Pl_TIFFPredictor.cc
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#include <qpdf/Pl_TIFFPredictor.hh>
#include <qpdf/BitStream.hh>
#include <qpdf/BitWriter.hh>
#include <qpdf/QTC.hh>
#include <climits>
#include <stdexcept>
Pl_TIFFPredictor::Pl_TIFFPredictor(
char const* identifier,
Pipeline* next,
action_e action,
unsigned int columns,
unsigned int samples_per_pixel,
unsigned int bits_per_sample) :
Pipeline(identifier, next),
action(action),
columns(columns),
samples_per_pixel(samples_per_pixel),
bits_per_sample(bits_per_sample),
p_next(getNext())
{
if (samples_per_pixel < 1) {
throw std::runtime_error("TIFFPredictor created with invalid samples_per_pixel");
}
if ((bits_per_sample < 1) || (bits_per_sample > (8 * (sizeof(unsigned long long))))) {
throw std::runtime_error("TIFFPredictor created with invalid bits_per_sample");
}
unsigned long long bpr = ((columns * bits_per_sample * samples_per_pixel) + 7) / 8;
if ((bpr == 0) || (bpr > (UINT_MAX - 1))) {
throw std::runtime_error("TIFFPredictor created with invalid columns value");
}
this->bytes_per_row = bpr & UINT_MAX;
}
void
Pl_TIFFPredictor::write(unsigned char const* data, size_t len)
{
auto end = data + len;
auto row_end = data + (bytes_per_row - cur_row.size());
while (row_end <= end) {
// finish off current row
cur_row.insert(cur_row.end(), data, row_end);
data = row_end;
row_end += bytes_per_row;
processRow();
// Prepare for next row
cur_row.clear();
}
cur_row.insert(cur_row.end(), data, end);
}
void
Pl_TIFFPredictor::processRow()
{
QTC::TC("libtests", "Pl_TIFFPredictor processRow", (action == a_decode ? 0 : 1));
BitWriter bw(p_next);
BitStream in(cur_row.data(), cur_row.size());
previous.assign(samples_per_pixel, 0);
for (unsigned int col = 0; col < this->columns; ++col) {
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;
prev = sample;
} else {
new_sample += prev;
prev = new_sample;
}
bw.writeBitsSigned(new_sample, this->bits_per_sample);
}
}
bw.flush();
}
void
Pl_TIFFPredictor::finish()
{
if (!cur_row.empty()) {
// write partial row
cur_row.insert(cur_row.end(), bytes_per_row - cur_row.size(), 0);
processRow();
}
cur_row.clear();
p_next->finish();
}