--- /dev/null
+/* -*- 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"
+#include "image.h"
+
+static gboolean RrImagePicEqual(const RrImagePic *p1,
+ const RrImagePic *p2);
+
+RrImageCache* RrImageCacheNew(gint max_resized_saved)
+{
+ RrImageCache *self;
+
+ g_assert(max_resized_saved >= 0);
+
+ self = g_new(RrImageCache, 1);
+ self->ref = 1;
+ self->max_resized_saved = max_resized_saved;
+ 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;
+
+ RrImagePicInit(&pic, w, h, data);
+ return g_hash_table_lookup(self->table, &pic);
+}
+
+#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); \
+}
+
+/* This is a fast, reversable hash function called "lookup3", found here:
+ http://burtleburtle.net/bob/c/lookup3.c, by Bob Jenkins
+
+ This hashing algorithm is "reversible", that is, not cryptographically
+ secure at all. But we don't care about that, we just want something to
+ tell when images are the same or different relatively quickly.
+*/
+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;
+}
+
+/*! This is some arbitrary initial value for the hashing function. It's
+ constant so that you get the same result from the same data each time.
+*/
+#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)
+{
+ return p1->width == p2->width && p1->height == p2->height &&
+ p1->sum == p2->sum;
+}