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#ifndef __PL_PNGFILTER_HH__
#define __PL_PNGFILTER_HH__
// This pipeline applies or reverses the application of a PNG filter
// as described in the PNG specification.
// NOTE: In its current implementation, this filter always encodes
// using the "up" filter, but it decodes all the filters.
#include <qpdf/Pipeline.hh>
class Pl_PNGFilter: public Pipeline
{
public:
// Encoding is not presently supported
enum action_e { a_encode, a_decode };
QPDF_DLL
Pl_PNGFilter(char const* identifier, Pipeline* next,
action_e action, unsigned int columns,
unsigned int bytes_per_pixel);
QPDF_DLL
virtual ~Pl_PNGFilter();
QPDF_DLL
virtual void write(unsigned char* data, size_t len);
QPDF_DLL
virtual void finish();
private:
void decodeSub();
void decodeUp();
void decodeAverage();
void decodePaeth();
void processRow();
void encodeRow();
void decodeRow();
int PaethPredictor(int a, int b, int c);
action_e action;
unsigned int columns;
unsigned char* cur_row;
unsigned char* prev_row;
unsigned char* buf1;
unsigned char* buf2;
unsigned int bytes_per_pixel;
size_t pos;
size_t incoming;
};
#endif // __PL_PNGFILTER_HH__
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