Develop Reference

JScrollPane and Zooming Images

I'm trying to write a simple class that extends from JPanel that can zoom in and zoom out on an image and then uses a JScrollPane at the top level to allow someone to scroll back and forth across the zoomed image. I've having trouble with the JScrollPane portion.
When clicking one of the zoom buttons (whether it be in, out, or reset), the button must be clicked twice in order for the JScrollBars to appear(or in the case of the reset button, disappear). Even after they've appear if you continue to zoom in or out the bars do not update according to the new level of zoom. Resizing the window fixes this issue but I'm looking for a more concrete solution.
ImagePanel Code:
package com.zephyr.graphics;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class ImagePanel extends JPanel implements PropertyChangeListener{
private File imageFile;
private BufferedImage image;
private double zoomMultiplier;
public ImagePanel()
{
imageFile = null;
image = null;
zoomMultiplier = 1;
}
public ImagePanel(File imageFile)
{
this.imageFile = imageFile;
try {
image = ImageIO.read(imageFile);
} catch (IOException e) {
image = null;
}
zoomMultiplier = 1;
}
public void setImageFile(File imageFile)
{
this.imageFile = imageFile;
if(imageFile == null)
{
image = null;
}
else
{
try {
image = ImageIO.read(imageFile);
} catch (IOException e) {
image = null;
}
}
zoomMultiplier = 1;
this.revalidate();
this.repaint();
}
public File getImageFile()
{
return imageFile;
}
public void paintComponent(Graphics g)
{
g.clearRect(0, 0, this.getWidth(), this.getHeight());
if(image == null)
{
this.setPreferredSize(new Dimension(this.getParent().getWidth(), this.getParent().getHeight()));
g.setColor(Color.black);
g.fillRect(0, 0, this.getWidth(), this.getHeight());
}
else
{
double preferredWidth = this.getParent().getWidth() * zoomMultiplier;
double preferredHeight = this.getParent().getHeight() * zoomMultiplier;
this.setPreferredSize(new Dimension((int)preferredWidth, (int)preferredHeight));
Image scaled = image.getScaledInstance((int)preferredWidth, (int)preferredHeight, Image.SCALE_DEFAULT);
g.drawImage(scaled, 0, 0, null);
}
}
#Override
public void propertyChange(PropertyChangeEvent evt) {
if(evt.getPropertyName().equals("Image File"))
{
setImageFile((File)evt.getNewValue());
}
else if(evt.getPropertyName().equals("Zoom In"))
{
double additive = ((Number)evt.getNewValue()).doubleValue();
zoomMultiplier += additive;
this.revalidate();
this.repaint();
}
else if(evt.getPropertyName().equals("Zoom Out"))
{
double subtractive = ((Number)evt.getNewValue()).doubleValue();
zoomMultiplier -= subtractive;
this.revalidate();
this.repaint();
}
else if(evt.getPropertyName().equals("Zoom Reset"))
{
zoomMultiplier = 1;
this.revalidate();
this.repaint();
}
}
}
Main Class
package com.zephyr.graphics;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeSupport;
import java.io.File;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class Main {
public static void main(String[] args)
{
PropertyChangeSupport pcs = new PropertyChangeSupport(Main.class);
JFileChooser chooser = new JFileChooser(System.getProperty("user.home"));
chooser.setDialogTitle("Select an image");
chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
File file = null;
if(chooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION)
{
file = chooser.getSelectedFile();
}
else
{
System.err.println("NO FILE WAS SELECTED OR THE WINDOW WAS CLOSED");
return;
}
JFrame frame = new JFrame("ImagePanel Tester");
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ImagePanel iPanel = new ImagePanel(file);
pcs.addPropertyChangeListener(iPanel);
JScrollPane iScroll = new JScrollPane(iPanel, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
iScroll.setPreferredSize(new Dimension(1024, 768));
JPanel controlPanel = new JPanel();
controlPanel.setLayout(new FlowLayout(FlowLayout.CENTER));
JButton zoomIn = new JButton("Zoom In");
zoomIn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
pcs.firePropertyChange("Zoom In", null, new Double(.25));
frame.revalidate();
frame.repaint();
}
});
controlPanel.add(zoomIn);
JButton zoomOut = new JButton("Zoom Out");
zoomOut.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
pcs.firePropertyChange("Zoom Out", null, new Double(.25));
frame.revalidate();
frame.repaint();
}
});
controlPanel.add(zoomOut);
JButton zoomReset = new JButton("Zoom Reset");
zoomReset.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
pcs.firePropertyChange("Zoom Reset", null, null);
frame.revalidate();
frame.repaint();
}
});
controlPanel.add(zoomReset);
JButton changeImage = new JButton("Change Image");
changeImage.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(chooser.showOpenDialog(frame) == JFileChooser.APPROVE_OPTION)
{
File tempFile = chooser.getSelectedFile();
pcs.firePropertyChange("Image File", null, tempFile);
frame.revalidate();
frame.repaint();
}
}
});
controlPanel.add(changeImage);
frame.add(iScroll, BorderLayout.CENTER);
frame.add(controlPanel, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
frame.revalidate(); //Shouldn't really be necessary, but seems to be helping
}
}

After some heavy digging, the Scrollable interface saved me. Implementing this and it's respective methods following this example as well as removing the preferredSize references from paintComponent fixes the issues that I was having.

Painting issue in custom layered container?

So I am working on a project here that requires a custom JLayeredPane - like class.
It has two members 'ground' and 'foreground' that are JPanel and an background (Image) member.
The way it was supposed to show was that the background Image should have been drawn and then all the components of the ground on top of it and then foreground's components at the apex. So foreground covers up ground which covers up background. Background should be shown only at places that do not have a Component in ground and foreground or where there is transparency in the JPanels.
It's paint function goes like this:
#Override
public void paint(Graphics g){
g.drawImage(background, 0, 0, null);
ground.paint(g.create());
foreground.paint(g.create());
g.dispose();
}
But nothing like that happens. Just the background image gets painted and nothing else shows.
I have used System.out.println() function to check that ground and foreground actually hold components and they do. But they just don't show.
Can anyone help me here?

The most significant issue is you're not calling super.paint, which is preventing what ever was previously painted to the Graphics context from been cleared or any child components from been painted.
For painting the background, you should be using paintComponent, which is used to paint the background of the component.
If you need to paint under the child components, but above the background, you should still use paintComponent, but paint the background first and then the next layer. The components will be painted after paintComponent.
Painting over components is actually more complex
Take a closer look at Custom Painting and Painting in Swing and AWT
Updated based on code snippets
In Screen which extends from Container, you are doing...
#Override
public void paint(Graphics g) {
super.paint(g);
GraphicsUtilities.drawPictureTiled(background, g);
paintComponents(g);
g.dispose();
}
Don't call paintComponents, super.paint has already done this.
Don't call dispose on a Graphics context you don't create
Based on the rest of the example code I have, you should be extending from JPanel and overriding paintComponent instead. This will allow you to put under the component layer
Because GroundPanel and ForeGroundPanel are both JPanels, there's no need to ever paint them yourself. In fact, you could simply use OverlayLayout or even a GridBagLayout and add them directly to the NestedScreen which is itself a container...
So, I stripped down you example code so I could get it working with the missing code as an example. I got a little more fancy and simply made a JPanel to act as the pause screen
This is all done by simply overlaying the components on top of each other using a GridBagLayout
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test1001 {
public static void main(String[] args) {
new Test1001();
}
public Test1001() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
NestedScreen screen = new NestedScreen();
screen.setBackgroundLayer(ImageIO.read(getClass().getResource("/Sky.png")));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(screen);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
public interface GraphicsEngineComponents {
}
public class NestedScreen extends Screen implements GraphicsEngineComponents {
GroundPanel ground;
ForeGroundPanel foreground;
private PausePane pausePane;
public NestedScreen() {
ground = new GroundPanel();
foreground = new ForeGroundPanel();
pausePane = new PausePane();
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1;
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
add(pausePane, gbc);
add(foreground, gbc);
add(ground, gbc);
MouseAdapter handler = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
pausePane.setVisible(!pausePane.isVisible());
}
};
addMouseListener(handler);
foreground.addMouseListener(handler);
ground.addMouseListener(handler);
}
public GroundPanel getGroundLayer() {
return ground;
}
public ForeGroundPanel getForegroundLayer() {
return foreground;
}
public void setBackgroundLayer(BufferedImage background) {
super.setBackgroundLayer(background);
}
public class GroundPanel extends JPanel {
public GroundPanel() {
setOpaque(false);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.GREEN);
g.fillRect(0, getHeight() - 200, getWidth(), 200);
}
}
public class PausePane extends JPanel {
private JLabel label;
public PausePane() {
setVisible(false);
setOpaque(false);
setBackground(new Color(0, 0, 0, 128));
setLayout(new GridBagLayout());
label = new JLabel("Paused");
label.setHorizontalAlignment(JLabel.CENTER);
label.setVerticalAlignment(JLabel.CENTER);
Font font = label.getFont();
font = font.deriveFont(Font.BOLD, 48f);
label.setFont(font);
label.setForeground(Color.WHITE);
add(label);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
public class ForeGroundPanel extends JPanel {
private BufferedImage pony;
public ForeGroundPanel() {
setOpaque(false);
try {
pony = ImageIO.read(getClass().getResource("/Pony.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (pony != null) {
int x = (getWidth() - pony.getWidth()) / 2;
int y = getHeight() - 200 - (pony.getHeight() / 2);
g.drawImage(pony, x, y, this);
}
}
}
}
public class Screen extends JPanel implements GraphicsEngineComponents {
private BufferedImage background;
public Screen() {
}
#Override
public String toString() {
return "Screen{" + "background=" + background + '}';
}
public BufferedImage getBackgroundPicture() {
return background;
}
#Override
public Dimension getPreferredSize() {
return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight());
}
protected void setBackgroundLayer(BufferedImage background) {
if (background != null && background.getHeight() != 0 && background.getWidth() != 0) {
this.background = background;
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
g.drawImage(background, 0, 0, this);
}
}
}
}
Take a look at Painting in AWT and Swing and Performing Custom Painting to understand how painting works in Swing.
A basic idea would be to avoid using all these compound or nested components and instead, create an engine that can paint the layers directly onto a Graphics context, maybe even painting to a BufferedImage which you can the paint onto a single component...

There are a few ways you go about doing this. I'll just introduce one way.
Create a background panel where you paint the background image (in the example below, it is BackgroundPanel with the image only being the forresty background). Set that panel as the content pane to the frame.
Create another ground panel where you can also paint something (in the example below if it the GroundPanel with only the image of bugs bunny painted.
Create your foreground panel and add it to the ground panel. You can add your foreground components to it. (in the example below the foreground image is the grassy hill, and I also add a button to it
All the panels' opaque property should be set to false, as to allow the panel behind it to be shown under any transparency.
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
public class ThreeTier {
public static final int DIM_WIDTH = 600;
public static final int DIM_HEIGHT = 400;
private BufferedImage backgroundImage;
private BufferedImage groundImage;
private BufferedImage foregroundImage;
public ThreeTier() {
initImages();
JFrame frame = new JFrame();
frame.setContentPane(new BackgroundPanel());
frame.add(new GroundPanel());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void initImages() {
try {
backgroundImage = ImageIO.read(getClass().getResource("/resources/background.png"));
foregroundImage = ImageIO.read(getClass().getResource("/resources/foreground.png"));
groundImage = ImageIO.read(getClass().getResource("/resources/bugsBunny.png"));
} catch (IOException ex) {
Logger.getLogger(ThreeTier.class.getName()).log(Level.SEVERE, null, ex);
}
}
class BackgroundPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(backgroundImage, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
class GroundPanel extends JPanel {
private static final String RIGHT_ACTION = "rightAction";
private int imageX = 50;
private int imageY = 140;
public GroundPanel() {
setOpaque(false);
add(new ForegroundPanel());
InputMap im = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
im.put(KeyStroke.getKeyStroke("RIGHT"), RIGHT_ACTION);
getActionMap().put(RIGHT_ACTION, new AbstractAction() {
public void actionPerformed(ActionEvent e) {
if (imageX >= DIM_WIDTH) {
imageX = 0 - groundImage.getWidth();
repaint();
} else {
imageX += 10;
repaint();
}
}
});
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(groundImage, imageX, imageY, groundImage.getWidth(), groundImage.getHeight(), this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
class ForegroundPanel extends JPanel {
public ForegroundPanel() {
setOpaque(false);
setLayout(new FlowLayout(FlowLayout.TRAILING, 10, 0));
JButton button = new JButton("I'm in the Foreground!");
add(button);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(foregroundImage, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ThreeTier();
}
});
}
}
UPDATE
Of course you could always just use the JLayeredPane. That's what it's for. See this example
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.border.LineBorder;
public class LayeredPaneDemo {
public static final int DIM_WIDTH = 600;
public static final int DIM_HEIGHT = 400;
public LayeredPaneDemo() {
ContainerPanel container = new ContainerPanel();
JLabel title = new JLabel("Lame Google Map");
title.setFont(new Font("verdana", Font.BOLD, 36));
title.setHorizontalAlignment(JLabel.CENTER);
JPanel panel = new JPanel(new GridBagLayout());
panel.add(container);
JFrame frame = new JFrame();
frame.add(panel);
frame.add(title, BorderLayout.NORTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new LayeredPaneDemo();
}
});
}
public class ContainerPanel extends JPanel {
public ContainerPanel() {
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new Dimension(DIM_WIDTH, DIM_HEIGHT));
BackgroundPanel bg = new BackgroundPanel();
GroundPanel gg = new GroundPanel();
ForegroundPanel fg = new ForegroundPanel();
bg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(bg, new Integer(1));
gg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(gg, new Integer(2));
fg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(fg, new Integer(3));
setLayout(new GridBagLayout());
add(layeredPane);
setBorder(new LineBorder(Color.BLUE, 10));
}
}
public class ForegroundPanel extends JPanel {
public ForegroundPanel() {
JPanel buttonPanel = new JPanel(new GridLayout(3, 3));
buttonPanel.setOpaque(false);
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("UP"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Left"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Right"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Down"));
buttonPanel.add(new JLabel());
FlowLayout flow = (FlowLayout) getLayout();
flow.setAlignment(FlowLayout.TRAILING);
flow.setHgap(0);
flow.setVgap(0);
add(buttonPanel);
setOpaque(false);
}
}
public class GroundPanel extends JPanel {
Image image = null;
public GroundPanel() {
try {
image = ImageIO.read(getClass().getResource("/resources/california.png"));
} catch (IOException ex) {
Logger.getLogger(LayeredPaneDemo.class.getName()).log(Level.SEVERE, null, ex);
}
setOpaque(false);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
}
public class BackgroundPanel extends JPanel {
public BackgroundPanel() {
setLayout(new GridBagLayout());
setBackground(Color.WHITE);
try {
Image img = ImageIO.read(getClass().getResource("/resources/google.jpg"));
add(new JLabel(new ImageIcon(img)));
} catch (IOException ex) {
Logger.getLogger(LayeredPaneDemo.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}

Drawing an image in JScrollPane within scale

I have a scrollpane where load an image. I wont this image with her natural size, and if this image is too big, I wont activated the scrollbar, but this instruction
g.drawImage(immagine, 0, 0, getWidth(), getHeight(), this);
scaled image for placing in scrollpane. What can I do?
Class Gui:
import java.awt.*;
import java.awt.event.*;
import java.io.File;
import javax.swing.*;
public class Gui implements ActionListener {
private JFrame frmEditor;
private Mappa content;
private JMenuItem mntmSfondo;
private JScrollPane scrollabile;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Gui window = new Gui();
window.frmEditor.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public Gui() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frmEditor = new JFrame();
frmEditor.setFont(UIManager.getFont("TextArea.font"));
frmEditor.setBounds(50, 50, 1024, 768);
frmEditor.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmEditor.getContentPane().setLayout(new BorderLayout(0, 0));
JPanel panelTile = new JPanel();
panelTile.setLayout(new BorderLayout(0, 0));
content = new Mappa(null);
content.setMinimumSize(new Dimension(150, 150));
scrollabile = new JScrollPane(content);
frmEditor.getContentPane().add(scrollabile, BorderLayout.CENTER);
inizializzaMenu();
}
/**
* Initialize the menu.
*/
private void inizializzaMenu() {
JMenuBar menuBar = new JMenuBar();
frmEditor.setJMenuBar(menuBar);
JMenu mnAltro = new JMenu("Modify");
menuBar.add(mnAltro);
mntmSfondo = new JMenuItem("Load Background");
mntmSfondo.addActionListener(this);
mnAltro.add(mntmSfondo);
}
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if (source == mntmSfondo) {
JFileChooser fc = new JFileChooser("tuttiSfondi");
int result = fc.showOpenDialog(null);
if (result == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
try {
content.setImage(file);
//content = new Mappa(file);
//scrollabile.setViewportView(content);
} catch (Exception ex) {
}
}
if (result == JFileChooser.CANCEL_OPTION) {
}
}
}
}
Class Mappa:
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Mappa extends JPanel {
BufferedImage immagine;
public Mappa(File fileImmagine) {
if (fileImmagine != null ) {
BufferedImage img = null;
try {
img = ImageIO.read(new File(fileImmagine.getPath()));
} catch (IOException e) {
e.printStackTrace();
}
this.immagine = img;
}
repaint();
}
public void setImage(File file) throws IOException {
this.immagine = ImageIO.read(file);
String name = file.getPath();
System.out.println(name);
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.clearRect(0, 0, 4000, 4000);
g.drawImage(this.immagine, 0, 0, getWidth(), getHeight(), this);
System.out.println("Called Repaint() on Mappa");
}
}

JScrollPane, or more to the point JViewport will use the component's (or in this case the "view's") preferred size as a bases for determining how big the view should be.
When the view expands beyond the size of the scroll pane, it will show the scroll bars.
So basically, you need to override the getPreferredSize of the public class Mappa extends JPanel { panel, for example
public class Mappa extends JPanel {
//...
public Dimension getPreferredSize() {
return immagine == null ? new Dimension(200, 200) : new Dimension(immagine.getWidth(), immagine.getHeight());
}
//...
}
This will encourage the JViewport to always be the same size as the image.
Also, two things...
First, you shouldn't rely on magic numbers, for example
g.clearRect(0, 0, 4000, 4000);
Should be more like...
g.clearRect(0, 0, getWidth(), getHeight());
And secondly,
super.paintComponent(g);
Will do this any way, so calling clearRect is kind of pointless...
You might also like to take a look at Scrollable, but it is quite an advanced topic

I wont this image with her natural size, and if this image is too
big, I wont activated the scrollbar,
Using JLabel to contain the image and wrap it in a JScrollPane should easily achieve what you want. Take hints from the following example:
class AFrame extends JFrame
{
public AFrame()
{
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Image view Demo with JScrollPane");
ImageIcon image = new ImageIcon("myImage.png"); // pass the file location of an image
JLabel label = new JLabel(image);
JScrollPane scrollPane = new JScrollPane(label);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
add(scrollPane, BorderLayout.CENTER);
pack();
}
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new AFrame().setVisible(true);
}
});
}
}

Deleting images from JFrame

I created one JFrame. and set layout shown in below code
this.setLayout(new GridLayout());
JPanel panel=new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
panel.add(new PicturePanel1());
JTabbedPane jtp=new JTabbedPane();
jtp.addTab("show Images", panel);
jtp.addTab("Compare Image", new JButton());
this.add(jtp);
I created another class that draws Images from particular location.
protected void paintComponent(Graphics g) {
super.paintComponents(g);
Graphics2D g2 = (Graphics2D) g;
int k = 20,y=10;
for (int j = 0; j <= listOfFiles.length - 1; j++) {
g2.drawImage(b[j], k, y, 100, 100, null);
// add(new javax.swing.JCheckBox());
k = k + 120;
if(k>=960)
{
k=20;
y=y+120;
}
}
Its working fine. I want to delete Images when user clicks on particular Image.
This is my output window. I want to delete Image from list.

Here is an example I made (bored and tired of studying :)). It is by no means the best just a quick thing to show you an example, click the image you want to delete and then press the delete button or DEL to remove and image from the panel:
When app starts up (orange just shows focused label for hovering):
Image to delete is selected by clicking on the Label (Border becomes green highlighted and will remain this way until another label is clicked):
After delete button or key is pressed:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.util.ArrayList;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.border.LineBorder;
public class JavaApplication5 {
public static void main(String[] args) {
createAndShowJFrame();
}
public static void createAndShowJFrame() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = createJFrame();
frame.setVisible(true);
}
});
}
private static JFrame createJFrame() {
JFrame frame = new JFrame();
//frame.setResizable(false);//make it un-resizeable
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Test");
ArrayList<BufferedImage> images = null;
try {
images = getImagesArrayList();
} catch (Exception ex) {
ex.printStackTrace();
}
final ImageViewPanel imageViewPanel = new ImageViewPanel(images);
JScrollPane jsp = new JScrollPane(imageViewPanel);
jsp.setPreferredSize(new Dimension(400, 400));
frame.add(jsp);
JPanel controlPanel = new JPanel();
JButton addLabelButton = new JButton("Delete Selected Image");
addLabelButton.addActionListener(new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
imageViewPanel.removeFocusedImageLabel();
}
});
controlPanel.add(addLabelButton);
frame.add(controlPanel, BorderLayout.SOUTH);
frame.pack();
return frame;
}
private static ArrayList<BufferedImage> getImagesArrayList() throws Exception {
ArrayList<BufferedImage> images = new ArrayList<>();
images.add(resize(ImageIO.read(new URL("http://icons.iconarchive.com/icons/deleket/sleek-xp-software/256/Yahoo-Messenger-icon.png")), 100, 100));
images.add(resize(ImageIO.read(new URL("https://upload.wikimedia.org/wikipedia/commons/6/64/Gnu_meditate_levitate.png")), 100, 100));
return images;
}
public static BufferedImage resize(BufferedImage image, int width, int height) {
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(image, 0, 0, width, height, null);
g2d.dispose();
return bi;
}
}
class ImageViewPanel extends JPanel {
JLabel NO_IMAGES = new JLabel("No Images");
ArrayList<BufferedImage> images;
ArrayList<MyLabel> imageLabels;
public ImageViewPanel(ArrayList<BufferedImage> images) {
this.images = images;
imageLabels = new ArrayList<>();
for (BufferedImage bi : images) {
imageLabels.add(new MyLabel(new ImageIcon(bi), this));
}
layoutLabels();
getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_DELETE, 0, true), "Delete pressed");
getActionMap().put("Delete pressed", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
removeFocusedImageLabel();
}
});
}
void removeFocusedImageLabel() {
if (focusedLabel == null) {
return;
}
imageLabels.remove(focusedLabel);
remove(focusedLabel);
layoutLabels();
}
private void layoutLabels() {
if (imageLabels.isEmpty()) {
add(NO_IMAGES);
} else {
remove(NO_IMAGES);
for (JLabel il : imageLabels) {
add(il);
}
}
revalidate();
repaint();
}
private MyLabel focusedLabel;
void setFocusedLabel(MyLabel labelToFocus) {
if (focusedLabel != null) {
focusedLabel.setBorder(null);
focusedLabel.setClicked(false);
}
focusedLabel = labelToFocus;
focusedLabel.setBorder(new LineBorder(Color.GREEN));
}
}
class MyLabel extends JLabel {
private final ImageViewPanel imageViewPanel;
private boolean clicked = false;
public MyLabel(Icon image, ImageViewPanel imageViewPanel) {
super(image);
this.imageViewPanel = imageViewPanel;
initLabel();
}
public MyLabel(String text, ImageViewPanel imageViewPanel) {
super(text);
this.imageViewPanel = imageViewPanel;
initLabel();
}
private void initLabel() {
setFocusable(true);
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
super.mouseClicked(e);
clicked = true;
imageViewPanel.setFocusedLabel(MyLabel.this);
}
#Override
public void mouseEntered(MouseEvent me) {
super.mouseEntered(me);
if (clicked) {
return;
}
setBorder(new LineBorder(Color.ORANGE));
//call for focus mouse is over this component
requestFocusInWindow();
}
});
addFocusListener(new FocusAdapter() {
#Override
public void focusLost(FocusEvent e) {
super.focusLost(e);
if (clicked) {
return;
}
setBorder(null);
}
});
}
public void setClicked(boolean clicked) {
this.clicked = clicked;
}
public boolean isClicked() {
return clicked;
}
}

simply find the location (x, and y) and the size(width, and height) of image, then with the Graphics object (g2) fill a rectangle over the image drawn, like this
g2.setColor(this.getBackground());//set the color you want to clear the bound this point to JFrame/JPanel
g2.fillRect(x, y, width, height);
where x and y where is the location that images is located, and width and height are size of the picture

How to resize BufferedImage but conserve it's Graphics?

I have my own custom control which maintains backing image for it's content. This buffer is of type BufferedImage.
ATTENTION! The usage of backing image is due to requirements. Don't teach me to draw within paintComponent()
Currently I am resizing image in the following way:
#Override
public void setBounds(int x, int y, int width, int height) {
if( bufferedImage == null ) {
bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
}
else {
if( bufferedImage.getWidth() < width || bufferedImage.getHeight() < height ) {
BufferedImage newImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
newImage.createGraphics().drawImage(bufferedImage, 0, 0, null);
bufferedImage = newImage;
}
}
super.setBounds(x, y, width, height);
}
unfortunately, this requires to create new BufferedImage object and hence makes previously obtained Graphics object invalid.
So I have to have my own method
public Graphics2D createImageGraphics() {
if( bufferedImage != null ) {
return bufferedImage.createGraphics();
}
else {
return null;
}
}
although I would like to override getGraphics().
Is it possible to resize image so that it conserve Graphics object?

Here is small example of how you perform custom painting in Swing:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class JFrameTest {
private boolean drawOval = false;
protected void initUI() {
final JPanel panel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (drawOval) {
g.setColor(Color.BLUE);
g.drawOval(0, 0, 100, 100);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
};
AbstractAction drawAction = new AbstractAction("Draw") {
#Override
public void actionPerformed(ActionEvent e) {
drawOval = true;
panel.repaint();
}
};
JButton drawButton = new JButton(drawAction);
JPanel buttonPanel = new JPanel();
buttonPanel.add(drawButton);
JFrame frame = new JFrame();
frame.add(panel, BorderLayout.CENTER);
frame.add(buttonPanel, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JFrameTest().initUI();
}
});
}
}