SkBBoxHierarchy.h revision ac2c82c8528ae45bcdac1f7c4b578aff1d9bbb7e 
1
2/*
3 * Copyright 2012 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#ifndef SkBBoxHierarchy_DEFINED
10#define SkBBoxHierarchy_DEFINED
11
12#include "SkRect.h"
13#include "SkTDArray.h"
14#include "SkRefCnt.h"
15
16/**
17 * Interface for a client class that implements utility methods needed
18 * by SkBBoxHierarchy that require intrinsic knowledge of the data
19 * object type that is stored in the bounding box hierarchy.
20 */
21class SkBBoxHierarchyClient {
22public:
23    virtual ~SkBBoxHierarchyClient() {}
24
25    /**
26     * Implements a rewind stop condition used by rewindInserts
27     * Must returns true if 'data' points to an object that should be re-wound
28     * by rewinfInserts.
29     */
30    virtual bool shouldRewind(void* data) = 0;
31};
32
33/**
34 * Interface for a spatial data structure that associates user data pointers with axis-aligned
35 * bounding boxes, and allows efficient retrieval of intersections with query rectangles.
36 */
37class SkBBoxHierarchy : public SkRefCnt {
38public:
39    SK_DECLARE_INST_COUNT(SkBBoxHierarchy)
40
41    SkBBoxHierarchy() : fClient(NULL) {}
42
43    /**
44     * Insert a data pointer and corresponding bounding box
45     * @param data The data pointer, may be NULL
46     * @param bounds The bounding box, should not be empty
47     * @param defer Whether or not it is acceptable to delay insertion of this element (building up
48     *        an entire spatial data structure at once is often faster and produces better
49     *        structures than repeated inserts) until flushDeferredInserts is called or the first
50     *        search.
51     */
52    virtual void insert(void* data, const SkIRect& bounds, bool defer = false) = 0;
53
54    /**
55     * If any insertions have been deferred, this forces them to be inserted
56     */
57    virtual void flushDeferredInserts() = 0;
58
59    /**
60     * Populate 'results' with data pointers corresponding to bounding boxes that intersect 'query'
61     */
62    virtual void search(const SkIRect& query, SkTDArray<void*>* results) = 0;
63
64    virtual void clear() = 0;
65
66    /**
67     * Gets the number of insertions
68     */
69    virtual int getCount() const = 0;
70
71    /**
72     * Rewinds all the most recently inserted data elements until an element
73     * is encountered for which client->shouldRewind(data) returns false. May
74     * not rewind elements that were inserted prior to the last call to
75     * flushDeferredInserts.
76     */
77    virtual void rewindInserts() = 0;
78
79    void setClient(SkBBoxHierarchyClient* client) { fClient = client; }
80
81protected:
82    SkBBoxHierarchyClient* fClient;
83
84private:
85    typedef SkRefCnt INHERITED;
86};
87
88#endif
89