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+ − 1 /* Efficient caching of Gtk GCs (graphics contexts).
+ − 2 Copyright (C) 1993 Free Software Foundation, Inc.
+ − 3 Copyright (C) 1994, 1995 Board of Trustees, University of Illinois.
+ − 4
+ − 5 This file is part of XEmacs.
+ − 6
+ − 7 XEmacs is free software; you can redistribute it and/or modify it
+ − 8 under the terms of the GNU General Public License as published by the
+ − 9 Free Software Foundation; either version 2, or (at your option) any
+ − 10 later version.
+ − 11
+ − 12 XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ − 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ − 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ − 15 for more details.
+ − 16
+ − 17 You should have received a copy of the GNU General Public License
+ − 18 along with XEmacs; see the file COPYING. If not, write to
+ − 19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ − 20 Boston, MA 02111-1307, USA. */
+ − 21
+ − 22 /* Synched up with: Not in FSF. */
+ − 23
+ − 24 /* Emacs uses a lot of different display attributes; for example, assume
+ − 25 that only four fonts are in use (normal, bold, italic, and bold-italic).
+ − 26 Then assume that one stipple or background is used for text selections,
+ − 27 and another is used for highlighting mousable regions. That makes 16
+ − 28 GCs already. Add in the fact that another GC may be needed to display
+ − 29 the text cursor in any of those regions, and you've got 32. Add in
+ − 30 more fonts, and it keeps increasing exponentially.
+ − 31
+ − 32 We used to keep these GCs in a cache of merged (fully qualified) faces.
+ − 33 However, a lot of other code in xterm.c used XChangeGC of existing GCs,
+ − 34 which is kind of slow and kind of random. Also, managing the face cache
+ − 35 was tricky because it was hard to know when a face was no longer visible
+ − 36 on the frame -- we had to mark all frames as garbaged whenever a face
+ − 37 was changed, which caused an unpleasant amount of flicker (since faces are
+ − 38 created/destroyed (= changed) whenever a frame is created/destroyed.
+ − 39
+ − 40 So this code maintains a cache at the GC level instead of at the face
+ − 41 level. There is an upper limit on the size of the cache, after which we
+ − 42 will stop creating GCs and start reusing them (reusing the least-recently-
+ − 43 used ones first). So if faces get changed, their GCs will eventually be
+ − 44 recycled. Also more sharing of GCs is possible.
+ − 45
+ − 46 This code uses hashtables. It could be that, if the cache size is small
+ − 47 enough, a linear search might be faster; but I doubt it, since we need
+ − 48 `equal' comparisons, not `eq', and I expect that the optimal cache size
+ − 49 will be ~100.
+ − 50
+ − 51 Written by jwz, 14 jun 93
+ − 52 Hacked by William Perry, apr 2000
+ − 53 */
+ − 54
+ − 55 #include <config.h>
+ − 56 #include <gtk/gtk.h>
+ − 57 #include "lisp.h"
+ − 58 #include "gccache-gtk.h"
+ − 59
+ − 60 #define GC_CACHE_SIZE 100
+ − 61
+ − 62 #define GCCACHE_HASH
+ − 63
+ − 64 #ifdef GCCACHE_HASH
+ − 65 #include "lisp.h"
+ − 66 #include "hash.h"
+ − 67 #endif
+ − 68
+ − 69 struct gcv_and_mask {
+ − 70 GdkGCValues gcv;
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+ − 71 unsigned long mask; /* contains a GdkGCValuesMask bitmask. */
462
+ − 72 };
+ − 73
+ − 74 struct gc_cache_cell {
+ − 75 GdkGC *gc;
+ − 76 struct gcv_and_mask gcvm;
+ − 77 struct gc_cache_cell *prev, *next;
+ − 78 };
+ − 79
+ − 80 struct gc_cache {
+ − 81 GdkWindow *window; /* used only as arg to XCreateGC */
+ − 82 int size;
+ − 83 struct gc_cache_cell *head;
+ − 84 struct gc_cache_cell *tail;
+ − 85 #ifdef GCCACHE_HASH
+ − 86 struct hash_table * table;
+ − 87 #endif
+ − 88
+ − 89 int create_count;
+ − 90 int delete_count;
+ − 91 };
+ − 92
+ − 93 #ifdef GCCACHE_HASH
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+ − 94 static Hashcode
462
+ − 95 gc_cache_hash (const void *arg)
+ − 96 {
+ − 97 const struct gcv_and_mask *gcvm = (const struct gcv_and_mask *) arg;
+ − 98 unsigned long *longs = (unsigned long *) &gcvm->gcv;
2515
+ − 99 Hashcode hash = gcvm->mask;
778
+ − 100 unsigned int i;
462
+ − 101 /* This could look at the mask and only use the used slots in the
+ − 102 hash code. That would win in that we wouldn't have to initialize
+ − 103 every slot of the gcv when calling gc_cache_lookup. But we need
+ − 104 the hash function to be as fast as possible; some timings should
+ − 105 be done. */
+ − 106 for (i = 0; i < (sizeof (GdkGCValues) / sizeof (unsigned long)); i++)
2515
+ − 107 hash = (hash << 1) ^ *longs++;
462
+ − 108 return hash;
+ − 109 }
+ − 110
+ − 111 #endif /* GCCACHE_HASH */
+ − 112
+ − 113 static int
+ − 114 gc_cache_eql (const void *arg1, const void *arg2)
+ − 115 {
+ − 116 /* See comment in gc_cache_hash */
+ − 117 const struct gcv_and_mask *gcvm1 = (const struct gcv_and_mask *) arg1;
+ − 118 const struct gcv_and_mask *gcvm2 = (const struct gcv_and_mask *) arg2;
+ − 119
+ − 120 return !memcmp(&gcvm1->gcv, &gcvm2->gcv, sizeof(gcvm1->gcv))
+ − 121 && gcvm1->mask == gcvm2->mask;
+ − 122 }
+ − 123
+ − 124 struct gc_cache *
+ − 125 make_gc_cache (GtkWidget *widget)
+ − 126 {
+ − 127 struct gc_cache *cache = xnew (struct gc_cache);
+ − 128 cache->window = widget->window;
+ − 129 cache->size = 0;
+ − 130 cache->head = cache->tail = 0;
+ − 131 cache->create_count = cache->delete_count = 0;
+ − 132 #ifdef GCCACHE_HASH
+ − 133 cache->table =
+ − 134 make_general_hash_table (GC_CACHE_SIZE, gc_cache_hash, gc_cache_eql);
+ − 135 #endif
+ − 136 return cache;
+ − 137 }
+ − 138
+ − 139 void
+ − 140 free_gc_cache (struct gc_cache *cache)
+ − 141 {
+ − 142 struct gc_cache_cell *rest, *next;
+ − 143 rest = cache->head;
+ − 144 while (rest)
+ − 145 {
+ − 146 gdk_gc_destroy(rest->gc);
+ − 147 next = rest->next;
1726
+ − 148 xfree (rest, struct gc_cache_cell *);
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+ − 149 rest = next;
+ − 150 }
+ − 151 #ifdef GCCACHE_HASH
+ − 152 free_hash_table (cache->table);
+ − 153 #endif
1726
+ − 154 xfree (cache, struct gc_cache *);
462
+ − 155 }
+ − 156
+ − 157 GdkGC *
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+ − 158 gc_cache_lookup (struct gc_cache *cache, GdkGCValues *gcv, unsigned long mask)
462
+ − 159 {
+ − 160 struct gc_cache_cell *cell, *next, *prev;
+ − 161 struct gcv_and_mask gcvm;
+ − 162
2500
+ − 163 if ((!!cache->head) != (!!cache->tail)) ABORT ();
+ − 164 if (cache->head && (cache->head->prev || cache->tail->next)) ABORT ();
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+ − 165
+ − 166 /* Gdk does not have the equivalent of 'None' for the clip_mask, so
+ − 167 we need to check it carefully, or gdk_gc_new_with_values will
+ − 168 coredump */
+ − 169 if ((mask & GDK_GC_CLIP_MASK) && !gcv->clip_mask)
+ − 170 {
+ − 171 mask &= ~GDK_GC_CLIP_MASK;
+ − 172 }
+ − 173
+ − 174 gcvm.mask = mask;
+ − 175 gcvm.gcv = *gcv; /* this copies... */
+ − 176
+ − 177 #ifdef GCCACHE_HASH
+ − 178
+ − 179 if (gethash (&gcvm, cache->table, (const void **) &cell))
+ − 180
+ − 181 #else /* !GCCACHE_HASH */
+ − 182
+ − 183 cell = cache->tail; /* start at the end (most recently used) */
+ − 184 while (cell)
+ − 185 {
+ − 186 if (gc_cache_eql (&gcvm, &cell->gcvm))
+ − 187 break;
+ − 188 else
+ − 189 cell = cell->prev;
+ − 190 }
+ − 191
+ − 192 /* #### This whole file needs some serious overhauling. */
+ − 193 if (!(mask | GDK_GC_TILE) && cell->gcvm.gcv.tile)
+ − 194 cell = 0;
+ − 195 else if (!(mask | GDK_GC_STIPPLE) && cell->gcvm.gcv.stipple)
+ − 196 cell = 0;
+ − 197
+ − 198 if (cell)
+ − 199
+ − 200 #endif /* !GCCACHE_HASH */
+ − 201
+ − 202 {
+ − 203 /* Found a cell. Move this cell to the end of the list, so that it
+ − 204 will be less likely to be collected than a cell that was accessed
+ − 205 less recently.
+ − 206 */
+ − 207 if (cell == cache->tail)
+ − 208 return cell->gc;
+ − 209
+ − 210 next = cell->next;
+ − 211 prev = cell->prev;
+ − 212 if (prev) prev->next = next;
+ − 213 if (next) next->prev = prev;
+ − 214 if (cache->head == cell) cache->head = next;
+ − 215 cell->next = 0;
+ − 216 cell->prev = cache->tail;
+ − 217 cache->tail->next = cell;
+ − 218 cache->tail = cell;
2500
+ − 219 if (cache->head == cell) ABORT ();
+ − 220 if (cell->next) ABORT ();
+ − 221 if (cache->head->prev) ABORT ();
+ − 222 if (cache->tail->next) ABORT ();
462
+ − 223 return cell->gc;
+ − 224 }
+ − 225
+ − 226 /* else, cache miss. */
+ − 227
+ − 228 if (cache->size == GC_CACHE_SIZE)
+ − 229 /* Reuse the first cell on the list (least-recently-used).
+ − 230 Remove it from the list, and unhash it from the table.
+ − 231 */
+ − 232 {
+ − 233 cell = cache->head;
+ − 234 cache->head = cell->next;
+ − 235 cache->head->prev = 0;
+ − 236 if (cache->tail == cell) cache->tail = 0; /* only one */
+ − 237 gdk_gc_destroy (cell->gc);
+ − 238 cache->delete_count++;
+ − 239 #ifdef GCCACHE_HASH
+ − 240 remhash (&cell->gcvm, cache->table);
+ − 241 #endif
+ − 242 }
+ − 243 else if (cache->size > GC_CACHE_SIZE)
2500
+ − 244 ABORT ();
462
+ − 245 else
+ − 246 {
+ − 247 /* Allocate a new cell (don't put it in the list or table yet). */
+ − 248 cell = xnew (struct gc_cache_cell);
+ − 249 cache->size++;
+ − 250 }
+ − 251
+ − 252 /* Now we've got a cell (new or reused). Fill it in. */
+ − 253 memcpy (&cell->gcvm.gcv, gcv, sizeof (GdkGCValues));
+ − 254 cell->gcvm.mask = mask;
+ − 255
+ − 256 /* Put the cell on the end of the list. */
+ − 257 cell->next = 0;
+ − 258 cell->prev = cache->tail;
+ − 259 if (cache->tail) cache->tail->next = cell;
+ − 260 cache->tail = cell;
+ − 261 if (! cache->head) cache->head = cell;
+ − 262
+ − 263 cache->create_count++;
+ − 264 #ifdef GCCACHE_HASH
+ − 265 /* Hash it in the table */
+ − 266 puthash (&cell->gcvm, cell, cache->table);
+ − 267 #endif
+ − 268
+ − 269 /* Now make and return the GC. */
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+ − 270 cell->gc = gdk_gc_new_with_values (cache->window, gcv, (GdkGCValuesMask) mask);
462
+ − 271
+ − 272 /* debug */
+ − 273 assert (cell->gc == gc_cache_lookup (cache, gcv, mask));
+ − 274
+ − 275 return cell->gc;
+ − 276 }
