src/com/googlecode/lanterna/gui2/TextGUI.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.gui2;
  20
  21 import com.googlecode.lanterna.graphics.Theme;
  22 import com.googlecode.lanterna.input.KeyStroke;
  23
  24 import java.io.IOException;
  25
  26 /**
  27  * This is the base interface for advanced text GUIs supported in Lanterna. You may want to use this in combination with
  28  * a TextGUIThread, that can be created/retrieved by using {@code getGUIThread()}.
  29  * @author Martin
  30  */
  31 public interface TextGUI {
  32     /**
  33      * Sets the global theme to be used by this TextGUI. This value will be set on every TextGUIGraphics object created
  34      * for drawing the GUI, but individual components can override this if they want. If you don't call this method
  35      * you should assume that a default theme is assigned by the library.
  36      * @param theme Theme to use as the default theme for this TextGUI
  37      */
  38     void setTheme(Theme theme);
  39
  40     /**
  41      * Drains the input queue and passes the key strokes to the GUI system for processing. For window-based system, it
  42      * will send each key stroke to the active window for processing. If the input read gives an EOF, it will throw
  43      * EOFException and this is normally the signal to shut down the GUI (any command coming in before the EOF will be
  44      * processed as usual before this).
  45      * @return {@code true} if at least one key stroke was read and processed, {@code false} if there was nothing on the
  46      * input queue (only for non-blocking IO)
  47      * @throws java.io.IOException In case there was an underlying I/O error
  48      * @throws java.io.EOFException In the input stream received an EOF marker
  49      */
  50     boolean processInput() throws IOException;
  51
  52     /**
  53      * Updates the screen, to make any changes visible to the user.
  54      * @throws java.io.IOException In case there was an underlying I/O error
  55      */
  56     void updateScreen() throws IOException;
  57
  58     /**
  59      * This method can be used to determine if any component has requested a redraw. If this method returns
  60      * {@code true}, you may want to call {@code updateScreen()}.
  61      * @return {@code true} if this TextGUI has a change and is waiting for someone to call {@code updateScreen()}
  62      */
  63     boolean isPendingUpdate();
  64
  65     /**
  66      * The first time this method is called, it will create a new TextGUIThread object that you can use to automatically
  67      * manage this TextGUI instead of manually calling {@code processInput()} and {@code updateScreen()}. After the
  68      * initial call, it will return the same object as it was originally returning.
  69      * @return A {@code TextGUIThread} implementation that can be used to asynchronously manage the GUI
  70      */
  71     TextGUIThread getGUIThread();
  72
  73     /**
  74      * Returns the interactable component currently in focus
  75      * @return Component that is currently in input focus
  76      */
  77     Interactable getFocusedInteractable();
  78
  79     /**
  80      * Adds a listener to this TextGUI to fire events on.
  81      * @param listener Listener to add
  82      */
  83     void addListener(Listener listener);
  84
  85     /**
  86      * Removes a listener from this TextGUI so that it will no longer receive events
  87      * @param listener Listener to remove
  88      */
  89     void removeListener(Listener listener);
  90
  91     /**
  92      * Listener interface for TextGUI, firing on events related to the overall GUI
  93      */
  94     interface Listener {
  95         /**
  96          * Fired either when no component was in focus during a keystroke or if the focused component and all its parent
  97          * containers chose not to handle the event. This event listener should also return {@code true} if the event
  98          * was processed in any way that requires the TextGUI to update itself, otherwise {@code false}.
  99          * @param textGUI TextGUI that had the event
 100          * @param keyStroke Keystroke that was unhandled
 101          * @return If the outcome of this KeyStroke processed by the implementer requires the TextGUI to re-draw, return
 102          * {@code true} here, otherwise {@code false}
 103          */
 104         boolean onUnhandledKeyStroke(TextGUI textGUI, KeyStroke keyStroke);
 105     }
 106 }