What is the importance of JViewport class in Java?

AWTJavaObject Oriented ProgrammingProgrammingSwing

JViewport

  • A JViewport class defines the basic scrolling model and it is designed to support both logical scrolling and pixel-based scrolling.
  • The viewport's child called the view is scrolled by calling JViewport.setViewPosition() method.
  • A JViewport class supports logical scrolling, that is a kind of scrolling in which view coordinates are not pixels.
  • To support a logical scrolling, JViewport defines a small set of methods that can be used to define the geometry of a viewport and a view. By default, these methods just report the pixel dimensions of the viewport and view.

Example

import java.awt.*;
import javax.swing.*;
public class JViewportTest extends JFrame {
   public JViewportTest() {
      setTitle("JViewport Test");
      setLayout(new FlowLayout());
      JLabel label = new JLabel(new ImageIcon("C:/Users/User/Desktop/Java Answers/logo.jpg"));
      JViewport viewport = new JViewport();
      viewport.setView(label);
      viewport.setExtentSize(new Dimension(350, 350));
      viewport.setViewPosition(new Point(50, 25));
      viewport.setPreferredSize(new Dimension(350, 275));
      add(viewport);
      setSize(400, 300);
      setLocationRelativeTo(null);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setVisible(true);
   }
   public static void main(String[] args) {
      new JViewportTest();
   }
}

Output

raja
Published on 17-Jul-2019 14:31:53
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