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			227 lines
		
	
	
	
		
			8.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			227 lines
		
	
	
	
		
			8.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2021, Linus Groh <linusg@serenityos.org>
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|  *
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|  * SPDX-License-Identifier: BSD-2-Clause
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|  */
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| 
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| #include <AK/Endian.h>
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| #include <AK/MemoryStream.h>
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| #include <LibGfx/Bitmap.h>
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| #include <LibGfx/ImageFormats/QOILoader.h>
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| 
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| namespace Gfx {
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| 
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| static constexpr auto QOI_MAGIC = "qoif"sv;
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| static constexpr u8 QOI_OP_RGB = 0b11111110;
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| static constexpr u8 QOI_OP_RGBA = 0b11111111;
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| static constexpr u8 QOI_OP_INDEX = 0b00000000;
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| static constexpr u8 QOI_OP_DIFF = 0b01000000;
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| static constexpr u8 QOI_OP_LUMA = 0b10000000;
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| static constexpr u8 QOI_OP_RUN = 0b11000000;
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| static constexpr u8 QOI_MASK_2 = 0b11000000;
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| static constexpr u8 END_MARKER[] = { 0, 0, 0, 0, 0, 0, 0, 1 };
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| 
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| static ErrorOr<QOIHeader> decode_qoi_header(Stream& stream)
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| {
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|     auto header = TRY(stream.read_value<QOIHeader>());
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|     if (StringView { header.magic, array_size(header.magic) } != QOI_MAGIC)
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|         return Error::from_string_literal("Invalid QOI image: incorrect header magic");
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|     header.width = AK::convert_between_host_and_big_endian(header.width);
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|     header.height = AK::convert_between_host_and_big_endian(header.height);
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|     return header;
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| }
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| 
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| static ErrorOr<Color> decode_qoi_op_rgb(Stream& stream, u8 first_byte, Color pixel)
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| {
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|     VERIFY(first_byte == QOI_OP_RGB);
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|     u8 bytes[3];
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|     TRY(stream.read_until_filled({ &bytes, array_size(bytes) }));
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| 
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|     // The alpha value remains unchanged from the previous pixel.
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|     return Color { bytes[0], bytes[1], bytes[2], pixel.alpha() };
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| }
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| 
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| static ErrorOr<Color> decode_qoi_op_rgba(Stream& stream, u8 first_byte)
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| {
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|     VERIFY(first_byte == QOI_OP_RGBA);
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|     u8 bytes[4];
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|     TRY(stream.read_until_filled({ &bytes, array_size(bytes) }));
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|     return Color { bytes[0], bytes[1], bytes[2], bytes[3] };
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| }
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| 
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| static ErrorOr<u8> decode_qoi_op_index(Stream&, u8 first_byte)
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| {
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|     VERIFY((first_byte & QOI_MASK_2) == QOI_OP_INDEX);
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|     u8 index = first_byte & ~QOI_MASK_2;
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|     VERIFY(index <= 63);
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|     return index;
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| }
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| 
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| static ErrorOr<Color> decode_qoi_op_diff(Stream&, u8 first_byte, Color pixel)
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| {
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|     VERIFY((first_byte & QOI_MASK_2) == QOI_OP_DIFF);
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|     u8 dr = (first_byte & 0b00110000) >> 4;
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|     u8 dg = (first_byte & 0b00001100) >> 2;
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|     u8 db = (first_byte & 0b00000011);
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|     VERIFY(dr <= 3 && dg <= 3 && db <= 3);
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| 
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|     // Values are stored as unsigned integers with a bias of 2.
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|     return Color {
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|         static_cast<u8>(pixel.red() + static_cast<i8>(dr - 2)),
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|         static_cast<u8>(pixel.green() + static_cast<i8>(dg - 2)),
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|         static_cast<u8>(pixel.blue() + static_cast<i8>(db - 2)),
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|         pixel.alpha(),
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|     };
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| }
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| 
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| static ErrorOr<Color> decode_qoi_op_luma(Stream& stream, u8 first_byte, Color pixel)
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| {
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|     VERIFY((first_byte & QOI_MASK_2) == QOI_OP_LUMA);
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|     auto byte = TRY(stream.read_value<u8>());
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|     u8 diff_green = (first_byte & ~QOI_MASK_2);
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|     u8 dr_dg = (byte & 0b11110000) >> 4;
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|     u8 db_dg = (byte & 0b00001111);
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| 
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|     // Values are stored as unsigned integers with a bias of 32 for the green channel and a bias of 8 for the red and blue channel.
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|     return Color {
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|         static_cast<u8>(pixel.red() + static_cast<i8>((diff_green - 32) + (dr_dg - 8))),
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|         static_cast<u8>(pixel.green() + static_cast<i8>(diff_green - 32)),
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|         static_cast<u8>(pixel.blue() + static_cast<i8>((diff_green - 32) + (db_dg - 8))),
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|         pixel.alpha(),
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|     };
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| }
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| 
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| static ErrorOr<u8> decode_qoi_op_run(Stream&, u8 first_byte)
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| {
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|     VERIFY((first_byte & QOI_MASK_2) == QOI_OP_RUN);
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|     u8 run = first_byte & ~QOI_MASK_2;
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| 
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|     // The run-length is stored with a bias of -1.
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|     run += 1;
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| 
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|     // Note that the run-lengths 63 and 64 (b111110 and b111111) are illegal as they are occupied by the QOI_OP_RGB and QOI_OP_RGBA tags.
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|     if (run == QOI_OP_RGB || run == QOI_OP_RGBA)
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|         return Error::from_string_literal("Invalid QOI image: illegal run length");
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| 
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|     VERIFY(run >= 1 && run <= 62);
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|     return run;
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| }
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| 
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| static ErrorOr<void> decode_qoi_end_marker(Stream& stream)
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| {
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|     u8 bytes[array_size(END_MARKER)];
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|     TRY(stream.read_until_filled({ &bytes, array_size(bytes) }));
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|     if (!stream.is_eof())
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|         return Error::from_string_literal("Invalid QOI image: expected end of stream but more bytes are available");
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|     if (memcmp(&END_MARKER, &bytes, array_size(bytes)) != 0)
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|         return Error::from_string_literal("Invalid QOI image: incorrect end marker");
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|     return {};
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| }
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| 
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| static ErrorOr<NonnullRefPtr<Bitmap>> decode_qoi_image(Stream& stream, u32 width, u32 height)
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| {
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|     // FIXME: Why is Gfx::Bitmap's size signed? Makes no sense whatsoever.
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|     if (width > NumericLimits<int>::max())
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|         return Error::from_string_literal("Cannot create bitmap for QOI image of valid size, width exceeds maximum Gfx::Bitmap width");
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|     if (height > NumericLimits<int>::max())
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|         return Error::from_string_literal("Cannot create bitmap for QOI image of valid size, height exceeds maximum Gfx::Bitmap height");
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| 
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|     auto bitmap = TRY(Bitmap::create(BitmapFormat::BGRA8888, { width, height }));
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| 
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|     u8 run = 0;
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|     Color pixel = { 0, 0, 0, 255 };
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|     Color previous_pixels[64] {};
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| 
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|     for (u32 y = 0; y < height; ++y) {
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|         for (u32 x = 0; x < width; ++x) {
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|             if (run > 0)
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|                 --run;
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|             if (run == 0) {
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|                 auto first_byte = TRY(stream.read_value<u8>());
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|                 if (first_byte == QOI_OP_RGB)
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|                     pixel = TRY(decode_qoi_op_rgb(stream, first_byte, pixel));
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|                 else if (first_byte == QOI_OP_RGBA)
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|                     pixel = TRY(decode_qoi_op_rgba(stream, first_byte));
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|                 else if ((first_byte & QOI_MASK_2) == QOI_OP_INDEX)
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|                     pixel = previous_pixels[TRY(decode_qoi_op_index(stream, first_byte))];
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|                 else if ((first_byte & QOI_MASK_2) == QOI_OP_DIFF)
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|                     pixel = TRY(decode_qoi_op_diff(stream, first_byte, pixel));
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|                 else if ((first_byte & QOI_MASK_2) == QOI_OP_LUMA)
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|                     pixel = TRY(decode_qoi_op_luma(stream, first_byte, pixel));
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|                 else if ((first_byte & QOI_MASK_2) == QOI_OP_RUN)
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|                     run = TRY(decode_qoi_op_run(stream, first_byte));
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|                 else
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|                     return Error::from_string_literal("Invalid QOI image: unknown chunk tag");
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|             }
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|             auto index_position = (pixel.red() * 3 + pixel.green() * 5 + pixel.blue() * 7 + pixel.alpha() * 11) % 64;
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|             previous_pixels[index_position] = pixel;
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|             bitmap->set_pixel(x, y, pixel);
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|         }
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|     }
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|     TRY(decode_qoi_end_marker(stream));
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|     return { move(bitmap) };
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| }
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| 
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| QOIImageDecoderPlugin::QOIImageDecoderPlugin(NonnullOwnPtr<Stream> stream)
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| {
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|     m_context = make<QOILoadingContext>();
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|     m_context->stream = move(stream);
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| }
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| 
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| IntSize QOIImageDecoderPlugin::size()
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| {
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|     return { m_context->header.width, m_context->header.height };
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| }
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| 
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| bool QOIImageDecoderPlugin::sniff(ReadonlyBytes data)
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| {
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|     FixedMemoryStream stream { { data.data(), data.size() } };
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|     return !decode_qoi_header(stream).is_error();
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| }
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| 
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| ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> QOIImageDecoderPlugin::create(ReadonlyBytes data)
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| {
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|     auto stream = TRY(try_make<FixedMemoryStream>(data));
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|     auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) QOIImageDecoderPlugin(move(stream))));
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|     TRY(plugin->decode_header_and_update_context());
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|     return plugin;
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| }
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| 
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| ErrorOr<ImageFrameDescriptor> QOIImageDecoderPlugin::frame(size_t index, Optional<IntSize>)
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| {
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|     if (index > 0)
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|         return Error::from_string_literal("Invalid frame index");
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| 
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|     // No one should try to decode the frame again after an error was already returned.
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|     VERIFY(m_context->state != QOILoadingContext::State::Error);
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| 
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|     if (m_context->state == QOILoadingContext::State::HeaderDecoded)
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|         TRY(decode_image_and_update_context());
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| 
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|     VERIFY(m_context->state == QOILoadingContext::State::ImageDecoded);
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|     VERIFY(m_context->bitmap);
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|     return ImageFrameDescriptor { m_context->bitmap, 0 };
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| }
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| 
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| ErrorOr<void> QOIImageDecoderPlugin::decode_header_and_update_context()
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| {
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|     VERIFY(m_context->state < QOILoadingContext::State::HeaderDecoded);
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|     m_context->header = TRY(decode_qoi_header(*m_context->stream));
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|     m_context->state = QOILoadingContext::State::HeaderDecoded;
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|     return {};
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| }
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| 
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| ErrorOr<void> QOIImageDecoderPlugin::decode_image_and_update_context()
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| {
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|     VERIFY(m_context->state < QOILoadingContext::State::ImageDecoded);
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|     auto error_or_bitmap = decode_qoi_image(*m_context->stream, m_context->header.width, m_context->header.height);
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|     if (error_or_bitmap.is_error()) {
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|         m_context->state = QOILoadingContext::State::Error;
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|         return error_or_bitmap.release_error();
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|     }
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|     m_context->state = QOILoadingContext::State::ImageDecoded;
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|     m_context->bitmap = error_or_bitmap.release_value();
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|     return {};
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| }
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| 
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| }
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