private void addCellToPattern(Cell newCell) {
        cellManager.draw(newCell, true);
        mPattern.add(newCell);
        notifyCellAdded();
    }
Determines whether the point x, y will add a new point to the current
pattern (in addition to finding the cell, also makes heuristic choices
such as filling in gaps based on current pattern).

@param x The x coordinate.
@param y The y coordinate.
android-patternview/src/main/java/com/eftimoff/patternview/PatternView.java