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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/extras/dec/gif.h"
#include "lib/jxl/base/status.h"
#if JPEGXL_ENABLE_GIF
#include <gif_lib.h>
#endif
#include <jxl/codestream_header.h>
#include <cstring>
#include <memory>
#include <utility>
#include <vector>
#include "lib/extras/size_constraints.h"
#include "lib/jxl/base/compiler_specific.h"
#include "lib/jxl/base/rect.h"
#include "lib/jxl/base/sanitizers.h"
namespace jxl {
namespace extras {
#if JPEGXL_ENABLE_GIF
namespace {
struct ReadState {
Span<const uint8_t> bytes;
};
struct DGifCloser {
void operator()(GifFileType* const ptr) const { DGifCloseFile(ptr, nullptr); }
};
using GifUniquePtr = std::unique_ptr<GifFileType, DGifCloser>;
struct PackedRgba {
uint8_t r, g, b, a;
};
struct PackedRgb {
uint8_t r, g, b;
};
Status ensure_have_alpha(PackedFrame* frame) {
if (!frame->extra_channels.empty()) return true;
const JxlPixelFormat alpha_format{
/*num_channels=*/1u,
/*data_type=*/JXL_TYPE_UINT8,
/*endianness=*/JXL_NATIVE_ENDIAN,
/*align=*/0,
};
JXL_ASSIGN_OR_RETURN(PackedImage image,
PackedImage::Create(frame->color.xsize,
frame->color.ysize, alpha_format));
frame->extra_channels.emplace_back(std::move(image));
// We need to set opaque-by-default.
std::fill_n(static_cast<uint8_t*>(frame->extra_channels[0].pixels()),
frame->color.xsize * frame->color.ysize, 255u);
return true;
}
} // namespace
#endif
bool CanDecodeGIF() {
#if JPEGXL_ENABLE_GIF
return true;
#else
return false;
#endif
}
Status DecodeImageGIF(Span<const uint8_t> bytes, const ColorHints& color_hints,
PackedPixelFile* ppf,
const SizeConstraints* constraints) {
#if JPEGXL_ENABLE_GIF
int error = GIF_OK;
ReadState state = {bytes};
const auto ReadFromSpan = [](GifFileType* const gif, GifByteType* const bytes,
int n) {
ReadState* const state = reinterpret_cast<ReadState*>(gif->UserData);
// giflib API requires the input size `n` to be signed int.
if (static_cast<size_t>(n) > state->bytes.size()) {
n = state->bytes.size();
}
memcpy(bytes, state->bytes.data(), n);
if (!state->bytes.remove_prefix(n)) return 0;
return n;
};
GifUniquePtr gif(DGifOpen(&state, ReadFromSpan, &error));
if (gif == nullptr) {
if (error == D_GIF_ERR_NOT_GIF_FILE) {
// Not an error.
return false;
} else {
return JXL_FAILURE("Failed to read GIF: %s", GifErrorString(error));
}
}
error = DGifSlurp(gif.get());
if (error != GIF_OK) {
return JXL_FAILURE("Failed to read GIF: %s", GifErrorString(gif->Error));
}
msan::UnpoisonMemory(gif.get(), sizeof(*gif));
if (gif->SColorMap) {
msan::UnpoisonMemory(gif->SColorMap, sizeof(*gif->SColorMap));
msan::UnpoisonMemory(
gif->SColorMap->Colors,
sizeof(*gif->SColorMap->Colors) * gif->SColorMap->ColorCount);
}
msan::UnpoisonMemory(gif->SavedImages,
sizeof(*gif->SavedImages) * gif->ImageCount);
JXL_RETURN_IF_ERROR(
VerifyDimensions<uint32_t>(constraints, gif->SWidth, gif->SHeight));
uint64_t total_pixel_count =
static_cast<uint64_t>(gif->SWidth) * gif->SHeight;
for (int i = 0; i < gif->ImageCount; ++i) {
const SavedImage& image = gif->SavedImages[i];
uint32_t w = image.ImageDesc.Width;
uint32_t h = image.ImageDesc.Height;
JXL_RETURN_IF_ERROR(VerifyDimensions<uint32_t>(constraints, w, h));
uint64_t pixel_count = static_cast<uint64_t>(w) * h;
if (total_pixel_count + pixel_count < total_pixel_count) {
return JXL_FAILURE("Image too big");
}
total_pixel_count += pixel_count;
if (constraints && (total_pixel_count > constraints->dec_max_pixels)) {
return JXL_FAILURE("Image too big");
}
}
if (!gif->SColorMap) {
for (int i = 0; i < gif->ImageCount; ++i) {
if (!gif->SavedImages[i].ImageDesc.ColorMap) {
return JXL_FAILURE("Missing GIF color map");
}
}
}
if (gif->ImageCount > 1) {
ppf->info.have_animation = JXL_TRUE;
// Delays in GIF are specified in censiseconds.
ppf->info.animation.tps_numerator = 100;
ppf->info.animation.tps_denominator = 1;
}
ppf->frames.clear();
ppf->frames.reserve(gif->ImageCount);
ppf->info.xsize = gif->SWidth;
ppf->info.ysize = gif->SHeight;
ppf->info.bits_per_sample = 8;
ppf->info.exponent_bits_per_sample = 0;
// alpha_bits is later set to 8 if we find a frame with transparent pixels.
ppf->info.alpha_bits = 0;
ppf->info.alpha_exponent_bits = 0;
JXL_RETURN_IF_ERROR(ApplyColorHints(color_hints, /*color_already_set=*/false,
/*is_gray=*/false, ppf));
ppf->info.num_color_channels = 3;
// Pixel format for the 'canvas' onto which we paint
// the (potentially individually cropped) GIF frames
// of an animation.
const JxlPixelFormat canvas_format{
/*num_channels=*/4u,
/*data_type=*/JXL_TYPE_UINT8,
/*endianness=*/JXL_NATIVE_ENDIAN,
/*align=*/0,
};
// Pixel format for the JXL PackedFrame that goes into the
// PackedPixelFile. Here, we use 3 color channels, and provide
// the alpha channel as an extra_channel wherever it is used.
const JxlPixelFormat packed_frame_format{
/*num_channels=*/3u,
/*data_type=*/JXL_TYPE_UINT8,
/*endianness=*/JXL_NATIVE_ENDIAN,
/*align=*/0,
};
GifColorType background_color;
if (gif->SColorMap == nullptr ||
gif->SBackGroundColor >= gif->SColorMap->ColorCount) {
background_color = {0, 0, 0};
} else {
background_color = gif->SColorMap->Colors[gif->SBackGroundColor];
}
const PackedRgba background_rgba{background_color.Red, background_color.Green,
background_color.Blue, 0};
JXL_ASSIGN_OR_RETURN(
PackedFrame canvas,
PackedFrame::Create(gif->SWidth, gif->SHeight, canvas_format));
std::fill_n(static_cast<PackedRgba*>(canvas.color.pixels()),
canvas.color.xsize * canvas.color.ysize, background_rgba);
Rect canvas_rect{0, 0, canvas.color.xsize, canvas.color.ysize};
Rect previous_rect_if_restore_to_background;
bool replace = true;
bool last_base_was_none = true;
for (int i = 0; i < gif->ImageCount; ++i) {
const SavedImage& image = gif->SavedImages[i];
msan::UnpoisonMemory(image.RasterBits, sizeof(*image.RasterBits) *
image.ImageDesc.Width *
image.ImageDesc.Height);
const Rect image_rect(image.ImageDesc.Left, image.ImageDesc.Top,
image.ImageDesc.Width, image.ImageDesc.Height);
Rect total_rect;
if (previous_rect_if_restore_to_background.xsize() != 0 ||
previous_rect_if_restore_to_background.ysize() != 0) {
const size_t xbegin = std::min(
image_rect.x0(), previous_rect_if_restore_to_background.x0());
const size_t ybegin = std::min(
image_rect.y0(), previous_rect_if_restore_to_background.y0());
const size_t xend =
std::max(image_rect.x0() + image_rect.xsize(),
previous_rect_if_restore_to_background.x0() +
previous_rect_if_restore_to_background.xsize());
const size_t yend =
std::max(image_rect.y0() + image_rect.ysize(),
previous_rect_if_restore_to_background.y0() +
previous_rect_if_restore_to_background.ysize());
total_rect = Rect(xbegin, ybegin, xend - xbegin, yend - ybegin);
previous_rect_if_restore_to_background = Rect();
replace = true;
} else {
total_rect = image_rect;
replace = false;
}
if (!image_rect.IsInside(canvas_rect)) {
return JXL_FAILURE("GIF frame extends outside of the canvas");
}
// Allocates the frame buffer.
{
JXL_ASSIGN_OR_RETURN(
PackedFrame frame,
PackedFrame::Create(total_rect.xsize(), total_rect.ysize(),
packed_frame_format));
ppf->frames.emplace_back(std::move(frame));
}
PackedFrame* frame = &ppf->frames.back();
// We cannot tell right from the start whether there will be a
// need for an alpha channel. This is discovered only as soon as
// we see a transparent pixel. We hence initialize alpha lazily.
auto set_pixel_alpha = [&frame](size_t x, size_t y, uint8_t a) -> Status {
// If we do not have an alpha-channel and a==255 (fully opaque),
// we can skip setting this pixel-value and rely on
// "no alpha channel = no transparency".
if (a == 255 && !frame->extra_channels.empty()) return true;
JXL_RETURN_IF_ERROR(ensure_have_alpha(frame));
static_cast<uint8_t*>(
frame->extra_channels[0].pixels())[y * frame->color.xsize + x] = a;
return true;
};
const ColorMapObject* const color_map =
image.ImageDesc.ColorMap ? image.ImageDesc.ColorMap : gif->SColorMap;
JXL_ENSURE(color_map);
msan::UnpoisonMemory(color_map, sizeof(*color_map));
msan::UnpoisonMemory(color_map->Colors,
sizeof(*color_map->Colors) * color_map->ColorCount);
GraphicsControlBlock gcb;
DGifSavedExtensionToGCB(gif.get(), i, &gcb);
msan::UnpoisonMemory(&gcb, sizeof(gcb));
bool is_full_size = total_rect.x0() == 0 && total_rect.y0() == 0 &&
total_rect.xsize() == canvas.color.xsize &&
total_rect.ysize() == canvas.color.ysize;
if (ppf->info.have_animation) {
frame->frame_info.duration = gcb.DelayTime;
frame->frame_info.layer_info.have_crop = static_cast<int>(!is_full_size);
frame->frame_info.layer_info.crop_x0 = total_rect.x0();
frame->frame_info.layer_info.crop_y0 = total_rect.y0();
frame->frame_info.layer_info.xsize = frame->color.xsize;
frame->frame_info.layer_info.ysize = frame->color.ysize;
if (last_base_was_none) {
replace = true;
}
frame->frame_info.layer_info.blend_info.blendmode =
replace ? JXL_BLEND_REPLACE : JXL_BLEND_BLEND;
// We always only reference at most the last frame
frame->frame_info.layer_info.blend_info.source =
last_base_was_none ? 0u : 1u;
frame->frame_info.layer_info.blend_info.clamp = 1;
frame->frame_info.layer_info.blend_info.alpha = 0;
// TODO(veluca): this could in principle be implemented.
if (last_base_was_none &&
(total_rect.x0() != 0 || total_rect.y0() != 0 ||
total_rect.xsize() != canvas.color.xsize ||
total_rect.ysize() != canvas.color.ysize || !replace)) {
return JXL_FAILURE(
"GIF with dispose-to-0 is not supported for non-full or "
"blended frames");
}
switch (gcb.DisposalMode) {
case DISPOSE_DO_NOT:
case DISPOSE_BACKGROUND:
frame->frame_info.layer_info.save_as_reference = 1u;
last_base_was_none = false;
break;
case DISPOSE_PREVIOUS:
frame->frame_info.layer_info.save_as_reference = 0u;
break;
default:
frame->frame_info.layer_info.save_as_reference = 0u;
last_base_was_none = true;
}
}
// Update the canvas by creating a copy first.
JXL_ASSIGN_OR_RETURN(
PackedImage new_canvas_image,
PackedImage::Create(canvas.color.xsize, canvas.color.ysize,
canvas.color.format));
memcpy(new_canvas_image.pixels(), canvas.color.pixels(),
new_canvas_image.pixels_size);
for (size_t y = 0, byte_index = 0; y < image_rect.ysize(); ++y) {
// Assumes format.align == 0. row points to the beginning of the y row in
// the image_rect.
PackedRgba* row = static_cast<PackedRgba*>(new_canvas_image.pixels()) +
(y + image_rect.y0()) * new_canvas_image.xsize +
image_rect.x0();
for (size_t x = 0; x < image_rect.xsize(); ++x, ++byte_index) {
const GifByteType byte = image.RasterBits[byte_index];
if (byte >= color_map->ColorCount) {
return JXL_FAILURE("GIF color is out of bounds");
}
if (byte == gcb.TransparentColor) continue;
GifColorType color = color_map->Colors[byte];
row[x].r = color.Red;
row[x].g = color.Green;
row[x].b = color.Blue;
row[x].a = 255;
}
}
const PackedImage& sub_frame_image = frame->color;
if (replace) {
// Copy from the new canvas image to the subframe
for (size_t y = 0; y < total_rect.ysize(); ++y) {
const PackedRgba* row_in =
static_cast<const PackedRgba*>(new_canvas_image.pixels()) +
(y + total_rect.y0()) * new_canvas_image.xsize + total_rect.x0();
PackedRgb* row_out = static_cast<PackedRgb*>(sub_frame_image.pixels()) +
y * sub_frame_image.xsize;
for (size_t x = 0; x < sub_frame_image.xsize; ++x) {
row_out[x].r = row_in[x].r;
row_out[x].g = row_in[x].g;
row_out[x].b = row_in[x].b;
JXL_RETURN_IF_ERROR(set_pixel_alpha(x, y, row_in[x].a));
}
}
} else {
for (size_t y = 0, byte_index = 0; y < image_rect.ysize(); ++y) {
// Assumes format.align == 0
PackedRgb* row = static_cast<PackedRgb*>(sub_frame_image.pixels()) +
y * sub_frame_image.xsize;
for (size_t x = 0; x < image_rect.xsize(); ++x, ++byte_index) {
const GifByteType byte = image.RasterBits[byte_index];
if (byte > color_map->ColorCount) {
return JXL_FAILURE("GIF color is out of bounds");
}
if (byte == gcb.TransparentColor) {
row[x].r = 0;
row[x].g = 0;
row[x].b = 0;
JXL_RETURN_IF_ERROR(set_pixel_alpha(x, y, 0));
continue;
}
GifColorType color = color_map->Colors[byte];
row[x].r = color.Red;
row[x].g = color.Green;
row[x].b = color.Blue;
JXL_RETURN_IF_ERROR(set_pixel_alpha(x, y, 255));
}
}
}
if (!frame->extra_channels.empty()) {
ppf->info.alpha_bits = 8;
}
switch (gcb.DisposalMode) {
case DISPOSE_DO_NOT:
canvas.color = std::move(new_canvas_image);
break;
case DISPOSE_BACKGROUND:
std::fill_n(static_cast<PackedRgba*>(canvas.color.pixels()),
canvas.color.xsize * canvas.color.ysize, background_rgba);
previous_rect_if_restore_to_background = image_rect;
break;
case DISPOSE_PREVIOUS:
break;
case DISPOSAL_UNSPECIFIED:
default:
std::fill_n(static_cast<PackedRgba*>(canvas.color.pixels()),
canvas.color.xsize * canvas.color.ysize, background_rgba);
}
}
// Finally, if any frame has an alpha-channel, every frame will need
// to have an alpha-channel.
bool seen_alpha = false;
for (const PackedFrame& frame : ppf->frames) {
if (!frame.extra_channels.empty()) {
seen_alpha = true;
break;
}
}
if (seen_alpha) {
for (PackedFrame& frame : ppf->frames) {
JXL_RETURN_IF_ERROR(ensure_have_alpha(&frame));
}
}
return true;
#else
return false;
#endif
}
} // namespace extras
} // namespace jxl