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7730b743db
These two options are additions of the PDF specification. They are valid for both 1D and 2D, but let's bail out if we encounter them in a 2D image, as we don't have a test case yet.
71 lines
2.0 KiB
C++
71 lines
2.0 KiB
C++
/*
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* Copyright (c) 2023, Lucas Chollet <lucas.chollet@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/ByteBuffer.h>
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namespace Gfx::CCITT {
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// You can find a great overview of CCITT compression schemes here:
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// https://www.fileformat.info/mirror/egff/ch09_05.htm
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// The CCITT3 specification is accessible at this page:
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// https://www.itu.int/rec/T-REC-T.4/en
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// And CCITT4's specification is available here:
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// https://www.itu.int/rec/T-REC-T.6/en
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// The unidimensional scheme is originally described in:
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// 4.1 One-dimensional coding scheme
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// However, this function implements the TIFF variant (see TIFFLoader.h for a spec link),
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// differences are detailed in section:
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// Section 10: Modified Huffman Compression
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ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 image_height);
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// While this is named for a CCITT context, this struct holds data like TIFF's T4Options tag
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struct Group3Options {
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enum class Mode : u8 {
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OneDimension,
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TwoDimensions,
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};
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enum class Compression : u8 {
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Uncompressed,
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Compressed,
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};
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enum class UseFillBits : u8 {
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No = 0,
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Yes = 1,
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};
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// Addition from the PDF specification
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enum class RequireEndOfLine : u8 {
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No = 0,
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Yes = 1,
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};
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enum class EncodedByteAligned : u8 {
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No = 0,
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Yes = 1,
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};
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Mode dimensions = Mode::OneDimension;
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Compression compression = Compression::Compressed;
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UseFillBits use_fill_bits = UseFillBits::No;
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// Default values are set to be compatible with the CCITT specification
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RequireEndOfLine require_end_of_line = RequireEndOfLine::Yes;
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EncodedByteAligned encoded_byte_aligned = EncodedByteAligned::No;
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};
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ErrorOr<ByteBuffer> decode_ccitt_group3(ReadonlyBytes bytes, u32 image_width, u32 image_height, Group3Options const& options);
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ErrorOr<ByteBuffer> decode_ccitt_group4(ReadonlyBytes bytes, u32 image_width, u32 image_height);
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}
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