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Commit 35199f5c authored by Gilles Debunne's avatar Gilles Debunne
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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.

Change-Id: Ibf8e98274bda84b7176aac181ff267fc1f1fa4cb
parent 28d9f024

core/java/android/widget/SpellChecker.java

+42 −18
Original line number Diff line number Diff line
@@ -42,7 +42,17 @@ 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 = 10;



    // Safe estimate, will ensure that the interval below usually does not have to be updated

    public static final int AVERAGE_WORD_LENGTH = 10;



    // 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;



    private final static int SPELL_PAUSE_DURATION = 400; // milliseconds



    private final TextView mTextView;
@@ -213,6 +223,7 @@ public class SpellChecker implements SpellCheckerSessionListener { 
        TextInfo[] textInfos = new TextInfo[mLength];

        int textInfosCount = 0;



        final String text = editable.toString();

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

            final SpellCheckSpan spellCheckSpan = mSpellCheckSpans[i];

            if (spellCheckSpan.isSpellCheckInProgress()) continue;
@@ -222,7 +233,7 @@ public class SpellChecker implements SpellCheckerSessionListener { 


            // Do not check this word if the user is currently editing it

            if (start >= 0 && end > start && (selectionEnd < start || selectionStart > end)) {

                final String word = editable.subSequence(start, end).toString();

                final String word = text.substring(start, end);

                spellCheckSpan.setSpellCheckInProgress(true);

                textInfos[textInfosCount++] = new TextInfo(word, mCookie, mIds[i]);

            }
@@ -234,6 +245,7 @@ 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 */);

        }
@@ -266,6 +278,9 @@ public class SpellChecker implements SpellCheckerSessionListener { 
            }

        }



        mTextView.postDelayed(new Runnable() {

            @Override

            public void run() {

                final int length = mSpellParsers.length;

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

                    final SpellParser spellParser = mSpellParsers[i];
@@ -274,6 +289,8 @@ public class SpellChecker implements SpellCheckerSessionListener { 
                    }

                }

            }

        }, SPELL_PAUSE_DURATION);

    }



    private void createMisspelledSuggestionSpan(Editable editable,

            SuggestionsInfo suggestionsInfo, SpellCheckSpan spellCheckSpan) {
@@ -335,9 +352,6 @@ public class SpellChecker implements SpellCheckerSessionListener { 
        SuggestionSpan suggestionSpan = new SuggestionSpan(mTextView.getContext(), suggestions,

                SuggestionSpan.FLAG_EASY_CORRECT | SuggestionSpan.FLAG_MISSPELLED);

        editable.setSpan(suggestionSpan, start, end, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);



        // TODO limit to the word rectangle region

        mTextView.invalidate();

    }



    private class SpellParser {
@@ -361,7 +375,9 @@ 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);
@@ -386,11 +402,16 @@ 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) {
@@ -426,17 +447,20 @@ 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) {