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efb3445ee1
In order to efficient store small images, we need to pack them into a large texture. The rtree handles allocation of small rectangles out of a much larger whole. As well as tracking free rectangles, it can also be used to note which parts of the texture are 'pinned' -- that is have operations currently pending and so can not be modified until that batch of operations have been flushed. When the rtree is full, i.e. there is no single free rectangle to accommodate the allocation request, it will randomly evict an unpinned block large enough to fit the request. The block may comprise just a single glyph, or a subtree of many glyphs. This may not be the best strategy, but it is an effective start.
349 lines
9 KiB
C
349 lines
9 KiB
C
/* cairo - a vector graphics library with display and print output
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*
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* Copyright © 2009 Chris Wilson
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*
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* This library is free software; you can redistribute it and/or
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* modify it either under the terms of the GNU Lesser General Public
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* License version 2.1 as published by the Free Software Foundation
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* (the "LGPL") or, at your option, under the terms of the Mozilla
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* Public License Version 1.1 (the "MPL"). If you do not alter this
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* notice, a recipient may use your version of this file under either
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* the MPL or the LGPL.
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*
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* You should have received a copy of the LGPL along with this library
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* in the file COPYING-LGPL-2.1; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* You should have received a copy of the MPL along with this library
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* in the file COPYING-MPL-1.1
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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* OF ANY KIND, either express or implied. See the LGPL or the MPL for
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* the specific language governing rights and limitations.
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*
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* The Original Code is the cairo graphics library.
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*
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* The Initial Developer of the Original Code is Chris Wilson.
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*
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* Contributor(s):
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* Chris Wilson <chris@chris-wilson.co.uk>
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*
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*/
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#include "cairoint.h"
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#include "cairo-rtree-private.h"
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cairo_rtree_node_t *
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_cairo_rtree_node_create (cairo_rtree_t *rtree,
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cairo_rtree_node_t *parent,
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int x,
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int y,
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int width,
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int height)
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{
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cairo_rtree_node_t *node;
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node = _cairo_freepool_alloc (&rtree->node_freepool);
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if (node == NULL) {
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_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
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return NULL;
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}
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node->children[0] = NULL;
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node->parent = parent;
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node->state = CAIRO_RTREE_NODE_AVAILABLE;
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node->pinned = FALSE;
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node->x = x;
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node->y = y;
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node->width = width;
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node->height = height;
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cairo_list_add (&node->link, &rtree->available);
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return node;
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}
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void
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_cairo_rtree_node_destroy (cairo_rtree_t *rtree, cairo_rtree_node_t *node)
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{
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int i;
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cairo_list_del (&node->link);
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if (node->state == CAIRO_RTREE_NODE_OCCUPIED) {
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if (rtree->evict != NULL)
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rtree->evict (node);
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} else {
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for (i = 0; i < 4 && node->children[i] != NULL; i++)
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_cairo_rtree_node_destroy (rtree, node->children[i]);
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}
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_cairo_freepool_free (&rtree->node_freepool, node);
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}
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void
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_cairo_rtree_node_collapse (cairo_rtree_t *rtree, cairo_rtree_node_t *node)
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{
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int i;
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assert (node->pinned == FALSE);
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do {
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assert (node->state == CAIRO_RTREE_NODE_DIVIDED);
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for (i = 0; i < 4 && node->children[i] != NULL; i++)
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if (node->children[i]->state != CAIRO_RTREE_NODE_AVAILABLE)
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return;
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for (i = 0; i < 4 && node->children[i] != NULL; i++)
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_cairo_rtree_node_destroy (rtree, node->children[i]);
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node->children[0] = NULL;
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node->state = CAIRO_RTREE_NODE_AVAILABLE;
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cairo_list_move (&node->link, &rtree->available);
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node = node->parent;
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} while (node != NULL && ! node->pinned);
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}
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cairo_status_t
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_cairo_rtree_node_insert (cairo_rtree_t *rtree,
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cairo_rtree_node_t *node,
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int width,
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int height,
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cairo_rtree_node_t **out)
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{
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int w, h, i;
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assert (node->state == CAIRO_RTREE_NODE_AVAILABLE);
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assert (node->pinned == FALSE);
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if (node->width - width > rtree->min_size ||
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node->height - height > rtree->min_size)
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{
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w = node->width - width;
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h = node->height - height;
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i = 0;
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node->children[i] = _cairo_rtree_node_create (rtree, node,
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node->x, node->y,
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width, height);
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if (unlikely (node->children[i] == NULL))
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return _cairo_error (CAIRO_STATUS_NO_MEMORY);
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i++;
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if (w > rtree->min_size) {
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node->children[i] = _cairo_rtree_node_create (rtree, node,
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node->x + width,
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node->y,
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w, height);
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if (unlikely (node->children[i] == NULL))
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return _cairo_error (CAIRO_STATUS_NO_MEMORY);
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i++;
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}
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if (h > rtree->min_size) {
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node->children[i] = _cairo_rtree_node_create (rtree, node,
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node->x,
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node->y + height,
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width, h);
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if (unlikely (node->children[i] == NULL))
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return _cairo_error (CAIRO_STATUS_NO_MEMORY);
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i++;
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if (w > rtree->min_size) {
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node->children[i] = _cairo_rtree_node_create (rtree, node,
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node->x + width,
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node->y + height,
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w, h);
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if (unlikely (node->children[i] == NULL))
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return _cairo_error (CAIRO_STATUS_NO_MEMORY);
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i++;
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}
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}
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if (i < 4)
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node->children[i] = NULL;
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node->state = CAIRO_RTREE_NODE_DIVIDED;
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cairo_list_move (&node->link, &rtree->evictable);
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node = node->children[0];
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}
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node->state = CAIRO_RTREE_NODE_OCCUPIED;
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cairo_list_move (&node->link, &rtree->evictable);
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*out = node;
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return CAIRO_STATUS_SUCCESS;
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}
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cairo_int_status_t
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_cairo_rtree_insert (cairo_rtree_t *rtree,
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int width,
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int height,
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cairo_rtree_node_t **out)
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{
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cairo_rtree_node_t *node;
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cairo_list_foreach_entry (node, cairo_rtree_node_t,
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&rtree->available, link)
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{
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if (node->width >= width && node->height >= height)
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return _cairo_rtree_node_insert (rtree, node, width, height, out);
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}
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return CAIRO_INT_STATUS_UNSUPPORTED;
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}
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static uint32_t
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hars_petruska_f54_1_random (void)
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{
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#define rol(x,k) ((x << k) | (x >> (32-k)))
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static uint32_t x;
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return x = (x ^ rol (x, 5) ^ rol (x, 24)) + 0x37798849;
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#undef rol
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}
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cairo_int_status_t
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_cairo_rtree_evict_random (cairo_rtree_t *rtree,
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int width,
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int height,
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cairo_rtree_node_t **out)
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{
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cairo_rtree_node_t *node;
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int i, cnt;
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cnt = 0;
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cairo_list_foreach_entry (node, cairo_rtree_node_t,
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&rtree->evictable, link)
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{
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if (node->width >= width && node->height >= height)
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cnt++;
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}
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if (cnt == 0)
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return CAIRO_INT_STATUS_UNSUPPORTED;
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cnt = hars_petruska_f54_1_random () % cnt;
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cairo_list_foreach_entry (node, cairo_rtree_node_t,
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&rtree->evictable, link)
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{
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if (node->width >= width && node->height >= height && cnt-- == 0) {
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if (node->state == CAIRO_RTREE_NODE_OCCUPIED) {
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if (rtree->evict != NULL)
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rtree->evict (node);
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} else {
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for (i = 0; i < 4 && node->children[i] != NULL; i++)
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_cairo_rtree_node_destroy (rtree, node->children[i]);
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node->children[0] = NULL;
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}
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node->state = CAIRO_RTREE_NODE_AVAILABLE;
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cairo_list_move (&node->link, &rtree->available);
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*out = node;
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return CAIRO_STATUS_SUCCESS;
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}
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}
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return CAIRO_INT_STATUS_UNSUPPORTED;
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}
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void *
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_cairo_rtree_pin (cairo_rtree_t *rtree, cairo_rtree_node_t *node)
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{
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void *ptr = node;
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while (node->pinned == FALSE) {
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cairo_list_move (&node->link, &rtree->pinned);
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node->pinned = TRUE;
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node = node->parent;
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if (node == NULL)
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break;
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}
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return ptr;
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}
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void
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_cairo_rtree_unpin (cairo_rtree_t *rtree)
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{
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cairo_rtree_node_t *node, *next;
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cairo_list_foreach_entry_safe (node, next,
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cairo_rtree_node_t, &rtree->pinned, link)
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{
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node->pinned = FALSE;
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cairo_list_move (&node->link, &rtree->evictable);
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}
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}
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void
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_cairo_rtree_init (cairo_rtree_t *rtree,
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int width,
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int height,
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int min_size,
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int node_size,
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void (*evict) (void *node))
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{
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rtree->evict = evict;
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assert (node_size >= (int) sizeof (cairo_rtree_node_t));
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_cairo_freepool_init (&rtree->node_freepool, node_size);
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cairo_list_init (&rtree->available);
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cairo_list_init (&rtree->pinned);
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cairo_list_init (&rtree->evictable);
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rtree->min_size = min_size;
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memset (&rtree->root, 0, sizeof (rtree->root));
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rtree->root.width = width;
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rtree->root.height = height;
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rtree->root.state = CAIRO_RTREE_NODE_AVAILABLE;
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cairo_list_add (&rtree->root.link, &rtree->available);
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}
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void
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_cairo_rtree_reset (cairo_rtree_t *rtree)
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{
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int i;
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if (rtree->root.state == CAIRO_RTREE_NODE_OCCUPIED) {
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if (rtree->evict != NULL)
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rtree->evict (&rtree->root);
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} else {
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for (i = 0; i < 4 && rtree->root.children[i] != NULL; i++)
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_cairo_rtree_node_destroy (rtree, rtree->root.children[i]);
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rtree->root.children[0] = NULL;
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}
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cairo_list_init (&rtree->available);
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cairo_list_init (&rtree->evictable);
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cairo_list_init (&rtree->pinned);
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rtree->root.state = CAIRO_RTREE_NODE_AVAILABLE;
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rtree->root.pinned = FALSE;
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cairo_list_add (&rtree->root.link, &rtree->available);
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}
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void
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_cairo_rtree_fini (cairo_rtree_t *rtree)
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{
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int i;
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if (rtree->root.state == CAIRO_RTREE_NODE_OCCUPIED) {
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if (rtree->evict != NULL)
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rtree->evict (&rtree->root);
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} else {
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for (i = 0; i < 4 && rtree->root.children[i] != NULL; i++)
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_cairo_rtree_node_destroy (rtree, rtree->root.children[i]);
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}
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_cairo_freepool_fini (&rtree->node_freepool);
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}
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