src/jexer/backend/GenericBackend.java

   1 /*
   2  * Jexer - Java Text User Interface
   3  *
   4  * The MIT License (MIT)
   5  *
   6  * Copyright (C) 2019 Kevin Lamonte
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * @author Kevin Lamonte [kevin.lamonte@gmail.com]
  27  * @version 1
  28  */
  29 package jexer.backend;
  30
  31 import java.util.List;
  32
  33 import jexer.event.TInputEvent;
  34 import jexer.event.TCommandEvent;
  35 import static jexer.TCommand.*;
  36
  37 /**
  38  * This abstract class provides a screen, keyboard, and mouse to
  39  * TApplication.  It also exposes session information as gleaned from lower
  40  * levels of the communication stack.
  41  */
  42 public abstract class GenericBackend implements Backend {
  43
  44     // ------------------------------------------------------------------------
  45     // Variables --------------------------------------------------------------
  46     // ------------------------------------------------------------------------
  47
  48     /**
  49      * The session information.
  50      */
  51     protected SessionInfo sessionInfo;
  52
  53     /**
  54      * The screen to draw on.
  55      */
  56     protected Screen screen;
  57
  58     /**
  59      * Input events are processed by this Terminal.
  60      */
  61     protected TerminalReader terminal;
  62
  63     /**
  64      * By default, GenericBackend adds a cmAbort after it sees
  65      * cmBackendDisconnect, so that TApplication will exit when the user
  66      * closes the Swing window or disconnects the ECMA48 streams.  But
  67      * MultiBackend wraps multiple Backends, and needs to decide when to send
  68      * cmAbort differently.  Setting this to false is how it manages that.
  69      * Note package private access.
  70      */
  71     boolean abortOnDisconnect = true;
  72
  73     // ------------------------------------------------------------------------
  74     // Constructors -----------------------------------------------------------
  75     // ------------------------------------------------------------------------
  76
  77     // ------------------------------------------------------------------------
  78     // Backend ----------------------------------------------------------------
  79     // ------------------------------------------------------------------------
  80
  81     /**
  82      * Getter for sessionInfo.
  83      *
  84      * @return the SessionInfo
  85      */
  86     public final SessionInfo getSessionInfo() {
  87         return sessionInfo;
  88     }
  89
  90     /**
  91      * Getter for screen.
  92      *
  93      * @return the Screen
  94      */
  95     public final Screen getScreen() {
  96         return screen;
  97     }
  98
  99     /**
 100      * Sync the logical screen to the physical device.
 101      */
 102     public void flushScreen() {
 103         screen.flushPhysical();
 104     }
 105
 106     /**
 107      * Check if there are events in the queue.
 108      *
 109      * @return if true, getEvents() has something to return to the application
 110      */
 111     public boolean hasEvents() {
 112         return terminal.hasEvents();
 113     }
 114
 115     /**
 116      * Get keyboard, mouse, and screen resize events.
 117      *
 118      * @param queue list to append new events to
 119      */
 120     public void getEvents(final List<TInputEvent> queue) {
 121         if (terminal.hasEvents()) {
 122             terminal.getEvents(queue);
 123
 124             // This default backend assumes a single user, and if that user
 125             // becomes disconnected we should terminate the application.
 126             if ((queue.size() > 0) && (abortOnDisconnect == true)) {
 127                 TInputEvent event = queue.get(queue.size() - 1);
 128                 if (event instanceof TCommandEvent) {
 129                     TCommandEvent command = (TCommandEvent) event;
 130                     if (command.equals(cmBackendDisconnect)) {
 131                         queue.add(new TCommandEvent(cmAbort));
 132                     }
 133                 }
 134             }
 135         }
 136     }
 137
 138     /**
 139      * Close the I/O, restore the console, etc.
 140      */
 141     public void shutdown() {
 142         terminal.closeTerminal();
 143     }
 144
 145     /**
 146      * Set the window title.
 147      *
 148      * @param title the new title
 149      */
 150     public void setTitle(final String title) {
 151         screen.setTitle(title);
 152     }
 153
 154     /**
 155      * Set listener to a different Object.
 156      *
 157      * @param listener the new listening object that run() wakes up on new
 158      * input
 159      */
 160     public void setListener(final Object listener) {
 161         terminal.setListener(listener);
 162     }
 163
 164     /**
 165      * Reload backend options from System properties.
 166      */
 167     public void reloadOptions() {
 168         terminal.reloadOptions();
 169     }
 170
 171 }