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LibPDF: Let Filter::handle_lzw_and_flate_parameters() read decode params

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...instead of reading them in Filter::decode() for all filters and
then passing them around to only the LZW and flate filters.

(EarlyChange is LZWDecode-only, so that's read there instead.)

No behavior change.
This commit is contained in:
Nico Weber 2024-02-12 19:35:31 -05:00 • committed by Andreas Kling
parent 9875ce0c78
commit 454a10774e
2 changed files with 30 additions and 29 deletions
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53
Userland/Libraries/LibPDF/Filter.cpp
View file

@ -19,33 +19,14 @@ namespace PDF {
PDFErrorOr<ByteBuffer> Filter::decode(ReadonlyBytes bytes, DeprecatedFlyString const& encoding_type, RefPtr<DictObject> decode_parms) PDFErrorOr<ByteBuffer> Filter::decode(ReadonlyBytes bytes, DeprecatedFlyString const& encoding_type, RefPtr<DictObject> decode_parms)
{ {
int predictor = 1;
int columns = 1;
int colors = 1;
int bits_per_component = 8;
int early_change = 1;
if (decode_parms) {
if (decode_parms->contains(CommonNames::Predictor))
predictor = decode_parms->get_value(CommonNames::Predictor).get<int>();
if (decode_parms->contains(CommonNames::Columns))
columns = decode_parms->get_value(CommonNames::Columns).get<int>();
if (decode_parms->contains(CommonNames::Colors))
colors = decode_parms->get_value(CommonNames::Colors).get<int>();
if (decode_parms->contains(CommonNames::BitsPerComponent))
bits_per_component = decode_parms->get_value(CommonNames::BitsPerComponent).get<int>();
if (decode_parms->contains(CommonNames::EarlyChange))
early_change = decode_parms->get_value(CommonNames::EarlyChange).get<int>();
}
if (encoding_type == CommonNames::ASCIIHexDecode) if (encoding_type == CommonNames::ASCIIHexDecode)
return decode_ascii_hex(bytes); return decode_ascii_hex(bytes);
if (encoding_type == CommonNames::ASCII85Decode) if (encoding_type == CommonNames::ASCII85Decode)
return decode_ascii85(bytes); return decode_ascii85(bytes);
if (encoding_type == CommonNames::LZWDecode) if (encoding_type == CommonNames::LZWDecode)
return decode_lzw(bytes, predictor, columns, colors, bits_per_component, early_change); return decode_lzw(bytes, decode_parms);
if (encoding_type == CommonNames::FlateDecode) if (encoding_type == CommonNames::FlateDecode)
return decode_flate(bytes, predictor, columns, colors, bits_per_component); return decode_flate(bytes, decode_parms);
if (encoding_type == CommonNames::RunLengthDecode) if (encoding_type == CommonNames::RunLengthDecode)
return decode_run_length(bytes); return decode_run_length(bytes);
if (encoding_type == CommonNames::CCITTFaxDecode) if (encoding_type == CommonNames::CCITTFaxDecode)
@ -228,9 +209,24 @@ PDFErrorOr<ByteBuffer> Filter::decode_tiff_prediction(Bytes bytes, int columns,
return decoded; return decoded;
} }
PDFErrorOr<ByteBuffer> Filter::handle_lzw_and_flate_parameters(ByteBuffer buffer, int predictor, int columns, int colors, int bits_per_component) PDFErrorOr<ByteBuffer> Filter::handle_lzw_and_flate_parameters(ByteBuffer buffer, RefPtr<DictObject> decode_parms)
{ {
// Table 3.7 Optional parameters for LZWDecode and FlateDecode filters // Table 3.7 Optional parameters for LZWDecode and FlateDecode filters
int predictor = 1;
int colors = 1;
int bits_per_component = 8;
int columns = 1;
if (decode_parms) {
if (decode_parms->contains(CommonNames::Predictor))
predictor = decode_parms->get_value(CommonNames::Predictor).get<int>();
if (decode_parms->contains(CommonNames::Colors))
colors = decode_parms->get_value(CommonNames::Colors).get<int>();
if (decode_parms->contains(CommonNames::BitsPerComponent))
bits_per_component = decode_parms->get_value(CommonNames::BitsPerComponent).get<int>();
if (decode_parms->contains(CommonNames::Columns))
columns = decode_parms->get_value(CommonNames::Columns).get<int>();
}
if (predictor == 1) if (predictor == 1)
return buffer; return buffer;
@ -257,16 +253,21 @@ PDFErrorOr<ByteBuffer> Filter::handle_lzw_and_flate_parameters(ByteBuffer buffer
return decode_png_prediction(buffer_bytes, bytes_per_row, bytes_per_pixel); return decode_png_prediction(buffer_bytes, bytes_per_row, bytes_per_pixel);
} }
PDFErrorOr<ByteBuffer> Filter::decode_lzw(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component, int early_change) PDFErrorOr<ByteBuffer> Filter::decode_lzw(ReadonlyBytes bytes, RefPtr<DictObject> decode_parms)
{ {
// Table 3.7 Optional parameters for LZWDecode and FlateDecode filters
int early_change = 1;
if (decode_parms && decode_parms->contains(CommonNames::EarlyChange))
early_change = decode_parms->get_value(CommonNames::EarlyChange).get<int>();
auto decoded = TRY(Compress::LZWDecoder<BigEndianInputBitStream>::decode_all(bytes, 8, -early_change)); auto decoded = TRY(Compress::LZWDecoder<BigEndianInputBitStream>::decode_all(bytes, 8, -early_change));
return handle_lzw_and_flate_parameters(move(decoded), predictor, columns, colors, bits_per_component); return handle_lzw_and_flate_parameters(move(decoded), decode_parms);
} }
PDFErrorOr<ByteBuffer> Filter::decode_flate(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component) PDFErrorOr<ByteBuffer> Filter::decode_flate(ReadonlyBytes bytes, RefPtr<DictObject> decode_parms)
{ {
auto buff = TRY(Compress::DeflateDecompressor::decompress_all(bytes.slice(2))); auto buff = TRY(Compress::DeflateDecompressor::decompress_all(bytes.slice(2)));
return handle_lzw_and_flate_parameters(move(buff), predictor, columns, colors, bits_per_component); return handle_lzw_and_flate_parameters(move(buff), decode_parms);
} }
PDFErrorOr<ByteBuffer> Filter::decode_run_length(ReadonlyBytes bytes) PDFErrorOr<ByteBuffer> Filter::decode_run_length(ReadonlyBytes bytes)

6
Userland/Libraries/LibPDF/Filter.h
View file

@ -22,8 +22,8 @@ private:
static PDFErrorOr<ByteBuffer> decode_ascii85(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_ascii85(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_png_prediction(Bytes bytes, size_t bytes_per_row, size_t bytes_per_pixel); static PDFErrorOr<ByteBuffer> decode_png_prediction(Bytes bytes, size_t bytes_per_row, size_t bytes_per_pixel);
static PDFErrorOr<ByteBuffer> decode_tiff_prediction(Bytes bytes, int columns, int colors, int bits_per_component); static PDFErrorOr<ByteBuffer> decode_tiff_prediction(Bytes bytes, int columns, int colors, int bits_per_component);
static PDFErrorOr<ByteBuffer> decode_lzw(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component, int early_change); static PDFErrorOr<ByteBuffer> decode_lzw(ReadonlyBytes bytes, RefPtr<DictObject> decode_parms);
static PDFErrorOr<ByteBuffer> decode_flate(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component); static PDFErrorOr<ByteBuffer> decode_flate(ReadonlyBytes bytes, RefPtr<DictObject> decode_parms);
static PDFErrorOr<ByteBuffer> decode_run_length(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_run_length(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_ccitt(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_ccitt(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_jbig2(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_jbig2(ReadonlyBytes bytes);
@ -31,7 +31,7 @@ private:
static PDFErrorOr<ByteBuffer> decode_jpx(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_jpx(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_crypt(ReadonlyBytes bytes); static PDFErrorOr<ByteBuffer> decode_crypt(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> handle_lzw_and_flate_parameters(ByteBuffer buffer, int predictor, int columns, int colors, int bits_per_component); static PDFErrorOr<ByteBuffer> handle_lzw_and_flate_parameters(ByteBuffer buffer, RefPtr<DictObject> decode_parms);
}; };
} }