Mapeando a��es atrav�s de keystrokes

Mapeando aç�es atrav�s de keystrokes

Esta dica de Java ilustra um m�todo de mapear aç�es com keystrokes. O desenvolvedor pode usar este c�digo para fornecer atalhos aos usu�rios. Por exemplo o desenvolvedor pode ajustar CTRL-U para deixar toda a palavra selecionada com letras mai�sculas, etc.

import javax.swing.*;
import javax.swing.text.*;
import java.util.Hashtable;
import java.awt.event.*;
import java.awt.BorderLayout;

public class KeymapExample {
 public static void main(String[] args) {

JTextArea area = new JTextArea(6, 32);
Keymap parent = area.getKeymap();
Keymap newmap = JTextComponent.addKeymap("KeymapExampleMap", parent);

// CTRL-U: muda a palavra para upper case
KeyStroke u = KeyStroke.getKeyStroke(KeyEvent.VK_U, InputEvent.CTRL_MASK);
Action actionU = new UpWord(); 
newmap.addActionForKeyStroke(u, actionU);

Action actionList[] = area.getActions();

Hashtable lookup = new Hashtable();
for (int j=0; j < actionList.length; j+=1)
lookup.put(actionList[j].getValue(Action.NAME), actionList[j]);

// CTRL-L: seleciona toda a linha
KeyStroke L = KeyStroke.getKeyStroke(KeyEvent.VK_L, InputEvent.CTRL_MASK);
Action actionL = (Action)lookup.get(DefaultEditorKit.selectLineAction);
newmap.addActionForKeyStroke(L, actionL);

// CTRL-W: seleciona a palavra pr�xima do cursor
KeyStroke W = KeyStroke.getKeyStroke(KeyEvent.VK_W, InputEvent.CTRL_MASK);
Action actionW = (Action)lookup.get(DefaultEditorKit.selectWordAction);
newmap.addActionForKeyStroke(W, actionW);

area.setKeymap(newmap);

JFrame f = new JFrame("KeymapExample");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
area.setText("This is the story\nof the hare who\nlost his spectacles.");
f.pack();
f.setVisible(true);
 }

 public static class UpWord extends TextAction {
public UpWord() {
super("uppercase-word-action");
}

public void actionPerformed(ActionEvent e) {
JTextComponent comp = getTextComponent(e);
if (comp == null) return;
Document doc = comp.getDocument();
int start = comp.getSelectionStart();
int end = comp.getSelectionEnd();
try {
int left = javax.swing.text.Utilities.getWordStart(comp, start);
int right = javax.swing.text.Utilities.getWordEnd(comp, end);
String word = doc.getText(left, right-left);
doc.remove(left, right-left);
doc.insertString(left, word.toUpperCase(), null);
comp.setSelectionStart(start); 
comp.setSelectionEnd(end);
} catch (BadLocationException ble) { return; }
}
 } 
}

Mapeando a��es atrav�s de keystrokes

Esta dica de Java ilustra um método de mapear ações com keystrokes.

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