mirror of https://github.com/nothings/stb.git
Add support for writing through callback functions in stb_image_write.h.
Emmanuel Julien
parent
a7c8694d69
commit
529d8163b2
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@ -19,16 +19,23 @@ ABOUT:
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The PNG output is not optimal; it is 20-50% larger than the file
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written by a decent optimizing implementation. This library is designed
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for source code compactness and simplicitly, not optimal image file size
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for source code compactness and simplicity, not optimal image file size
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or run-time performance.
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USAGE:
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There are three functions, one for each image file format:
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There are functions for each image file format and output method:
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int stbi_write_png(char const *filename, int w, int h, int comp, const void *data, int stride_in_bytes);
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int stbi_write_bmp(char const *filename, int w, int h, int comp, const void *data);
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int stbi_write_tga(char const *filename, int w, int h, int comp, const void *data);
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int stbi_write_png_to_file(char const *filename, int x, int y, int comp, const void *data, int stride_bytes);
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int stbi_write_bmp_to_file(char const *filename, int x, int y, int comp, const void *data);
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int stbi_write_tga_to_file(char const *filename, int x, int y, int comp, const void *data);
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int stbi_write_png_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data, int stride_bytes);
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int stbi_write_bmp_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data);
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int stbi_write_tga_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data);
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You can define STBI_WRITE_NO_STDIO to disable the file variant of these
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functions.
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Each function returns 0 on failure and non-0 on success.
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@ -51,6 +58,16 @@ USAGE:
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formats do not. (Thus you cannot write a native-format BMP through the BMP
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writer, both because it is in BGR order and because it may have padding
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at the end of the line.)
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===========================================================================
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I/O callbacks
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I/O callbacks allow you to write to arbitrary sources, like packaged
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files or some other source.
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The function you must define is "write" (writes some bytes of data).
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*/
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#ifndef INCLUDE_STB_IMAGE_WRITE_H
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@ -60,9 +77,22 @@ USAGE:
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extern "C" {
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#endif
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extern int stbi_write_png(char const *filename, int w, int h, int comp, const void *data, int stride_in_bytes);
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extern int stbi_write_bmp(char const *filename, int w, int h, int comp, const void *data);
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extern int stbi_write_tga(char const *filename, int w, int h, int comp, const void *data);
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typedef struct
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{
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int (*write) (void *user,void *data,int size); // write 'size' bytes from 'data'. return number of bytes actually written
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} stbi_io_write_callbacks;
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extern int stbi_write_png_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data, int stride_bytes);
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extern int stbi_write_bmp_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data);
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extern int stbi_write_tga_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data);
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#ifndef STBI_WRITE_NO_STDIO
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extern int stbi_write_png_to_file(char const *filename, int x, int y, int comp, const void *data, int stride_bytes);
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extern int stbi_write_bmp_to_file(char const *filename, int x, int y, int comp, const void *data);
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extern int stbi_write_tga_to_file(char const *filename, int x, int y, int comp, const void *data);
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#endif // !STBI_WRITE_NO_STDIO
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#ifdef __cplusplus
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}
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@ -72,28 +102,68 @@ extern int stbi_write_tga(char const *filename, int w, int h, int comp, const vo
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#ifdef STB_IMAGE_WRITE_IMPLEMENTATION
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#ifndef STBI_WRITE_NO_STDIO
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#include <stdio.h>
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#endif // STBI_WRITE_NO_STDIO
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#include <stdarg.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <assert.h>
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typedef struct
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{
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stbi_io_write_callbacks io;
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void *io_user_data;
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} stbi__write_context;
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// initialize a callback-based context
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static void stbi__start_write_callbacks(stbi__write_context *s, stbi_io_write_callbacks const *c, void *user)
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{
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s->io = *c;
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s->io_user_data = user;
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}
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#ifndef STBI_WRITE_NO_STDIO
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static int stbi__stdio_write(void *user, void *data, int size)
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{
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return (int) fwrite(data,1,size,(FILE*) user);
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}
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static stbi_io_write_callbacks stbi__stdio_write_callbacks =
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{
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stbi__stdio_write
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};
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static void stbi__start_write_file(stbi__write_context *s, const char *filename)
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{
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FILE *f = fopen(filename, "wb");
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stbi__start_write_callbacks(s, &stbi__stdio_write_callbacks, (void *) f);
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}
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static void stbi__end_write_file(stbi__write_context *s)
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{
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fclose((FILE *)s->io_user_data);
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}
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#endif // !STBI_WRITE_NO_STDIO
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typedef unsigned int stbiw_uint32;
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typedef int stb_image_write_test[sizeof(stbiw_uint32)==4 ? 1 : -1];
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static void writefv(FILE *f, const char *fmt, va_list v)
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static void writefv(stbi__write_context const *s, const char *fmt, va_list v)
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{
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while (*fmt) {
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switch (*fmt++) {
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case ' ': break;
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case '1': { unsigned char x = (unsigned char) va_arg(v, int); fputc(x,f); break; }
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case '1': { unsigned char x = (unsigned char) va_arg(v, int); s->io.write(s->io_user_data,&x,1); break; }
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case '2': { int x = va_arg(v,int); unsigned char b[2];
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b[0] = (unsigned char) x; b[1] = (unsigned char) (x>>8);
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fwrite(b,2,1,f); break; }
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s->io.write(s->io_user_data,b,2); break; }
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case '4': { stbiw_uint32 x = va_arg(v,int); unsigned char b[4];
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b[0]=(unsigned char)x; b[1]=(unsigned char)(x>>8);
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b[2]=(unsigned char)(x>>16); b[3]=(unsigned char)(x>>24);
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fwrite(b,4,1,f); break; }
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s->io.write(s->io_user_data,b,4); break; }
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default:
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assert(0);
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return;
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@ -101,14 +171,14 @@ static void writefv(FILE *f, const char *fmt, va_list v)
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}
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}
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static void write3(FILE *f, unsigned char a, unsigned char b, unsigned char c)
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static void write3(stbi__write_context const *s, unsigned char a, unsigned char b, unsigned char c)
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{
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unsigned char arr[3];
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arr[0] = a, arr[1] = b, arr[2] = c;
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fwrite(arr, 3, 1, f);
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s->io.write(s->io_user_data, arr, 3);
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}
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static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad)
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static void write_pixels(stbi__write_context const *s, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad)
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{
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unsigned char bg[3] = { 255, 0, 255}, px[3];
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stbiw_uint32 zero = 0;
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@ -126,65 +196,100 @@ static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp,
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for (i=0; i < x; ++i) {
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unsigned char *d = (unsigned char *) data + (j*x+i)*comp;
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if (write_alpha < 0)
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fwrite(&d[comp-1], 1, 1, f);
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s->io.write(s->io_user_data, &d[comp-1], 1);
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switch (comp) {
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case 1:
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case 2: fwrite(d, 1, 1, f);
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case 2: s->io.write(s->io_user_data, d, 1);
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break;
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case 4:
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if (!write_alpha) {
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// composite against pink background
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for (k=0; k < 3; ++k)
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px[k] = bg[k] + ((d[k] - bg[k]) * d[3])/255;
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write3(f, px[1-rgb_dir],px[1],px[1+rgb_dir]);
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write3(s, px[1-rgb_dir],px[1],px[1+rgb_dir]);
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break;
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}
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/* FALLTHROUGH */
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case 3:
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write3(f, d[1-rgb_dir],d[1],d[1+rgb_dir]);
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write3(s, d[1-rgb_dir],d[1],d[1+rgb_dir]);
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break;
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}
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if (write_alpha > 0)
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fwrite(&d[comp-1], 1, 1, f);
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s->io.write(s->io_user_data, &d[comp-1], 1);
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}
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fwrite(&zero,scanline_pad,1,f);
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s->io.write(s->io_user_data,&zero,scanline_pad);
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}
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}
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static int outfile(char const *filename, int rgb_dir, int vdir, int x, int y, int comp, void *data, int alpha, int pad, const char *fmt, ...)
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static int outfile(stbi__write_context const *s, int rgb_dir, int vdir, int x, int y, int comp, void *data, int alpha, int pad, const char *fmt, ...)
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{
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FILE *f;
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if (y < 0 || x < 0) return 0;
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f = fopen(filename, "wb");
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if (f) {
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va_list v;
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va_start(v, fmt);
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writefv(f, fmt, v);
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va_end(v);
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write_pixels(f,rgb_dir,vdir,x,y,comp,data,alpha,pad);
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fclose(f);
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}
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return f != NULL;
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va_list v;
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va_start(v, fmt);
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writefv(s, fmt, v);
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va_end(v);
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write_pixels(s,rgb_dir,vdir,x,y,comp,data,alpha,pad);
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return 1;
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}
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int stbi_write_bmp(char const *filename, int x, int y, int comp, const void *data)
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int stbi_write_bmp(stbi__write_context const *s, int x, int y, int comp, const void *data)
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{
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int pad = (-x*3) & 3;
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return outfile(filename,-1,-1,x,y,comp,(void *) data,0,pad,
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return outfile(s,-1,-1,x,y,comp,(void *) data,0,pad,
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"11 4 22 4" "4 44 22 444444",
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'B', 'M', 14+40+(x*3+pad)*y, 0,0, 14+40, // file header
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40, x,y, 1,24, 0,0,0,0,0,0); // bitmap header
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}
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int stbi_write_tga(char const *filename, int x, int y, int comp, const void *data)
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int stbi_write_bmp_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data)
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{
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stbi__write_context s;
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stbi__start_write_callbacks(&s, clbk, user);
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return stbi_write_bmp(&s, x, y, comp, data);
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}
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#ifndef STBI_WRITE_NO_STDIO
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int stbi_write_bmp_to_file(char const *filename, int x, int y, int comp, const void *data)
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{
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stbi__write_context s;
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stbi__start_write_file(&s,filename);
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int r = stbi_write_bmp(&s, x, y, comp, data);
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stbi__end_write_file(&s);
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return r;
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}
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#endif //!STBI_WRITE_NO_STDIO
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int stbi_write_tga(stbi__write_context const *s, int x, int y, int comp, const void *data)
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{
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int has_alpha = (comp == 2 || comp == 4);
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int colorbytes = has_alpha ? comp-1 : comp;
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int format = colorbytes < 2 ? 3 : 2; // 3 color channels (RGB/RGBA) = 2, 1 color channel (Y/YA) = 3
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return outfile(filename, -1,-1, x, y, comp, (void *) data, has_alpha, 0,
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return outfile(s, -1,-1, x, y, comp, (void *) data, has_alpha, 0,
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"111 221 2222 11", 0,0,format, 0,0,0, 0,0,x,y, (colorbytes+has_alpha)*8, has_alpha*8);
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}
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int stbi_write_tga_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data)
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{
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stbi__write_context s;
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stbi__start_write_callbacks(&s, clbk, user);
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return stbi_write_tga(&s, x, y, comp, data);
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}
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#ifndef STBI_WRITE_NO_STDIO
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int stbi_write_tga_to_file(char const *filename, int x, int y, int comp, const void *data)
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{
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stbi__write_context s;
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stbi__start_write_file(&s,filename);
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int r = stbi_write_tga(&s, x, y, comp, data);
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stbi__end_write_file(&s);
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return r;
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}
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#endif //!STBI_WRITE_NO_STDIO
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// stretchy buffer; stbiw__sbpush() == vector<>::push_back() -- stbiw__sbcount() == vector<>::size()
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#define stbiw__sbraw(a) ((int *) (a) - 2)
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#define stbiw__sbm(a) stbiw__sbraw(a)[0]
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@ -490,19 +595,35 @@ unsigned char *stbi_write_png_to_mem(unsigned char *pixels, int stride_bytes, in
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return out;
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}
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int stbi_write_png(char const *filename, int x, int y, int comp, const void *data, int stride_bytes)
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int stbi_write_png(stbi__write_context const *s, int x, int y, int comp, const void *data, int stride_bytes)
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{
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FILE *f;
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int len;
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unsigned char *png = stbi_write_png_to_mem((unsigned char *) data, stride_bytes, x, y, comp, &len);
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if (!png) return 0;
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f = fopen(filename, "wb");
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if (!f) { free(png); return 0; }
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fwrite(png, 1, len, f);
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fclose(f);
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int r = s->io.write(s->io_user_data, png, len);
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free(png);
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return 1;
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return r;
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}
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int stbi_write_png_to_callbacks(stbi_io_write_callbacks const *clbk, void *user, int x, int y, int comp, const void *data, int stride_bytes)
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{
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stbi__write_context s;
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stbi__start_write_callbacks(&s, clbk, user);
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return stbi_write_png(&s, x, y, comp, data, stride_bytes);
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}
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#ifndef STBI_WRITE_NO_STDIO
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int stbi_write_png_to_file(char const *filename, int x, int y, int comp, const void *data, int stride_bytes)
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{
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stbi__write_context s;
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stbi__start_write_file(&s,filename);
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int r = stbi_write_png(&s, x, y, comp, data, stride_bytes);
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stbi__end_write_file(&s);
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return r;
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}
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#endif //!STBI_WRITE_NO_STDIO
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#endif // STB_IMAGE_WRITE_IMPLEMENTATION
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/* Revision history
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