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LibGfx/JBIG2: Decode the file header

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Running `image` with `#define JBIG2_DEBUG 1` now prints number of pages.
This commit is contained in:
Nico Weber 2024-03-03 20:05:21 -05:00 committed by Andreas Kling
parent 58838db445
commit 5cefcad2fe
Notes: sideshowbarker 2024-07-16 23:17:55 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/5cefcad2fe
Pull-request: https://github.com/SerenityOS/serenity/pull/23503
Reviewed-by: https://github.com/LucasChollet ✅
2 changed files with 95 additions and 4 deletions
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90
Userland/Libraries/LibGfx/ImageFormats/JBIG2Loader.cpp
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@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <LibGfx/ImageFormats/JBIG2Loader.h>
// Spec: ITU-T_T_88__08_2018.pdf in the zip file here:
@ -11,16 +12,97 @@
namespace Gfx {
// JBIG2 spec, Annex D, D.4.1 ID string
static constexpr u8 id_string[] = { 0x97, 0x4A, 0x42, 0x32, 0x0D, 0x0A, 0x1A, 0x0A };
// Annex D
enum class Organization {
// D.1 Sequential organization
Sequential,
// D.2 Random-access organization
RandomAccess,
// D.3 Embedded organization
Embedded,
};
struct JBIG2LoadingContext {
enum class State {
NotDecoded = 0,
Error,
};
State state { State::NotDecoded };
ReadonlyBytes data;
Organization organization { Organization::Sequential };
IntSize size;
Optional<u32> number_of_pages;
};
static ErrorOr<void> decode_jbig2_header(JBIG2LoadingContext& context)
{
if (!JBIG2ImageDecoderPlugin::sniff(context.data))
return Error::from_string_literal("JBIG2LoadingContext: Invalid JBIG2 header");
FixedMemoryStream stream(context.data.slice(sizeof(id_string)));
// D.4.2 File header flags
u8 header_flags = TRY(stream.read_value<u8>());
if (header_flags & 0b11110000)
return Error::from_string_literal("JBIG2LoadingContext: Invalid header flags");
context.organization = (header_flags & 1) ? Organization::Sequential : Organization::RandomAccess;
bool has_known_number_of_pages = (header_flags & 2) ? false : true;
bool uses_templates_with_12_AT_pixels = (header_flags & 4) ? true : false;
bool contains_colored_region_segments = (header_flags & 8) ? true : false;
// FIXME: Do something with these?
(void)uses_templates_with_12_AT_pixels;
(void)contains_colored_region_segments;
// D.4.3 Number of pages
if (has_known_number_of_pages) {
context.number_of_pages = TRY(stream.read_value<BigEndian<u32>>());
dbgln_if(JBIG2_DEBUG, "JBIG2LoadingContext: Number of pages: {}", context.number_of_pages.value());
}
return {};
}
JBIG2ImageDecoderPlugin::JBIG2ImageDecoderPlugin(ReadonlyBytes data)
{
m_context = make<JBIG2LoadingContext>();
m_context->data = data;
}
IntSize JBIG2ImageDecoderPlugin::size()
{
return m_context->size;
}
bool JBIG2ImageDecoderPlugin::sniff(ReadonlyBytes data)
{
// JBIG2 spec, Annex D, D.4.1 ID string
u8 id_string[] = { 0x97, 0x4A, 0x42, 0x32, 0x0D, 0x0A, 0x1A, 0x0A };
return data.starts_with(id_string);
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> JBIG2ImageDecoderPlugin::create(ReadonlyBytes)
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> JBIG2ImageDecoderPlugin::create(ReadonlyBytes data)
{
return Error::from_string_view("FIXME: Draw the rest of the owl"sv);
auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) JBIG2ImageDecoderPlugin(data)));
TRY(decode_jbig2_header(*plugin->m_context));
return plugin;
}
ErrorOr<ImageFrameDescriptor> JBIG2ImageDecoderPlugin::frame(size_t index, Optional<IntSize>)
{
// FIXME: Use this for multi-page JBIG2 files?
if (index != 0)
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Invalid frame index");
if (m_context->state == JBIG2LoadingContext::State::Error)
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Decoding failed");
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Draw the rest of the owl");
}
}

9
Userland/Libraries/LibGfx/ImageFormats/JBIG2Loader.h
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@ -20,6 +20,15 @@ public:
static ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> create(ReadonlyBytes);
virtual ~JBIG2ImageDecoderPlugin() override = default;
virtual IntSize size() override;
virtual ErrorOr<ImageFrameDescriptor> frame(size_t index, Optional<IntSize> ideal_size = {}) override;
private:
JBIG2ImageDecoderPlugin(ReadonlyBytes);
OwnPtr<JBIG2LoadingContext> m_context;
};
}