File indexing completed on 2025-03-09 04:09:53

 /* Pixel and tile functions for xcftools
  *
  * This file was written by Henning Makholm <henning@makholm.net>
  * It is hereby in the public domain.
  * 
  * In jurisdictions that do not recognise grants of copyright to the
  * public domain: I, the author and (presumably, in those jurisdictions)
  * copyright holder, hereby permit anyone to distribute and use this code,
  * in source code or binary form, with or without modifications. This
  * permission is world-wide and irrevocable.
  *
  * Of course, I will not be liable for any errors or shortcomings in the
  * code, since I give it away without asking any compenstations.
  *
  * If you use or distribute this code, I would appreciate receiving
  * credit for writing it, in whichever way you find proper and customary.
  */
 
 #ifndef PIXELS_H
 #define PIXELS_H
 
 #include "xcftools.h"
 
 /* MACROS FOR INTERNAL PIXEL ORDERING HERE */
 /*=========================================*/
 /* In principle the internal representation of pixels may change.
  * - this was supposed to allow an optimization where a layer could
  * be represented as a pointer into the mmapped xcf file, if
  * alignment, bpp, and endianness agreed (the point was that the
  * pixel representation had to agree with the endianness).
  *
  * However, it turns out that the current Gimp _always_ saves images
  * with RLE encoding of tiles, so such an effort would be in vain.
  *
  * Just for modularity, nevertheless try to isolate knowledge of
  * the RGBA-to-machine-word packing in this section of the
  * header file. Define new macros if necessary.
  *
  * Given that we don't have to agree with the uncompressed
  * RLE format, we choose to have the alpha in the _least_
  * significant byte on all archs - it is tested and used more
  * often than the visible channels.
  */
 typedef uint32_t rgba ;
 
 #define ALPHA_SHIFT 0
 #define RED_SHIFT 8
 #define GREEN_SHIFT 16
 #define BLUE_SHIFT 24
 
 #define ALPHA(rgba) ((uint8_t)(rgba))
 #define FULLALPHA(rgba) ((uint8_t)(rgba) == 255)
 #define NULLALPHA(rgba) ((uint8_t)(rgba) == 0)
 #define NEWALPHA(rgb,a) (((rgba)(rgb) & 0xFFFFFF00) + (a))
 
 #ifdef PRECOMPUTED_SCALETABLE
 extern const uint8_t scaletable[256][256] ;
 #define INIT_SCALETABLE_IF(foo) ((void)0)
 #else
 extern uint8_t scaletable[256][256] ;
 extern int ok_scaletable ;
 void mk_scaletable(void);
 #define INIT_SCALETABLE_IF(foo) \
              (ok_scaletable || !(foo) || (mk_scaletable(),0) )
 #endif
 
 extern const rgba graytable[256] ;
 extern rgba colormap[256] ;
 extern unsigned colormapLength ;
 int initLayer(struct xcfLayer *);
 int initColormap();
 
 int degrayPixel(rgba); /* returns -1 for non-gray pixels */
 
 /* ******************************************************* */
 
 #define TILEXn(dim,tx) \
     ((tx)==(dim).tilesx ? (dim).c.r : (dim).c.l + ((tx)*TILE_WIDTH))
 #define TILEYn(dim,ty) \
     ((ty)==(dim).tilesy ? (dim).c.b : (dim).c.t + ((ty)*TILE_HEIGHT))
 
 #if defined(__i386__)
 /* This is probably the only common architecture where small constants
  * are more efficient for byte operations.
  */
 typedef int8_t summary_t ;
 typedef short int refcount_t ;
 #else
 typedef int summary_t ;
 typedef int refcount_t ;
 #endif
 
 #define TILESUMMARY_UPTODATE 8
 #define TILESUMMARY_ALLNULL 4
 #define TILESUMMARY_ALLFULL 2
 #define TILESUMMARY_CRISP   1 /* everything either null or full */
 struct Tile {
   refcount_t refcount ;
   summary_t summary ; /* a combination of TIMESUMMARY_FOO constatns */
   unsigned count ;
   rgba pixels[TILE_WIDTH * TILE_HEIGHT];
 };
 /* Actually, the Tile structures that get allocated many not have
  * room for that many pixels. We subtract the space for those we don't
  * use - which is Not Legal C, but ought to be portable.
  *  OTOH, one can also use a static struct Tile for temporary storage.
  */
 
 
 #define assertTileCompatibility(t1,t2) assert((t1)->count==(t2)->count)
 
 struct Tile *newTile(struct rect);
 struct Tile *forkTile(struct Tile*);
 void freeTile(struct Tile*);
 #define invalidateSummary(tile,mask) \
   do{ assert((tile)->refcount==1); (tile)->summary &= mask; } while(0)
 summary_t __ATTRIBUTE__((pure)) tileSummary(struct Tile *);
 
 void fillTile(struct Tile*,rgba);
 
 /* applyMask() destructively changes tile,
  * applyMask() gets ownership of mask
  */
 void applyMask(struct Tile *tile, struct Tile *mask);
 
 struct Tile *getLayerTile(struct xcfLayer *,const struct rect *);
 
 struct Tile * getMaskOrLayerTile(struct tileDimensions *dim, struct xcfTiles *tiles, struct rect want);
 
 #endif /* FLATTEN_H */