_assert(AssertSize<acTL_Chunk, 8>());
struct fcTL_Chunk {
enum class DisposeOp : u8 {
APNG_DISPOSE_OP_NONE = 0,
APNG_DISPOSE_OP_BACKGROUND,
APNG_DISPOSE_OP_PREVIOUS
};
enum class BlendOp : u8 {
APNG_BLEND_OP_SOURCE = 0,
APNG_BLEND_OP_OVER
};
NetworkOrdered<u32> sequence_number;
NetworkOrdered<u32> width;
NetworkOrdered<u32> height;
NetworkOrdered<u32> x_offset;
NetworkOrdered<u32> y_offset;
NetworkOrdered<u16> delay_num;
NetworkOrdered<u16> delay_den;
DisposeOp dispose_op { DisposeOp::APNG_DISPOSE_OP_NONE };
BlendOp blend_op { BlendOp::APNG_BLEND_OP_SOURCE };
};
static_assert(AssertSize<fcTL_Chunk, 26>());
struct ChromaticitiesAndWhitepoint {
NetworkOrdered<u32> white_point_x;
NetworkOrdered<u32> white_point_y;
NetworkOrdered<u32> red_x;
NetworkOrdered<u32> red_y;
NetworkOrdered<u32> green_x;
NetworkOrdered<u32> green_y;
NetworkOrdered<u32> blue_x;
NetworkOrdered<u32> blue_y;
};
static_assert(AssertSize<ChromaticitiesAndWhitepoint, 32>());
struct CodingIndependentCodePoints {
u8 color_primaries;
u8 transfer_function;
u8 matrix_coefficients;
u8 video_full_range_flag;
};
static_assert(AssertSize<CodingIndependentCodePoints, 4>());
struct EmbeddedICCProfile {
StringView profile_name;
ReadonlyBytes compressed_data;
};
struct Scanline {
PNG::FilterType filter;
ReadonlyBytes data {};
};
struct [[gnu::packed]] PaletteEntry {
u8 r;
u8 g;
u8 b;
// u8 a;
};
template<typename T>
struct [[gnu::packed]] Tuple {
T gray;
T a;
};
template<typename T>
struct [[gnu::packed]] Triplet {
T r;
T g;
T b;
bool operator==(Triplet const& other) const = default;
};
template<typename T>
struct [[gnu::packed]] Quartet {
T r;
T g;
T b;
T a;
};
enum PngInterlaceMethod {
Null = 0,
Adam7 = 1
};
enum RenderingIntent {
Perceptual = 0,
RelativeColorimetric = 1,
Saturation = 2,
AbsoluteColorimetric = 3,
};
struct AnimationFrame {
fcTL_Chunk const& fcTL;
RefPtr<Bitmap> bitmap;
ByteBuffer compressed_data;
AnimationFrame(fcTL_Chunk const& fcTL)
: fcTL(fcTL)
{
}
u32 duration_ms() const
{
u32 num = fcTL.delay_num;
if (num == 0)
return 1;
u32 denom = fcTL.delay_den != 0 ? static_cast<u32>(fcTL.delay_den) : 100u;
return (num * 1000) / denom;
}
IntRect rect() const
{
return { fcTL.x_offset, fcTL.y_offset, fcTL.width, fcTL.height };
}
};
struct PNGLoadingContext {
enum State {
NotDecoded = 0,
Error,
HeaderDecoded,
IHDRDecoded,
ImageDataChunkDecoded,
ChunksDecoded,
BitmapDecoded,
};
State state { State::NotDecoded };
u8 const* data { nullptr };
u8 const* data_current_ptr { nullptr };
size_t data_size { 0 };
int width { -1 };
int height { -1 };
u8 bit_depth { 0 };
PNG::ColorType color_type { 0 };
u8 compression_method { 0 };
u8 filter_method { 0 };
u8 interlace_method { 0 };
u8 channels { 0 };
u32 animation_next_expected_seq { 0 };
u32 animation_next_frame_to_render { 0 };
u32 animation_frame_count { 0 };
u32 animation_loop_count { 0 };
Optional<u32> last_completed_animation_frame_index;
bool is_first_idat_part_of_animation { false };
bool has_seen_iend { false };
bool has_seen_idat_chunk { false };
bool has_seen_actl_chunk_before_idat { false };
bool has_alpha() const { return to_underlying(color_type) & 4 || palette_transparency_data.size() > 0; }
Vector<Scanline> scanlines;
ByteBuffer unfiltered_data;
RefPtr<Gfx::Bitmap> bitmap;
ByteBuffer compressed_data;
Vector<PaletteEntry> palette_data;
ByteBuffer palette_transparency_data;
Vector<AnimationFrame> animation_frames;
Optional<ChromaticitiesAndWhitepoint> chromaticities_and_whitepoint;
Optional<CodingIndependentCodePoints> coding_independent_code_points;
Optional<u32> gamma;
Optional<EmbeddedICCProfile> embedded_icc_profile;
Optional<ByteBuffer> decompressed_icc_profile;
Optional<RenderingIntent> sRGB_rendering_intent;
Checked<int> compute_row_size_for_width(int width)
{
Checked<int> row_size = width;
row_size *= channels;
row_size *= bit_depth;
row_size += 7;
row_size /= 8;
if (row_size.has_overflow()) {
dbgln("PNG too large, integer overflow while computing row size");
state = State::Error;
}
return row_size;
}
PNGLoadingContext create_subimage_context(int width, int height)
{
PNGLoadingContext subimage_context;
subimage_context.state = State::ChunksDecoded;
subimage_context.width = width;
subimage_context.height = height;
subimage_context.channels = channels;
subimage_context.color_type = color_type;
subimage_context.palette_data = palette_data;
subimage_context.palette_transparency_data = palette_transparency_data;
subimage_context.bit_depth = bit_depth;
subimage_context.filter_method = filter_method;
return subimage_context;
}
};
class Streamer {
public:
Streamer(u8 const* data, size_t size)
: m_data_ptr(data)
, m_size_remaining(size)
{
}
template<typename T>
bool read(T& value)
{
if (m_size_remaining < sizeof(T))
return false;
value = *((NetworkOrdered<T> const*)m_data_ptr);
m_data_ptr += sizeof(T);
m_size_remaining -= sizeof(T);
return true;
}
bool read_bytes(u8* buffer, size_t count)
{
if (m_size_remaining < count)
return false;
memcpy(buffer, m_data_ptr, count);
m_data_ptr += count;
m_size_remaining -= count;
return true;
}
bool wrap_bytes(ReadonlyBytes& buffer, size_t count)
{
if (m_size_remaining < count)
return false;
buffer = ReadonlyBytes { m_data_ptr, count };
m_data_ptr += count;
m_size_remaining -= count;
return true;
}
u8 const* current_data_ptr() const { return m_data_ptr; }
bool at_end() const { return !m_size_remaining; }
private:
u8 const* m_data_ptr { nullptr };
size_t m_size_remaining { 0 };
};
static ErrorOr<void> process_chunk(Streamer&, PNGLoadingContext& context);
union [[gnu::packed]] Pixel {
ARGB32 rgba { 0 };
u8 v[4];
struct {
u8 r;
u8 g;
u8 b;
u8 a;
};
};
static_assert(AssertSize<Pixel, 4>());
static void unfilter_scanline(PNG::FilterType filter, Bytes scanline_data, ReadonlyBytes previous_scanlines_data, u8 bytes_per_complete_pixel)
{
VERIFY(filter != PNG::FilterType::None);
switch (filter) {
case PNG::FilterType::Sub:
// This loop starts at bytes_per_complete_pixel because all bytes before that are
// guaranteed to have no valid byte at index (i - bytes_per_complete pixel).
// All such invalid byte indexes should be treated as 0, and adding 0 to the current
// byte would do nothing, so the first bytes_per_complete_pixel bytes can instead
// just be skipped.
for (size_t i = bytes_per_complete_pixel; i < scanline_data.size(); ++i) {
u8 left = scanline_data[i - bytes_per_complete_pixel];
scanline_data[i] += left;
}
break;
case PNG::FilterType::Up:
for (size_t i = 0; i < scanline_data.size(); ++i) {
u8 above = previous_scanlines_data[i];
scanline_data[i] += above;
}
break;
case PNG::FilterType::Average:
for (size_t i = 0; i < scanline_data.size(); ++i) {
u32 left = (i < bytes_per_complete_pixel) ? 0 : scanline_data[i - bytes_per_complete_pixel];
u32 above = previous_scanlines_data[i];
u8 average = (left + above) / 2;
scanline_data[i] += average;
}
break;
case PNG::FilterType::Paeth:
for (size_t i = 0; i < scanline_data.size(); ++i) {
u8 left = (i < bytes_per_complete_pixel) ? 0 : scanline_data[i - bytes_per_complete_pixel];
u8 above = previous_scanlines_data[i];
u8 upper_left = (i < bytes_per_complete_pixel) ? 0 : previous_scanlines_data[i - bytes_per_complete_pixel];
i32 predictor = left + above - upper_left;
u32 predictor_left = abs(predictor - left);
u32 predictor_above = abs(predictor - above);
u32 predictor_upper_left = abs(predictor - upper_left);
u8 nearest;
if (predictor_left <= predictor_above && predictor_left <= predictor_upper_left) {
nearest = left;
} else if (predictor_above <= predictor_upper_left) {
nearest = above;
} else {
nearest = upper_left;
}
scanline_data[i] += nearest;
}
break;
default:
VERIFY_NOT_REACHED();
}
}
template<typename T>
ALWAYS_INLINE static void unpack_grayscale_without_alpha(PNGLoadingContext& context)
{
for (int y = 0; y < context.height; ++y) {
auto* gray_values = reinterpret_cast<T const*>(context.scanlines[y].data.data());
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = gray_values[i];
pixel.g = gray_values[i];
pixel.b = gray_values[i];
pixel.a = 0xff;
}
}
}
template<typename T>
ALWAYS_INLINE static void unpack_grayscale_with_alpha(PNGLoadingContext& context)
{
for (int y = 0; y < context.height; ++y) {
auto* tuples = reinterpret_cast<Tuple<T> const*>(context.scanlines[y].data.data());
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = tuples[i].gray;
pixel.g = tuples[i].gray;
pixel.b = tuples[i].gray;
pixel.a = tuples[i].a;
}
}
}
template<typename T>
ALWAYS_INLINE static void unpack_triplets_without_alpha(PNGLoadingContext& context)
{
for (int y = 0; y < context.height; ++y) {
auto* triplets = reinterpret_cast<Triplet<T> const*>(context.scanlines[y].data.data());
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = triplets[i].r;
pixel.g = triplets[i].g;
pixel.b = triplets[i].b;
pixel.a = 0xff;
}
}
}
template<typename T>
ALWAYS_INLINE static void unpack_triplets_with_transparency_value(PNGLoadingContext& context, Triplet<T> transparency_value)
{
for (int y = 0; y < context.height; ++y) {
auto* triplets = reinterpret_cast<Triplet<T> const*>(context.scanlines[y].data.data());
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = triplets[i].r;
pixel.g = triplets[i].g;
pixel.b = triplets[i].b;
if (triplets[i] == transparency_value)
pixel.a = 0x00;
else
pixel.a = 0xff;
}
}
}
NEVER_INLINE FLATTEN static ErrorOr<void> unfilter(PNGLoadingContext& context)
{
// First unfilter the scanlines:
// FIXME: Instead of creating a separate buffer for the scanlines that need to be
// mutated, the mutation could be done in place (if the data was non-const).
size_t bytes_per_scanline = context.scanlines[0].data.size();
size_t bytes_needed_for_all_unfiltered_scanlines = 0;
for (int y = 0; y < context.height; ++y) {
if (context.scanlines[y].filter != PNG::FilterType::None) {
bytes_needed_for_all_unfiltered_scanlines += bytes_per_scanline;
}
}
context.unfiltered_data = TRY(ByteBuffer::create_uninitialized(bytes_needed_for_all_unfiltered_scanlines));
// From section 6.3 of http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
// "bpp is defined as the number of bytes per complete pixel, rounding up to one.
// For example, for color type 2 with a bit depth of 16, bpp is equal to 6
// (three samples, two bytes per sample); for color type 0 with a bit depth of 2,
// bpp is equal to 1 (rounding up); for color type 4 with a bit depth of 16, bpp
// is equal to 4 (two-byte grayscale sample, plus two-byte alpha sample)."
u8 bytes_per_complete_pixel = (context.bit_depth + 7) / 8 * context.channels;
u8 dummy_scanline_bytes[bytes_per_scanline];
memset(dummy_scanline_bytes, 0, sizeof(dummy_scanline_bytes));
auto previous_scanlines_data = ReadonlyBytes { dummy_scanline_bytes, sizeof(dummy_scanline_bytes) };
for (int y = 0, data_start = 0; y < context.height; ++y) {
if (context.scanlines[y].filter != PNG::FilterType::None) {
auto scanline_data_slice = context.unfiltered_data.bytes().slice(data_start, bytes_per_scanline);
// Copy the current values over and set the scanline's data to the to-be-mutated slice
context.scanlines[y].data.copy_to(scanline_data_slice);
context.scanlines[y].data = scanline_data_slice;
unfilter_scanline(context.scanlines[y].filter, scanline_data_slice, previous_scanlines_data, bytes_per_complete_pixel);
data_start += bytes_per_scanline;
}
previous_scanlines_data = context.scanlines[y].data;
}
// Now unpack the scanlines to RGBA:
switch (context.color_type) {
case PNG::ColorType::Greyscale:
if (context.bit_depth == 8) {
unpack_grayscale_without_alpha<u8>(context);
} else if (context.bit_depth == 16) {
unpack_grayscale_without_alpha<u16>(context);
} else if (context.bit_depth == 1 || context.bit_depth == 2 || context.bit_depth == 4) {
auto bit_depth_squared = context.bit_depth * context.bit_depth;
auto pixels_per_byte = 8 / context.bit_depth;
auto mask = (1 << context.bit_depth) - 1;
for (int y = 0; y < context.height; ++y) {
auto* gray_values = context.scanlines[y].data.data();
for (int x = 0; x < context.width; ++x) {
auto bit_offset = (8 - context.bit_depth) - (context.bit_depth * (x % pixels_per_byte));
auto value = (gray_values[x / pixels_per_byte] >> bit_offset) & mask;
auto& pixel = (Pixel&)context.bitmap->scanline(y)[x];
pixel.r = value * (0xff / bit_depth_squared);
pixel.g = value * (0xff / bit_depth_squared);
pixel.b = value * (0xff / bit_depth_squared);
pixel.a = 0xff;
}
}
} else {
VERIFY_NOT_REACHED();
}
break;
case PNG::ColorType::GreyscaleWithAlpha:
if (context.bit_depth == 8) {
unpack_grayscale_with_alpha<u8>(context);
} else if (context.bit_depth == 16) {
unpack_grayscale_with_alpha<u16>(context);
} else {
VERIFY_NOT_REACHED();
}
break;
case PNG::ColorType::Truecolor:
if (context.palette_transparency_data.size() == 6) {
if (context.bit_depth == 8) {
unpack_triplets_with_transparency_value<u8>(context, Triplet<u8> { context.palette_transparency_data[0], context.palette_transparency_data[2], context.palette_transparency_data[4] });
} else if (context.bit_depth == 16) {
u16 tr = context.palette_transparency_data[0] | context.palette_transparency_data[1] << 8;
u16 tg = context.palette_transparency_data[2] | context.palette_transparency_data[3] << 8;
u16 tb = context.palette_transparency_data[4] | context.palette_transparency_data[5] << 8;
unpack_triplets_with_transparency_value<u16>(context, Triplet<u16> { tr, tg, tb });
} else {
VERIFY_NOT_REACHED();
}
} else {
if (context.bit_depth == 8)
unpack_triplets_without_alpha<u8>(context);
else if (context.bit_depth == 16)
unpack_triplets_without_alpha<u16>(context);
else
VERIFY_NOT_REACHED();
}
break;
case PNG::ColorType::TruecolorWithAlpha:
if (context.bit_depth == 8) {
for (int y = 0; y < context.height; ++y) {
memcpy(context.bitmap->scanline(y), context.scanlines[y].data.data(), context.scanlines[y].data.size());
}
} else if (context.bit_depth == 16) {
for (int y = 0; y < context.height; ++y) {
auto* quartets = reinterpret_cast<Quartet<u16> const*>(context.scanlines[y].data.data());
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
pixel.r = quartets[i].r & 0xFF;
pixel.g = quartets[i].g & 0xFF;
pixel.b = quartets[i].b & 0xFF;
pixel.a = quartets[i].a & 0xFF;
}
}
} else {
VERIFY_NOT_REACHED();
}
break;
case PNG::ColorType::IndexedColor:
if (context.bit_depth == 8) {
for (int y = 0; y < context.height; ++y) {
auto* palette_index = context.scanlines[y].data.data();
for (int i = 0; i < context.width; ++i) {
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
if (palette_index[i] >= context.palette_data.size())
return Error::from_string_literal("PNGImageDecoderPlugin: Palette index out of range");
auto& color = context.palette_data.at((int)palette_index[i]);
auto transparency = context.palette_transparency_data.size() >= palette_index[i] + 1u
? context.palette_transparency_data[palette_index[i]]
: 0xff;
pixel.r = color.r;
pixel.g = color.g;
pixel.b = color.b;
pixel.a = transparency;
}
}
} else if (context.bit_depth == 1 || context.bit_depth == 2 || context.bit_depth == 4) {
auto pixels_per_byte = 8 / context.bit_depth;
auto mask = (1 << context.bit_depth) - 1;
for (int y = 0; y < context.height; ++y) {
auto* palette_indices = context.scanlines[y].data.data();
for (int i = 0; i < context.width; ++i) {
auto bit_offset = (8 - context.bit_depth) - (context.bit_depth * (i % pixels_per_byte));
auto palette_index = (palette_indices[i / pixels_per_byte] >> bit_offset) & mask;
auto& pixel = (Pixel&)context.bitmap->scanline(y)[i];
if ((size_t)palette_index >= context.palette_data.size())
return Error::from_string_literal("PNGImageDecoderPlugin: Palette index out of range");
auto& color = context.palette_data.at(palette_index);
auto transparency = context.palette_transparency_data.size() >= palette_index + 1u
? context.palette_transparency_data[palette_index]
: 0xff;
pixel.r = color.r;
pixel.g = color.g;
pixel.b = color.b;
pixel.a = transparency;
}
}
} else {
VERIFY_NOT_REACHED();
}
break;
default:
VERIFY_NOT_REACHED();
break;
}
// Swap r and b values:
for (int y = 0; y < context.height; ++y) {
auto* pixels = (Pixel*)context.bitmap->scanline(y);
for (int i = 0; i < context.bitmap->width(); ++i) {
auto& x = pixels[i];
swap(x.r, x.b);
}
}
return {};
}
static bool decode_png_header(PNGLoadingContext& context)
{
if (context.state >= PNGLoadingContext::HeaderDecoded)
return true;
if (!context.data || context.data_size < sizeof(PNG::header)) {
dbgln_if(PNG_DEBUG, "Missing PNG header");
context.state = PNGLoadingContext::State::Error;
return false;
}
if (memcmp(context.data, PNG::header.span().data(), sizeof(PNG::header)) != 0) {
dbgln_if(PNG_DEBUG, "Invalid PNG header");
context.state = PNGLoadingContext::State::Error;
return false;
}
context.data_current_ptr = context.data + sizeof(PNG::header);
context.state = PNGLoadingContext::HeaderDecoded;
return true;
}
static bool decode_png_ihdr(PNGLoadingContext& context)
{
if (context.state >= PNGLoadingContext::IHDRDecoded)
return true;
if (context.state < PNGLoadingContext::HeaderDecoded) {
if (!decode_png_header(context))
return false;
}
size_t data_remaining = context.data_size - (context.data_current_ptr - context.data);
Streamer streamer(context.data_current_ptr, data_remaining);
while (!streamer.at_end() && !context.has_seen_iend) {
if (auto result = process_chunk(streamer, context); result.is_error()) {
context.state = PNGLoadingContext::State::Error;
return false;
}
context.data_current_ptr = streamer.current_data_ptr();
if (context.state == PNGLoadingContext::State::IHDRDecoded)
return true;
}
return false;
}
static bool decode_png_image_data_chunk(PNGLoadingContext& context)
{
if (context.state >= PNGLoadingContext::ImageDataChunkDecoded)
return true;
if (context.state < PNGLoadingContext::IHDRDecoded) {
if (!decode_png_ihdr(context))
return false;
}
size_t data_remaining = context.data_size - (context.data_current_ptr - context.data);
Streamer streamer(context.data_current_ptr, data_remaining);
while (!streamer.at_end() && !context.has_seen_iend) {
if (auto result = process_chunk(streamer, context); result.is_error()) {
context.state = PNGLoadingContext::State::Error;
return false;
}
context.data_current_ptr = streamer.current_data_ptr();
if (context.state >= PNGLoadingContext::State::ImageDataChunkDecoded)
return true;
}
return false;
}
static bool decode_png_animation_data_chunks(PNGLoadingContext& context, u32 requested_animation_frame_index)
{
if (context.state >= PNGLoadingContext::ImageDataChunkDecoded) {
if (context.last_completed_animation_frame_index.has_value()) {
if (requested_animation_frame_index <= context.last_completed_animation_frame_index.value())
return true;
}
} else if (!decode_png_image_data_chunk(context)) {
return false;
}
size_t data_remaining = context.data_size - (context.data_current_ptr - context.data);
Streamer streamer(context.data_current_ptr, data_remaining);
while (!streamer.at_end() && !context.has_seen_iend) {
if (auto result = process_chunk(streamer, context); result.is_error()) {
context.state = PNGLoadingContext::State::Error;
return false;
}
context.data_current_ptr = streamer.current_data_ptr();
if (context.last_completed_animation_frame_index.has_value()) {
if (requested_animation_frame_index <= context.last_completed_animation_frame_index.value())
break;
}
}
if (!context.last_completed_animation_frame_index.has_value())
return false;
return requested_animation_frame_index <= context.last_completed_animation_frame_index.value();
}
static bool decode_png_chunks(PNGLoadingContext& context)
{
if (context.state >= PNGLoadingContext::State::ChunksDecoded)
return true;
if (context.state < PNGLoadingContext::HeaderDecoded) {
if (!decode_png_header(context))
return false;
}
size_t data_remaining = context.data_size - (context.data_current_ptr - context.data);
context.compressed_data.ensure_capacity(context.data_size);
Streamer streamer(context.data_current_ptr, data_remaining);
while (!streamer.at_end() && !context.has_seen_iend) {
if (auto result = process_chunk(streamer, context); result.is_error()) {
// Ignore failed chunk and just consider chunk decoding being done.
// decode_png_bitmap() will check whether we got all required ones anyway.
break;
}
context.data_current_ptr = streamer.current_data_ptr();
}
context.state = PNGLoadingContext::State::ChunksDecoded;
return true;
}
static ErrorOr<void> decode_png_bitmap_simple(PNGLoadingContext& context, ByteBuffer& decompression_buffer)
{
Streamer streamer(decompression_buffer.data(), decompression_buffer.size());
for (int y = 0; y < context.height; ++y) {
PNG::FilterType filter;
if (!streamer.read(filter)) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
}
if (to_underlying(filter) > 4) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid PNG filter");
}
context.scanlines.append({ filter });
auto& scanline_buffer = context.scanlines.last().data;
auto row_size = context.compute_row_size_for_width(context.width);
if (row_size.has_overflow())
return Error::from_string_literal("PNGImageDecoderPlugin: Row size overflow");
if (!streamer.wrap_bytes(scanline_buffer, row_size.value())) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
}
}
context.bitmap = TRY(Bitmap::create(context.has_alpha() ? BitmapFormat::BGRA8888 : BitmapFormat::BGRx8888, { context.width, context.height }));
return unfilter(context);
}
static int adam7_height(PNGLoadingContext& context, int pass)
{
switch (pass) {
case 1:
return (context.height + 7) / 8;
case 2:
return (context.height + 7) / 8;
case 3:
return (context.height + 3) / 8;
case 4:
return (context.height + 3) / 4;
case 5:
return (context.height + 1) / 4;
case 6:
return (context.height + 1) / 2;
case 7:
return context.height / 2;
default:
VERIFY_NOT_REACHED();
}
}
static int adam7_width(PNGLoadingContext& context, int pass)
{
switch (pass) {
case 1:
return (context.width + 7) / 8;
case 2:
return (context.width + 3) / 8;
case 3:
return (context.width + 3) / 4;
case 4:
return (context.width + 1) / 4;
case 5:
return (context.width + 1) / 2;
case 6:
return context.width / 2;
case 7:
return context.width;
default:
VERIFY_NOT_REACHED();
}
}
// Index 0 unused (non-interlaced case)
static int adam7_starty[8] = { 0, 0, 0, 4, 0, 2, 0, 1 };
static int adam7_startx[8] = { 0, 0, 4, 0, 2, 0, 1, 0 };
static int adam7_stepy[8] = { 1, 8, 8, 8, 4, 4, 2, 2 };
static int adam7_stepx[8] = { 1, 8, 8, 4, 4, 2, 2, 1 };
static ErrorOr<void> decode_adam7_pass(PNGLoadingContext& context, Streamer& streamer, int pass)
{
auto subimage_context = context.create_subimage_context(adam7_width(context, pass), adam7_height(context, pass));
// For small images, some passes might be empty
if (!subimage_context.width || !subimage_context.height)
return {};
for (int y = 0; y < subimage_context.height; ++y) {
PNG::FilterType filter;
if (!streamer.read(filter)) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
}
if (to_underlying(filter) > 4) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid PNG filter");
}
subimage_context.scanlines.append({ filter });
auto& scanline_buffer = subimage_context.scanlines.last().data;
auto row_size = context.compute_row_size_for_width(subimage_context.width);
if (row_size.has_overflow())
return Error::from_string_literal("PNGImageDecoderPlugin: Row size overflow");
if (!streamer.wrap_bytes(scanline_buffer, row_size.value())) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
}
}
subimage_context.bitmap = TRY(Bitmap::create(context.bitmap->format(), { subimage_context.width, subimage_context.height }));
TRY(unfilter(subimage_context));
// Copy the subimage data into the main image according to the pass pattern
for (int y = 0, dy = adam7_starty[pass]; y < subimage_context.height && dy < context.height; ++y, dy += adam7_stepy[pass]) {
for (int x = 0, dx = adam7_startx[pass]; x < subimage_context.width && dx < context.width; ++x, dx += adam7_stepx[pass]) {
context.bitmap->set_pixel(dx, dy, subimage_context.bitmap->get_pixel(x, y));
}
}
return {};
}
static ErrorOr<void> decode_png_adam7(PNGLoadingContext& context, ByteBuffer& decompression_buffer)
{
Streamer streamer(decompression_buffer.data(), decompression_buffer.size());
context.bitmap = TRY(Bitmap::create(context.has_alpha() ? BitmapFormat::BGRA8888 : BitmapFormat::BGRx8888, { context.width, context.height }));
for (int pass = 1; pass <= 7; ++pass)
TRY(decode_adam7_pass(context, streamer, pass));
return {};
}
static ErrorOr<void> decode_png_bitmap(PNGLoadingContext& context)
{
if (context.state < PNGLoadingContext::State::ChunksDecoded) {
if (!decode_png_chunks(context))
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
}
if (context.state >= PNGLoadingContext::State::BitmapDecoded)
return {};
if (context.width == -1 || context.height == -1)
return Error::from_string_literal("PNGImageDecoderPlugin: Didn't see an IHDR chunk.");
if (context.color_type == PNG::ColorType::IndexedColor && context.palette_data.is_empty())
return Error::from_string_literal("PNGImageDecoderPlugin: Didn't see a PLTE chunk for a palletized image, or it was empty.");
auto result = Compress::ZlibDecompressor::decompress_all(context.compressed_data.span());
if (!result.has_value()) {
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Decompression failed");
}
auto& decompression_buffer = result.value();
context.compressed_data.clear();
context.scanlines.ensure_capacity(context.height);
switch (context.interlace_method) {
case PngInterlaceMethod::Null:
TRY(decode_png_bitmap_simple(context, decompression_buffer));
break;
case PngInterlaceMethod::Adam7:
TRY(decode_png_adam7(context, decompression_buffer));
break;
default:
context.state = PNGLoadingContext::State::Error;
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid interlace method");
}
context.state = PNGLoadingContext::State::BitmapDecoded;
return {};
}
static ErrorOr<RefPtr<Bitmap>> decode_png_animation_frame_bitmap(PNGLoadingContext& context, AnimationFrame& animation_frame)
{
if (context.color_type == PNG::ColorType::IndexedColor && context.palette_data.is_empty())
return Error::from_string_literal("PNGImageDecoderPlugin: Didn't see a PLTE chunk for a palletized image, or it was empty.");
VERIFY(!animation_frame.bitmap);
auto frame_rect = animation_frame.rect();
auto frame_context = context.create_subimage_context(frame_rect.width(), frame_rect.height());
auto result = Compress::ZlibDecompressor::decompress_all(animation_frame.compressed_data.span());
if (!result.has_value())
return Error::from_string_literal("PNGImageDecoderPlugin: Decompression of animation frame failed");
auto& decompression_buffer = result.value();
frame_context.compressed_data.clear();
frame_context.scanlines.ensure_capacity(frame_context.height);
switch (context.interlace_method) {
case PngInterlaceMethod::Null:
TRY(decode_png_bitmap_simple(frame_context, decompression_buffer));
break;
case PngInterlaceMethod::Adam7:
TRY(decode_png_adam7(frame_context, decompression_buffer));
break;
default:
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid interlace method");
}
context.state = PNGLoadingContext::State::BitmapDecoded;
return move(frame_context.bitmap);
}
static bool is_valid_compression_method(u8 compression_method)
{
return compression_method == 0;
}
static bool is_valid_filter_method(u8 filter_method)
{
return filter_method == 0;
}
static ErrorOr<void> process_IHDR(ReadonlyBytes data, PNGLoadingContext& context)
{
if (data.size() < (int)sizeof(PNG_IHDR))
return Error::from_string_literal("IHDR chunk has an abnormal size");
auto const& ihdr = *(const PNG_IHDR*)data.data();
if (ihdr.width > maximum_width_for_decoded_images || ihdr.height > maximum_height_for_decoded_images) {
dbgln("This PNG is too large for comfort: {}x{}", (u32)ihdr.width, (u32)ihdr.height);
return Error::from_string_literal("This PNG is too large for comfort");
}
if (!is_valid_compression_method(ihdr.compression_method)) {
dbgln("PNG has invalid compression method {}", ihdr.compression_method);
return Error::from_string_literal("Unsupported compression method");
}
if (!is_valid_filter_method(ihdr.filter_method)) {
dbgln("PNG has invalid filter method {}", ihdr.filter_method);
return Error::from_string_literal("Unsupported filter method");
}
context.width = ihdr.width;
context.height = ihdr.height;
context.bit_depth = ihdr.bit_depth;
context.color_type = ihdr.color_type;
context.compression_method = ihdr.compression_method;
context.filter_method = ihdr.filter_method;
context.interlace_method = ihdr.interlace_method;
dbgln_if(PNG_DEBUG, "PNG: {}x{} ({} bpp)", context.width, context.height, context.bit_depth);
dbgln_if(PNG_DEBUG, " Color type: {}", to_underlying(context.color_type));
dbgln_if(PNG_DEBUG, "Compress Method: {}", context.compression_method);
dbgln_if(PNG_DEBUG, " Filter Method: {}", context.filter_method);
dbgln_if(PNG_DEBUG, " Interlace type: {}", context.interlace_method);
if (context.interlace_method != PngInterlaceMethod::Null && context.interlace_method != PngInterlaceMethod::Adam7) {
dbgln_if(PNG_DEBUG, "PNGLoader::process_IHDR: unknown interlace method: {}", context.interlace_method);
return Error::from_string_literal("Unsupported interlacing method");
}
switch (context.color_type) {
case PNG::ColorType::Greyscale:
if (context.bit_depth != 1 && context.bit_depth != 2 && context.bit_depth != 4 && context.bit_depth != 8 && context.bit_depth != 16)
return Error::from_string_literal("Unsupported bit depth for a greyscale image");
context.channels = 1;
break;
case PNG::ColorType::GreyscaleWithAlpha:
if (context.bit_depth != 8 && context.bit_depth != 16)
return Error::from_string_literal("Unsupported bit depth for a greyscale image with alpha");
context.channels = 2;
break;
case PNG::ColorType::Truecolor:
if (context.bit_depth != 8 && context.bit_depth != 16)
return Error::from_string_literal("Unsupported bit depth for a true color image");
context.channels = 3;
break;
case PNG::ColorType::IndexedColor:
if (context.bit_depth != 1 && context.bit_depth != 2 && context.bit_depth != 4 && context.bit_depth != 8)
return Error::from_string_literal("Unsupported bit depth for a indexed color image");
context.channels = 1;
break;
case PNG::ColorType::TruecolorWithAlpha:
if (context.bit_depth != 8 && context.bit_depth != 16)
return Error::from_string_literal("Unsupported bit depth for a true color image with alpha");
context.channels = 4;
break;
default:
return Error::from_string_literal("Unsupported color type");
}
context.state = PNGLoadingContext::IHDRDecoded;
return {};
}
static ErrorOr<void> process_IDAT(ReadonlyBytes data, PNGLoadingContext& context)
{
context.compressed_data.append(data);
if (context.state < PNGLoadingContext::State::ImageDataChunkDecoded)
context.state = PNGLoadingContext::State::ImageDataChunkDecoded;
return {};
}
static ErrorOr<void> process_PLTE(ReadonlyBytes data, PNGLoadingContext& context)
{
TRY(context.palette_data.try_append((PaletteEntry const*)data.data(), data.size() / 3));
return {};
}
static ErrorOr<void> process_tRNS(ReadonlyBytes data, PNGLoadingContext& context)
{
switch (context.color_type) {
case PNG::ColorType::Greyscale:
case PNG::ColorType::Truecolor:
case PNG::ColorType::IndexedColor:
TRY(context.palette_transparency_data.try_append(data));
break;
default:
break;
}
return {};
}
static ErrorOr<void> process_cHRM(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11cHRM
if (data.size() != 32)
return Error::from_string_literal("cHRM chunk has an abnormal size");
context.chromaticities_and_whitepoint = *bit_cast<ChromaticitiesAndWhitepoint* const>(data.data());
return {};
}
static ErrorOr<void> process_cICP(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#cICP-chunk
if (data.size() != 4)
return Error::from_string_literal("cICP chunk has an abnormal size");
context.coding_independent_code_points = *bit_cast<CodingIndependentCodePoints* const>(data.data());
return {};
}
static ErrorOr<void> process_iCCP(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11iCCP
size_t profile_name_length_max = min(80u, data.size());
size_t profile_name_length = strnlen((char const*)data.data(), profile_name_length_max);
if (profile_name_length == 0 || profile_name_length == profile_name_length_max)
return Error::from_string_literal("iCCP chunk does not contain a profile name");
if (data.size() < profile_name_length + 2)
return Error::from_string_literal("iCCP chunk is too small");
u8 compression_method = data[profile_name_length + 1];
if (compression_method != 0)
return Error::from_string_literal("Unsupported compression method in the iCCP chunk");
context.embedded_icc_profile = EmbeddedICCProfile { { data.data(), profile_name_length }, data.slice(profile_name_length + 2) };
return {};
}
static ErrorOr<void> process_gAMA(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11gAMA
if (data.size() != 4)
return Error::from_string_literal("gAMA chunk has an abnormal size");
u32 gamma = *bit_cast<NetworkOrdered<u32> const*>(data.data());
if (gamma & 0x8000'0000)
return Error::from_string_literal("Gamma value is too high");
context.gamma = gamma;
return {};
}
static ErrorOr<void> process_sRGB(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#srgb-standard-colour-space
if (data.size() != 1) {
// Invalid per spec, but (rarely) happens in the wild. Log and ignore.
warnln("warning: PNG sRGB chunk has an abnormal size; ignoring");
return {};
}
u8 rendering_intent = data[0];
if (rendering_intent > 3)
return Error::from_string_literal("Unsupported rendering intent");
context.sRGB_rendering_intent = (RenderingIntent)rendering_intent;
return {};
}
static ErrorOr<void> process_acTL(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#acTL-chunk
if (context.has_seen_idat_chunk)
return {}; // Ignore if we encounter it after the first idat
if (data.size() != sizeof(acTL_Chunk))
return Error::from_string_literal("acTL chunk has an abnormal size");
auto const& acTL = *bit_cast<acTL_Chunk* const>(data.data());
context.animation_frame_count = acTL.num_frames;
context.animation_loop_count = acTL.num_plays;
context.has_seen_actl_chunk_before_idat = true;
TRY(context.animation_frames.try_ensure_capacity(context.animation_frame_count));
return {};
}
static ErrorOr<void> process_fcTL(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#fcTL-chunk
if (!context.has_seen_actl_chunk_before_idat)
return {}; // Ignore if it's not a valid animated png
if (data.size() != sizeof(fcTL_Chunk))
return Error::from_string_literal("fcTL chunk has an abnormal size");
auto const& fcTL = *bit_cast<fcTL_Chunk* const>(data.data());
if (fcTL.sequence_number != context.animation_next_expected_seq)
return Error::from_string_literal("Unexpected sequence number");
context.animation_next_expected_seq++;
if (fcTL.width == 0 || fcTL.height == 0)
return Error::from_string_literal("width and height must be greater than zero in fcTL chunk");
Checked<int> left { static_cast<int>(fcTL.x_offset) };
Checked<int> top { static_cast<int>(fcTL.y_offset) };
Checked<int> width { static_cast<int>(fcTL.width) };
Checked<int> height { static_cast<int>(fcTL.height) };
auto right = left + width;
auto bottom = top + height;
if (left < 0 || width <= 0 || right.has_overflow() || right > context.width)
return Error::from_string_literal("Invalid x_offset value in fcTL chunk");
if (top < 0 || height <= 0 || bottom.has_overflow() || bottom > context.height)
return Error::from_string_literal("Invalid y_offset value in fcTL chunk");
bool is_first_animation_frame = context.animation_frames.is_empty();
if (!is_first_animation_frame)
context.last_completed_animation_frame_index = context.animation_frames.size() - 1;
context.animation_frames.append({ fcTL });
if (!context.has_seen_idat_chunk && is_first_animation_frame)
context.is_first_idat_part_of_animation = true;
return {};
}
static ErrorOr<void> process_fdAT(ReadonlyBytes data, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#fdAT-chunk
if (data.size() <= 4)
return Error::from_string_literal("fdAT chunk has an abnormal size");
u32 sequence_number = *bit_cast<NetworkOrdered<u32> const*>(data.data());
if (sequence_number != context.animation_next_expected_seq)
return Error::from_string_literal("Unexpected sequence number");
context.animation_next_expected_seq++;
if (context.animation_frames.is_empty())
return Error::from_string_literal("No frame available");
auto& current_animation_frame = context.animation_frames[context.animation_frames.size() - 1];
auto compressed_data = data.slice(4);
current_animation_frame.compressed_data.append(compressed_data.data(), compressed_data.size());
return {};
}
static void process_IEND(ReadonlyBytes, PNGLoadingContext& context)
{
// https://www.w3.org/TR/png/#11IEND
if (context.has_seen_actl_chunk_before_idat)
context.last_completed_animation_frame_index = context.animation_frames.size();
context.has_seen_iend = true;
}
static ErrorOr<void> process_chunk(Streamer& streamer, PNGLoadingContext& context)
{
u32 chunk_size;
if (!streamer.read(chunk_size)) {
dbgln_if(PNG_DEBUG, "Bail at chunk_size");
return Error::from_string_literal("Error while reading from Streamer");
}
Array<u8, 4> chunk_type_buffer;
StringView const chunk_type { chunk_type_buffer.span() };
if (!streamer.read_bytes(chunk_type_buffer.data(), chunk_type_buffer.size())) {
dbgln_if(PNG_DEBUG, "Bail at chunk_type");
return Error::from_string_literal("Error while reading from Streamer");
}
ReadonlyBytes chunk_data;
if (!streamer.wrap_bytes(chunk_data, chunk_size)) {
dbgln_if(PNG_DEBUG, "Bail at chunk_data");
return Error::from_string_literal("Error while reading from Streamer");
}
u32 chunk_crc;
if (!streamer.read(chunk_crc)) {
dbgln_if(PNG_DEBUG, "Bail at chunk_crc");
return Error::from_string_literal("Error while reading from Streamer");
}
dbgln_if(PNG_DEBUG, "Chunk type: '{}', size: {}, crc: {:x}", chunk_type, chunk_size, chunk_crc);
if (chunk_type == "IHDR"sv)
return process_IHDR(chunk_data, context);
if (chunk_type == "IDAT"sv)
return process_IDAT(chunk_data, context);
if (chunk_type == "PLTE"sv)
return process_PLTE(chunk_data, context);
if (chunk_type == "cHRM"sv)
return process_cHRM(chunk_data, context);
if (chunk_type == "cICP"sv)
return process_cICP(chunk_data, context);
if (chunk_type == "iCCP"sv)
return process_iCCP(chunk_data, context);
if (chunk_type == "gAMA"sv)
return process_gAMA(chunk_data, context);
if (chunk_type == "sRGB"sv)
return process_sRGB(chunk_data, context);
if (chunk_type == "tRNS"sv)
return process_tRNS(chunk_data, context);
if (chunk_type == "acTL"sv)
return process_acTL(chunk_data, context);
if (chunk_type == "fcTL"sv)
return process_fcTL(chunk_data, context);
if (chunk_type == "fdAT"sv)
return process_fdAT(chunk_data, context);
if (chunk_type == "IEND"sv)
process_IEND(chunk_data, context);
return {};
}
PNGImageDecoderPlugin::PNGImageDecoderPlugin(u8 const* data, size_t size)
{
m_context = make<PNGLoadingContext>();
m_context->data = m_context->data_current_ptr = data;
m_context->data_size = size;
}
PNGImageDecoderPlugin::~PNGImageDecoderPlugin() = default;
bool PNGImageDecoderPlugin::ensure_image_data_chunk_was_decoded()
{
if (m_context->state == PNGLoadingContext::State::Error)
return false;
if (m_context->state < PNGLoadingContext::State::ImageDataChunkDecoded) {
if (!decode_png_image_data_chunk(*m_context))
return false;
}
return true;
}
bool PNGImageDecoderPlugin::ensure_animation_frame_was_decoded(u32 animation_frame_index)
{
if (m_context->state == PNGLoadingContext::State::Error)
return false;
if (m_context->state < PNGLoadingContext::State::ImageDataChunkDecoded) {
if (!decode_png_image_data_chunk(*m_context))
return false;
}
if (m_context->last_completed_animation_frame_index.has_value()) {
if (m_context->last_completed_animation_frame_index.value() >= animation_frame_index)
return true;
}
return decode_png_animation_data_chunks(*m_context, animation_frame_index);
}
IntSize PNGImageDecoderPlugin::size()
{
if (m_context->state == PNGLoadingContext::State::Error)
return {};
if (m_context->state < PNGLoadingContext::State::IHDRDecoded) {
bool success = decode_png_ihdr(*m_context);
if (!success)
return {};
}
return { m_context->width, m_context->height };
}
ErrorOr<void> PNGImageDecoderPlugin::initialize()
{
if (decode_png_header(*m_context))
return {};
return Error::from_string_literal("bad image header");
}
bool PNGImageDecoderPlugin::sniff(ReadonlyBytes data)
{
PNGLoadingContext context;
context.data = context.data_current_ptr = data.data();
context.data_size = data.size();
return decode_png_header(context);
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> PNGImageDecoderPlugin::create(ReadonlyBytes data)
{
return adopt_nonnull_own_or_enomem(new (nothrow) PNGImageDecoderPlugin(data.data(), data.size()));
}
bool PNGImageDecoderPlugin::is_animated()
{
if (!ensure_image_data_chunk_was_decoded())
return false;
return m_context->has_seen_actl_chunk_before_idat;
}
size_t PNGImageDecoderPlugin::loop_count()
{
if (!ensure_image_data_chunk_was_decoded())
return 0;
return m_context->animation_loop_count;
}
size_t PNGImageDecoderPlugin::frame_count()
{
if (!ensure_image_data_chunk_was_decoded())
return 0;
if (!m_context->has_seen_actl_chunk_before_idat)
return 1;
auto total_frames = m_context->animation_frame_count;
if (!m_context->is_first_idat_part_of_animation)
total_frames++;
return total_frames;
}
size_t PNGImageDecoderPlugin::first_animated_frame_index()
{
if (!ensure_image_data_chunk_was_decoded())
return 0;
if (!m_context->has_seen_actl_chunk_before_idat)
return 0;
return m_context->is_first_idat_part_of_animation ? 0 : 1;
}
static ErrorOr<RefPtr<Bitmap>> render_animation_frame(AnimationFrame const& prev_animation_frame, AnimationFrame& animation_frame, Bitmap const& decoded_frame_bitmap)
{
auto rendered_bitmap = TRY(prev_animation_frame.bitmap->clone());
Painter painter(rendered_bitmap);
static constexpr Color transparent_black = { 0, 0, 0, 0 };
auto frame_rect = animation_frame.rect();
switch (prev_animation_frame.fcTL.dispose_op) {
case fcTL_Chunk::DisposeOp::APNG_DISPOSE_OP_NONE:
break;
case fcTL_Chunk::DisposeOp::APNG_DISPOSE_OP_BACKGROUND:
painter.clear_rect(rendered_bitmap->rect(), transparent_black);
break;
case fcTL_Chunk::DisposeOp::APNG_DISPOSE_OP_PREVIOUS: {
painter.blit(frame_rect.location(), *prev_animation_frame.bitmap, frame_rect, 1.0f, false);
break;
}
}
switch (animation_frame.fcTL.blend_op) {
case fcTL_Chunk::BlendOp::APNG_BLEND_OP_SOURCE:
painter.blit(frame_rect.location(), decoded_frame_bitmap, decoded_frame_bitmap.rect(), 1.0f, false);
break;
case fcTL_Chunk::BlendOp::APNG_BLEND_OP_OVER:
painter.blit(frame_rect.location(), decoded_frame_bitmap, decoded_frame_bitmap.rect(), 1.0f, true);
break;
}
return rendered_bitmap;
}
ErrorOr<ImageFrameDescriptor> PNGImageDecoderPlugin::frame(size_t index, Optional<IntSize>)
{
if (m_context->state == PNGLoadingContext::State::Error)
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding failed");
if (!ensure_image_data_chunk_was_decoded())
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding image data chunk");
auto set_descriptor_duration = [](ImageFrameDescriptor& descriptor, AnimationFrame const& animation_frame) {
descriptor.duration = static_cast<int>(animation_frame.duration_ms());
if (descriptor.duration < 0)
descriptor.duration = NumericLimits<int>::min();
};
auto load_default_image = [&]() -> ErrorOr<void> {
if (m_context->state < PNGLoadingContext::State::BitmapDecoded) {
// NOTE: This forces the chunk decoding to happen.
TRY(decode_png_bitmap(*m_context));
}
VERIFY(m_context->bitmap);
return {};
};
if (index == 0) {
TRY(load_default_image());
ImageFrameDescriptor descriptor { m_context->bitmap };
if (m_context->has_seen_actl_chunk_before_idat && m_context->is_first_idat_part_of_animation)
set_descriptor_duration(descriptor, m_context->animation_frames[0]);
return descriptor;
}
if (!m_context->has_seen_actl_chunk_before_idat)
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid frame index");
if (!ensure_animation_frame_was_decoded(index))
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding image data chunk");
if (index >= m_context->animation_frames.size())
return Error::from_string_literal("PNGImageDecoderPlugin: Invalid animation frame index");
// We need to assemble each frame up until the one requested,
// so decode all bitmaps that haven't been decoded yet.
for (size_t i = m_context->animation_next_frame_to_render; i <= index; i++) {
if (i == 0) {
// If the default image hasn't been loaded, load it now
TRY(load_default_image()); // May modify animation_frames!
auto& animation_frame = m_context->animation_frames[i];
animation_frame.bitmap = m_context->bitmap;
} else {
auto& animation_frame = m_context->animation_frames[i];
VERIFY(!animation_frame.bitmap);
auto decoded_bitmap = TRY(decode_png_animation_frame_bitmap(*m_context, animation_frame));
auto prev_animation_frame = m_context->animation_frames[i - 1];
animation_frame.bitmap = TRY(render_animation_frame(prev_animation_frame, animation_frame, *decoded_bitmap));
}
m_context->animation_next_frame_to_render = i + 1;
}
auto const& animation_frame = m_context->animation_frames[index];
VERIFY(animation_frame.bitmap);
ImageFrameDescriptor descriptor { animation_frame.bitmap };
set_descriptor_duration(descriptor, animation_frame);
return descriptor;
}
ErrorOr<Optional<ReadonlyBytes>> PNGImageDecoderPlugin::icc_data()
{
if (!decode_png_chunks(*m_context))
return Error::from_string_literal("PNGImageDecoderPlugin: Decoding chunks failed");
if (m_context->embedded_icc_profile.has_value()) {
if (!m_context->decompressed_icc_profile.has_value()) {
auto result = Compress::ZlibDecompressor::decompress_all(m_context->embedded_icc_profile->compressed_data);
if (!result.has_value()) {
m_context->embedded_icc_profile.clear();
return Error::from_string_literal("PNGImageDecoderPlugin: Decompression of ICC profile failed");
}
m_context->decompressed_icc_profile = move(*result);
}
return m_context->decompressed_icc_profile.value();
}
// FIXME: Eventually, look at coding_independent_code_points, chromaticities_and_whitepoint, gamma, sRGB_rendering_intent too.
// The order is:
// 1. Use coding_independent_code_points if it exists, ignore the rest.
// 2. Use embedded_icc_profile if it exists, ignore the rest.
// 3. Use sRGB_rendering_intent if it exists, ignore the rest.
// 4. Use gamma to adjust gamma and chromaticities_and_whitepoint to adjust color.
// (Order between 2 and 3 isn't fully clear, but "It is recommended that the sRGB and iCCP chunks do not appear simultaneously in a PNG datastream."
return OptionalNone {};
}
}
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