Changes for scroll-to-cursor functionality.

ReactTextInputManager.java

import android.text.Layout;

...
  
private class ReactSelectionWatcher implements SelectionWatcher {

    private ReactEditText mReactEditText;
    private EventDispatcher mEventDispatcher;
    private int mPreviousSelectionStart;
    private int mPreviousSelectionEnd;

    public ReactSelectionWatcher(ReactEditText editText) {
      mReactEditText = editText;
      ReactContext reactContext = (ReactContext) editText.getContext();
      mEventDispatcher = reactContext.getNativeModule(UIManagerModule.class).getEventDispatcher();
    }

    @Override
    public void onSelectionChanged(int start, int end) {
      /* >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> */
      // Calculate cursor position
      // Credit: yuku
      // https://stackoverflow.com/questions/5044342/how-to-get-cursor-position-x-y-in-edittext-android
      Layout layout = mReactEditText.getLayout();
      int line = layout.getLineForOffset(start);
      int baseline = layout.getLineBaseline(line);
      int ascent = layout.getLineAscent(line);
      float cursorPositionX = layout.getPrimaryHorizontal(start);
      float cursorPositionY = baseline + ascent;
      /* <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< */

      // Android will call us back for both the SELECTION_START span and SELECTION_END span in text
      // To prevent double calling back into js we cache the result of the previous call and only
      // forward it on if we have new values
      if (mPreviousSelectionStart != start || mPreviousSelectionEnd != end) {
        mEventDispatcher.dispatchEvent(
            new ReactTextInputSelectionEvent(
                mReactEditText.getId(),
                start,
                end,
      /* >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> */
                PixelUtil.toDIPFromPixel(cursorPositionX),
                PixelUtil.toDIPFromPixel(cursorPositionY)
      /* <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< */
            ));

        mPreviousSelectionStart = start;
        mPreviousSelectionEnd = end;
      }
    }
  }