Question

我正在尝试让JScrollPane在此程序中始终滚动。即使在单击按钮后图像缩小，我也试图让它滚动。我可以让滚动窗格仅在JFrame最大化时滚动。此外，一旦单击按钮，JScrollPane内的图像减少了一半，JScrollPane就不再出现了。我认为我可以让JScrollPane始终拥有水平和垂直滚动条，方法是使Panel保持它比容纳Panel的JFrame大得多。请参阅下面的代码并尽可能帮助调试。

package Ex3;

import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.File;
import java.io.IOException;
import java.awt.AWTException;
import javax.swing.JScrollPane;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JFrame;
import java.awt.FlowLayout;
import java.awt.Image;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.BoxLayout;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.BorderLayout;
import java.awt.GridBagLayout;




public class Ex3MF { 

  JFrame jframe = new JFrame("Crappy Screen Grabber 1.0");
  ImageIcon icon = new ImageIcon(this.getClass().getClassLoader().getResource("screenshot-ex3mf.png"));
  JLabel jl;
  JScrollPane jsp;
  Container c = jframe.getContentPane();
  JButton button1 = new JButton("Resize Image");
  static Ex3MF e;
  static Toolkit t = Toolkit.getDefaultToolkit();
  static Dimension d = t.getScreenSize();
  static int x_width = d.width/2;
  static int x_height = d.width/2;
  JPanel p1 = new JPanel();
  JPanel p2 = new JPanel();


  void setupJFrame() {
      jframe.setSize(300, 300);
      jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      jframe.setLocationRelativeTo(null);
      button1.addActionListener(new TrimImage());
      p2.setSize(200,100);
      //p2.setLayout(new BorderLayout());
      p2.add(button1);
      jframe.add(p2, BorderLayout.NORTH);


  }

  void image2ScrollPane(ImageIcon ic) {
      setupJFrame();
      p1.setSize(3000,3000);
      p1.setLayout(new BorderLayout());

      if (jl == null) {
          jl = new JLabel("Crappy Screencapture", ic, JLabel.CENTER);
      } else {
          jl.setIcon(ic);
      } 
      if (jsp == null) {
          jsp = new JScrollPane(jl);
      } else {
          jsp.setViewportView(jl);
      }
      p1.add(jsp);
      //c.add(p1);

      //p1.add(jl); //and the jlabel to the panel
     // jsp = new JScrollPane(p1); //and the panel to the ScrollPane

     // c.add(jsp); //add the JScrollPane to the Container

      jframe.add(p1, BorderLayout.CENTER);
      jframe.setVisible(true);
      jframe.pack();


  }

  void createScreenCapture() {
      try {
          Robot ro = new Robot();
          Toolkit t = Toolkit.getDefaultToolkit();
          final Dimension d = t.getScreenSize();
          Rectangle re = new Rectangle(d.width, d.height);
          BufferedImage image = ro.createScreenCapture(re);


          //write screen capture to disk
          ImageIO.write(image, "png", new File("screenshot-ex3mf.png"));
      } catch(IOException ioe) {
          System.out.println("IOException thrown " + ioe);
      }
        catch(AWTException awte) {
          System.out.println("AWTException thrown " + awte);
      }



  }

  ImageIcon resizeTheCapture() {

      Image image = icon.getImage();
      x_width = x_width / 2;
      x_height = x_height / 2;

      Image newimg = image.getScaledInstance((x_width), (x_height), java.awt.Image.SCALE_SMOOTH);
      return new ImageIcon(newimg);


  }

  public static void main(String[] args) {
      e = new Ex3MF();
      e.createScreenCapture();
      e.image2ScrollPane(e.icon);


      System.out.println("\nProgram complete...");

  }


} //end class

控制按钮的代码遵循这句话。

package Ex3;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;


public class TrimImage implements ActionListener {

    public void actionPerformed(ActionEvent ae) {
        Ex3MF ex3 = new Ex3MF();
        ex3.e.image2ScrollPane(ex3.e.resizeTheCapture());

    }


}

感谢您阅读所有这些内容。我感谢任何恼人的讽刺评论，以及任何实际的帮助，使我成为一个更好的程序员和世界各地的其他人更好的程序员，正在阅读他们最喜欢的搜索引擎后阅读。：）

Answer 1

您的JScrollPane将匹配其内容的大小。如果JScrollPane中的图像小于JScrollPane，则不需要滚动条。我建议你增加图像的大小，以强制你的JScrollPane滚动。

您可以指定BufferedImage的大小。阅读BufferedImages here并使用this作为如何在BufferedImage上绘制图像的示例。

如何让jscrollpane区域滚动？

1 个答案: