chroma

/* stb_image_write - v1.16 - public domain - http://nothings.org/stb

   writes out PNG/BMP/TGA/JPEG/HDR images to C stdio - Sean Barrett 2010-2015

                                     no warranty implied; use at your own risk

   Before #including,

       #define STB_IMAGE_WRITE_IMPLEMENTATION

   in the file that you want to have the implementation.

   Will probably not work correctly with strict-aliasing optimizations.

ABOUT:

   This header file is a library for writing images to C stdio or a callback.

   The PNG output is not optimal; it is 20-50% larger than the file

   written by a decent optimizing implementation; though providing a custom

   zlib compress function (see STBIW_ZLIB_COMPRESS) can mitigate that.

   This library is designed for source code compactness and simplicity,

   not optimal image file size or run-time performance.

BUILDING:

   You can #define STBIW_ASSERT(x) before the #include to avoid using assert.h.

   You can #define STBIW_MALLOC(), STBIW_REALLOC(), and STBIW_FREE() to replace

   malloc,realloc,free.

   You can #define STBIW_MEMMOVE() to replace memmove()

   You can #define STBIW_ZLIB_COMPRESS to use a custom zlib-style compress function

   for PNG compression (instead of the builtin one), it must have the following signature:

   unsigned char * my_compress(unsigned char *data, int data_len, int *out_len, int quality);

   The returned data will be freed with STBIW_FREE() (free() by default),

   so it must be heap allocated with STBIW_MALLOC() (malloc() by default),

UNICODE:

   If compiling for Windows and you wish to use Unicode filenames, compile

   with

       #define STBIW_WINDOWS_UTF8

   and pass utf8-encoded filenames. Call stbiw_convert_wchar_to_utf8 to convert

   Windows wchar_t filenames to utf8.

USAGE:

   There are five functions, one for each image file format:

     int stbi_write_png(char const *filename, int w, int h, int comp, const void *data, int stride_in_bytes);

     int stbi_write_bmp(char const *filename, int w, int h, int comp, const void *data);

     int stbi_write_tga(char const *filename, int w, int h, int comp, const void *data);

     int stbi_write_jpg(char const *filename, int w, int h, int comp, const void *data, int quality);

     int stbi_write_hdr(char const *filename, int w, int h, int comp, const float *data);

     void stbi_flip_vertically_on_write(int flag); // flag is non-zero to flip data vertically

   There are also five equivalent functions that use an arbitrary write function. You are

   expected to open/close your file-equivalent before and after calling these:

     int stbi_write_png_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data, int stride_in_bytes);

     int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);

     int stbi_write_tga_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);

     int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const float *data);

     int stbi_write_jpg_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data, int quality);

   where the callback is:

      void stbi_write_func(void *context, void *data, int size);

   You can configure it with these global variables:

      int stbi_write_tga_with_rle;             // defaults to true; set to 0 to disable RLE

      int stbi_write_png_compression_level;    // defaults to 8; set to higher for more compression

      int stbi_write_force_png_filter;         // defaults to -1; set to 0..5 to force a filter mode

   You can define STBI_WRITE_NO_STDIO to disable the file variant of these

   functions, so the library will not use stdio.h at all. However, this will

   also disable HDR writing, because it requires stdio for formatted output.

   Each function returns 0 on failure and non-0 on success.

   The functions create an image file defined by the parameters. The image

   is a rectangle of pixels stored from left-to-right, top-to-bottom.

   Each pixel contains 'comp' channels of data stored interleaved with 8-bits

   per channel, in the following order: 1=Y, 2=YA, 3=RGB, 4=RGBA. (Y is

   monochrome color.) The rectangle is 'w' pixels wide and 'h' pixels tall.

   The *data pointer points to the first byte of the top-left-most pixel.

   For PNG, "stride_in_bytes" is the distance in bytes from the first byte of

   a row of pixels to the first byte of the next row of pixels.

   PNG creates output files with the same number of components as the input.

   The BMP format expands Y to RGB in the file format and does not

   output alpha.

   PNG supports writing rectangles of data even when the bytes storing rows of

   data are not consecutive in memory (e.g. sub-rectangles of a larger image),

   by supplying the stride between the beginning of adjacent rows. The other

   formats do not. (Thus you cannot write a native-format BMP through the BMP

   writer, both because it is in BGR order and because it may have padding

   at the end of the line.)

   PNG allows you to set the deflate compression level by setting the global

   variable 'stbi_write_png_compression_level' (it defaults to 8).

   HDR expects linear float data. Since the format is always 32-bit rgb(e)

   data, alpha (if provided) is discarded, and for monochrome data it is

   replicated across all three channels.

   TGA supports RLE or non-RLE compressed data. To use non-RLE-compressed

   data, set the global variable 'stbi_write_tga_with_rle' to 0.

   JPEG does ignore alpha channels in input data; quality is between 1 and 100.

   Higher quality looks better but results in a bigger image.

   JPEG baseline (no JPEG progressive).

CREDITS:

   Sean Barrett           -    PNG/BMP/TGA

   Baldur Karlsson        -    HDR

   Jean-Sebastien Guay    -    TGA monochrome

   Tim Kelsey             -    misc enhancements

   Alan Hickman           -    TGA RLE

   Emmanuel Julien        -    initial file IO callback implementation

   Jon Olick              -    original jo_jpeg.cpp code

   Daniel Gibson          -    integrate JPEG, allow external zlib

   Aarni Koskela          -    allow choosing PNG filter

   bugfixes:

      github:Chribba

      Guillaume Chereau

      github:jry2

      github:romigrou

      Sergio Gonzalez

      Jonas Karlsson

      Filip Wasil

      Thatcher Ulrich

      github:poppolopoppo

      Patrick Boettcher

      github:xeekworx

      Cap Petschulat

      Simon Rodriguez

      Ivan Tikhonov

      github:ignotion

      Adam Schackart

      Andrew Kensler

LICENSE

  See end of file for license information.

*/

#ifndef INCLUDE_STB_IMAGE_WRITE_H

#define INCLUDE_STB_IMAGE_WRITE_H

#include <stdlib.h>

// if STB_IMAGE_WRITE_STATIC causes problems, try defining STBIWDEF to 'inline' or 'static inline'

#ifndef STBIWDEF

#ifdef STB_IMAGE_WRITE_STATIC

#define STBIWDEF  static

#else

#ifdef __cplusplus

#define STBIWDEF  extern "C"

#else

#define STBIWDEF  extern

#endif

#endif

#endif

#ifndef STB_IMAGE_WRITE_STATIC  // C++ forbids static forward declarations

STBIWDEF int stbi_write_tga_with_rle;

STBIWDEF int stbi_write_png_compression_level;

STBIWDEF int stbi_write_force_png_filter;

#endif

#ifndef STBI_WRITE_NO_STDIO

STBIWDEF int stbi_write_png(char const *filename, int w, int h, int comp, const void  *data, int stride_in_bytes);

STBIWDEF int stbi_write_bmp(char const *filename, int w, int h, int comp, const void  *data);

STBIWDEF int stbi_write_tga(char const *filename, int w, int h, int comp, const void  *data);

STBIWDEF int stbi_write_hdr(char const *filename, int w, int h, int comp, const float *data);

STBIWDEF int stbi_write_jpg(char const *filename, int x, int y, int comp, const void  *data, int quality);

#ifdef STBIW_WINDOWS_UTF8

STBIWDEF int stbiw_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input);

#endif

#endif

typedef void stbi_write_func(void *context, void *data, int size);

STBIWDEF int stbi_write_png_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data, int stride_in_bytes);

STBIWDEF int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);

STBIWDEF int stbi_write_tga_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const void  *data);

STBIWDEF int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int w, int h, int comp, const float *data);

STBIWDEF int stbi_write_jpg_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void  *data, int quality);

STBIWDEF void stbi_flip_vertically_on_write(int flip_boolean);

#endif//INCLUDE_STB_IMAGE_WRITE_H

#ifdef STB_IMAGE_WRITE_IMPLEMENTATION

#ifdef _WIN32

   #ifndef _CRT_SECURE_NO_WARNINGS

   #define _CRT_SECURE_NO_WARNINGS

   #endif

   #ifndef _CRT_NONSTDC_NO_DEPRECATE

   #define _CRT_NONSTDC_NO_DEPRECATE

   #endif

#endif

#ifndef STBI_WRITE_NO_STDIO

#include <stdio.h>

#endif // STBI_WRITE_NO_STDIO

#include <stdarg.h>

#include <stdlib.h>

#include <string.h>

#include <math.h>

#if defined(STBIW_MALLOC) && defined(STBIW_FREE) && (defined(STBIW_REALLOC) || defined(STBIW_REALLOC_SIZED))

// ok

#elif !defined(STBIW_MALLOC) && !defined(STBIW_FREE) && !defined(STBIW_REALLOC) && !defined(STBIW_REALLOC_SIZED)

// ok

#else

#error "Must define all or none of STBIW_MALLOC, STBIW_FREE, and STBIW_REALLOC (or STBIW_REALLOC_SIZED)."

#endif

#ifndef STBIW_MALLOC

#define STBIW_MALLOC(sz)        malloc(sz)

#define STBIW_REALLOC(p,newsz)  realloc(p,newsz)

#define STBIW_FREE(p)           free(p)

#endif

#ifndef STBIW_REALLOC_SIZED

#define STBIW_REALLOC_SIZED(p,oldsz,newsz) STBIW_REALLOC(p,newsz)

#endif

#ifndef STBIW_MEMMOVE

#define STBIW_MEMMOVE(a,b,sz) memmove(a,b,sz)

#endif

#ifndef STBIW_ASSERT

#include <assert.h>

#define STBIW_ASSERT(x) assert(x)

#endif

#define STBIW_UCHAR(x) (unsigned char) ((x) & 0xff)

#ifdef STB_IMAGE_WRITE_STATIC

static int stbi_write_png_compression_level = 8;

static int stbi_write_tga_with_rle = 1;

static int stbi_write_force_png_filter = -1;

#else

int stbi_write_png_compression_level = 8;

int stbi_write_tga_with_rle = 1;

int stbi_write_force_png_filter = -1;

#endif

static int stbi__flip_vertically_on_write = 0;

STBIWDEF void stbi_flip_vertically_on_write(int flag)

{

   stbi__flip_vertically_on_write = flag;

}

typedef struct

{

   stbi_write_func *func;

   void *context;

   unsigned char buffer[64];

   int buf_used;

} stbi__write_context;

// initialize a callback-based context

static void stbi__start_write_callbacks(stbi__write_context *s, stbi_write_func *c, void *context)

{

   s->func    = c;

   s->context = context;

}

#ifndef STBI_WRITE_NO_STDIO

static void stbi__stdio_write(void *context, void *data, int size)

{

   fwrite(data,1,size,(FILE*) context);

}

#if defined(_WIN32) && defined(STBIW_WINDOWS_UTF8)

#ifdef __cplusplus

#define STBIW_EXTERN extern "C"

#else

#define STBIW_EXTERN extern

#endif

STBIW_EXTERN __declspec(dllimport) int __stdcall MultiByteToWideChar(unsigned int cp, unsigned long flags, const char *str, int cbmb, wchar_t *widestr, int cchwide);

STBIW_EXTERN __declspec(dllimport) int __stdcall WideCharToMultiByte(unsigned int cp, unsigned long flags, const wchar_t *widestr, int cchwide, char *str, int cbmb, const char *defchar, int *used_default);

STBIWDEF int stbiw_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input)

{

   return WideCharToMultiByte(65001 /* UTF8 */, 0, input, -1, buffer, (int) bufferlen, NULL, NULL);

}

#endif

static FILE *stbiw__fopen(char const *filename, char const *mode)

{

   FILE *f;

#if defined(_WIN32) && defined(STBIW_WINDOWS_UTF8)

   wchar_t wMode[64];

   wchar_t wFilename[1024];

   if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, filename, -1, wFilename, sizeof(wFilename)/sizeof(*wFilename)))

      return 0;

   if (0 == MultiByteToWideChar(65001 /* UTF8 */, 0, mode, -1, wMode, sizeof(wMode)/sizeof(*wMode)))

      return 0;

#if defined(_MSC_VER) && _MSC_VER >= 1400

   if (0 != _wfopen_s(&f, wFilename, wMode))

      f = 0;

#else

   f = _wfopen(wFilename, wMode);

#endif

#elif defined(_MSC_VER) && _MSC_VER >= 1400

   if (0 != fopen_s(&f, filename, mode))

      f=0;

#else

   f = fopen(filename, mode);

#endif

   return f;

}

static int stbi__start_write_file(stbi__write_context *s, const char *filename)

{

   FILE *f = stbiw__fopen(filename, "wb");

   stbi__start_write_callbacks(s, stbi__stdio_write, (void *) f);

   return f != NULL;

}

static void stbi__end_write_file(stbi__write_context *s)

{

   fclose((FILE *)s->context);

}

#endif // !STBI_WRITE_NO_STDIO

typedef unsigned int stbiw_uint32;

typedef int stb_image_write_test[sizeof(stbiw_uint32)==4 ? 1 : -1];

static void stbiw__writefv(stbi__write_context *s, const char *fmt, va_list v)

{

   while (*fmt) {

      switch (*fmt++) {

         case ' ': break;

         case '1': { unsigned char x = STBIW_UCHAR(va_arg(v, int));

                     s->func(s->context,&x,1);

                     break; }

         case '2': { int x = va_arg(v,int);

                     unsigned char b[2];

                     b[0] = STBIW_UCHAR(x);

                     b[1] = STBIW_UCHAR(x>>8);

                     s->func(s->context,b,2);

                     break; }

         case '4': { stbiw_uint32 x = va_arg(v,int);

                     unsigned char b[4];

                     b[0]=STBIW_UCHAR(x);

                     b[1]=STBIW_UCHAR(x>>8);

                     b[2]=STBIW_UCHAR(x>>16);

                     b[3]=STBIW_UCHAR(x>>24);

                     s->func(s->context,b,4);

                     break; }

         default:

            STBIW_ASSERT(0);

            return;

      }

   }

}

static void stbiw__writef(stbi__write_context *s, const char *fmt, ...)

{

   va_list v;

   va_start(v, fmt);

   stbiw__writefv(s, fmt, v);

   va_end(v);

}

static void stbiw__write_flush(stbi__write_context *s)

{

   if (s->buf_used) {

      s->func(s->context, &s->buffer, s->buf_used);

      s->buf_used = 0;

   }

}

static void stbiw__putc(stbi__write_context *s, unsigned char c)

{

   s->func(s->context, &c, 1);

}

static void stbiw__write1(stbi__write_context *s, unsigned char a)

{

   if ((size_t)s->buf_used + 1 > sizeof(s->buffer))

      stbiw__write_flush(s);

   s->buffer[s->buf_used++] = a;

}

static void stbiw__write3(stbi__write_context *s, unsigned char a, unsigned char b, unsigned char c)

{

   int n;

   if ((size_t)s->buf_used + 3 > sizeof(s->buffer))

      stbiw__write_flush(s);

   n = s->buf_used;

   s->buf_used = n+3;

   s->buffer[n+0] = a;

   s->buffer[n+1] = b;

   s->buffer[n+2] = c;

}

static void stbiw__write_pixel(stbi__write_context *s, int rgb_dir, int comp, int write_alpha, int expand_mono, unsigned char *d)

{

   unsigned char bg[3] = { 255, 0, 255}, px[3];

   int k;

   if (write_alpha < 0)

      stbiw__write1(s, d[comp - 1]);

   switch (comp) {

      case 2: // 2 pixels = mono + alpha, alpha is written separately, so same as 1-channel case

      case 1:

         if (expand_mono)

            stbiw__write3(s, d[0], d[0], d[0]); // monochrome bmp

         else

            stbiw__write1(s, d[0]);  // monochrome TGA

         break;

      case 4:

         if (!write_alpha) {

            // composite against pink background

            for (k = 0; k < 3; ++k)

               px[k] = bg[k] + ((d[k] - bg[k]) * d[3]) / 255;

            stbiw__write3(s, px[1 - rgb_dir], px[1], px[1 + rgb_dir]);

            break;

         }

         /* FALLTHROUGH */

      case 3:

         stbiw__write3(s, d[1 - rgb_dir], d[1], d[1 + rgb_dir]);

         break;

   }

   if (write_alpha > 0)

      stbiw__write1(s, d[comp - 1]);

}

static void stbiw__write_pixels(stbi__write_context *s, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad, int expand_mono)

{

   stbiw_uint32 zero = 0;

   int i,j, j_end;

   if (y <= 0)

      return;

   if (stbi__flip_vertically_on_write)

      vdir *= -1;

   if (vdir < 0) {

      j_end = -1; j = y-1;

   } else {

      j_end =  y; j = 0;

   }

   for (; j != j_end; j += vdir) {

      for (i=0; i < x; ++i) {

         unsigned char *d = (unsigned char *) data + (j*x+i)*comp;

         stbiw__write_pixel(s, rgb_dir, comp, write_alpha, expand_mono, d);

      }

      stbiw__write_flush(s);

      s->func(s->context, &zero, scanline_pad);

   }

}

static int stbiw__outfile(stbi__write_context *s, int rgb_dir, int vdir, int x, int y, int comp, int expand_mono, void *data, int alpha, int pad, const char *fmt, ...)

{

   if (y < 0 || x < 0) {

      return 0;

   } else {

      va_list v;

      va_start(v, fmt);

      stbiw__writefv(s, fmt, v);

      va_end(v);

      stbiw__write_pixels(s,rgb_dir,vdir,x,y,comp,data,alpha,pad, expand_mono);

      return 1;

   }

}

static int stbi_write_bmp_core(stbi__write_context *s, int x, int y, int comp, const void *data)

{

   if (comp != 4) {

      // write RGB bitmap

      int pad = (-x*3) & 3;

      return stbiw__outfile(s,-1,-1,x,y,comp,1,(void *) data,0,pad,

              "11 4 22 4" "4 44 22 444444",

              'B', 'M', 14+40+(x*3+pad)*y, 0,0, 14+40,  // file header

               40, x,y, 1,24, 0,0,0,0,0,0);             // bitmap header

   } else {

      // RGBA bitmaps need a v4 header

      // use BI_BITFIELDS mode with 32bpp and alpha mask

      // (straight BI_RGB with alpha mask doesn't work in most readers)

      return stbiw__outfile(s,-1,-1,x,y,comp,1,(void *)data,1,0,

         "11 4 22 4" "4 44 22 444444 4444 4 444 444 444 444",

         'B', 'M', 14+108+x*y*4, 0, 0, 14+108, // file header

         108, x,y, 1,32, 3,0,0,0,0,0, 0xff0000,0xff00,0xff,0xff000000u, 0, 0,0,0, 0,0,0, 0,0,0, 0,0,0); // bitmap V4 header

   }

}

STBIWDEF int stbi_write_bmp_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data)

{

   stbi__write_context s = { 0 };

   stbi__start_write_callbacks(&s, func, context);

   return stbi_write_bmp_core(&s, x, y, comp, data);

}

#ifndef STBI_WRITE_NO_STDIO

STBIWDEF int stbi_write_bmp(char const *filename, int x, int y, int comp, const void *data)

{

   stbi__write_context s = { 0 };

   if (stbi__start_write_file(&s,filename)) {

      int r = stbi_write_bmp_core(&s, x, y, comp, data);

      stbi__end_write_file(&s);

      return r;

   } else

      return 0;

}

#endif //!STBI_WRITE_NO_STDIO

static int stbi_write_tga_core(stbi__write_context *s, int x, int y, int comp, void *data)

{

   int has_alpha = (comp == 2 || comp == 4);

   int colorbytes = has_alpha ? comp-1 : comp;

   int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 2, 1 color channel (Y/YA) = 3

   if (y < 0 || x < 0)

      return 0;

   if (!stbi_write_tga_with_rle) {

      return stbiw__outfile(s, -1, -1, x, y, comp, 0, (void *) data, has_alpha, 0,

         "111 221 2222 11", 0, 0, format, 0, 0, 0, 0, 0, x, y, (colorbytes + has_alpha) * 8, has_alpha * 8);

   } else {

      int i,j,k;

      int jend, jdir;

      stbiw__writef(s, "111 221 2222 11", 0,0,format+8, 0,0,0, 0,0,x,y, (colorbytes + has_alpha) * 8, has_alpha * 8);

      if (stbi__flip_vertically_on_write) {

         j = 0;

         jend = y;

         jdir = 1;

      } else {

         j = y-1;

         jend = -1;

         jdir = -1;

      }

      for (; j != jend; j += jdir) {

         unsigned char *row = (unsigned char *) data + j * x * comp;

         int len;

         for (i = 0; i < x; i += len) {

            unsigned char *begin = row + i * comp;

            int diff = 1;

            len = 1;

            if (i < x - 1) {

               ++len;

               diff = memcmp(begin, row + (i + 1) * comp, comp);

               if (diff) {

                  const unsigned char *prev = begin;

                  for (k = i + 2; k < x && len < 128; ++k) {

                     if (memcmp(prev, row + k * comp, comp)) {

                        prev += comp;

                        ++len;

                     } else {

                        --len;

                        break;

                     }

                  }

               } else {

                  for (k = i + 2; k < x && len < 128; ++k) {

                     if (!memcmp(begin, row + k * comp, comp)) {

                        ++len;

                     } else {

                        break;

                     }

                  }

               }

            }

            if (diff) {

               unsigned char header = STBIW_UCHAR(len - 1);

               stbiw__write1(s, header);

               for (k = 0; k < len; ++k) {

                  stbiw__write_pixel(s, -1, comp, has_alpha, 0, begin + k * comp);

               }

            } else {

               unsigned char header = STBIW_UCHAR(len - 129);

               stbiw__write1(s, header);

               stbiw__write_pixel(s, -1, comp, has_alpha, 0, begin);

            }

         }

      }

      stbiw__write_flush(s);

   }

   return 1;

}

STBIWDEF int stbi_write_tga_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const void *data)

{

   stbi__write_context s = { 0 };

   stbi__start_write_callbacks(&s, func, context);

   return stbi_write_tga_core(&s, x, y, comp, (void *) data);

}

#ifndef STBI_WRITE_NO_STDIO

STBIWDEF int stbi_write_tga(char const *filename, int x, int y, int comp, const void *data)

{

   stbi__write_context s = { 0 };

   if (stbi__start_write_file(&s,filename)) {

      int r = stbi_write_tga_core(&s, x, y, comp, (void *) data);

      stbi__end_write_file(&s);

      return r;

   } else

      return 0;

}

#endif

// *************************************************************************************************

// Radiance RGBE HDR writer

// by Baldur Karlsson

#define stbiw__max(a, b)  ((a) > (b) ? (a) : (b))

#ifndef STBI_WRITE_NO_STDIO

static void stbiw__linear_to_rgbe(unsigned char *rgbe, float *linear)

{

   int exponent;

   float maxcomp = stbiw__max(linear[0], stbiw__max(linear[1], linear[2]));

   if (maxcomp < 1e-32f) {

      rgbe[0] = rgbe[1] = rgbe[2] = rgbe[3] = 0;

   } else {

      float normalize = (float) frexp(maxcomp, &exponent) * 256.0f/maxcomp;

      rgbe[0] = (unsigned char)(linear[0] * normalize);

      rgbe[1] = (unsigned char)(linear[1] * normalize);

      rgbe[2] = (unsigned char)(linear[2] * normalize);

      rgbe[3] = (unsigned char)(exponent + 128);

   }

}

static void stbiw__write_run_data(stbi__write_context *s, int length, unsigned char databyte)

{

   unsigned char lengthbyte = STBIW_UCHAR(length+128);

   STBIW_ASSERT(length+128 <= 255);

   s->func(s->context, &lengthbyte, 1);

   s->func(s->context, &databyte, 1);

}

static void stbiw__write_dump_data(stbi__write_context *s, int length, unsigned char *data)

{

   unsigned char lengthbyte = STBIW_UCHAR(length);

   STBIW_ASSERT(length <= 128); // inconsistent with spec but consistent with official code

   s->func(s->context, &lengthbyte, 1);

   s->func(s->context, data, length);

}

static void stbiw__write_hdr_scanline(stbi__write_context *s, int width, int ncomp, unsigned char *scratch, float *scanline)

{

   unsigned char scanlineheader[4] = { 2, 2, 0, 0 };

   unsigned char rgbe[4];

   float linear[3];

   int x;

   scanlineheader[2] = (width&0xff00)>>8;

   scanlineheader[3] = (width&0x00ff);

   /* skip RLE for images too small or large */

   if (width < 8 || width >= 32768) {

      for (x=0; x < width; x++) {

         switch (ncomp) {

            case 4: /* fallthrough */

            case 3: linear[2] = scanline[x*ncomp + 2];

                    linear[1] = scanline[x*ncomp + 1];

                    linear[0] = scanline[x*ncomp + 0];

                    break;

            default:

                    linear[0] = linear[1] = linear[2] = scanline[x*ncomp + 0];

                    break;

         }

         stbiw__linear_to_rgbe(rgbe, linear);

         s->func(s->context, rgbe, 4);

      }

   } else {

      int c,r;

      /* encode into scratch buffer */

      for (x=0; x < width; x++) {

         switch(ncomp) {

            case 4: /* fallthrough */

            case 3: linear[2] = scanline[x*ncomp + 2];

                    linear[1] = scanline[x*ncomp + 1];

                    linear[0] = scanline[x*ncomp + 0];

                    break;

            default:

                    linear[0] = linear[1] = linear[2] = scanline[x*ncomp + 0];

                    break;

         }

         stbiw__linear_to_rgbe(rgbe, linear);

         scratch[x + width*0] = rgbe[0];

         scratch[x + width*1] = rgbe[1];

         scratch[x + width*2] = rgbe[2];

         scratch[x + width*3] = rgbe[3];

      }

      s->func(s->context, scanlineheader, 4);

      /* RLE each component separately */

      for (c=0; c < 4; c++) {

         unsigned char *comp = &scratch[width*c];

         x = 0;

         while (x < width) {

            // find first run

            r = x;

            while (r+2 < width) {

               if (comp[r] == comp[r+1] && comp[r] == comp[r+2])

                  break;

               ++r;

            }

            if (r+2 >= width)

               r = width;

            // dump up to first run

            while (x < r) {

               int len = r-x;

               if (len > 128) len = 128;

               stbiw__write_dump_data(s, len, &comp[x]);

               x += len;

            }

            // if there's a run, output it

            if (r+2 < width) { // same test as what we break out of in search loop, so only true if we break'd

               // find next byte after run

               while (r < width && comp[r] == comp[x])

                  ++r;

               // output run up to r

               while (x < r) {

                  int len = r-x;

                  if (len > 127) len = 127;

                  stbiw__write_run_data(s, len, comp[x]);

                  x += len;

               }

            }

         }

      }

   }

}

static int stbi_write_hdr_core(stbi__write_context *s, int x, int y, int comp, float *data)

{

   if (y <= 0 || x <= 0 || data == NULL)

      return 0;

   else {

      // Each component is stored separately. Allocate scratch space for full output scanline.

      unsigned char *scratch = (unsigned char *) STBIW_MALLOC(x*4);

      int i, len;

      char buffer[128];

      char header[] = "#?RADIANCE\n# Written by stb_image_write.h\nFORMAT=32-bit_rle_rgbe\n";

      s->func(s->context, header, sizeof(header)-1);

#ifdef __STDC_LIB_EXT1__

      len = sprintf_s(buffer, sizeof(buffer), "EXPOSURE=          1.0000000000000\n\n-Y %d +X %d\n", y, x);

#else

      len = sprintf(buffer, "EXPOSURE=          1.0000000000000\n\n-Y %d +X %d\n", y, x);

#endif

      s->func(s->context, buffer, len);

      for(i=0; i < y; i++)

         stbiw__write_hdr_scanline(s, x, comp, scratch, data + comp*x*(stbi__flip_vertically_on_write ? y-1-i : i));

      STBIW_FREE(scratch);

      return 1;

   }

}

STBIWDEF int stbi_write_hdr_to_func(stbi_write_func *func, void *context, int x, int y, int comp, const float *data)

{

   stbi__write_context s = { 0 };

   stbi__start_write_callbacks(&s, func, context);

   return stbi_write_hdr_core(&s, x, y, comp, (float *) data);

}

STBIWDEF int stbi_write_hdr(char const *filename, int x, int y, int comp, const float *data)

{

   stbi__write_context s = { 0 };

   if (stbi__start_write_file(&s,filename)) {

      int r = stbi_write_hdr_core(&s, x, y, comp, (float *) data);

      stbi__end_write_file(&s);

      return r;

   } else

      return 0;

}

#endif // STBI_WRITE_NO_STDIO

//////////////////////////////////////////////////////////////////////////////

//

// PNG writer

//

#ifndef STBIW_ZLIB_COMPRESS

// stretchy buffer; stbiw__sbpush() == vector<>::push_back() -- stbiw__sbcount() == vector<>::size()

#define stbiw__sbraw(a) ((int *) (void *) (a) - 2)

#define stbiw__sbm(a)   stbiw__sbraw(a)[0]

#define stbiw__sbn(a)   stbiw__sbraw(a)[1]

#define stbiw__sbneedgrow(a,n)  ((a)==0 || stbiw__sbn(a)+n >= stbiw__sbm(a))

#define stbiw__sbmaybegrow(a,n) (stbiw__sbneedgrow(a,(n)) ? stbiw__sbgrow(a,n) : 0)

#define stbiw__sbgrow(a,n)  stbiw__sbgrowf((void **) &(a), (n), sizeof(*(a)))

#define stbiw__sbpush(a, v)      (stbiw__sbmaybegrow(a,1), (a)[stbiw__sbn(a)++] = (v))

#define stbiw__sbcount(a)        ((a) ? stbiw__sbn(a) : 0)

#define stbiw__sbfree(a)         ((a) ? STBIW_FREE(stbiw__sbraw(a)),0 : 0)

static void *stbiw__sbgrowf(void **arr, int increment, int itemsize)

{

   int m = *arr ? 2*stbiw__sbm(*arr)+increment : increment+1;

   void *p = STBIW_REALLOC_SIZED(*arr ? stbiw__sbraw(*arr) : 0, *arr ? (stbiw__sbm(*arr)*itemsize + sizeof(int)*2) : 0, itemsize * m + sizeof(int)*2);

   STBIW_ASSERT(p);

   if (p) {

      if (!*arr) ((int *) p)[1] = 0;

      *arr = (void *) ((int *) p + 2);

      stbiw__sbm(*arr) = m;

   }