我正在编写一个类似于十六进制编辑器的视图,它由两个JTextComponents(十六进制和ASCII)组成。我想同步两个视图之间的选择,所以我为这两个组件实现了一个CaretListener。这适用于响应用户长按,拖动和释放鼠标的选择事件。当用户释放鼠标时,组件会收到caretUpdate。
当用户按下鼠标并拖动鼠标而不释放时,组件如何接收增量caretUpdate事件?
答案 0 :(得分:7)
遗憾的是,JTextArea
没有选择模型,否则这将非常简单......
相反,我被迫在每个文本区域的ChangeListener
添加Caret
。这让我可以看到实时更改插入位置的时间。
当我意识到只有当前文本区域实际显示它的选择突出显示时,出现了下一个问题....( nb这可以很容易地纠正,检查下一次更新)
然后我必须将荧光笔应用于未聚焦的文本区域......
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.io.File;
import java.io.FileReader;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
public class CaretTest {
public static void main(String[] args) {
new CaretTest();
}
public CaretTest() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridLayout(1, 2));
JTextArea left = new JTextArea(10, 20);
JTextArea right = new JTextArea(10, 20);
left.setEditable(false);
right.setEditable(false);
left.getCaret().addChangeListener(new ChangeHandler(left, right));
right.getCaret().addChangeListener(new ChangeHandler(right, left));
left.addFocusListener(new FocusHandler(left, right));
right.addFocusListener(new FocusHandler(right, left));
JScrollPane leftSP = new JScrollPane(left);
JScrollPane rightSP = new JScrollPane(right);
leftSP.getHorizontalScrollBar().setModel(rightSP.getHorizontalScrollBar().getModel());
leftSP.getVerticalScrollBar().setModel(rightSP.getVerticalScrollBar().getModel());
add(leftSP);
add(rightSP);
FileReader reader = null;
try {
reader = new FileReader(new File("Ni.txt"));
left.read(reader, null);
reader.close();
reader = new FileReader(new File("Ni.txt"));
right.read(reader, null);
} catch (Exception exp) {
exp.printStackTrace();
} finally {
try {
reader.close();
} catch (Exception e) {
}
}
}
protected void updateHighlighting(JTextArea source, JTextArea target) {
DefaultHighlighter.DefaultHighlightPainter painter = new DefaultHighlighter.DefaultHighlightPainter(target.getSelectionColor());
int start = source.getSelectionStart();
int end = source.getSelectionEnd();
try {
target.getHighlighter().addHighlight(start, end, painter);
} catch (BadLocationException ex) {
ex.printStackTrace();
}
}
public class ChangeHandler implements ChangeListener {
private final JTextArea source;
private final JTextArea target;
public ChangeHandler(JTextArea source, JTextArea target) {
this.source = source;
this.target = target;
}
@Override
public void stateChanged(ChangeEvent e) {
if (e.getSource() == source.getCaret()) {
target.getHighlighter().removeAllHighlights();
updateHighlighting(source, target);
}
}
}
public class FocusHandler extends FocusAdapter {
private final JTextArea source;
private final JTextArea target;
public FocusHandler(JTextArea source, JTextArea target) {
this.source = source;
this.target = target;
}
@Override
public void focusGained(FocusEvent e) {
source.getHighlighter().removeAllHighlights();
target.getHighlighter().removeAllHighlights();
updateHighlighting(source, target);
}
}
}
}
ps-你需要提供自己的文字;)
使用“非荧光笔”示例进行更新
感谢StanislavL指出您可以使用JTextComponent#getCaret()#setSelectionVisible(true)
使非聚焦文本组件显示它的选定文本。
我确实发现焦点更改再次成为false
,所以我在更改处理程序中更新为true
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.io.File;
import java.io.FileReader;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
public class CaretTest {
public static void main(String[] args) {
new CaretTest();
}
public CaretTest() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridLayout(1, 2));
JTextArea left = new JTextArea(10, 20);
JTextArea right = new JTextArea(10, 20);
left.setEditable(false);
right.setEditable(false);
left.getCaret().setSelectionVisible(true);
right.getCaret().setSelectionVisible(true);
left.getCaret().addChangeListener(new ChangeHandler(left, right));
right.getCaret().addChangeListener(new ChangeHandler(right, left));
JScrollPane leftSP = new JScrollPane(left);
JScrollPane rightSP = new JScrollPane(right);
leftSP.getHorizontalScrollBar().setModel(rightSP.getHorizontalScrollBar().getModel());
leftSP.getVerticalScrollBar().setModel(rightSP.getVerticalScrollBar().getModel());
add(leftSP);
add(rightSP);
FileReader reader = null;
try {
reader = new FileReader(new File("Ni.txt"));
left.read(reader, null);
reader.close();
reader = new FileReader(new File("Ni.txt"));
right.read(reader, null);
} catch (Exception exp) {
exp.printStackTrace();
} finally {
try {
reader.close();
} catch (Exception e) {
}
}
}
}
public static class ChangeHandler implements ChangeListener {
private static boolean ignoreUpdates = false;
private final JTextArea source;
private final JTextArea target;
public ChangeHandler(JTextArea source, JTextArea target) {
this.source = source;
this.target = target;
}
@Override
public void stateChanged(ChangeEvent e) {
if (e.getSource() == source.getCaret()) {
if (!ignoreUpdates) {
ignoreUpdates = true;
try {
target.getCaret().setSelectionVisible(true);
source.getCaret().setSelectionVisible(true);
target.setSelectionStart(source.getSelectionStart());
target.setSelectionEnd(source.getSelectionEnd());
} finally {
ignoreUpdates = false;
}
}
}
}
}
}