Auto-capitalization in Android Custom Keyboard When User Move Cursor to Beginning of A Sentence

Question

I'm newbie in Android programming and learning to make my own Android custom keyboard from sample HackersKeyboard and SoftKeyboard. I'm facing with auto-caps problem and have no idea how to overcome this: when user taps somewhere in input screen to move cursor to a beginning point of a sentence, keyboard should be auto-shifted.

Example: First, this is a sentence. Second, this is also a sentence. Third, this is a sentence too. When user taps to beginning of "Second" (after period and space from first sentence), keyboard should be shifted automatically.

For normal typing, when user reaches an end of a sentence (marked with sentence separator such as period or question mark), I've make it with below code in onKey method (in main class that extends InputMethodService):

@Override
public void onKey(int primaryCode, int[] keyCodes) {
    InputConnection ic = getCurrentInputConnection();
    switch(primaryCode){
        case Keyboard.KEYCODE_DELETE :
            CharSequence selectedText = ic.getSelectedText(0);
            if (TextUtils.isEmpty(selectedText)) {
                ic.deleteSurroundingText(1, 0);
            } else {
                ic.commitText("", 1);
            }
            break;
        case Keyboard.KEYCODE_SHIFT:
            bCaps = !bCaps;
            myKeyboard.setShifted(bCaps);
            myKeyboardView.invalidateAllKeys();
            break;
        case Keyboard.KEYCODE_DONE:
            ic.sendKeyEvent(new KeyEvent(KeyEvent.ACTION_DOWN, KeyEvent.KEYCODE_ENTER));
            break;
        default:
            char code = (char)primaryCode;
            if(Character.isLetter(code) && bCaps){
                code = Character.toUpperCase(code);
            }
            ic.commitText(String.valueOf(code),1);

            //--------------------------------------------
            //Detect end of a sentence then shift keyboard.
            //This is not done yet. It should turned back to lower after typing first letter of sentence.
            //--------------------------------------------
            CharSequence lastTwo = ic.getTextBeforeCursor(2, 0);
            if (lastTwo == null || lastTwo.length()<=0 ||
               (lastTwo.charAt(1) == ASCII_SPACE && isSentenceSeparator(lastTwo.charAt(0)))) {
                bCaps = true;
                myKeyboard.setShifted(bCaps);
                myKeyboardView.invalidateAllKeys();
            }
    }
}

I couldn't find any parts of sample HackersKeyboard and SoftKeyboard related to this auto-caps matter. Any help is really appreciated. Thanks very much.

Edit: this is not similar with First letter capitalization for EditText. Android custom keyboard is working at service level, and mainly aim to work globally with all kind of EditText.

Answer 1

This isn't how you do it (and I'm not sure what onKey is at all, it isn't part of InputMethodService). What you need to do is detect cursor changes, then evaluate the context of the cursor. Do this via onUpdateCursor, get the position of the cursor, then request the context surrounding it via InputConnection. After that, parse the context and determine if you need to be capitalized.

Please note that just looking for sentence enders isn't sufficient. A . can also be part of a number, abbreviation, etc. Getting it right actually requires some work.