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      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 
     17 package android.text;
     18 
     19 import 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  */
     30 public 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