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resampler.h
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resampler.h
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// resampler.h, Separable filtering image rescaler v2.21, Rich Geldreich - richgel99@gmail.com
// See unlicense.org text at the bottom of this file.
#ifndef __RESAMPLER_H__
#define __RESAMPLER_H__
#define RESAMPLER_DEBUG_OPS 0
#define RESAMPLER_DEFAULT_FILTER "lanczos4"
#define RESAMPLER_MAX_DIMENSION 16384
// float or double
typedef float Resample_Real;
class Resampler
{
public:
typedef Resample_Real Sample;
struct Contrib
{
Resample_Real weight;
unsigned short pixel;
};
struct Contrib_List
{
unsigned short n;
Contrib* p;
};
enum Boundary_Op
{
BOUNDARY_WRAP = 0,
BOUNDARY_REFLECT = 1,
BOUNDARY_CLAMP = 2
};
enum Status
{
STATUS_OKAY = 0,
STATUS_OUT_OF_MEMORY = 1,
STATUS_BAD_FILTER_NAME = 2,
STATUS_SCAN_BUFFER_FULL = 3
};
// src_x/src_y - Input dimensions
// dst_x/dst_y - Output dimensions
// boundary_op - How to sample pixels near the image boundaries
// sample_low/sample_high - Clamp output samples to specified range, or disable clamping if sample_low >= sample_high
// Pclist_x/Pclist_y - Optional pointers to contributor lists from another instance of a Resampler
// src_x_ofs/src_y_ofs - Offset input image by specified amount (fractional values okay)
Resampler(
int src_x, int src_y,
int dst_x, int dst_y,
Boundary_Op boundary_op = BOUNDARY_CLAMP,
Resample_Real sample_low = 0.0f, Resample_Real sample_high = 0.0f,
const char* Pfilter_name = RESAMPLER_DEFAULT_FILTER,
Contrib_List* Pclist_x = NULL,
Contrib_List* Pclist_y = NULL,
Resample_Real filter_x_scale = 1.0f,
Resample_Real filter_y_scale = 1.0f,
Resample_Real src_x_ofs = 0.0f,
Resample_Real src_y_ofs = 0.0f);
~Resampler();
// Reinits resampler so it can handle another frame.
void restart();
// false on out of memory.
bool put_line(const Sample* Psrc);
// NULL if no scanlines are currently available (give the resampler more scanlines!)
const Sample* get_line();
Status status() const { return m_status; }
// Returned contributor lists can be shared with another Resampler.
void get_clists(Contrib_List** ptr_clist_x, Contrib_List** ptr_clist_y);
Contrib_List* get_clist_x() const { return m_Pclist_x; }
Contrib_List* get_clist_y() const { return m_Pclist_y; }
// Filter accessors.
static int get_filter_num();
static char* get_filter_name(int filter_num);
private:
Resampler();
Resampler(const Resampler& o);
Resampler& operator= (const Resampler& o);
#ifdef RESAMPLER_DEBUG_OPS
int total_ops;
#endif
int m_intermediate_x;
int m_resample_src_x;
int m_resample_src_y;
int m_resample_dst_x;
int m_resample_dst_y;
Boundary_Op m_boundary_op;
Sample* m_Pdst_buf;
Sample* m_Ptmp_buf;
Contrib_List* m_Pclist_x;
Contrib_List* m_Pclist_y;
bool m_clist_x_forced;
bool m_clist_y_forced;
bool m_delay_x_resample;
int* m_Psrc_y_count;
unsigned char* m_Psrc_y_flag;
// The maximum number of scanlines that can be buffered at one time.
enum { MAX_SCAN_BUF_SIZE = RESAMPLER_MAX_DIMENSION };
struct Scan_Buf
{
int scan_buf_y[MAX_SCAN_BUF_SIZE];
Sample* scan_buf_l[MAX_SCAN_BUF_SIZE];
};
Scan_Buf* m_Pscan_buf;
int m_cur_src_y;
int m_cur_dst_y;
Status m_status;
void resample_x(Sample* Pdst, const Sample* Psrc);
void scale_y_mov(Sample* Ptmp, const Sample* Psrc, Resample_Real weight, int dst_x);
void scale_y_add(Sample* Ptmp, const Sample* Psrc, Resample_Real weight, int dst_x);
void clamp(Sample* Pdst, int n);
void resample_y(Sample* Pdst);
int reflect(const int j, const int src_x, const Boundary_Op boundary_op);
Contrib_List* make_clist(
int src_x, int dst_x, Boundary_Op boundary_op,
Resample_Real (*Pfilter)(Resample_Real),
Resample_Real filter_support,
Resample_Real filter_scale,
Resample_Real src_ofs);
inline int count_ops(Contrib_List* Pclist, int k)
{
int i, t = 0;
for (i = 0; i < k; i++)
t += Pclist[i].n;
return (t);
}
Resample_Real m_lo;
Resample_Real m_hi;
inline Resample_Real clamp_sample(Resample_Real f) const
{
if (f < m_lo)
f = m_lo;
else if (f > m_hi)
f = m_hi;
return f;
}
};
#endif // __RESAMPLER_H__
// This is free and unencumbered software released into the public domain.
//
// Anyone is free to copy, modify, publish, use, compile, sell, or
// distribute this software, either in source code form or as a compiled
// binary, for any purpose, commercial or non-commercial, and by any
// means.
//
// In jurisdictions that recognize copyright laws, the author or authors
// of this software dedicate any and all copyright interest in the
// software to the public domain. We make this dedication for the benefit
// of the public at large and to the detriment of our heirs and
// successors. We intend this dedication to be an overt act of
// relinquishment in perpetuity of all present and future rights to this
// software under copyright law.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
//
// For more information, please refer to <http://unlicense.org/>