Java image to icon image

ImageIcon

In this article we are going to work with ImageIcon . We will paint an icon, scale an icon, create a custom icon, and put icons into various Swing components.

ImageIcon

Icon is small fixed size picture, typically used to decorate components. ImageIcon is an implementation of the Icon interface that paints icons from images. Images can be created from a URL, filename, or byte array.

paintIcon(Component c, Graphics g, int x, int y)

The Icon’s paintIcon method draws the icon at the specified location.

ImageIcon constructors

• ImageIcon(byte[] imageData) — creates an ImageIcon from an array of bytes.
• ImageIcon(Image image ) — creates an ImageIcon from an image object.
• ImageIcon(String filename) — creates an ImageIcon the specified file.
• ImageIcon(URL location) — creates an ImageIcon from the specified URL.

ImageIcon can work with PNG, JPEG, and GIF images. If we want to work with BMP or ICO images, we can use the image4j library.

Painting icon

In the first example, we are going to paint an icon on the panel.

package com.zetcode; import java.awt.Container; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import javax.swing.GroupLayout; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JPanel; class DrawingPanel extends JPanel < private ImageIcon icon; public DrawingPanel() < loadImage(); initPanel(); >private void loadImage() < icon = new ImageIcon("book.jpg"); >private void initPanel() < int w = icon.getIconWidth(); int h = icon.getIconHeight(); setPreferredSize(new Dimension(w, h)); >@Override public void paintComponent(Graphics g) < super.paintComponent(g); icon.paintIcon(this, g, 0, 0); >> public class PaintingIconEx extends JFrame < public PaintingIconEx() < initUI(); >private void initUI() < DrawingPanel dpnl = new DrawingPanel(); createLayout(dpnl); setTitle("Image"); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); >private void createLayout(JComponent. arg) < Container pane = getContentPane(); GroupLayout gl = new GroupLayout(pane); pane.setLayout(gl); gl.setHorizontalGroup(gl.createSequentialGroup() .addComponent(arg[0]) ); gl.setVerticalGroup(gl.createParallelGroup() .addComponent(arg[0]) ); pack(); >public static void main(String[] args) < EventQueue.invokeLater(() ->< JFrame ex = new PaintingIconEx(); ex.setVisible(true); >); > >

The example loads an image from the filesystem into an ImageIcon and paints it on the JPanel component.

We load a JPG image into the ImageIcon . The image is located in the project root directory.

In the initPanel method, we determine the width and height of the icon with the getIconWidth and getIconHeight methods. We set the preferred size of the panel to match the icon size.

@Override public void paintComponent(Graphics g)

In the paintComponent method, we paint the icon on the panel with the paintIcon method. Figure: Painting icon

Scaling image

The following example shows a simple way to scale an image.

package com.zetcode; import java.awt.Container; import java.awt.EventQueue; import java.awt.Image; import javax.swing.GroupLayout; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; import javax.swing.JLabel; public class ImageIconScaleEx extends JFrame < public ImageIconScaleEx() < initUI(); >private void initUI() < ImageIcon originalIcon = new ImageIcon("slovakia.png"); JLabel originalLabel = new JLabel(originalIcon); int width = originalIcon.getIconWidth() / 2; int height = originalIcon.getIconHeight() / 2; Image scaled = scaleImage(originalIcon.getImage(), width, height); ImageIcon scaledIcon = new ImageIcon(scaled); JLabel newLabel = new JLabel(scaledIcon); createLayout(originalLabel, newLabel); setTitle("Scaled icon"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); >private Image scaleImage(Image image, int w, int h) < Image scaled = image.getScaledInstance(w, h, Image.SCALE_SMOOTH); return scaled; >private void createLayout(JComponent. arg) < Container pane = getContentPane(); GroupLayout gl = new GroupLayout(pane); pane.setLayout(gl); gl.setAutoCreateContainerGaps(true); gl.setAutoCreateGaps(true); gl.setHorizontalGroup(gl.createSequentialGroup() .addComponent(arg[0]) .addComponent(arg[1]) ); gl.setVerticalGroup(gl.createParallelGroup() .addComponent(arg[0]) .addComponent(arg[1]) ); pack(); >public static void main(String[] args) < EventQueue.invokeLater(() ->< ImageIconScaleEx ex = new ImageIconScaleEx(); ex.setVisible(true); >); > >

There are two images shown on the window: the original image and next to it the scaled image.

ImageIcon originalIcon = new ImageIcon("slovakia.png");

We read a PNG image into the ImageIcon . The image is located in the project root directory.

int width = originalIcon.getIconWidth() / 2; int height = originalIcon.getIconHeight() / 2;

We get the width and height of the original image with the getIconWidth and getIconHeight methods.

Image scaled = scaleImage(originalIcon.getImage(), width, height);

We pass the Image of the icon, its with and height to the scaleImage method, where we perform the scaling operation.

private Image scaleImage(Image image, int w, int h)

The getScaledInstance creates a scaled version of the Image . We use a Image.SCALE_SMOOTH scaling operation which gives higher priority to image smoothness than scaling speed.

ImageIcon scaledIcon = new ImageIcon(scaled); JLabel newLabel = new JLabel(scaledIcon);

We create an ImageIcon from the Image and pass it to a JLabel component. Figure: Scaling image

Custom icon

The Swing painting API can be also used to create a custom icon. The graphics context is passed to the paintIcon method.

package com.zetcode; import java.awt.BasicStroke; import java.awt.Color; import java.awt.Component; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import javax.swing.Icon; import javax.swing.JFrame; import javax.swing.JLabel; class MissingIcon implements Icon < private final int WIDTH = 32; private final int HEIGHT = 32; private final BasicStroke stroke = new BasicStroke(5); @Override public void paintIcon(Component c, Graphics g, int x, int y) < doDrawing(g, x, y); >public void doDrawing(Graphics g, int x, int y) < Graphics2D g2d = (Graphics2D) g.create(); g2d.setColor(Color.white); g2d.fillRect(x + 1, y + 1, WIDTH - 2, HEIGHT - 2); g2d.setColor(Color.darkGray); g2d.drawRect(x + 1, y + 1, WIDTH - 2, HEIGHT - 2); g2d.setColor(Color.red); g2d.setStroke(stroke); g2d.drawLine(x + 10, y + 10, x + WIDTH - 10, y + HEIGHT - 10); g2d.drawLine(x + 10, y + HEIGHT - 10, x + WIDTH - 10, y + 10); g2d.dispose(); >@Override public int getIconWidth() < return WIDTH; >@Override public int getIconHeight() < return HEIGHT; >> class MyLabel extends JLabel < public MyLabel(Icon icon) < super(icon); >@Override public boolean isOpaque() < return true; >> public class CustomIconEx extends JFrame < public CustomIconEx() < initUI(); >private void initUI() < JLabel lbl = new MyLabel(new MissingIcon()); lbl.setBackground(Color.gray); add(lbl); setSize(250, 150); setTitle("Custom icon"); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); >public static void main(String[] args) < EventQueue.invokeLater(() ->< CustomIconEx ex = new CustomIconEx(); ex.setVisible(true); >); > >

The example creates a missing custom icon and shows it on a window with JLabel .

class MissingIcon implements Icon 
To create a custom icon, we implement the Icon interface.
@Override public int getIconWidth() < return WIDTH; >@Override public int getIconHeight()
We override the getIconWidth and getIconHeight methods, which determine the size of the icon.
@Override public void paintIcon(Component c, Graphics g, int x, int y)
We override the paintIcon method, in which the icon is painted. The Graphics object exposes a number of methods for drawing 2D shapes and obtaining information about the application's graphics environment.
public void doDrawing(Graphics g, int x, int y)
Inside the doDrawing method, we draw the icon. The process is identical to drawing inside the paintComponent method. The Graphics2D class extends the Graphics class to provide more sophisticated control over geometry, coordinate transformations, color management, and text layout.
class MyLabel extends JLabel < public MyLabel(Icon icon) < super(icon); >@Override public boolean isOpaque() < return true; >>
 
We have a custom MyLabel component. We make it opaque, that is, the label has a background.
 
JLabel lbl = new MyLabel(new MissingIcon());
 
 
The icon is set to the label component. Figure: Missing custom icon
 
ImageIcon buttons
 
It is possible to place ImageIcons on JButton components.
 
package com.zetcode; import java.awt.Container; import java.awt.EventQueue; import javax.swing.GroupLayout; import javax.swing.ImageIcon; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; public class ImageIconButtonsEx extends JFrame < public ImageIconButtonsEx() < initUI(); >private void initUI() < ImageIcon quitIcon = new ImageIcon("quit.png"); ImageIcon saveIcon = new ImageIcon("save.png"); ImageIcon homeIcon = new ImageIcon("home.png"); JButton quitBtn = new JButton(quitIcon); JButton saveBtn = new JButton(saveIcon); JButton homeBtn = new JButton(homeIcon); createLayout(quitBtn, saveBtn, homeBtn); setTitle("JButtons"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); >private void createLayout(JComponent. arg) < Container pane = getContentPane(); GroupLayout gl = new GroupLayout(pane); pane.setLayout(gl); gl.setAutoCreateContainerGaps(true); gl.setAutoCreateGaps(true); gl.setHorizontalGroup(gl.createSequentialGroup() .addComponent(arg[0]) .addComponent(arg[1]) .addComponent(arg[2]) ); gl.setVerticalGroup(gl.createParallelGroup() .addComponent(arg[0]) .addComponent(arg[1]) .addComponent(arg[2]) ); gl.linkSize(arg[0], arg[1], arg[2]); pack(); >public static void main(String[] args) < EventQueue.invokeLater(() ->< ImageIconButtonsEx ex = new ImageIconButtonsEx(); ex.setVisible(true); >); > >
 
We have three buttons. Each of them displays an ImageIcon .
 
ImageIcon quitIcon = new ImageIcon("quit.png"); ImageIcon saveIcon = new ImageIcon("save.png"); ImageIcon homeIcon = new ImageIcon("home.png");
 
Three ImageIcons are created. We pass a file name to each of the constructors. The PNG files are located in the project root directory.
 
JButton quitBtn = new JButton(quitIcon); JButton saveBtn = new JButton(saveIcon); JButton homeBtn = new JButton(homeIcon);
 
 
JButton component accepts ImageIcon as a parameter. Figure: Image buttons
 
JFrame icon
 
JFrame component can show an icon in its titlebar. It is shown in the left part of the titlebar.
 
package com.zetcode; import java.awt.EventQueue; import javax.swing.ImageIcon; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; public class FrameIconEx extends JFrame < public FrameIconEx() < initUI(); >private void initUI() < ImageIcon webIcon = new ImageIcon("web.png"); setIconImage(webIcon.getImage()); setTitle("Icon"); setSize(300, 200); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); >public static void main(String[] args) < EventQueue.invokeLater(() ->< FrameIconEx ex = new FrameIconEx(); ex.setVisible(true); >); > >
 
The web.png is a small, 22x22px image file.
 
ImageIcon webIcon = new ImageIcon("web.png");
 
We create an ImageIcon from a PNG file, which is located in the project root directory.
 
setIconImage(webIcon.getImage());
 
 
The setIconImage sets the image to be displayed as the icon for this window. The getImage returns the icon's Image . Figure: Icon
 
ImageIcon in JLabel
 
In the following example, we place ImageIcons into JLabel components.
 
package com.zetcode; import java.awt.Container; import java.awt.EventQueue; import javax.swing.GroupLayout; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; import javax.swing.JLabel; public class ImageIconLabelEx extends JFrame < public ImageIconLabelEx() < initUI(); >private void initUI() < JLabel lbl1 = new JLabel(new ImageIcon("cpu.png")); JLabel lbl2 = new JLabel(new ImageIcon("drive.png")); JLabel lbl3 = new JLabel(new ImageIcon("laptop.png")); JLabel lbl4 = new JLabel(new ImageIcon("player.png")); JLabel lbl5 = new JLabel(new ImageIcon("pda.png")); createLayout(lbl1, lbl2, lbl3, lbl4, lbl5); setTitle("Icons"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); >private void createLayout(JComponent. arg) < Container pane = getContentPane(); GroupLayout gl = new GroupLayout(pane); pane.setLayout(gl); gl.setAutoCreateContainerGaps(true); gl.setAutoCreateGaps(true); gl.setHorizontalGroup(gl.createSequentialGroup() .addComponent(arg[0]) .addComponent(arg[1]) .addComponent(arg[2]) .addComponent(arg[3]) .addComponent(arg[4]) ); gl.setVerticalGroup(gl.createParallelGroup() .addComponent(arg[0]) .addComponent(arg[1]) .addComponent(arg[2]) .addComponent(arg[3]) .addComponent(arg[4]) ); pack(); >public static void main(String[] args) < EventQueue.invokeLater(() ->< ImageIconLabelEx ex = new ImageIconLabelEx(); ex.setVisible(true); >); > >
 
There are five PNG files in a project root directory. They are displayed on the windows in JLabel components.
 
JLabel lbl1 = new JLabel(new ImageIcon("cpu.png")); JLabel lbl2 = new JLabel(new ImageIcon("drive.png")); JLabel lbl3 = new JLabel(new ImageIcon("laptop.png")); JLabel lbl4 = new JLabel(new ImageIcon("player.png")); JLabel lbl5 = new JLabel(new ImageIcon("pda.png"));
 
 
JLabel has a constructor which takes an ImageIcon as a parameter. Figure: Icons in labels
 
ImageIcon in JTabbedPane
 
JTabbedPane is a Swing component that lets the user switch between a group of components by clicking on a tab. The tabs can contains ImageIcons .
 
package com.zetcode; import java.awt.Container; import java.awt.Dimension; import java.awt.EventQueue; import javax.swing.GroupLayout; import javax.swing.ImageIcon; import javax.swing.JComponent; import javax.swing.JFrame; import static javax.swing.JFrame.EXIT_ON_CLOSE; import javax.swing.JPanel; import javax.swing.JTabbedPane; public class ImageIconTabbedPaneEx extends JFrame < public ImageIconTabbedPaneEx() < initUI(); >private void initUI() < ImageIcon icon1 = new ImageIcon("dot1.png"); ImageIcon icon2 = new ImageIcon("dot2.png"); ImageIcon icon3 = new ImageIcon("dot3.png"); JTabbedPane tbp = new JTabbedPane(); tbp.setPreferredSize(new Dimension(350, 250)); tbp.addTab("", icon1, new JPanel()); tbp.addTab("", icon2, new JPanel()); tbp.addTab("", icon3, new JPanel()); createLayout(tbp); setTitle("Icons"); setLocationRelativeTo(null); setDefaultCloseOperation(EXIT_ON_CLOSE); >private void createLayout(JComponent. arg) < Container pane = getContentPane(); GroupLayout gl = new GroupLayout(pane); pane.setLayout(gl); gl.setAutoCreateContainerGaps(true); gl.setAutoCreateGaps(true); gl.setHorizontalGroup(gl.createSequentialGroup() .addComponent(arg[0]) ); gl.setVerticalGroup(gl.createParallelGroup() .addComponent(arg[0]) ); pack(); >public static void main(String[] args) < EventQueue.invokeLater(() ->< ImageIconTabbedPaneEx ex = new ImageIconTabbedPaneEx(); ex.setVisible(true); >); > >
 
The example shows ImageIcons in the tabs of a JTabbedPane component.
 
ImageIcon icon1 = new ImageIcon("dot1.png");
 
JTabbedPane tbp = new JTabbedPane();
 
tbp.addTab("", icon1, new JPanel());
 
 
The second parameter of the addTab method is an ImageIcon . Figure: JTabbedPane icons
 
This tutorial was dedicated to the Java ImageIcon .
 
Author
 
My name is Jan Bodnar and I am a passionate programmer with many years of programming experience. I have been writing programming articles since 2007. So far, I have written over 1400 articles and 8 e-books. I have over eight years of experience in teaching programming.
 
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