iscrollnotifier.java

Bluetooth chat Server and Client in j2me

/*
 I BlueTooth You -- Simple BlueTooth talker
 Copyright (C) 2007 Jan Tomka

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 as published by the Free Software Foundation; either version 2
 of the License, or (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 */
package net.sf.btw.ibtu.ui;

/**
 * This interface defines the capabilities that scrollbar notifier must have. It
 * defines three methods that notify {@link Scrollbar} about current actual
 * length of a subject being scrolled, it's visible length and current position.
 * Returned values are not required to be measured in any particular unit (e.g.
 * pixels). However, all three are expected to be measured in same unit (be it
 * pixels, lines, screens or like).
 * 
 * @author Jan Tomka
 */
public interface IScrollNotifier {

	/**
	 * Returns current actual length of a subject being scrolled.
	 * 
	 * @return Current actual length.
	 */
	public int getActualLength();

	/**
	 * Returns length of currently visible portion of a subject being scrolled.
	 * 
	 * @return Currently visible length.
	 */
	public int getVisibleLength();

	/**
	 * Returns current position of a subject being scrolled. Position of
	 * currently displayed part's top border is expected to be returned, where
	 * value <= 0 means the topmost part of a subject scrolled is visible, and
	 * value >= ({@link ScrollNotifier#getActualLength()} -
	 * {@link ScrollNotifier#getVisibleLength()} means the bottom part of a
	 * subject is currently being displayed.
	 * 
	 * @return Current position.
	 */
	public int getCurrentPosition();
}