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Commit be5f49fb authored by Gilles Debunne's avatar Gilles Debunne
Browse files

Performance improvements for long text edition. 

Limit each parse to batches of a few words, to keep the UI thread
responsive.

Possible optimizations for the future:
- SpellCheck in a thread, but that requires some locking mecanism
- Only spell check what is visible on screen. Will require additional
  spans to tag the pieces of text.

This is a cherry pick of 145656 into ICS-MR1

Patch Set 2: Make the Runnable shared and stop it when detached.

Change-Id: Ibf8e98274bda84b7176aac181ff267fc1f1fa4cb
parent df372289

core/java/android/widget/SpellChecker.java

+58 −14
Original line number Diff line number Diff line
@@ -43,7 +43,18 @@ import java.util.Locale; 
 */

public class SpellChecker implements SpellCheckerSessionListener {



    private final static int MAX_SPELL_BATCH_SIZE = 50;

    // No more than this number of words will be parsed on each iteration to ensure a minimum

    // lock of the UI thread

    public static final int MAX_NUMBER_OF_WORDS = 50;



    // Rough estimate, such that the word iterator interval usually does not need to be shifted

    public static final int AVERAGE_WORD_LENGTH = 7;



    // When parsing, use a character window of that size. Will be shifted if needed

    public static final int WORD_ITERATOR_INTERVAL = AVERAGE_WORD_LENGTH * MAX_NUMBER_OF_WORDS;



    // Pause between each spell check to keep the UI smooth

    private final static int SPELL_PAUSE_DURATION = 400; // milliseconds



    private final TextView mTextView;
@@ -71,6 +82,8 @@ public class SpellChecker implements SpellCheckerSessionListener { 


    private TextServicesManager mTextServicesManager;



    private Runnable mSpellRunnable;



    public SpellChecker(TextView textView) {

        mTextView = textView;
@@ -141,6 +154,10 @@ public class SpellChecker implements SpellCheckerSessionListener { 
        for (int i = 0; i < length; i++) {

            mSpellParsers[i].finish();

        }



        if (mSpellRunnable != null) {

            mTextView.removeCallbacks(mSpellRunnable);

        }

    }



    private int nextSpellCheckSpanIndex() {
@@ -254,6 +271,7 @@ public class SpellChecker implements SpellCheckerSessionListener { 
                System.arraycopy(textInfos, 0, textInfosCopy, 0, textInfosCount);

                textInfos = textInfosCopy;

            }



            mSpellCheckerSession.getSuggestions(textInfos, SuggestionSpan.SUGGESTIONS_MAX_SIZE,

                    false /* TODO Set sequentialWords to true for initial spell check */);

        }
@@ -288,13 +306,29 @@ public class SpellChecker implements SpellCheckerSessionListener { 
            }

        }



        scheduleNewSpellCheck();

    }



    private void scheduleNewSpellCheck() {

        if (mSpellRunnable == null) {

            mSpellRunnable = new Runnable() {

                @Override

                public void run() {

                    final int length = mSpellParsers.length;

                    for (int i = 0; i < length; i++) {

                        final SpellParser spellParser = mSpellParsers[i];

                        if (!spellParser.isFinished()) {

                            spellParser.parse();

                            break; // run one spell parser at a time to bound running time

                        }

                    }

                }

            };

        } else {

            mTextView.removeCallbacks(mSpellRunnable);

        }



        mTextView.postDelayed(mSpellRunnable, SPELL_PAUSE_DURATION);

    }



    private void createMisspelledSuggestionSpan(Editable editable, SuggestionsInfo suggestionsInfo,
@@ -383,7 +417,9 @@ public class SpellChecker implements SpellCheckerSessionListener { 
            // Iterate over the newly added text and schedule new SpellCheckSpans

            final int start = editable.getSpanStart(mRange);

            final int end = editable.getSpanEnd(mRange);

            mWordIterator.setCharSequence(editable, start, end);



            int wordIteratorWindowEnd = Math.min(end, start + WORD_ITERATOR_INTERVAL);

            mWordIterator.setCharSequence(editable, start, wordIteratorWindowEnd);



            // Move back to the beginning of the current word, if any

            int wordStart = mWordIterator.preceding(start);
@@ -408,11 +444,16 @@ public class SpellChecker implements SpellCheckerSessionListener { 
            SuggestionSpan[] suggestionSpans = editable.getSpans(start - 1, end + 1,

                    SuggestionSpan.class);



            int nbWordsChecked = 0;

            int wordCount = 0;

            boolean scheduleOtherSpellCheck = false;



            while (wordStart <= end) {

                if (wordEnd >= start && wordEnd > wordStart) {

                    if (wordCount >= MAX_NUMBER_OF_WORDS) {

                        scheduleOtherSpellCheck = true;

                        break;

                    }



                    // A new word has been created across the interval boundaries with this edit.

                    // Previous spans (ended on start / started on end) removed, not valid anymore

                    if (wordStart < start && wordEnd > start) {
@@ -448,17 +489,20 @@ public class SpellChecker implements SpellCheckerSessionListener { 
                    }



                    if (createSpellCheckSpan) {

                        if (nbWordsChecked == MAX_SPELL_BATCH_SIZE) {

                            scheduleOtherSpellCheck = true;

                            break;

                        }

                        addSpellCheckSpan(editable, wordStart, wordEnd);

                        nbWordsChecked++;

                    }

                    wordCount++;

                }



                // iterate word by word

                int originalWordEnd = wordEnd;

                wordEnd = mWordIterator.following(wordEnd);

                if ((wordIteratorWindowEnd < end) &&

                        (wordEnd == BreakIterator.DONE || wordEnd >= wordIteratorWindowEnd)) {

                    wordIteratorWindowEnd = Math.min(end, originalWordEnd + WORD_ITERATOR_INTERVAL);

                    mWordIterator.setCharSequence(editable, originalWordEnd, wordIteratorWindowEnd);

                    wordEnd = mWordIterator.following(originalWordEnd);

                }

                if (wordEnd == BreakIterator.DONE) break;

                wordStart = mWordIterator.getBeginning(wordEnd);

                if (wordStart == BreakIterator.DONE) {