stb_image.h

/* stb_image - v2.27 - public domain image loader - http://nothings.org/stb
                                  no warranty implied; use at your own risk

   Do this:
      #define STB_IMAGE_IMPLEMENTATION
   before you include this file in *one* C or C++ file to create the implementation.

   // i.e. it should look like this:
   #include ...
   #include ...
   #include ...
   #define STB_IMAGE_IMPLEMENTATION
   #include "stb_image.h"

   You can #define STBI_ASSERT(x) before the #include to avoid using assert.h.
   And #define STBI_MALLOC, STBI_REALLOC, and STBI_FREE to avoid using malloc,realloc,free


   QUICK NOTES:
      Primarily of interest to game developers and other people who can
          avoid problematic images and only need the trivial interface

      JPEG baseline & progressive (12 bpc/arithmetic not supported, same as stock IJG lib)
      PNG 1/2/4/8/16-bit-per-channel

      TGA (not sure what subset, if a subset)
      BMP non-1bpp, non-RLE
      PSD (composited view only, no extra channels, 8/16 bit-per-channel)

      GIF (*comp always reports as 4-channel)
      HDR (radiance rgbE format)
      PIC (Softimage PIC)
      PNM (PPM and PGM binary only)

      Animated GIF still needs a proper API, but here's one way to do it:
          http://gist.github.com/urraka/685d9a6340b26b830d49

      - decode from memory or through FILE (define STBI_NO_STDIO to remove code)
      - decode from arbitrary I/O callbacks
      - SIMD acceleration on x86/x64 (SSE2) and ARM (NEON)

   Full documentation under "DOCUMENTATION" below.


LICENSE

  See end of file for license information.

RECENT REVISION HISTORY:

      2.27  (2021-07-11) document stbi_info better, 16-bit PNM support, bug fixes
      2.26  (2020-07-13) many minor fixes
      2.25  (2020-02-02) fix warnings
      2.24  (2020-02-02) fix warnings; thread-local failure_reason and flip_vertically
      2.23  (2019-08-11) fix clang static analysis warning
      2.22  (2019-03-04) gif fixes, fix warnings
      2.21  (2019-02-25) fix typo in comment
      2.20  (2019-02-07) support utf8 filenames in Windows; fix warnings and platform ifdefs
      2.19  (2018-02-11) fix warning
      2.18  (2018-01-30) fix warnings
      2.17  (2018-01-29) bugfix, 1-bit BMP, 16-bitness query, fix warnings
      2.16  (2017-07-23) all functions have 16-bit variants; optimizations; bugfixes
      2.15  (2017-03-18) fix png-1,2,4; all Imagenet JPGs; no runtime SSE detection on GCC
      2.14  (2017-03-03) remove deprecated STBI_JPEG_OLD; fixes for Imagenet JPGs
      2.13  (2016-12-04) experimental 16-bit API, only for PNG so far; fixes
      2.12  (2016-04-02) fix typo in 2.11 PSD fix that caused crashes
      2.11  (2016-04-02) 16-bit PNGS; enable SSE2 in non-gcc x64
                         RGB-format JPEG; remove white matting in PSD;
                         allocate large structures on the stack;
                         correct channel count for PNG & BMP
      2.10  (2016-01-22) avoid warning introduced in 2.09
      2.09  (2016-01-16) 16-bit TGA; comments in PNM files; STBI_REALLOC_SIZED

   See end of file for full revision history.


 ============================    Contributors    =========================

 Image formats                          Extensions, features
    Sean Barrett (jpeg, png, bmp)          Jetro Lauha (stbi_info)
    Nicolas Schulz (hdr, psd)              Martin "SpartanJ" Golini (stbi_info)
    Jonathan Dummer (tga)                  James "moose2000" Brown (iPhone PNG)
    Jean-Marc Lienher (gif)                Ben "Disch" Wenger (io callbacks)
    Tom Seddon (pic)                       Omar Cornut (1/2/4-bit PNG)
    Thatcher Ulrich (psd)                  Nicolas Guillemot (vertical flip)
    Ken Miller (pgm, ppm)                  Richard Mitton (16-bit PSD)
    github:urraka (animated gif)           Junggon Kim (PNM comments)
    Christopher Forseth (animated gif)     Daniel Gibson (16-bit TGA)
                                           socks-the-fox (16-bit PNG)
                                           Jeremy Sawicki (handle all ImageNet JPGs)
 Optimizations & bugfixes                  Mikhail Morozov (1-bit BMP)
    Fabian "ryg" Giesen                    Anael Seghezzi (is-16-bit query)
    Arseny Kapoulkine                      Simon Breuss (16-bit PNM)
    John-Mark Allen
    Carmelo J Fdez-Aguera

 Bug & warning fixes
    Marc LeBlanc            David Woo          Guillaume George     Martins Mozeiko
    Christpher Lloyd        Jerry Jansson      Joseph Thomson       Blazej Dariusz Roszkowski
    Phil Jordan                                Dave Moore           Roy Eltham
    Hayaki Saito            Nathan Reed        Won Chun
    Luke Graham             Johan Duparc       Nick Verigakis       the Horde3D community
    Thomas Ruf              Ronny Chevalier                         github:rlyeh
    Janez Zemva             John Bartholomew   Michal Cichon        github:romigrou
    Jonathan Blow           Ken Hamada         Tero Hanninen        github:svdijk
    Eugene Golushkov        Laurent Gomila     Cort Stratton        github:snagar
    Aruelien Pocheville     Sergio Gonzalez    Thibault Reuille     github:Zelex
    Cass Everitt            Ryamond Barbiero                        github:grim210
    Paul Du Bois            Engin Manap        Aldo Culquicondor    github:sammyhw
    Philipp Wiesemann       Dale Weiler        Oriol Ferrer Mesia   github:phprus
    Josh Tobin                                 Matthew Gregan       github:poppolopoppo
    Julian Raschke          Gregory Mullen     Christian Floisand   github:darealshinji
    Baldur Karlsson         Kevin Schmidt      JR Smith             github:Michaelangel007
                            Brad Weinberger    Matvey Cherevko      github:mosra
    Luca Sas                Alexander Veselov  Zack Middleton       [reserved]
    Ryan C. Gordon          [reserved]                              [reserved]
                     DO NOT ADD YOUR NAME HERE

                     Jacko Dirks

  To add your name to the credits, pick a random blank space in the middle and fill it.
  80% of merge conflicts on stb PRs are due to people adding their name at the end
  of the credits.
*/
#ifndef STBI_INCLUDE_STB_IMAGE_H
#define STBI_INCLUDE_STB_IMAGE_H

// DOCUMENTATION
//
// Limitations:
//    - no 12-bit-per-channel JPEG
//    - no JPEGs with arithmetic coding
//    - GIF always returns *comp=4
//
// Basic usage (see HDR discussion below for HDR usage):
//    int x,y,n;
//    unsigned char *data = stbi_load(filename, &x, &y, &n, 0);
//    // ... process data if not NULL ...
//    // ... x = width, y = height, n = # 8-bit components per pixel ...
//    // ... replace '0' with '1'..'4' to force that many components per pixel
//    // ... but 'n' will always be the number that it would have been if you said 0
//    stbi_image_free(data)
//
// Standard parameters:
//    int *x                 -- outputs image width in pixels
//    int *y                 -- outputs image height in pixels
//    int *channels_in_file  -- outputs # of image components in image file
//    int desired_channels   -- if non-zero, # of image components requested in result
//
// The return value from an image loader is an 'unsigned char *' which points
// to the pixel data, or NULL on an allocation failure or if the image is
// corrupt or invalid. The pixel data consists of *y scanlines of *x pixels,
// with each pixel consisting of N interleaved 8-bit components; the first
// pixel pointed to is top-left-most in the image. There is no padding between
// image scanlines or between pixels, regardless of format. The number of
// components N is 'desired_channels' if desired_channels is non-zero, or
// *channels_in_file otherwise. If desired_channels is non-zero,
// *channels_in_file has the number of components that _would_ have been
// output otherwise. E.g. if you set desired_channels to 4, you will always
// get RGBA output, but you can check *channels_in_file to see if it's trivially
// opaque because e.g. there were only 3 channels in the source image.
//
// An output image with N components has the following components interleaved
// in this order in each pixel:
//
//     N=#comp     components
//       1           grey
//       2           grey, alpha
//       3           red, green, blue
//       4           red, green, blue, alpha
//
// If image loading fails for any reason, the return value will be NULL,
// and *x, *y, *channels_in_file will be unchanged. The function
// stbi_failure_reason() can be queried for an extremely brief, end-user
// unfriendly explanation of why the load failed. Define STBI_NO_FAILURE_STRINGS
// to avoid compiling these strings at all, and STBI_FAILURE_USERMSG to get slightly
// more user-friendly ones.
//
// Paletted PNG, BMP, GIF, and PIC images are automatically depalettized.
//
// To query the width, height and component count of an image without having to
// decode the full file, you can use the stbi_info family of functions:
//
//   int x,y,n,ok;
//   ok = stbi_info(filename, &x, &y, &n);
//   // returns ok=1 and sets x, y, n if image is a supported format,
//   // 0 otherwise.
//
// Note that stb_image pervasively uses ints in its public API for sizes,
// including sizes of memory buffers. This is now part of the API and thus
// hard to change without causing breakage. As a result, the various image
// loaders all have certain limits on image size; these differ somewhat
// by format but generally boil down to either just under 2GB or just under
// 1GB. When the decoded image would be larger than this, stb_image decoding
// will fail.
//
// Additionally, stb_image will reject image files that have any of their
// dimensions set to a larger value than the configurable STBI_MAX_DIMENSIONS,
// which defaults to 2**24 = 16777216 pixels. Due to the above memory limit,
// the only way to have an image with such dimensions load correctly
// is for it to have a rather extreme aspect ratio. Either way, the
// assumption here is that such larger images are likely to be malformed
// or malicious. If you do need to load an image with individual dimensions
// larger than that, and it still fits in the overall size limit, you can
// #define STBI_MAX_DIMENSIONS on your own to be something larger.
//
// ===========================================================================
//
// UNICODE:
//
//   If compiling for Windows and you wish to use Unicode filenames, compile
//   with
//       #define STBI_WINDOWS_UTF8
//   and pass utf8-encoded filenames. Call stbi_convert_wchar_to_utf8 to convert
//   Windows wchar_t filenames to utf8.
//
// ===========================================================================
//
// Philosophy
//
// stb libraries are designed with the following priorities:
//
//    1. easy to use
//    2. easy to maintain
//    3. good performance
//
// Sometimes I let "good performance" creep up in priority over "easy to maintain",
// and for best performance I may provide less-easy-to-use APIs that give higher
// performance, in addition to the easy-to-use ones. Nevertheless, it's important
// to keep in mind that from the standpoint of you, a client of this library,
// all you care about is #1 and #3, and stb libraries DO NOT emphasize #3 above all.
//
// Some secondary priorities arise directly from the first two, some of which
// provide more explicit reasons why performance can't be emphasized.
//
//    - Portable ("ease of use")
//    - Small source code footprint ("easy to maintain")
//    - No dependencies ("ease of use")
//
// ===========================================================================
//
// I/O callbacks
//
// I/O callbacks allow you to read from arbitrary sources, like packaged
// files or some other source. Data read from callbacks are processed
// through a small internal buffer (currently 128 bytes) to try to reduce
// overhead.
//
// The three functions you must define are "read" (reads some bytes of data),
// "skip" (skips some bytes of data), "eof" (reports if the stream is at the end).
//
// ===========================================================================
//
// SIMD support
//
// The JPEG decoder will try to automatically use SIMD kernels on x86 when
// supported by the compiler. For ARM Neon support, you must explicitly
// request it.
//
// (The old do-it-yourself SIMD API is no longer supported in the current
// code.)
//
// On x86, SSE2 will automatically be used when available based on a run-time
// test; if not, the generic C versions are used as a fall-back. On ARM targets,
// the typical path is to have separate builds for NEON and non-NEON devices
// (at least this is true for iOS and Android). Therefore, the NEON support is
// toggled by a build flag: define STBI_NEON to get NEON loops.
//
// If for some reason you do not want to use any of SIMD code, or if
// you have issues compiling it, you can disable it entirely by
// defining STBI_NO_SIMD.
//
// ===========================================================================
//
// HDR image support   (disable by defining STBI_NO_HDR)
//
// stb_image supports loading HDR images in general, and currently the Radiance
// .HDR file format specifically. You can still load any file through the existing
// interface; if you attempt to load an HDR file, it will be automatically remapped
// to LDR, assuming gamma 2.2 and an arbitrary scale factor defaulting to 1;
// both of these constants can be reconfigured through this interface:
//
//     stbi_hdr_to_ldr_gamma(2.2f);
//     stbi_hdr_to_ldr_scale(1.0f);
//
// (note, do not use _inverse_ constants; stbi_image will invert them
// appropriately).
//
// Additionally, there is a new, parallel interface for loading files as
// (linear) floats to preserve the full dynamic range:
//
//    float *data = stbi_loadf(filename, &x, &y, &n, 0);
//
// If you load LDR images through this interface, those images will
// be promoted to floating point values, run through the inverse of
// constants corresponding to the above:
//
//     stbi_ldr_to_hdr_scale(1.0f);
//     stbi_ldr_to_hdr_gamma(2.2f);
//
// Finally, given a filename (or an open file or memory block--see header
// file for details) containing image data, you can query for the "most
// appropriate" interface to use (that is, whether the image is HDR or
// not), using:
//
//     stbi_is_hdr(char *filename);
//
// ===========================================================================
//
// iPhone PNG support:
//
// We optionally support converting iPhone-formatted PNGs (which store
// premultiplied BGRA) back to RGB, even though they're internally encoded
// differently. To enable this conversion, call
// stbi_convert_iphone_png_to_rgb(1).
//
// Call stbi_set_unpremultiply_on_load(1) as well to force a divide per
// pixel to remove any premultiplied alpha *only* if the image file explicitly
// says there's premultiplied data (currently only happens in iPhone images,
// and only if iPhone convert-to-rgb processing is on).
//
// ===========================================================================
//
// ADDITIONAL CONFIGURATION
//
//  - You can suppress implementation of any of the decoders to reduce
//    your code footprint by #defining one or more of the following
//    symbols before creating the implementation.
//
//        STBI_NO_JPEG
//        STBI_NO_PNG
//        STBI_NO_BMP
//        STBI_NO_PSD
//        STBI_NO_TGA
//        STBI_NO_GIF
//        STBI_NO_HDR
//        STBI_NO_PIC
//        STBI_NO_PNM   (.ppm and .pgm)
//
//  - You can request *only* certain decoders and suppress all other ones
//    (this will be more forward-compatible, as addition of new decoders
//    doesn't require you to disable them explicitly):
//
//        STBI_ONLY_JPEG
//        STBI_ONLY_PNG
//        STBI_ONLY_BMP
//        STBI_ONLY_PSD
//        STBI_ONLY_TGA
//        STBI_ONLY_GIF
//        STBI_ONLY_HDR
//        STBI_ONLY_PIC
//        STBI_ONLY_PNM   (.ppm and .pgm)
//
//   - If you use STBI_NO_PNG (or _ONLY_ without PNG), and you still
//     want the zlib decoder to be available, #define STBI_SUPPORT_ZLIB
//
//  - If you define STBI_MAX_DIMENSIONS, stb_image will reject images greater
//    than that size (in either width or height) without further processing.
//    This is to let programs in the wild set an upper bound to prevent
//    denial-of-service attacks on untrusted data, as one could generate a
//    valid image of gigantic dimensions and force stb_image to allocate a
//    huge block of memory and spend disproportionate time decoding it. By
//    default this is set to (1 << 24), which is 16777216, but that's still
//    very big.

#ifndef STBI_NO_STDIO
#include <stdio.h>
#endif // STBI_NO_STDIO

#define STBI_VERSION 1

enum
{
   STBI_default = 0, // only used for desired_channels

   STBI_grey       = 1,
   STBI_grey_alpha = 2,
   STBI_rgb        = 3,
   STBI_rgb_alpha  = 4
};

#include <stdlib.h>
typedef unsigned char stbi_uc;
typedef unsigned short stbi_us;

#ifdef __cplusplus
extern "C" {
#endif

#ifndef STBIDEF
#ifdef STB_IMAGE_STATIC
#define STBIDEF static
#else
#define STBIDEF extern
#endif
#endif

//////////////////////////////////////////////////////////////////////////////
//
// PRIMARY API - works on images of any type
//

//
// load image by filename, open file, or memory buffer
//

typedef struct
{
   int      (*read)  (void *user,char *data,int size);   // fill 'data' with 'size' bytes.  return number of bytes actually read
   void     (*skip)  (void *user,int n);                 // skip the next 'n' bytes, or 'unget' the last -n bytes if negative
   int      (*eof)   (void *user);                       // returns nonzero if we are at end of file/data
} stbi_io_callbacks;

////////////////////////////////////
//
// 8-bits-per-channel interface
//

STBIDEF stbi_uc *stbi_load_from_memory   (stbi_uc           const *buffer, int len   , int *x, int *y, int *channels_in_file, int desired_channels);
STBIDEF stbi_uc *stbi_load_from_callbacks(stbi_io_callbacks const *clbk  , void *user, int *x, int *y, int *channels_in_file, int desired_channels);

#ifndef STBI_NO_STDIO
STBIDEF stbi_uc *stbi_load            (char const *filename, int *x, int *y, int *channels_in_file, int desired_channels);
STBIDEF stbi_uc *stbi_load_from_file  (FILE *f, int *x, int *y, int *channels_in_file, int desired_channels);
// for stbi_load_from_file, file pointer is left pointing immediately after image
#endif

#ifndef STBI_NO_GIF
STBIDEF stbi_uc *stbi_load_gif_from_memory(stbi_uc const *buffer, int len, int **delays, int *x, int *y, int *z, int *comp, int req_comp);
#endif

#ifdef STBI_WINDOWS_UTF8
STBIDEF int stbi_convert_wchar_to_utf8(char *buffer, size_t bufferlen, const wchar_t* input);
#endif

////////////////////////////////////
//
// 16-bits-per-channel interface
//

STBIDEF stbi_us *stbi_load_16_from_memory   (stbi_uc const *buffer, int len, int *x, int *y, int *channels_in_file, int desired_channels);
STBIDEF stbi_us *stbi_load_16_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *channels_in_file, int desired_channels);

#ifndef STBI_NO_STDIO
STBIDEF stbi_us *stbi_load_16          (char const *filename, int *x, int *y, int *channels_in_file, int desired_channels);
STBIDEF stbi_us *stbi_load_from_file_16(FILE *f, int *x, int *y, int *channels_in_file, int desired_channels);
#endif

////////////////////////////////////
//
// float-per-channel interface
//
#ifndef STBI_NO_LINEAR
   STBIDEF float *stbi_loadf_from_memory     (stbi_uc const *buffer, int len, int *x, int *y, int *channels_in_file, int desired_channels);
   STBIDEF float *stbi_loadf_from_callbacks  (stbi_io_callbacks const *clbk, void *user, int *x, int *y,  int *channels_in_file, int desired_channels);

   #ifndef STBI_NO_STDIO
   STBIDEF float *stbi_loadf            (char const *filename, int *x, int *y, int *channels_in_file, int desired_channels);
   STBIDEF float *stbi_loadf_from_file  (FILE *f, int *x, int *y, int *channels_in_file, int desired_channels);
   #endif
#endif

#ifndef STBI_NO_HDR
   STBIDEF void   stbi_hdr_to_ldr_gamma(float gamma);
   STBIDEF void   stbi_hdr_to_ldr_scale(float scale);
#endif // STBI_NO_HDR

#ifndef STBI_NO_LINEAR
   STBIDEF void   stbi_ldr_to_hdr_gamma(float gamma);
   STBIDEF void   stbi_ldr_to_hdr_scale(float scale);
#endif // STBI_NO_LINEAR

// stbi_is_hdr is always defined, but always returns false if STBI_NO_HDR
STBIDEF int    stbi_is_hdr_from_callbacks(stbi_io_callbacks const *clbk, void *user);
STBIDEF int    stbi_is_hdr_from_memory(stbi_uc const *buffer, int len);
#ifndef STBI_NO_STDIO
STBIDEF int      stbi_is_hdr          (char const *filename);
STBIDEF int      stbi_is_hdr_from_file(FILE *f);
#endif // STBI_NO_STDIO


// get a VERY brief reason for failure
// on most compilers (and ALL modern mainstream compilers) this is threadsafe
STBIDEF const char *stbi_failure_reason  (void);

// free the loaded image -- this is just free()
STBIDEF void     stbi_image_free      (void *retval_from_stbi_load);

// get image dimensions & components without fully decoding
STBIDEF int      stbi_info_from_memory(stbi_uc const *buffer, int len, int *x, int *y, int *comp);
STBIDEF int      stbi_info_from_callbacks(stbi_io_callbacks const *clbk, void *user, int *x, int *y, int *comp);
STBIDEF int      stbi_is_16_bit_from_memory(stbi_uc const *buffer, int len);
STBIDEF int      stbi_is_16_bit_from_callbacks(stbi_io_callbacks const *clbk, void *user);

#ifndef STBI_NO_STDIO
STBIDEF int      stbi_info               (char const *filename,     int *x, int *y, int *comp);
STBIDEF int      stbi_info_from_file     (FILE *f,                  int *x, int *y, int *comp);
STBIDEF int      stbi_is_16_bit          (char const *filename);
STBIDEF int      stbi_is_16_bit_from_file(FILE *f);
#endif



// for image formats that explicitly notate that they have premultiplied alpha,
// we just return the colors as stored in the file. set this flag to force
// unpremultiplication. results are undefined if the unpremultiply overflow.
STBIDEF void stbi_set_unpremultiply_on_load(int flag_true_if_should_unpremultiply);

// indicate whether we should process iphone images back to canonical format,
// or just pass them through "as-is"
STBIDEF void stbi_convert_iphone_png_to_rgb(int flag_true_if_should_convert);

// flip the image vertically, so the first pixel in the output array is the bottom left
STBIDEF void stbi_set_flip_vertically_on_load(int flag_true_if_should_flip);

// as above, but only applies to images loaded on the thread that calls the function
// this function is only available if your compiler supports thread-local variables;
// calling it will fail to link if your compiler doesn't
STBIDEF void stbi_set_unpremultiply_on_load_thread(int flag_true_if_should_unpremultiply);
STBIDEF void stbi_convert_iphone_png_to_rgb_thread(int flag_true_if_should_convert);
STBIDEF void stbi_set_flip_vertically_on_load_thread(int flag_true_if_should_flip);

// ZLIB client - used by PNG, available for other purposes

STBIDEF char *stbi_zlib_decode_malloc_guesssize(const char *buffer, int len, int initial_size, int *outlen);
STBIDEF char *stbi_zlib_decode_malloc_guesssize_headerflag(const char *buffer, int len, int initial_size, int *outlen, int parse_header);
STBIDEF char *stbi_zlib_decode_malloc(const char *buffer, int len, int *outlen);
STBIDEF int   stbi_zlib_decode_buffer(char *obuffer, int olen, const char *ibuffer, int ilen);

STBIDEF char *stbi_zlib_decode_noheader_malloc(const char *buffer, int len, int *outlen);
STBIDEF int   stbi_zlib_decode_noheader_buffer(char *obuffer, int olen, const char *ibuffer, int ilen);


#ifdef __cplusplus
}
#endif

//
//
////   end header file   /////////////////////////////////////////////////////
#endif // STBI_INCLUDE_STB_IMAGE_H