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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 android.annotation.UnsupportedAppUsage;
     20 import java.lang.reflect.Array;
     21 import java.util.Arrays;
     22 
     23 /**
     24  * A cached set of spans. Caches the result of {@link Spanned#getSpans(int, int, Class)} and then
     25  * provides faster access to {@link Spanned#nextSpanTransition(int, int, Class)}.
     26  *
     27  * Fields are left public for a convenient direct access.
     28  *
     29  * Note that empty spans are ignored by this class.
     30  * @hide
     31  */
     32 public class SpanSet<E> {
     33     private final Class<? extends E> classType;
     34 
     35     int numberOfSpans;
     36     @UnsupportedAppUsage
     37     E[] spans;
     38     int[] spanStarts;
     39     int[] spanEnds;
     40     int[] spanFlags;
     41 
     42     SpanSet(Class<? extends E> type) {
     43         classType = type;
     44         numberOfSpans = 0;
     45     }
     46 
     47     @SuppressWarnings("unchecked")
     48     public void init(Spanned spanned, int start, int limit) {
     49         final E[] allSpans = spanned.getSpans(start, limit, classType);
     50         final int length = allSpans.length;
     51 
     52         if (length > 0 && (spans == null || spans.length < length)) {
     53             // These arrays may end up being too large because of the discarded empty spans
     54             spans = (E[]) Array.newInstance(classType, length);
     55             spanStarts = new int[length];
     56             spanEnds = new int[length];
     57             spanFlags = new int[length];
     58         }
     59 
     60         int prevNumberOfSpans = numberOfSpans;
     61         numberOfSpans = 0;
     62         for (int i = 0; i < length; i++) {
     63             final E span = allSpans[i];
     64 
     65             final int spanStart = spanned.getSpanStart(span);
     66             final int spanEnd = spanned.getSpanEnd(span);
     67             if (spanStart == spanEnd) continue;
     68 
     69             final int spanFlag = spanned.getSpanFlags(span);
     70 
     71             spans[numberOfSpans] = span;
     72             spanStarts[numberOfSpans] = spanStart;
     73             spanEnds[numberOfSpans] = spanEnd;
     74             spanFlags[numberOfSpans] = spanFlag;
     75 
     76             numberOfSpans++;
     77         }
     78 
     79         // cleanup extra spans left over from previous init() call
     80         if (numberOfSpans < prevNumberOfSpans) {
     81             // prevNumberofSpans was > 0, therefore spans != null
     82             Arrays.fill(spans, numberOfSpans, prevNumberOfSpans, null);
     83         }
     84     }
     85 
     86     /**
     87      * Returns true if there are spans intersecting the given interval.
     88      * @param end must be strictly greater than start
     89      */
     90     public boolean hasSpansIntersecting(int start, int end) {
     91         for (int i = 0; i < numberOfSpans; i++) {
     92             // equal test is valid since both intervals are not empty by construction
     93             if (spanStarts[i] >= end || spanEnds[i] <= start) continue;
     94             return true;
     95         }
     96         return false;
     97     }
     98 
     99     /**
    100      * Similar to {@link Spanned#nextSpanTransition(int, int, Class)}
    101      */
    102     int getNextTransition(int start, int limit) {
    103         for (int i = 0; i < numberOfSpans; i++) {
    104             final int spanStart = spanStarts[i];
    105             final int spanEnd = spanEnds[i];
    106             if (spanStart > start && spanStart < limit) limit = spanStart;
    107             if (spanEnd > start && spanEnd < limit) limit = spanEnd;
    108         }
    109         return limit;
    110     }
    111 
    112     /**
    113      * Removes all internal references to the spans to avoid memory leaks.
    114      */
    115     public void recycle() {
    116         if (spans != null) {
    117             Arrays.fill(spans, 0, numberOfSpans, null);
    118         }
    119     }
    120 }
    121