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Diffstat (limited to 'render/imagecache.c')
| -rw-r--r-- | render/imagecache.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/render/imagecache.c b/render/imagecache.c new file mode 100644 index 00000000..ec2ff4d0 --- /dev/null +++ b/render/imagecache.c @@ -0,0 +1,149 @@ +/* -*- indent-tabs-mode: nil; tab-width: 4; c-basic-offset: 4; -*- + + imagecache.c for the Openbox window manager + Copyright (c) 2008 Dana Jansens + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + See the COPYING file for a copy of the GNU General Public License. +*/ + +#include "render.h" +#include "imagecache.h" + +static gboolean RrImagePicEqual(const RrImagePic *p1, + const RrImagePic *p2); + +RrImageCache* RrImageCacheNew() +{ + RrImageCache *self; + + self = g_new(RrImageCache, 1); + self->ref = 1; + self->table = g_hash_table_new((GHashFunc)RrImagePicHash, + (GEqualFunc)RrImagePicEqual); + return self; +} + +void RrImageCacheRef(RrImageCache *self) +{ + ++self->ref; +} + +void RrImageCacheUnref(RrImageCache *self) +{ + if (self && --self->ref == 0) { + g_assert(g_hash_table_size(self->table) == 0); + g_hash_table_unref(self->table); + + g_free(self); + } +} + +/*! Finds an image in the cache, if it is already in there */ +RrImage* RrImageCacheFind(RrImageCache *self, + RrPixel32 *data, gint w, gint h) +{ + RrImagePic pic; + pic.width = w; + pic.height = h; + pic.data = data; + return g_hash_table_lookup(self->table, &pic); +} + +/* This is a fast, reversable hash function called "lookup3", found here: + http://burtleburtle.net/bob/c/lookup3.c +*/ +#define hashsize(n) ((RrPixel32)1<<(n)) +#define hashmask(n) (hashsize(n)-1) +#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k)))) +/* mix -- mix 3 32-bit values reversibly. */ +#define mix(a,b,c) \ +{ \ + a -= c; a ^= rot(c, 4); c += b; \ + b -= a; b ^= rot(a, 6); a += c; \ + c -= b; c ^= rot(b, 8); b += a; \ + a -= c; a ^= rot(c,16); c += b; \ + b -= a; b ^= rot(a,19); a += c; \ + c -= b; c ^= rot(b, 4); b += a; \ +} +/* final -- final mixing of 3 32-bit values (a,b,c) into c */ +#define final(a,b,c) \ +{ \ + c ^= b; c -= rot(b,14); \ + a ^= c; a -= rot(c,11); \ + b ^= a; b -= rot(a,25); \ + c ^= b; c -= rot(b,16); \ + a ^= c; a -= rot(c,4); \ + b ^= a; b -= rot(a,14); \ + c ^= b; c -= rot(b,24); \ +} + +guint32 hashword(const guint32 *key, gint length, guint32 initval) +{ + guint32 a,b,c; + + /* Set up the internal state */ + a = b = c = 0xdeadbeef + (((guint32)length)<<2) + initval; + + /* handle most of the key */ + while (length > 3) + { + a += key[0]; + b += key[1]; + c += key[2]; + mix(a,b,c); + length -= 3; + key += 3; + } + + /* handle the last 3 guint32's */ + switch(length) /* all the case statements fall through */ + { + case 3: c+=key[2]; + case 2: b+=key[1]; + case 1: a+=key[0]; + final(a,b,c); + case 0: /* case 0: nothing left to add */ + break; + } + /* report the result */ + return c; +} + +#define HASH_INITVAL 0xf00d + +guint RrImagePicHash(const RrImagePic *p) +{ + return hashword(p->data, p->width * p->height, HASH_INITVAL); +} + +static gboolean RrImagePicEqual(const RrImagePic *p1, + const RrImagePic *p2) +{ + guint s1, s2; + RrPixel32 *data1, *data2; + gint i; + + if (p1->width != p2->width || p1->height != p2->height) return FALSE; + + /* strcmp() would probably suck on 4k of data.. sum all their values and + see if they get the same thing. they already matched on their hashes + at this point. */ + s1 = s2 = 0; + data1 = p1->data; + data2 = p2->data; + for (i = 0; i < p1->width * p1->height; ++i, ++data1) + s1 += *data1; + for (i = 0; i < p2->width * p2->height; ++i, ++data2) + s2 += *data2; + return s1 == s2; +} |