src/resize.h

   1 /* resize.c - has all you need to get high-quality interpolated image scaling - up & down! */
   2 /* please see resize.c for more information about who has contributed to this library */
   3
   4 #ifndef __RESIZE_FILTERS__
   5 #define __RESIZE_FILTERS__
   6
   7 #include <SDL.h>
   8
   9 /* Here are the only 2 functions you need: */
  10 /* NULL will be returned if the passed in surface "image" is invalid */
  11 SDL_Surface* SDL_ResizeFactor(SDL_Surface *image, float scalefactor,    int filter);
  12 SDL_Surface* SDL_ResizeXY    (SDL_Surface *image, int new_w, int new_h, int filter);
  13
  14 /* Here are overloaded C++ versions, with filter default as high quality. */
  15 #ifdef __cplusplus
  16 SDL_Surface* SDL_Resize(SDL_Surface *image, float scalefactor,    int filter = 7);
  17 SDL_Surface* SDL_Resize(SDL_Surface *image, int new_w, int new_h, int filter = 7);
  18 #endif
  19
  20 /*The passed-in surface is freed by SDL_Resize, so it works nicely to pass in surfaces
  21   as themselves:
  22   e.g. pic = SDL_ResizeFactor(pic, 0.75, 7); (or pic = SDL_Resize(pic, 0.75);)
  23   This will shrink pic to 75% of original size. No other cleanup necessary.
  24   Another good way to use it is on initialization:
  25   e.g. SDL_Surface *pic = SDL_ResizeXY(SDL_LoadBMP("mypic.bmp"),50,50,7);
  26   This will give you mypic.png at size 50x50(regardless of original dimensions)
  27   if mypic.bmp did not load correctly, pic will be NULL.
  28 */
  29
  30 /*
  31 Filters are as follows:
  32 1 = box filter - fastest/ugliest.
  33 2 =     triangle filter - possible visual anomalies
  34 3 = bell filter - possible visual anomalies
  35 4 = B_spline filter - here is where it starts to get good.
  36 5 =     hermite filter - relatively fast, good quality
  37 6 =     Mitchell filter - also speedy, good quality
  38 7 = Lanczos3 filter - slowest, but by far best quality. Very sharp!
  39 If filter is not specified, Lanczos3 will be selected by default
  40 */
  41
  42 /*The code should compile as either C or C++, without any fuss, except maybe you specifying
  43   which kind to compile it as... -Dave Olsen
  44 */
  45
  46 #endif