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LibGfx: Pass the first QOI chunk byte to the operation implementation

Browse source 
This reduces reliance on the peek operation, which the generic stream
implementation does not support.

This also corrects the naming, since "tag" wasn't entirely correct for
some of the operations, where the tag takes up only part of a byte, with
the rest being reserved for data.
This commit is contained in:
Tim Schumacher 2023-01-23 17:58:57 +01:00 • committed by Linus Groh
parent 55e45856ae
commit e6f5a208a0
1 changed files with 41 additions and 52 deletions
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93
Userland/Libraries/LibGfx/QOILoader.cpp
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@ -34,50 +34,42 @@ static ErrorOr<QOIHeader> decode_qoi_header(InputMemoryStream& stream)
return header;
}
static ErrorOr<Color> decode_qoi_op_rgb(InputMemoryStream& stream, Color pixel)
static ErrorOr<Color> decode_qoi_op_rgb(InputMemoryStream& stream, u8 first_byte, Color pixel)
{
u8 bytes[4];
VERIFY(first_byte == QOI_OP_RGB);
u8 bytes[3];
stream >> Bytes { &bytes, array_size(bytes) };
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_RGB chunk");
VERIFY(bytes[0] == QOI_OP_RGB);
// The alpha value remains unchanged from the previous pixel.
return Color { bytes[1], bytes[2], bytes[3], pixel.alpha() };
return Color { bytes[0], bytes[1], bytes[2], pixel.alpha() };
}
static ErrorOr<Color> decode_qoi_op_rgba(InputMemoryStream& stream)
static ErrorOr<Color> decode_qoi_op_rgba(InputMemoryStream& stream, u8 first_byte)
{
u8 bytes[5];
VERIFY(first_byte == QOI_OP_RGBA);
u8 bytes[4];
stream >> Bytes { &bytes, array_size(bytes) };
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_RGBA chunk");
VERIFY(bytes[0] == QOI_OP_RGBA);
return Color { bytes[1], bytes[2], bytes[3], bytes[4] };
return Color { bytes[0], bytes[1], bytes[2], bytes[3] };
}
static ErrorOr<u8> decode_qoi_op_index(InputMemoryStream& stream)
static ErrorOr<u8> decode_qoi_op_index(InputMemoryStream&, u8 first_byte)
{
u8 byte;
stream >> byte;
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_INDEX chunk");
VERIFY((byte & QOI_MASK_2) == QOI_OP_INDEX);
u8 index = byte & ~QOI_MASK_2;
VERIFY((first_byte & QOI_MASK_2) == QOI_OP_INDEX);
u8 index = first_byte & ~QOI_MASK_2;
VERIFY(index <= 63);
return index;
}
static ErrorOr<Color> decode_qoi_op_diff(InputMemoryStream& stream, Color pixel)
static ErrorOr<Color> decode_qoi_op_diff(InputMemoryStream&, u8 first_byte, Color pixel)
{
u8 byte;
stream >> byte;
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_DIFF chunk");
VERIFY((byte & QOI_MASK_2) == QOI_OP_DIFF);
u8 dr = (byte & 0b00110000) >> 4;
u8 dg = (byte & 0b00001100) >> 2;
u8 db = (byte & 0b00000011);
VERIFY((first_byte & QOI_MASK_2) == QOI_OP_DIFF);
u8 dr = (first_byte & 0b00110000) >> 4;
u8 dg = (first_byte & 0b00001100) >> 2;
u8 db = (first_byte & 0b00000011);
VERIFY(dr <= 3 && dg <= 3 && db <= 3);
// Values are stored as unsigned integers with a bias of 2.
@ -89,16 +81,16 @@ static ErrorOr<Color> decode_qoi_op_diff(InputMemoryStream& stream, Color pixel)
};
}
static ErrorOr<Color> decode_qoi_op_luma(InputMemoryStream& stream, Color pixel)
static ErrorOr<Color> decode_qoi_op_luma(InputMemoryStream& stream, u8 first_byte, Color pixel)
{
u8 bytes[2];
stream >> Bytes { &bytes, array_size(bytes) };
VERIFY((first_byte & QOI_MASK_2) == QOI_OP_LUMA);
u8 byte;
stream >> byte;
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_LUMA chunk");
VERIFY((bytes[0] & QOI_MASK_2) == QOI_OP_LUMA);
u8 diff_green = (bytes[0] & ~QOI_MASK_2);
u8 dr_dg = (bytes[1] & 0b11110000) >> 4;
u8 db_dg = (bytes[1] & 0b00001111);
u8 diff_green = (first_byte & ~QOI_MASK_2);
u8 dr_dg = (byte & 0b11110000) >> 4;
u8 db_dg = (byte & 0b00001111);
// 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.
return Color {
@ -109,14 +101,10 @@ static ErrorOr<Color> decode_qoi_op_luma(InputMemoryStream& stream, Color pixel)
};
}
static ErrorOr<u8> decode_qoi_op_run(InputMemoryStream& stream)
static ErrorOr<u8> decode_qoi_op_run(InputMemoryStream&, u8 first_byte)
{
u8 byte;
stream >> byte;
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading QOI_OP_RUN chunk");
VERIFY((byte & QOI_MASK_2) == QOI_OP_RUN);
u8 run = byte & ~QOI_MASK_2;
VERIFY((first_byte & QOI_MASK_2) == QOI_OP_RUN);
u8 run = first_byte & ~QOI_MASK_2;
// The run-length is stored with a bias of -1.
run += 1;
@ -161,21 +149,22 @@ static ErrorOr<NonnullRefPtr<Bitmap>> decode_qoi_image(InputMemoryStream& stream
if (run > 0)
--run;
if (run == 0) {
u8 tag = stream.peek_or_error();
u8 first_byte;
stream.read_or_error({ &first_byte, sizeof(first_byte) });
if (stream.handle_any_error())
return Error::from_string_literal("Invalid QOI image: end of stream while reading chunk tag");
if (tag == QOI_OP_RGB)
pixel = TRY(decode_qoi_op_rgb(stream, pixel));
else if (tag == QOI_OP_RGBA)
pixel = TRY(decode_qoi_op_rgba(stream));
else if ((tag & QOI_MASK_2) == QOI_OP_INDEX)
pixel = previous_pixels[TRY(decode_qoi_op_index(stream))];
else if ((tag & QOI_MASK_2) == QOI_OP_DIFF)
pixel = TRY(decode_qoi_op_diff(stream, pixel));
else if ((tag & QOI_MASK_2) == QOI_OP_LUMA)
pixel = TRY(decode_qoi_op_luma(stream, pixel));
else if ((tag & QOI_MASK_2) == QOI_OP_RUN)
run = TRY(decode_qoi_op_run(stream));
return Error::from_string_literal("Invalid QOI image: end of stream while reading the first chunk byte");
if (first_byte == QOI_OP_RGB)
pixel = TRY(decode_qoi_op_rgb(stream, first_byte, pixel));
else if (first_byte == QOI_OP_RGBA)
pixel = TRY(decode_qoi_op_rgba(stream, first_byte));
else if ((first_byte & QOI_MASK_2) == QOI_OP_INDEX)
pixel = previous_pixels[TRY(decode_qoi_op_index(stream, first_byte))];
else if ((first_byte & QOI_MASK_2) == QOI_OP_DIFF)
pixel = TRY(decode_qoi_op_diff(stream, first_byte, pixel));
else if ((first_byte & QOI_MASK_2) == QOI_OP_LUMA)
pixel = TRY(decode_qoi_op_luma(stream, first_byte, pixel));
else if ((first_byte & QOI_MASK_2) == QOI_OP_RUN)
run = TRY(decode_qoi_op_run(stream, first_byte));
else
return Error::from_string_literal("Invalid QOI image: unknown chunk tag");
}