1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.text;
18
19import java.lang.reflect.Array;
20
21/**
22 * A cached set of spans. Caches the result of {@link Spanned#getSpans(int, int, Class)} and then
23 * provides faster access to {@link Spanned#nextSpanTransition(int, int, Class)}.
24 *
25 * Fields are left public for a convenient direct access.
26 *
27 * Note that empty spans are ignored by this class.
28 * @hide
29 */
30public class SpanSet<E> {
31    private final Class<? extends E> classType;
32
33    int numberOfSpans;
34    E[] spans;
35    int[] spanStarts;
36    int[] spanEnds;
37    int[] spanFlags;
38
39    SpanSet(Class<? extends E> type) {
40        classType = type;
41        numberOfSpans = 0;
42    }
43
44    @SuppressWarnings("unchecked")
45    public void init(Spanned spanned, int start, int limit) {
46        final E[] allSpans = spanned.getSpans(start, limit, classType);
47        final int length = allSpans.length;
48
49        if (length > 0 && (spans == null || spans.length < length)) {
50            // These arrays may end up being too large because of the discarded empty spans
51            spans = (E[]) Array.newInstance(classType, length);
52            spanStarts = new int[length];
53            spanEnds = new int[length];
54            spanFlags = new int[length];
55        }
56
57        numberOfSpans = 0;
58        for (int i = 0; i < length; i++) {
59            final E span = allSpans[i];
60
61            final int spanStart = spanned.getSpanStart(span);
62            final int spanEnd = spanned.getSpanEnd(span);
63            if (spanStart == spanEnd) continue;
64
65            final int spanFlag = spanned.getSpanFlags(span);
66
67            spans[numberOfSpans] = span;
68            spanStarts[numberOfSpans] = spanStart;
69            spanEnds[numberOfSpans] = spanEnd;
70            spanFlags[numberOfSpans] = spanFlag;
71
72            numberOfSpans++;
73        }
74    }
75
76    /**
77     * Returns true if there are spans intersecting the given interval.
78     * @param end must be strictly greater than start
79     */
80    public boolean hasSpansIntersecting(int start, int end) {
81        for (int i = 0; i < numberOfSpans; i++) {
82            // equal test is valid since both intervals are not empty by construction
83            if (spanStarts[i] >= end || spanEnds[i] <= start) continue;
84            return true;
85        }
86        return false;
87    }
88
89    /**
90     * Similar to {@link Spanned#nextSpanTransition(int, int, Class)}
91     */
92    int getNextTransition(int start, int limit) {
93        for (int i = 0; i < numberOfSpans; i++) {
94            final int spanStart = spanStarts[i];
95            final int spanEnd = spanEnds[i];
96            if (spanStart > start && spanStart < limit) limit = spanStart;
97            if (spanEnd > start && spanEnd < limit) limit = spanEnd;
98        }
99        return limit;
100    }
101
102    /**
103     * Removes all internal references to the spans to avoid memory leaks.
104     */
105    public void recycle() {
106        // The spans array is guaranteed to be not null when numberOfSpans is > 0
107        for (int i = 0; i < numberOfSpans; i++) {
108            spans[i] = null; // prevent a leak: no reference kept when TextLine is recycled
109        }
110    }
111}
112