diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java index 78c65e0c7..b3f7e674d 100644 --- a/java/src/com/android/inputmethod/latin/LatinIME.java +++ b/java/src/com/android/inputmethod/latin/LatinIME.java @@ -825,7 +825,8 @@ public class LatinIME extends InputMethodService implements KeyboardActionListen // we know for sure the cursor moved while we were composing and we should reset // the state. final boolean noComposingSpan = composingSpanStart == -1 && composingSpanEnd == -1; - if (!mExpectingUpdateSelection) { + if (!mExpectingUpdateSelection + && !mConnection.isBelatedExpectedUpdate(oldSelStart, newSelStart)) { // TAKE CARE: there is a race condition when we enter this test even when the user // did not explicitly move the cursor. This happens when typing fast, where two keys // turn this flag on in succession and both onUpdateSelection() calls arrive after diff --git a/java/src/com/android/inputmethod/latin/RichInputConnection.java b/java/src/com/android/inputmethod/latin/RichInputConnection.java index 37e1dbb69..ce7049f4f 100644 --- a/java/src/com/android/inputmethod/latin/RichInputConnection.java +++ b/java/src/com/android/inputmethod/latin/RichInputConnection.java @@ -629,4 +629,34 @@ public class RichInputConnection { commitText(" " + textBeforeCursor.subSequence(0, 1), 1); return true; } + + /** + * Heuristic to determine if this is an expected update of the cursor. + * + * Sometimes updates to the cursor position are late because of their asynchronous nature. + * This method tries to determine if this update is one, based on the values of the cursor + * position in the update, and the currently expected position of the cursor according to + * LatinIME's internal accounting. If this is not a belated expected update, then it should + * mean that the user moved the cursor explicitly. + * This is quite robust, but of course it's not perfect. In particular, it will fail in the + * case we get an update A, the user types in N characters so as to move the cursor to A+N but + * we don't get those, and then the user places the cursor between A and A+N, and we get only + * this update and not the ones in-between. This is almost impossible to achieve even trying + * very very hard. + * + * @param oldSelStart The value of the old cursor position in the update. + * @param newSelStart The value of the new cursor position in the update. + * @return whether this is a belated expected update or not. + */ + public boolean isBelatedExpectedUpdate(final int oldSelStart, final int newSelStart) { + // If this is an update that arrives at our expected position, it's a belated update. + if (newSelStart == mCurrentCursorPosition) return true; + // If this is an update that moves the cursor from our expected position, it must be + // an explicit move. + if (oldSelStart == mCurrentCursorPosition) return false; + // The following returns true if newSelStart is between oldSelStart and + // mCurrentCursorPosition. We assume that if the updated position is between the old + // position and the expected position, then it must be a belated update. + return (newSelStart - oldSelStart) * (mCurrentCursorPosition - newSelStart) >= 0; + } }