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     // Constructors -----------------------------------------------------------
  65     // ------------------------------------------------------------------------
  66
  67     // ------------------------------------------------------------------------
  68     // Backend ----------------------------------------------------------------
  69     // ------------------------------------------------------------------------
  70
  71     /**
  72      * Getter for sessionInfo.
  73      *
  74      * @return the SessionInfo
  75      */
  76     public final SessionInfo getSessionInfo() {
  77         return sessionInfo;
  78     }
  79
  80     /**
  81      * Getter for screen.
  82      *
  83      * @return the Screen
  84      */
  85     public final Screen getScreen() {
  86         return screen;
  87     }
  88
  89     /**
  90      * Sync the logical screen to the physical device.
  91      */
  92     public void flushScreen() {
  93         screen.flushPhysical();
  94     }
  95
  96     /**
  97      * Check if there are events in the queue.
  98      *
  99      * @return if true, getEvents() has something to return to the application
 100      */
 101     public boolean hasEvents() {
 102         return terminal.hasEvents();
 103     }
 104
 105     /**
 106      * Get keyboard, mouse, and screen resize events.
 107      *
 108      * @param queue list to append new events to
 109      */
 110     public void getEvents(final List<TInputEvent> queue) {
 111         if (terminal.hasEvents()) {
 112             terminal.getEvents(queue);
 113
 114             // This default backend assumes a single user, and if that user
 115             // becomes disconnected we should terminate the application.
 116             if (queue.size() > 0) {
 117                 TInputEvent event = queue.get(queue.size() - 1);
 118                 if (event instanceof TCommandEvent) {
 119                     TCommandEvent command = (TCommandEvent) event;
 120                     if (command.equals(cmBackendDisconnect)) {
 121                         queue.add(new TCommandEvent(cmAbort));
 122                     }
 123                 }
 124             }
 125         }
 126     }
 127
 128     /**
 129      * Close the I/O, restore the console, etc.
 130      */
 131     public void shutdown() {
 132         terminal.closeTerminal();
 133     }
 134
 135     /**
 136      * Set the window title.
 137      *
 138      * @param title the new title
 139      */
 140     public void setTitle(final String title) {
 141         screen.setTitle(title);
 142     }
 143
 144     /**
 145      * Set listener to a different Object.
 146      *
 147      * @param listener the new listening object that run() wakes up on new
 148      * input
 149      */
 150     public void setListener(final Object listener) {
 151         terminal.setListener(listener);
 152     }
 153
 154     /**
 155      * Reload backend options from System properties.
 156      */
 157     public void reloadOptions() {
 158         terminal.reloadOptions();
 159     }
 160
 161 }