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LibPDF: Convert decode_png_prediction to use spans

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No behavior change.
This commit is contained in:
Nico Weber 2023-11-16 19:45:15 -05:00 • committed by Andreas Kling
parent 588d6fab22
commit b763960fc2
2 changed files with 10 additions and 10 deletions
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18
Userland/Libraries/LibPDF/Filter.cpp
View file

@ -149,7 +149,7 @@ PDFErrorOr<ByteBuffer> Filter::decode_ascii85(ReadonlyBytes bytes)
return buffer;
}
PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, int bytes_per_row)
PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, size_t bytes_per_row)
{
int number_of_rows = bytes.size() / bytes_per_row;
@ -157,25 +157,25 @@ PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, int bytes_per_
decoded.ensure_capacity(bytes.size() - number_of_rows);
auto empty_row = TRY(ByteBuffer::create_zeroed(bytes_per_row));
auto previous_row = empty_row.data();
auto previous_row = empty_row.bytes();
for (int row_index = 0; row_index < number_of_rows; ++row_index) {
auto row = bytes.data() + row_index * bytes_per_row;
auto row = Bytes { bytes.data() + row_index * bytes_per_row, bytes_per_row };
auto filter = TRY(Gfx::PNG::filter_type(row[0]));
switch (filter) {
case Gfx::PNG::FilterType::None:
break;
case Gfx::PNG::FilterType::Sub:
for (int i = 2; i < bytes_per_row; ++i)
for (size_t i = 2; i < row.size(); ++i)
row[i] += row[i - 1];
break;
case Gfx::PNG::FilterType::Up:
for (int i = 1; i < bytes_per_row; ++i)
for (size_t i = 1; i < row.size(); ++i)
row[i] += previous_row[i];
break;
case Gfx::PNG::FilterType::Average:
for (int i = 1; i < bytes_per_row; ++i) {
for (size_t i = 1; i < row.size(); ++i) {
u8 left = 0;
if (i > 1)
left = row[i - 1];
@ -184,7 +184,7 @@ PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, int bytes_per_
}
break;
case Gfx::PNG::FilterType::Paeth:
for (int i = 1; i < bytes_per_row; ++i) {
for (size_t i = 1; i < row.size(); ++i) {
u8 left = 0;
u8 upper_left = 0;
if (i > 1) {
@ -198,7 +198,7 @@ PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, int bytes_per_
}
previous_row = row;
decoded.append(row + 1, bytes_per_row - 1);
decoded.append(row.slice(1));
}
return decoded;
@ -218,7 +218,7 @@ PDFErrorOr<ByteBuffer> Filter::handle_lzw_and_flate_parameters(ByteBuffer buffer
return AK::Error::from_string_literal("Invalid predictor value");
// Rows are always a whole number of bytes long, starting with an algorithm tag
int const bytes_per_row = AK::ceil_div(columns * colors * bits_per_component, 8) + 1;
size_t const bytes_per_row = AK::ceil_div(columns * colors * bits_per_component, 8) + 1;
if (buffer.size() % bytes_per_row)
return AK::Error::from_string_literal("Flate input data is not divisible into columns");

2
Userland/Libraries/LibPDF/Filter.h
View file

@ -20,7 +20,7 @@ public:
private:
static PDFErrorOr<ByteBuffer> decode_ascii_hex(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_ascii85(ReadonlyBytes bytes);
static PDFErrorOr<ByteBuffer> decode_png_prediction(Bytes bytes, int bytes_per_row);
static PDFErrorOr<ByteBuffer> decode_png_prediction(Bytes bytes, size_t bytes_per_row);
static PDFErrorOr<ByteBuffer> decode_lzw(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component, int early_change);
static PDFErrorOr<ByteBuffer> decode_flate(ReadonlyBytes bytes, int predictor, int columns, int colors, int bits_per_component);
static PDFErrorOr<ByteBuffer> decode_run_length(ReadonlyBytes bytes);