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In Pl_TIFFPredictor::processRow avoid repeated vector allocation 

Also, modernize for loop.
This commit is contained in:
m-holger 2024-01-26 19:13:34 +00:00
parent 2e8b5f290c
commit c01fc3c2ae
2 changed files with 10 additions and 8 deletions
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17
libqpdf/Pl_TIFFPredictor.cc
View File

@ -7,6 +7,7 @@
#include <climits>
#include <stdexcept>
#include <vector>
#include <iostream>
Pl_TIFFPredictor::Pl_TIFFPredictor(
char const* identifier,
@ -60,23 +61,23 @@ Pl_TIFFPredictor::processRow()
{
QTC::TC("libtests", "Pl_TIFFPredictor processRow", (action == a_decode ? 0 : 1));
BitWriter bw(p_next);
BitStream in(this->cur_row.data(), this->bytes_per_row);
std::vector<long long> prev;
BitStream in(cur_row.data(), cur_row.size());
previous.clear();
for (unsigned int i = 0; i < this->samples_per_pixel; ++i) {
long long sample = in.getBitsSigned(this->bits_per_sample);
bw.writeBitsSigned(sample, this->bits_per_sample);
prev.push_back(sample);
previous.push_back(sample);
}
for (unsigned int col = 1; col < this->columns; ++col) {
for (unsigned int i = 0; i < this->samples_per_pixel; ++i) {
for (auto& prev : previous) {
long long sample = in.getBitsSigned(this->bits_per_sample);
long long new_sample = sample;
if (action == a_encode) {
new_sample -= prev[i];
prev[i] = sample;
new_sample -= prev;
prev = sample;
} else {
new_sample += prev[i];
prev[i] = new_sample;
new_sample += prev;
prev = new_sample;
}
bw.writeBitsSigned(new_sample, this->bits_per_sample);
}

1
libqpdf/qpdf/Pl_TIFFPredictor.hh
View File

@ -34,6 +34,7 @@ class Pl_TIFFPredictor: public Pipeline
unsigned int samples_per_pixel;
unsigned int bits_per_sample;
std::vector<unsigned char> cur_row;
std::vector<long long> previous;
Pipeline* p_next;
};