如何使JScrollPane(在BorderLayout中,包含JPanel)顺利地自动滚动 [英] How to make JScrollPane (In BorderLayout, containing JPanel) smoothly autoscroll
问题描述
我正在尝试在JScrollPanel内部放置一个不同大小的JPanel(可能比标准屏幕宽得多)。目前它效果很好,我已经配置滚动条手动工作正常,但我希望JPanel不断向左滚动,以便随着时间的推移显示整个事物。我发现的所有答案都是特定于JTextArea并使用Carets,或使用rectToVisible。这些都不会起作用,因为我试图在内部滚动到一个JPanel。
I'm trying to have a JPanel of varying size (potentially much wider than the standard screen) inside of a JScrollPanel. Currently it works out great, and I have configured the scrollbars to work fine manually, however I would like the JPanel to "scroll" constantly to the left, so that over time the whole thing is displayed. All of the answers I found are specific to JTextArea and use Carets, or use rectToVisible. Neither of these will work because I'm trying to scroll internally to a single JPanel.
我已经包含了我认为是下面所有相关代码的内容。
I've included what I believe to be all of the relevant code below.
center是JPanel(其中Grid是一个子类,用于专门绘制一些特定单元格的网格),带有我想要自动滚动的BorderLayout。
center is the JPanel (of which Grid is a subclass, used to paint specifically a grid with some specific cells colored) with a BorderLayout that I would like to autoscroll.
public GuiViewFrame(Song playMe) {
String[][] songArray = playMe.to2DArray();
this.displayPanel = new ConcreteGuiViewPanel(playMe);
main = new JPanel();
main.setLayout(new BorderLayout());
displayPanel.setLayout(new BorderLayout());
center = new Grid(playMe);
labels = new Labels(playMe);
horiz = new Horiz(playMe);
center.setPreferredSize(new Dimension(10 * songArray.length, 10 * songArray[0].length));
horiz.setPreferredSize(new Dimension(10 * songArray.length, 10));
horiz.setVisible(true);
main.add(center, BorderLayout.CENTER);
main.add(horiz, BorderLayout.NORTH);
scroll = new JScrollPane(main,
JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
add(scroll, BorderLayout.CENTER);
labels.setPreferredSize(new Dimension(20, 10 * songArray[0].length));
labels.setVisible(true);
add(labels, BorderLayout.WEST);
JScrollBar horiz = scroll.getHorizontalScrollBar();
InputMap im = horiz.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
im.put(KeyStroke.getKeyStroke("RIGHT"), "positiveUnitIncrement");
im.put(KeyStroke.getKeyStroke("LEFT"), "negativeUnitIncrement");
im.put(KeyStroke.getKeyStroke("HOME"), "minScroll");
im.put(KeyStroke.getKeyStroke("END"), "maxScroll");
this.setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
this.pack();
}
整个项目是为播放组合MIDI的音乐生成视图和GUI,但是现在一旦MIDI播放了足够的歌曲,相关的音符就会关闭。我想以一个速率滚动以跟上MIDI的步伐。
The project as a whole is to generate a view for playing music that combines MIDI and a GUI, but right now once MIDI plays enough of the song, the relevant notes are off screen. I would like to scroll at a rate to keep pace with MIDI.
推荐答案
您可以设置水平滚动条的值来控制当前可见的内容:
You can set the value of the horizontal scrollbar to control what is currently visible:
JScrollBar horizontal = scroll.getHorizontalScrollBar();
horizontal.setValue( horizontal.getValue() + ??? );
您需要使用 Swing Timer 以适当的间隔安排滚动。
You would need to use a Swing Timer to schedule the scrolling at an appropriate interval.
简单示例使用计时器
滚动文本:
Simple example of using a Timer
to scroll text:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class TimerTest extends JPanel implements ActionListener
{
JLabel timeLabel;
JLabel scrollLabel;
public TimerTest()
{
setLayout( new BorderLayout() );
timeLabel = new JLabel( new Date().toString() );
add(timeLabel, BorderLayout.NORTH);
scrollLabel = new JLabel( "Some continuously scrolling text!! " );
add(scrollLabel, BorderLayout.SOUTH);
int time = 1000;
javax.swing.Timer timer = new javax.swing.Timer(time, this);
timer.setInitialDelay(1);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
timeLabel.setText( new Date().toString() );
String oldText = scrollLabel.getText();
// Scroll right to left
String newText = oldText.substring(1) + oldText.substring(0, 1);
// Scroll left to right
// int length = oldText.length();
// String newText = oldText.substring(length-1, length)
// + oldText.substring(0, length-1);
scrollLabel.setText( newText );
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( new TimerTest() );
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
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