src/com/googlecode/lanterna/terminal/swing/TerminalScrollController.java

   1 /*
   2  * This file is part of lanterna (http://code.google.com/p/lanterna/).
   3  *
   4  * lanterna is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU Lesser General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  *
  17  * Copyright (C) 2010-2015 Martin
  18  */
  19 package com.googlecode.lanterna.terminal.swing;
  20
  21 /**
  22  * This interface can be used to control the backlog scrolling of a SwingTerminal. It's used as a callback by the
  23  * {@code SwingTerminal} when it needs to fetch the scroll position and also used whenever the backlog changes to that
  24  * some view class, like a scrollbar for example, can update its view accordingly.
  25  * @author Martin
  26  */
  27 public interface TerminalScrollController {
  28     /**
  29      * Called by the SwingTerminal when the terminal has changed or more lines are entered into the terminal
  30      * @param totalSize Total number of lines in the backlog currently
  31      * @param screenSize Number of lines covered by the terminal window at its current size
  32      */
  33     void updateModel(int totalSize, int screenSize);
  34
  35     /**
  36      * Called by the SwingTerminal to know the 'offset' into the backlog. Returning 0 here will always draw the latest
  37      * lines; if you return 5, it will draw from five lines into the backlog and skip the 5 most recent lines.
  38      * @return According to this scroll controller, how far back into the backlog are we?
  39      */
  40     int getScrollingOffset();
  41
  42     final class Null implements TerminalScrollController {
  43         @Override
  44         public void updateModel(int totalSize, int screenSize) {
  45         }
  46
  47         @Override
  48         public int getScrollingOffset() {
  49             return 0;
  50         }
  51     }
  52 }