src/com/googlecode/lanterna/gui2/CheckBox.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.TerminalTextUtils;
  22 import com.googlecode.lanterna.TerminalPosition;
  23 import com.googlecode.lanterna.TerminalSize;
  24 import com.googlecode.lanterna.graphics.ThemeDefinition;
  25 import com.googlecode.lanterna.input.KeyStroke;
  26 import com.googlecode.lanterna.input.KeyType;
  27
  28 import java.util.List;
  29 import java.util.concurrent.CopyOnWriteArrayList;
  30
  31 /**
  32  * The checkbox component looks like a regular checkbox that you can find in modern graphics user interfaces, a label
  33  * and a space that the user can toggle on and off by using enter or space keys.
  34  *
  35  * @author Martin
  36  */
  37 public class CheckBox extends AbstractInteractableComponent<CheckBox> {
  38
  39     /**
  40      * Listener interface that can be used to catch user events on the check box
  41      */
  42     public interface Listener {
  43         /**
  44          * This is fired when the user has altered the checked state of this {@code CheckBox}
  45          * @param checked If the {@code CheckBox} is now toggled on, this is set to {@code true}, otherwise
  46          * {@code false}
  47          */
  48         void onStatusChanged(boolean checked);
  49     }
  50
  51     private final List<Listener> listeners;
  52     private String label;
  53     private boolean checked;
  54
  55     /**
  56      * Creates a new checkbox with no label, initially set to un-checked
  57      */
  58     public CheckBox() {
  59         this("");
  60     }
  61
  62     /**
  63      * Creates a new checkbox with a specific label, initially set to un-checked
  64      * @param label Label to assign to the check box
  65      */
  66     public CheckBox(String label) {
  67         if(label == null) {
  68             throw new IllegalArgumentException("Cannot create a CheckBox with null label");
  69         }
  70         else if(label.contains("\n") || label.contains("\r")) {
  71             throw new IllegalArgumentException("Multiline checkbox labels are not supported");
  72         }
  73         this.listeners = new CopyOnWriteArrayList<Listener>();
  74         this.label = label;
  75         this.checked = false;
  76     }
  77
  78     /**
  79      * Programmatically updated the check box to a particular checked state
  80      * @param checked If {@code true}, the check box will be set to toggled on, otherwise {@code false}
  81      * @return Itself
  82      */
  83     public synchronized CheckBox setChecked(final boolean checked) {
  84         this.checked = checked;
  85         runOnGUIThreadIfExistsOtherwiseRunDirect(new Runnable() {
  86             @Override
  87             public void run() {
  88                 for(Listener listener : listeners) {
  89                     listener.onStatusChanged(checked);
  90                 }
  91             }
  92         });
  93         invalidate();
  94         return this;
  95     }
  96
  97     /**
  98      * Returns the checked state of this check box
  99      * @return {@code true} if the check box is toggled on, otherwise {@code false}
 100      */
 101     public boolean isChecked() {
 102         return checked;
 103     }
 104
 105     @Override
 106     public Result handleKeyStroke(KeyStroke keyStroke) {
 107         if((keyStroke.getKeyType() == KeyType.Character && keyStroke.getCharacter() == ' ') ||
 108                 keyStroke.getKeyType() == KeyType.Enter) {
 109             setChecked(!isChecked());
 110             return Result.HANDLED;
 111         }
 112         return super.handleKeyStroke(keyStroke);
 113     }
 114
 115     /**
 116      * Updates the label of the checkbox
 117      * @param label New label to assign to the check box
 118      * @return Itself
 119      */
 120     public synchronized CheckBox setLabel(String label) {
 121         if(label == null) {
 122             throw new IllegalArgumentException("Cannot set CheckBox label to null");
 123         }
 124         this.label = label;
 125         invalidate();
 126         return this;
 127     }
 128
 129     /**
 130      * Returns the label of check box
 131      * @return Label currently assigned to the check box
 132      */
 133     public String getLabel() {
 134         return label;
 135     }
 136
 137     /**
 138      * Adds a listener to this check box so that it will be notificed on certain user actions
 139      * @param listener Listener to fire events on
 140      * @return Itself
 141      */
 142     public CheckBox addListener(Listener listener) {
 143         if(listener != null && !listeners.contains(listener)) {
 144             listeners.add(listener);
 145         }
 146         return this;
 147     }
 148
 149     /**
 150      * Removes a listener from this check box so that, if it was previously added, it will no long receive any events
 151      * @param listener Listener to remove from the check box
 152      * @return Itself
 153      */
 154     public CheckBox removeListener(Listener listener) {
 155         listeners.remove(listener);
 156         return this;
 157     }
 158
 159     @Override
 160     protected CheckBoxRenderer createDefaultRenderer() {
 161         return new DefaultCheckBoxRenderer();
 162     }
 163
 164     /**
 165      * Helper interface that doesn't add any new methods but makes coding new check box renderers a little bit more clear
 166      */
 167     public static abstract class CheckBoxRenderer implements InteractableRenderer<CheckBox> {
 168     }
 169
 170     /**
 171      * The default renderer that is used unless overridden. This renderer will draw the checkbox label on the right side
 172      * of a "[ ]" block which will contain a "X" inside it if the check box has toggle status on
 173      */
 174     public static class DefaultCheckBoxRenderer extends CheckBoxRenderer {
 175         private static final TerminalPosition CURSOR_LOCATION = new TerminalPosition(1, 0);
 176         @Override
 177         public TerminalPosition getCursorLocation(CheckBox component) {
 178             return CURSOR_LOCATION;
 179         }
 180
 181         @Override
 182         public TerminalSize getPreferredSize(CheckBox component) {
 183             int width = 3;
 184             if(!component.label.isEmpty()) {
 185                 width += 1 + TerminalTextUtils.getColumnWidth(component.label);
 186             }
 187             return new TerminalSize(width, 1);
 188         }
 189
 190         @Override
 191         public void drawComponent(TextGUIGraphics graphics, CheckBox component) {
 192             ThemeDefinition themeDefinition = graphics.getThemeDefinition(CheckBox.class);
 193             if(component.isFocused()) {
 194                 graphics.applyThemeStyle(themeDefinition.getActive());
 195             }
 196             else {
 197                 graphics.applyThemeStyle(themeDefinition.getNormal());
 198             }
 199
 200             graphics.fill(' ');
 201             graphics.putString(4, 0, component.label);
 202
 203             String head = "[" + (component.isChecked() ? themeDefinition.getCharacter("MARKER", 'x') : " ") + "]";
 204             if(component.isFocused()) {
 205                 graphics.applyThemeStyle(themeDefinition.getPreLight());
 206             }
 207             else {
 208                 graphics.applyThemeStyle(themeDefinition.getNormal());
 209             }
 210             graphics.putString(0, 0, head);
 211         }
 212     }
 213 }