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pixels.h
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pixels.h
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/* 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 ;
void initLayer(struct xcfLayer *);
void 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 __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 /* everyting 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 *);
#endif /* FLATTEN_H */