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	cache.h - ledit - Text editor (WIP)
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	---
	cache.h (4471B)
	---
	1 #ifndef _CACHE_H_
	2 #define _CACHE_H_
	3
	4 #include <stddef.h>
	5 #include <X11/Xlib.h>
	6 #include <pango/pangoxft.h>
	7
	8 /*
	9 *The maximum number of layouts in the cache.
	10 */
	11 #define LAYOUT_CACHE_SIZE 40
	12
	13 /*
	14 * The initial number of pixmaps in the cache.
	15 * The size is increased when more pixmaps are visible
	16 * at the same time than there are entries in the cache.
	17 */
	18 #define PIXMAP_CACHE_INITIAL_SIZE 20
	19
	20 typedef struct {
	21 Pixmap pixmap;
	22 XftDraw *draw;
	23 int w, h; /* width and height of the pixmap */
	24 size_t line; /* the line associated with this entry */
	25 int valid; /* whether the entry is assigned to a line */
	26 } cache_pixmap;
	27
	28 typedef struct {
	29 PangoLayout *layout;
	30 size_t line; /* the line associated with this entry */
	31 int valid; /* whether the entry is assigned to a line */
	32 } cache_layout;
	33
	34 typedef struct {
	35 Display *dpy;
	36 cache_pixmap *pixmaps;
	37 cache_layout *layouts;
	38 size_t num_pixmaps;
	39 size_t num_layouts;
	40 size_t cur_pixmap_index; /* current replacement index for pixmap…
	41 size_t cur_layout_index; /* current replacement index for layout…
	42 } ledit_cache;
	43
	44 /* FIXME: maybe handle pixmap creation and resizing here */
	45
	46 /*
	47 * Create cache using X Display dpy (this is
	48 * needed to destroy the pixmaps in the end).
	49 */
	50 ledit_cache cache_create(Display dpy);
	51
	52 /*
	53 * Reset line index of every cache entry (pixmaps and layouts).
	54 * invalidate_pixmap_line is called with callback_data as its first
	55 * argument and a line index which has been removed from the pixmap
	56 * cache as the second argument.
	57 * invalidate_layout_line is the same, but for the layout cache.
	58 */
	59 void cache_flush(
	60 ledit_cache *cache,
	61 void *callback_data,
	62 void (invalidate_pixmap_line)(void , size_t),
	63 void (invalidate_layout_line)(void , size_t)
	64 );
	65
	66 /*
	67 * Like cache_flush, but only line numbers >= start are invalidated.
	68 */
	69 void cache_invalidate_from_line(
	70 ledit_cache *cache, size_t start,
	71 void *callback_data,
	72 void (invalidate_pixmap_line)(void , size_t),
	73 void (invalidate_layout_line)(void , size_t)
	74 );
	75
	76 /*
	77 * Destroy cache.
	78 */
	79 void cache_destroy(ledit_cache *cache);
	80
	81 /*
	82 * Get the cache_pixmap at index.
	83 */
	84 cache_pixmap cache_get_pixmap(ledit_cache cache, size_t index);
	85
	86 /*
	87 * Get the cache_layout at index.
	88 */
	89 cache_layout cache_get_layout(ledit_cache cache, size_t index);
	90
	91 /*
	92 * The following two functions have a somewhat cumbersome interface
	93 * because set_pixmap_line and set_layout_line are required as helper
	94 * functions instead of just returning the cache index and letting the
	95 * caller handle the updating. However, this has led to horrible bugs
	96 * in the past, when one of the updating steps was forgotten, so this
	97 * interface was designed instead to avoid some of those more basic bugs.
	98 */
	99
	100 /*
	101 * Assign an unneeded pixmap cache index to the line with index 'line'.
	102 * line_needed is used to check if a line is needed.
	103 * It is called with callback_data as the first argument and the
	104 * line to be checked as the second argument.
	105 * The line of the cache entry is set to 'line' and if a line was
	106 * set before, it is reset by calling 'invalidate_pixmap_line' with
	107 * 'callback_data' as the first argumentand the old line as the
	108 * second argument.
	109 * The cache index of the new line is changed by calling 'set_pixmap_lin…
	110 * with 'callback_data' as the first argument, 'line' as the second
	111 * argument, and the new cache index as the third argument.
	112 */
	113 void cache_assign_pixmap_index(
	114 ledit_cache *cache, size_t line,
	115 void *callback_data,
	116 int (line_needed)(void , size_t),
	117 void (set_pixmap_line)(void , size_t, size_t),
	118 void (invalidate_pixmap_line)(void , size_t)
	119 );
	120
	121 /*
	122 * Assign a layout cache index to the line with index 'line'.
	123 * Since it is not clear which layouts are needed more, this just
	124 * uses the next index in a clock fashion.
	125 * The line of the cache entry is set to 'line' and if a line was
	126 * set before, it is reset by calling 'invalidate_layout_line' with
	127 * 'callback_data' as the first argument and the old line as the
	128 * second argument.
	129 * The cache index of the new line is changed by calling 'set_layout_lin…
	130 * with 'callback_data' as the first argument, 'line' as the second
	131 * argument, and the new cache index as the third argument.
	132 */
	133 void cache_assign_layout_index(
	134 ledit_cache *cache, size_t line,
	135 void *callback_data,
	136 void (set_layout_line)(void , size_t, size_t),
	137 void (invalidate_layout_line)(void , size_t)
	138 );
	139
	140 #endif