Java by API/java.awt/Image

Image: getHeight(ImageObserver observer)

  
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JFrame {
  Main() {
    add(new ContentPanel());
    setSize(500, 300);
  }
  public static void main(String[] args) {
    Main jrframe = new Main();
    jrframe.setVisible(true);
  }
}
class ContentPanel extends JPanel {
  Image bgimage = null;
  ContentPanel() {
    MediaTracker mt = new MediaTracker(this);
    bgimage = Toolkit.getDefaultToolkit().getImage("a.jpg");
    mt.addImage(bgimage, 0);
    try {
      mt.waitForAll();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    int imwidth = bgimage.getWidth(null);
    int imheight = bgimage.getHeight(null);
    g.drawImage(bgimage, 1, 1, null);
  }
}

Image: getScaledInstance(int width, int height, int hints)

  

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JFrame implements ActionListener {
  Image img;
  JButton getPictureButton  = new JButton("Get Picture");
  public static void main(String[] args) {
    new Main();
  }
  public Main() {
    this.setSize(300, 300);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel picPanel = new PicturePanel();
    this.add(picPanel, BorderLayout.CENTER);
    JPanel buttonPanel = new JPanel();
    getPictureButton.addActionListener(this);
    buttonPanel.add(getPictureButton);
    this.add(buttonPanel, BorderLayout.SOUTH);
    this.setVisible(true);
  }
  public void actionPerformed(ActionEvent e) {
    String file = "a.png";
    if (file != null) {
      Toolkit kit = Toolkit.getDefaultToolkit();
      img = kit.getImage(file);
      img = img.getScaledInstance(300, -1, Image.SCALE_SMOOTH);
      this.repaint();
    }
  }
  class PicturePanel extends JPanel {
    public void paint(Graphics g) {
      g.drawImage(img, 0, 0, this);
    }
  }
}

Image: getWidth(ImageObserver observer)

  
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Toolkit;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JFrame {
  Main() {
    add(new ContentPanel());
    setSize(500, 300);
  }
  public static void main(String[] args) {
    Main jrframe = new Main();
    jrframe.setVisible(true);
  }
}
class ContentPanel extends JPanel {
  Image bgimage = null;
  ContentPanel() {
    MediaTracker mt = new MediaTracker(this);
    bgimage = Toolkit.getDefaultToolkit().getImage("a.jpg");
    mt.addImage(bgimage, 0);
    try {
      mt.waitForAll();
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
  protected void paintComponent(Graphics g) {
    super.paintComponent(g);
    int imwidth = bgimage.getWidth(null);
    int imheight = bgimage.getHeight(null);
    g.drawImage(bgimage, 1, 1, null);
  }
}

Image.SCALE_DEFAULT

  

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.RepaintManager;
public class Main extends JComponent implements MouseMotionListener {
  static int imageWidth = 60, imageHeight = 60;
  int imageX, imageY;
  Image image;
  public Main(Image i) {
    image = i;
    addMouseMotionListener(this);
  }
  public void mouseDragged(MouseEvent e) {
    imageX = e.getX();
    imageY = e.getY();
    repaint();
  }
  public void mouseMoved(MouseEvent e) {
  }
  public void paint(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;
    g2.drawImage(image, imageX, imageY, this);
  }
  public static void main(String[] args) {
    String imageFile = "A.jpg";
    RepaintManager.currentManager(null).setDoubleBufferingEnabled(false);
    Image image = Toolkit.getDefaultToolkit().getImage(Main.class.getResource(imageFile));
    image = image.getScaledInstance(imageWidth, imageHeight, Image.SCALE_DEFAULT);
    JFrame frame = new JFrame("DragImage");
    frame.getContentPane().add(new Main(image));
    frame.setSize(300, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }
}

Image.SCALE_SMOOTH

  
import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main extends JFrame implements ActionListener {
  Image img;
  JButton getPictureButton  = new JButton("Get Picture");
  public static void main(String[] args) {
    new Main();
  }
  public Main() {
    this.setSize(300, 300);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel picPanel = new PicturePanel();
    this.add(picPanel, BorderLayout.CENTER);
    JPanel buttonPanel = new JPanel();
    getPictureButton.addActionListener(this);
    buttonPanel.add(getPictureButton);
    this.add(buttonPanel, BorderLayout.SOUTH);
    this.setVisible(true);
  }
  public void actionPerformed(ActionEvent e) {
    String file = "a.png";
    if (file != null) {
      Toolkit kit = Toolkit.getDefaultToolkit();
      img = kit.getImage(file);
      img = img.getScaledInstance(300, -1, Image.SCALE_SMOOTH);
      this.repaint();
    }
  }
  class PicturePanel extends JPanel {
    public void paint(Graphics g) {
      g.drawImage(img, 0, 0, this);
    }
  }
}