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LibGfx/WebP: Change ImageData optional-ness

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Instead of ImageData having an Optional<Chunk> for the image data,
have it have a Chunk, and give the context an Optional<ImageData>.

This allows sharing a single code path for checking that either the
main image or an animation frame has a main image data chunk, and
that an alpha chunk is only present with a lossy main image data
chunk.

No behavior change.
This commit is contained in:
Nico Weber 2023-05-07 16:27:45 -04:00 • committed by Andreas Kling
parent 119ccfe5da
commit bdba70b38f
Notes: sideshowbarker 2024-07-17 20:19:08 +09:00
1 changed files with 42 additions and 41 deletions
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83
Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
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@ -107,8 +107,8 @@ struct ANMFChunk {
// A bitstream subchunk."
struct ImageData {
// "This optional chunk contains encoded alpha data for this frame. A frame containing a 'VP8L' chunk SHOULD NOT contain this chunk."
Optional<Chunk> alpha_chunk; // 'ALPH'
Optional<Chunk> image_data_chunk; // Either 'VP8 ' or 'VP8L'. For 'VP8L', alpha_chunk will not have a value.
Optional<Chunk> alpha_chunk; // 'ALPH'
Chunk image_data_chunk; // Either 'VP8 ' or 'VP8L'. For 'VP8L', alpha_chunk will not have a value.
};
}
@ -140,7 +140,8 @@ struct WebPLoadingContext {
VP8XHeader vp8x_header;
// If first_chunk is not a VP8X chunk, then only image_data.image_data_chunk is set and all the other Chunks are not set.
ImageData image_data;
// Once state is >= ChunksDecoded, for non-animated images, this will have a value, or decoding will have failed.
Optional<ImageData> image_data;
Optional<Chunk> animation_header_chunk; // 'ANIM'
Vector<Chunk> animation_frame_chunks; // 'ANMF'
@ -464,11 +465,28 @@ static ErrorOr<ANMFChunk> decode_webp_chunk_ANMF(WebPLoadingContext& context, Ch
return ANMFChunk { frame_x, frame_y, frame_width, frame_height, frame_duration, blending_method, disposal_method, frame_data };
}
static ErrorOr<ImageData> decode_webp_set_image_data(WebPLoadingContext& context, Optional<Chunk> alpha, Optional<Chunk> image_data)
{
if (!image_data.has_value())
return context.error("WebPImageDecoderPlugin: missing image data");
// https://developers.google.com/speed/webp/docs/riff_container#alpha
// "A frame containing a 'VP8L' chunk SHOULD NOT contain this chunk."
if (alpha.has_value() && image_data->type == FourCC("VP8L")) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: VP8L frames should not have ALPH chunks. Ignoring ALPH chunk.");
alpha.clear();
}
return ImageData { move(alpha), image_data.value() };
}
// https://developers.google.com/speed/webp/docs/riff_container#extended_file_format
static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyBytes chunks)
{
VERIFY(context.first_chunk->type == FourCC("VP8X"));
Optional<Chunk> alpha, image_data;
// FIXME: This isn't quite to spec, which says
// "All chunks SHOULD be placed in the same order as listed above.
// If a chunk appears in the wrong place, the file is invalid, but readers MAY parse the file, ignoring the chunks that are out of order."
@ -482,7 +500,7 @@ static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyB
if (chunk.type == FourCC("ICCP"))
store(context.iccp_chunk, chunk);
else if (chunk.type == FourCC("ALPH"))
store(context.image_data.alpha_chunk, chunk);
store(alpha, chunk);
else if (chunk.type == FourCC("ANIM"))
store(context.animation_header_chunk, chunk);
else if (chunk.type == FourCC("ANMF"))
@ -492,7 +510,7 @@ static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyB
else if (chunk.type == FourCC("XMP "))
store(context.xmp_chunk, chunk);
else if (chunk.type == FourCC("VP8 ") || chunk.type == FourCC("VP8L"))
store(context.image_data.image_data_chunk, chunk);
store(image_data, chunk);
}
// Validate chunks.
@ -512,18 +530,17 @@ static ErrorOr<void> decode_webp_extended(WebPLoadingContext& context, ReadonlyB
context.animation_frame_chunks.clear();
}
// https://developers.google.com/speed/webp/docs/riff_container#alpha
// "A frame containing a 'VP8L' chunk SHOULD NOT contain this chunk."
if (context.image_data.alpha_chunk.has_value() && context.image_data.image_data_chunk.has_value() && context.image_data.image_data_chunk->type == FourCC("VP8L")) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: VP8L frames should not have ALPH chunks. Ignoring ALPH chunk.");
context.image_data.alpha_chunk.clear();
}
// Image data is not optional -- but the spec doesn't explicitly say that an animated image must have more than 0 frames.
// The spec also doesn't say that animated images must not contain a regular image data segment.
if (!context.vp8x_header.has_animation || image_data.has_value())
context.image_data = TRY(decode_webp_set_image_data(context, move(alpha), move(image_data)));
// https://developers.google.com/speed/webp/docs/riff_container#color_profile
// "This chunk MUST appear before the image data."
if (context.iccp_chunk.has_value()
&& ((context.image_data.image_data_chunk.has_value() && context.iccp_chunk->data.data() > context.image_data.image_data_chunk->data.data())
|| (context.image_data.alpha_chunk.has_value() && context.iccp_chunk->data.data() > context.image_data.alpha_chunk->data.data())
&& ((context.image_data.has_value()
&& (context.iccp_chunk->data.data() > context.image_data->image_data_chunk.data.data()
|| (context.image_data->alpha_chunk.has_value() && context.iccp_chunk->data.data() > context.image_data->alpha_chunk->data.data())))
|| (!context.animation_frame_chunks.is_empty() && context.iccp_chunk->data.data() > context.animation_frame_chunks[0].data.data()))) {
return context.error("WebPImageDecoderPlugin: ICCP chunk is after image data");
}
@ -550,7 +567,7 @@ static ErrorOr<void> read_webp_first_chunk(WebPLoadingContext& context)
context.state = WebPLoadingContext::State::FirstChunkRead;
if (first_chunk.type == FourCC("VP8 ") || first_chunk.type == FourCC("VP8L"))
context.image_data.image_data_chunk = first_chunk;
context.image_data = TRY(decode_webp_set_image_data(context, OptionalNone {}, first_chunk));
return {};
}
@ -617,39 +634,28 @@ static ErrorOr<void> decode_webp_animation_frame_chunks(WebPLoadingContext& cont
static ErrorOr<ImageData> decode_webp_animation_frame_image_data(WebPLoadingContext& context, ANMFChunk const& frame)
{
ReadonlyBytes chunks = frame.frame_data;
ImageData image_data;
auto chunk = TRY(decode_webp_advance_chunk(context, chunks));
Optional<Chunk> alpha, image_data;
if (chunk.type == FourCC("ALPH")) {
image_data.alpha_chunk = chunk;
alpha = chunk;
chunk = TRY(decode_webp_advance_chunk(context, chunks));
}
if (chunk.type == FourCC("VP8 ") || chunk.type == FourCC("VP8L"))
image_data = chunk;
if (chunk.type != FourCC("VP8 ") && chunk.type != FourCC("VP8L"))
return context.error("WebPImageDecoderPlugin: no image data found in animation frame");
image_data.image_data_chunk = chunk;
// https://developers.google.com/speed/webp/docs/riff_container#alpha
// "A frame containing a 'VP8L' chunk SHOULD NOT contain this chunk."
if (image_data.alpha_chunk.has_value() && image_data.image_data_chunk.has_value() && image_data.image_data_chunk->type == FourCC("VP8L")) {
dbgln_if(WEBP_DEBUG, "WebPImageDecoderPlugin: VP8L frames should not have ALPH chunks. Ignoring ALPH chunk.");
image_data.alpha_chunk.clear();
}
return image_data;
return decode_webp_set_image_data(context, move(alpha), move(image_data));
}
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_image_data(WebPLoadingContext& context, ImageData const& image_data)
{
if (image_data.image_data_chunk->type == FourCC("VP8L")) {
if (image_data.image_data_chunk.type == FourCC("VP8L")) {
VERIFY(!image_data.alpha_chunk.has_value());
return decode_webp_chunk_VP8L(context, image_data.image_data_chunk.value());
return decode_webp_chunk_VP8L(context, image_data.image_data_chunk);
}
VERIFY(image_data.image_data_chunk->type == FourCC("VP8 "));
auto bitmap = TRY(decode_webp_chunk_VP8(context, image_data.image_data_chunk.value()));
VERIFY(image_data.image_data_chunk.type == FourCC("VP8 "));
auto bitmap = TRY(decode_webp_chunk_VP8(context, image_data.image_data_chunk));
if (image_data.alpha_chunk.has_value())
TRY(decode_webp_chunk_ALPH(context, image_data.alpha_chunk.value(), *bitmap));
@ -694,8 +700,6 @@ static ErrorOr<ImageFrameDescriptor> decode_webp_animation_frame(WebPLoadingCont
}
auto frame_image_data = TRY(decode_webp_animation_frame_image_data(context, frame_description));
VERIFY(frame_image_data.image_data_chunk.has_value());
auto frame_bitmap = TRY(decode_webp_image_data(context, frame_image_data));
if (static_cast<u32>(frame_bitmap->width()) != frame_description.frame_width || static_cast<u32>(frame_bitmap->height()) != frame_description.frame_height)
return context.error("WebPImageDecoderPlugin: decoded frame bitmap size doesn't match frame description size");
@ -824,11 +828,8 @@ ErrorOr<ImageFrameDescriptor> WebPImageDecoderPlugin::frame(size_t index)
return decode_webp_animation_frame(*m_context, index);
}
if (!m_context->image_data.image_data_chunk.has_value())
return m_context->error("WebPImageDecoderPlugin: Did not find image data chunk");
if (m_context->state < WebPLoadingContext::State::BitmapDecoded) {
auto bitmap = TRY(decode_webp_image_data(*m_context, m_context->image_data));
auto bitmap = TRY(decode_webp_image_data(*m_context, m_context->image_data.value()));
// Check that size in VP8X chunk matches dimensions in VP8 or VP8L chunk if both are present.
if (m_context->first_chunk->type == FourCC("VP8X")) {