mirror of
https://github.com/RGBCube/serenity
synced 2025-07-26 01:57:45 +00:00
LibPDF: Make filter byte not part of row in decode_png_prediction()
No behavior change.
This commit is contained in:
parent
b763960fc2
commit
0416a07d56
1 changed files with 10 additions and 8 deletions
|
@ -156,38 +156,40 @@ PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, size_t bytes_p
|
|||
ByteBuffer decoded;
|
||||
decoded.ensure_capacity(bytes.size() - number_of_rows);
|
||||
|
||||
auto empty_row = TRY(ByteBuffer::create_zeroed(bytes_per_row));
|
||||
auto empty_row = TRY(ByteBuffer::create_zeroed(bytes_per_row - 1));
|
||||
auto previous_row = empty_row.bytes();
|
||||
|
||||
for (int row_index = 0; row_index < number_of_rows; ++row_index) {
|
||||
auto row = Bytes { bytes.data() + row_index * bytes_per_row, bytes_per_row };
|
||||
|
||||
auto filter = TRY(Gfx::PNG::filter_type(row[0]));
|
||||
row = row.slice(1);
|
||||
|
||||
switch (filter) {
|
||||
case Gfx::PNG::FilterType::None:
|
||||
break;
|
||||
case Gfx::PNG::FilterType::Sub:
|
||||
for (size_t i = 2; i < row.size(); ++i)
|
||||
for (size_t i = 1; i < row.size(); ++i)
|
||||
row[i] += row[i - 1];
|
||||
break;
|
||||
case Gfx::PNG::FilterType::Up:
|
||||
for (size_t i = 1; i < row.size(); ++i)
|
||||
for (size_t i = 0; i < row.size(); ++i)
|
||||
row[i] += previous_row[i];
|
||||
break;
|
||||
case Gfx::PNG::FilterType::Average:
|
||||
for (size_t i = 1; i < row.size(); ++i) {
|
||||
for (size_t i = 0; i < row.size(); ++i) {
|
||||
u8 left = 0;
|
||||
if (i > 1)
|
||||
if (i > 0)
|
||||
left = row[i - 1];
|
||||
u8 above = previous_row[i];
|
||||
row[i] += (left + above) / 2;
|
||||
}
|
||||
break;
|
||||
case Gfx::PNG::FilterType::Paeth:
|
||||
for (size_t i = 1; i < row.size(); ++i) {
|
||||
for (size_t i = 0; i < row.size(); ++i) {
|
||||
u8 left = 0;
|
||||
u8 upper_left = 0;
|
||||
if (i > 1) {
|
||||
if (i > 0) {
|
||||
left = row[i - 1];
|
||||
upper_left = previous_row[i - 1];
|
||||
}
|
||||
|
@ -198,7 +200,7 @@ PDFErrorOr<ByteBuffer> Filter::decode_png_prediction(Bytes bytes, size_t bytes_p
|
|||
}
|
||||
|
||||
previous_row = row;
|
||||
decoded.append(row.slice(1));
|
||||
decoded.append(row);
|
||||
}
|
||||
|
||||
return decoded;
|
||||
|
|
Loading…
Add table
Add a link
Reference in a new issue