Update to STB conventions

stb_image.h

@@ -6336,8 +6336,9 @@ static stbi_uc *stbi__process_gif_raster(stbi__context *s, stbi__gif *g)
 
 // this function is designed to support animated gifs, although stb_image doesn't support it
 // two back is the image from two frames ago, used for a very specific disposal format
-static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int, stbi_uc *two_back)
+static stbi_uc *stbi__gif_load_next(stbi__context *s, stbi__gif *g, int *comp, int req_comp, stbi_uc *two_back)
 {
+   STBI_NOTUSED(req_comp);
    int dispose; 
    int first_frame; 
    int pi; 
@@ -6560,8 +6561,9 @@ static void *stbi__load_gif_main(stbi__context *s, int **delays, int *x, int *y,
    }
 }
 
-static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *)
+static void *stbi__gif_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri)
 {
+   STBI_NOTUSED(ri);
    stbi_uc *u = 0;
    stbi__gif g;
    memset(&g, 0, sizeof(g));

stb_image_write.h

@@ -985,14 +985,14 @@ static unsigned char stbiw__paeth(int a, int b, int c)
 }
 
 // @OPTIMIZE: provide an option that always forces left-predict or paeth predict
-static void stbiw__encode_png_line(const unsigned char *pixels, int stride_bytes, int width, int height, int y, int n, int filter_type, signed char *line_buffer)
+static void stbiw__encode_png_line(unsigned char *pixels, int stride_bytes, int width, int height, int y, int n, int filter_type, signed char *line_buffer)
 {
    static int mapping[] = { 0,1,2,3,4 };
    static int firstmap[] = { 0,1,0,5,6 };
    int *mymap = (y != 0) ? mapping : firstmap;
    int i;
    int type = mymap[filter_type];
-   const unsigned char *z = pixels + stride_bytes * (stbi__flip_vertically_on_write ? height-1-y : y);
+   unsigned char *z = pixels + stride_bytes * (stbi__flip_vertically_on_write ? height-1-y : y);
    int signed_stride = stbi__flip_vertically_on_write ? -stride_bytes : stride_bytes;
    for (i = 0; i < n; ++i) {
       switch (type) {
@@ -1040,11 +1040,11 @@ unsigned char *stbi_write_png_to_mem(const unsigned char *pixels, int stride_byt
       int filter_type;
       if (force_filter > -1) {
          filter_type = force_filter;
-         stbiw__encode_png_line(pixels, stride_bytes, x, y, j, n, force_filter, line_buffer);
+         stbiw__encode_png_line(const_cast<unsigned char*>(pixels), stride_bytes, x, y, j, n, force_filter, line_buffer);
       } else { // Estimate the best filter by running through all of them:
          int best_filter = 0, best_filter_val = 0x7fffffff, est, i;
          for (filter_type = 0; filter_type < 5; filter_type++) {
-            stbiw__encode_png_line(pixels, stride_bytes, x, y, j, n, filter_type, line_buffer);
+            stbiw__encode_png_line(const_cast<unsigned char*>(pixels), stride_bytes, x, y, j, n, filter_type, line_buffer);
 
             // Estimate the entropy of the line using this filter; the less, the better.
             est = 0;
@@ -1057,7 +1057,7 @@ unsigned char *stbi_write_png_to_mem(const unsigned char *pixels, int stride_byt
             }
          }
          if (filter_type != best_filter) {  // If the last iteration already got us the best filter, don't redo it
-            stbiw__encode_png_line(pixels, stride_bytes, x, y, j, n, best_filter, line_buffer);
+            stbiw__encode_png_line(const_cast<unsigned char*>(pixels), stride_bytes, x, y, j, n, best_filter, line_buffer);
             filter_type = best_filter;
          }
       }