JViewport: setViewPosition(Point p) : JViewport « javax.swing « Java by API

1. Java by API
2. javax.swing
3. JViewport

JViewport: setViewPosition(Point p)

 
import java.awt.Container;
import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.MouseEvent;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.event.MouseInputAdapter;

public class Main extends JFrame {
  public Main() {
    super("Grab and drag Demo");
    ImageIcon ii = new ImageIcon("largeJava2sLogo.jpg");
    JScrollPane jsp = new JScrollPane(new GrabAndScrollLabel(ii));
    getContentPane().add(jsp);
    setSize(300, 250);
    setVisible(true);

    super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }

  public static void main(String[] args) {
    new Main();
  }
}

class GrabAndScrollLabel extends JLabel {
  public GrabAndScrollLabel(ImageIcon i) {
    super(i);

    MouseInputAdapter mia = new MouseInputAdapter() {
      int xDiff, yDiff;
      Container c;
      public void mouseDragged(MouseEvent e) {
        c = GrabAndScrollLabel.this.getParent();
        if (c instanceof JViewport) {
          JViewport jv = (JViewport) c;
          Point p = jv.getViewPosition();
          int newX = p.x - (e.getX() - xDiff);
          int newY = p.y - (e.getY() - yDiff);

          int maxX = GrabAndScrollLabel.this.getWidth() - jv.getWidth();
          int maxY = GrabAndScrollLabel.this.getHeight() - jv.getHeight();
          if (newX < 0)
            newX = 0;
          if (newX > maxX)
            newX = maxX;
          if (newY < 0)
            newY = 0;
          if (newY > maxY)
            newY = maxY;

          jv.setViewPosition(new Point(newX, newY));
        }
      }

      public void mousePressed(MouseEvent e) {
        setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
        xDiff = e.getX();
        yDiff = e.getY();
      }

      public void mouseReleased(MouseEvent e) {
        setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
      }
    };
    addMouseMotionListener(mia);
    addMouseListener(mia);
  }
}

   
  

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