We Keep Coding

paintComponent not called when I scroll both Horizontal and Vertical scrollbars in a JScrollPane

I am having trouble with Swing and the JScrollPane.
I am having a strange behaviour.
I extended JScrollPane. I display an image in it and draw rectangles over it to define areas.
With a big image, I have an Horizontal and a Vertical scrollbars.
I - ok - When I move one scrollbar or the other I see my image move too as it should.
II - not ok - When I move one scrollbar an leave it in between max and min position, then when I move my second scrollbar my image disappears.
With some debug prints, I found out that paintComponent, is not called when in case II.
I would like to know why it is not calling paintComponent and how I can fix it.
Here below is my class:
package GUI;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Point;
import javax.swing.JScrollPane;
public class DrawingPanel extends JScrollPane {
private static final long serialVersionUID = 1L;
private static final Color DRAWING_COLOR = new Color(255, 100, 200);
private static final Color FINAL_DRAWING_COLOR = Color.red;
private static final double ZOOMING_STEP = 1.1;
private Image sImg;
private Point startPt;
private Point endPt;
private Point currentPt;
private int prefW;
private int prefH;
private double zoomFactor = 1;
private boolean zoomer = false;
private boolean loaded = false;
public DrawingPanel() {
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
public void loadImage(Image img) {
sImg = img;
prefW = sImg.getWidth(null);
prefH = sImg.getHeight(null);
zoomFactor = getSize().getWidth() / prefW;
zoomer = true;
loaded = true;
repaint();
revalidate();
}
int countPaint = 0;
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println("paintComponent " + countPaint);
if (loaded) {
int zoomWidth = (int) (prefW * zoomFactor);
int zoomHeight = (int) (prefH * zoomFactor);
if (zoomer) {
((Graphics2D) g).scale(zoomFactor, zoomFactor);
setSize(zoomWidth, zoomHeight);
zoomer = false;
}
g.drawImage(sImg, 0, 0, zoomWidth, zoomHeight, null);
drawRectangle(g);
}
g.dispose();
countPaint++;
}
#Override
public Dimension getPreferredSize() {
return loaded ?
this.getSize() :
new Dimension((int) (prefW*zoomFactor), (int) (prefH*zoomFactor));
}
private void drawRectangle(Graphics g) {
Point secondPoint = (currentPt != null) ? currentPt : endPt;
Color color = (currentPt != null) ? DRAWING_COLOR : FINAL_DRAWING_COLOR;
if (startPt!=null && secondPoint!=null) {
int x = Math.min(startPt.x, secondPoint.x);
int y = Math.min(startPt.y, secondPoint.y);
int rectangleWidth = Math.abs(startPt.x - secondPoint.x);
int rectangleHeight = Math.abs(startPt.y - secondPoint.y);
g.setColor(color);
g.drawRect(x, y, rectangleWidth, rectangleHeight);
}
}
public void deleteRectangle(){
startPt = null;
endPt = null;
}
public void increaseZoom(Point p) {
double oldZoom = zoomFactor;
zoomFactor *= ZOOMING_STEP;
repositonPointAfterZoom(oldZoom, zoomFactor);
}
public void decreaseZoom(Point p) {
double oldZoom = zoomFactor;
zoomFactor /= ZOOMING_STEP;
repositonPointAfterZoom(oldZoom, zoomFactor);
}
public void repositonPointAfterZoom(double oldZoom, double newZoom) {
double evolution = newZoom/oldZoom;
if (startPt!=null) {
startPt.setLocation(startPt.x * evolution, startPt.y * evolution);
}
if (endPt!=null) {
endPt.setLocation(endPt.x * evolution, endPt.y * evolution);
}
repaint();
}
// Getter et setter
public void setStartPt(Point startPt) {
this.startPt = startPt;
}
public void setEndPt(Point endPt) {
this.endPt = endPt;
}
public void setCurrentPt(Point currentPt) {
this.currentPt = currentPt;
}
public int getZoomCalculateX(int value){
return (int) (value / zoomFactor);
}
public int getZoomCalculateY(int value){
return (int) (value / zoomFactor);
}
public void setZoomer(boolean zoomer) {
this.zoomer = zoomer;
}
}
EDIT : Bellow is the class (simplified) that uses DrawingPanel so you can have a reproducible exemple.
package GUI;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;
import org.apache.commons.io.FilenameUtils;
import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;
import fileHandler.*;
public class GUI {
private JFrame frame;
private MenuBar menubar;
private DrawingPanel panelImage;
private JScrollPane scroll;
private GroundTruth openFile;
private int[] panelImageDown = new int[2];
private int[] panelImageUp = new int[2];
private Menu CoordinateMenu1 = new Menu();
private Menu CoordinateMenu2 = new Menu();
private int actualPagePdf;
private PDFRenderer renderer;
public static void main(String[] args) throws IOException {
new GUI();
}
public GUI() throws IOException {
JFrame frame = CreateFrame();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JFrame CreateFrame() throws IOException {
frame = new JFrame();
frame.setMenuBar(CreateMenuBar());
frame.setContentPane(SplitScreen());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("GTA - Ground Truth Annotator");
frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
return frame;
}
private MenuBar CreateMenuBar() {
menubar = new MenuBar();
menubar.add(CreateFileMenu());
menubar.add(new Menu("Selection coordinates:"));
menubar.add(CoordinateMenu1);
menubar.add(new Menu("Width/Height:"));
menubar.add(CoordinateMenu2);
return menubar;
}
private Menu CreateFileMenu() {
Menu mFile = new Menu("File");
MenuItem miOpenImage = new MenuItem("Open Image/PDF File");
mFile.add(miOpenImage);
miOpenImage.addActionListener(OpenFileActionListener);
mFile.addSeparator();
MenuItem miExit = new MenuItem("Exit Program");
mFile.add(miExit);
miExit.addActionListener(ExitActionListener);
return mFile;
}
private JPanel SplitScreen() throws IOException {
JPanel splittedScreen = new JPanel(new GridLayout(1, 2));
splittedScreen.add(CreateLeftPanel());
splittedScreen.add(CreateRightPanel());
return splittedScreen;
}
private JLayeredPane CreateLeftPanel() throws IOException {
JLayeredPane panel = new JLayeredPane();
panel.setLayout(new BorderLayout());
panel.setBorder(BorderFactory.createLineBorder(Color.gray));
panel.add(CreateImageScrollPane());
return panel;
}
private JScrollPane CreateImageScrollPane() throws IOException {
scroll = new JScrollPane(CreateImagePanel((String) null));
scroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scroll.getViewport().setScrollMode(JViewport.BLIT_SCROLL_MODE);
return scroll;
}
private DrawingPanel CreateImagePanel(String path) throws IOException {
if (panelImage == null) {
panelImage = new DrawingPanel();
}
if (path != null) {
panelImage.loadImage(ImageIO.read(new File(path)));
}
panelImage.addMouseListener(PanelImageMouseListener);
panelImage.addMouseWheelListener(PanelImageMouseWheelListener);
panelImage.addMouseMotionListener(PanelImageMouseMotionAdapter);
panelImage.setOpaque(false);
panelImage.revalidate();
panelImage.repaint();
panelImage.requestFocus();
return panelImage;
}
private DrawingPanel CreateImagePanel(Image image) throws IOException {
if (panelImage == null) {
panelImage = new DrawingPanel();
}
panelImage.loadImage(image);
panelImage.addMouseListener(PanelImageMouseListener);
panelImage.addMouseWheelListener(PanelImageMouseWheelListener);
panelImage.addMouseMotionListener(PanelImageMouseMotionAdapter);
panelImage.setOpaque(false);
panelImage.revalidate();
panelImage.repaint();
return panelImage;
}
private JPanel CreateRightPanel() {
JPanel panel = new JPanel(new GridLayout(0, 1));
//...
return panel;
}
ActionListener OpenFileActionListener = new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
OpenFile();
}
};
ActionListener ExitActionListener = new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Object[] options = {"Yes, quit now", "No, go back"};
int n = JOptionPane.showOptionDialog(
frame, "ATTENTION: closing without saving will cause any unsaved files to be lost. Do you want to proceed?",
"Warning", JOptionPane.YES_NO_OPTION, JOptionPane.WARNING_MESSAGE, null, options, options[0]
);
switch (n) {
case JOptionPane.YES_OPTION:
System.exit(0);
case JOptionPane.NO_OPTION:
case JOptionPane.CANCEL_OPTION:
}
}
};
MouseListener PanelImageMouseListener = new MouseListener() {
public void mousePressed(MouseEvent me) {
panelImageDown = new int[]{
panelImage.getZoomCalculateX(me.getX()), panelImage.getZoomCalculateY(me.getY())
};
panelImageUp = null;
CoordinateMenu1.setLabel(String.format("%s:%s", panelImageDown[0], panelImageDown[1]));
CoordinateMenu2.setLabel("");
panelImage.setStartPt(me.getPoint());
panelImage.repaint();
}
public void mouseReleased(MouseEvent me) {
panelImageUp = new int[]{
Math.abs(panelImage.getZoomCalculateX(me.getX()) - panelImageDown[0]),
Math.abs(panelImageDown[1] - panelImage.getZoomCalculateY(me.getY()))
};
CoordinateMenu2.setLabel(String.format("%s:%s", panelImageUp[0], panelImageUp[1]));
panelImage.setEndPt(me.getPoint());
panelImage.setCurrentPt(null);
panelImage.repaint();
}
public void mouseClicked(MouseEvent arg0) {
}
public void mouseEntered(MouseEvent arg0) {
}
public void mouseExited(MouseEvent arg0) {
}
};
MouseMotionAdapter PanelImageMouseMotionAdapter = new MouseMotionAdapter() {
#Override
public void mouseDragged(MouseEvent me) {
panelImageUp = new int[]{
Math.abs(panelImage.getZoomCalculateX(me.getX()) - panelImageDown[0]),
Math.abs(panelImageDown[1] - panelImage.getZoomCalculateY(me.getY()))
};
CoordinateMenu2.setLabel(String.format("%s:%s", panelImageUp[0], panelImageUp[1]));
panelImage.setCurrentPt(me.getPoint());
panelImage.repaint();
}
};
MouseWheelListener PanelImageMouseWheelListener = new MouseWheelListener() {
public void mouseWheelMoved(MouseWheelEvent me) {
if (me.isAltDown()) {
if (me.getWheelRotation() < 0) {
panelImage.setZoomer(true);
panelImage.increaseZoom();
panelImage.repaint();
panelImage.requestFocus();
//scroll.repaint();
//Zoom out
} else if(me.getWheelRotation() > 0) {
panelImage.setZoomer(true);
panelImage.decreaseZoom();
panelImage.repaint();
panelImage.requestFocus();
//scroll.repaint();
}
}
}
};
private void OpenFile() {
openFile = new GroundTruth();
JFileChooser fileChooser = new JFileChooser();
fileChooser.setCurrentDirectory(new File(System.getProperty("user.home")));
fileChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
fileChooser.setAcceptAllFileFilterUsed(false);
fileChooser.addChoosableFileFilter(new FileNameExtensionFilter(
"Images / PDF Scan",
"bmp", "jpeg", "jpg", "png", "tif", "tiff", "pdf"
));
if (fileChooser.showOpenDialog(frame) != 0) {
return;
}
openFile.setFilename(fileChooser.getSelectedFile().getAbsolutePath());
if (getExtension(fileChooser.getSelectedFile().getName()).equals("pdf")) {
try {
PDDocument doc = PDDocument.load(fileChooser.getSelectedFile());
numberPagePdf = doc.getNumberOfPages();
actualPagePdf = 0;
renderer = new PDFRenderer(doc);
setPdfPage(actualPagePdf);
} catch (IOException e) {
e.printStackTrace();
}
} else {
try {
CreateImagePanel(fileChooser.getSelectedFile().getAbsolutePath());
} catch (IOException e) {
e.printStackTrace();
}
}
}
private void setPdfPage(int pageNumber){
try {
BufferedImage bim = renderer.renderImageWithDPI(pageNumber, 300);
refreshInfoPageSection();
CreateImagePanel(bim);
} catch (IOException e) {
e.printStackTrace();
}
}
// refresh the label who indicate the page display and set visible or inivisble the previous and next button
private void refreshInfoPageSection(){
panelImage.deleteRectangle();
}
public String getExtension(String filename) {
return FilenameUtils.getExtension(filename);
}
}

Here's a simplified example of a drawing JPanel that's larger than the scrolling JPanel.
You can see in the image that the drawing JPanel is larger both horizontally and vertically than the scrolling JPanel.
I don't call the paintComponent method at all in this code. Because I set up the GUI properly, Swing itself calls the repaint method when you move the scroll bars.
Here are the important things I did.
I started the Swing GUI with a call to the SwingUtilities invokeLater method. This method makes sure that the Swing components are created and executed on the Event Dispatch Thread.
I used a JFrame, two JPanels, and a JScrollPane. I extended JPanel to create the drawing panel. I used a JScrollPane, JPanel, and JFrame. The only time you extend a Swing component, or any Java class, is when you want to override one or more class methods.
I used Swing layout managers. I used a BorderLayout for the JFrame and scrolling JPanel.
Here's the complete runnable code. Why, you can even call it a minimal reproducible example!
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
public class LargeDrawingPanel implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new LargeDrawingPanel());
}
#Override
public void run() {
JFrame frame = new JFrame("Large Drawing Panel");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(createMainPanel(), BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel createMainPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
panel.setPreferredSize(new Dimension(400, 400));
JScrollPane scrollPane = new JScrollPane(new DrawingPanel());
panel.add(scrollPane, BorderLayout.CENTER);
return panel;
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawingPanel() {
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(2000, 2000));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLUE);
int x = 100;
int y = 100;
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
g.fillRect(x, y, 100, 100);
x += 200;
}
y += 200;
x = 100;
}
}
}
}
Edited to add: The OP posted additional questions in a comment.
Thanks for the example but it doesn't show me how to print an image in
a JPanel.
Pretty simple. Read an image using the ImageIO class, save the image in an application model consisting of one or more plain Java getter / setter classes and use the Graphics drawImage method to draw the image.
Your preview has only one scrollbar moved not both - which is my
problem.
Did you actually run the code I provided? I can only move one scrollbar at a time. The drawing JPanel extends both horizontally and vertically.
And it doesn't explain why my example doesn't work.
Your example is riddled with errors. Start over, building a Swing application one Swing component at a time using sound principles. The Oracle tutorial, Creating a GUI With JFC/Swing, will show you the correct way to create a Swing application. You can skip the Netbeans section.

How to put an image from a JFileChooser?

I have a problem using Graphics to put an image in a jPanel. I have the next code:
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
lienzo.paintComponents(imagenAbrir.getGraphics());
} catch (IOException e) {
JOptionPane.showMessageDialog(this, "Ocurriò un error al guardar la imàgen");
}
}
The code is part of a button, the user could select an imagen from any path, but it doesn't show anything in the panel. What could be the problem?

I think you have to change you method with BufferedImage object not a Graphics object
#Override
public void actionPerformed(ActionEvent e) {
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.drawImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurriò un error al guardar la imàgen");
}
}
}
Then, if you want to draw image, create customized JPanel class on your own.
The paintCompoent method of JComponent will be invoked automatically, every time you call repaint method in your code.
final class ImagePane extends JPanel {
private static final long serialVersionUID = 1L;
private BufferedImage myImage;
public ImagePane(final BufferedImage myImage) {
this.myImage = myImage;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(240, 220);
}
public void drawImage(BufferedImage img)
{
this.myImage = img;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (myImage != null) {
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - myImage.getWidth()) / 2;
int y = (getHeight() - myImage.getHeight()) / 2;
g2d.drawImage(myImage, x, y, this);
g2d.dispose();
}
}
}
Here is full source code.
public class JFileChooserTest {
static Runnable doRun = new Runnable()
{
final class ChooseAction implements ActionListener
{
final ImagePane drawPan;
ChooseAction(final ImagePane drawPan)
{
this.drawPan = drawPan;
}
#Override
public void actionPerformed(ActionEvent e) {
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.drawImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurriò un error al guardar la imàgen");
}
}
}
}
final class ImagePane extends JPanel {
private static final long serialVersionUID = 1L;
private BufferedImage myImage;
public ImagePane(final BufferedImage myImage) {
this.myImage = myImage;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(240, 220);
}
public void drawImage(BufferedImage img)
{
this.myImage = img;
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (myImage != null) {
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - myImage.getWidth()) / 2;
int y = (getHeight() - myImage.getHeight()) / 2;
g2d.drawImage(myImage, x, y, this);
g2d.dispose();
}
}
}
#Override
public void run() {
final JFrame frame = new JFrame();
//frame.setSize(new Dimension(300,400));
JPanel lienzo = new JPanel();
lienzo.setLayout(new BorderLayout());
ImagePane drawPan = new ImagePane(null);
JButton drawMe = new JButton("draw me");
lienzo.add(drawMe, BorderLayout.NORTH);
lienzo.add(drawPan, BorderLayout.CENTER);
frame.add(lienzo);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
drawMe.addActionListener(new ChooseAction(drawPan));
}
};
public static void main(String[] args)
{
SwingUtilities.invokeLater(doRun);
}
}
I hope this will help you.

The code is part of a button, the user could select an imagen from any path, but it doesn't show anything in the panel. What could be the problem?
Basically, this is not how custom painting works in Swing. Never call paintComponent or paintComponents yourself, it's not your responsibility.
What you want to do is paint the image to the component via its Graphics context
Take a look at Painting in AWT and Swing and Performing Custom Painting for more details about how painting works and how you're suppose to use it
Then take a look at How to use lables for a simple solution for displaying images
You can also have a look at How to set a background picture in JPanel. It demonstrates using a JLabel and custom component for displaying an image

So, Do you want add image on the panel in which some base image is displayed?
If so, there is some trick to achieve to do this.
I prepare two images on the internet ( I am afraid these are licensed images )
Then, now i have three buttons put on your class
JButton drawMe = new JButton("draw me");
JButton pickMe = new JButton("pick me");
JButton clearMe = new JButton("clear me");
I decided to let the DrawAction class reuse with three action commands that are a draw, pick and clear together.
drawMe.addActionListener(drawAct);
drawMe.setActionCommand("draw");
pickMe.addActionListener(drawAct);
pickMe.setActionCommand("pick");
clearMe.addActionListener(drawAct);
clearMe.setActionCommand("clear");
We'll see the ImagePane class again. If you want to add a image on a image, you should have a paintcomponent method inherited from JComponent whatever components you want to use.
The 'draw me' button is to set the base image after clearing all images in the image list in which array list of the bufferedimage class.
public void drawImage(BufferedImage img)
{
if (imageList.size() > 0) imageList.clear();
imageList.add(img);
repaint();
}
The 'pick me' button is the method that add a image to the image list.
public void addImage(BufferedImage imagenAbrir) {
imageList.add(imagenAbrir);
repaint();
}
The last one is clear button, flush and clear all image buffers in the image list.
public void clearImage() {
imageList.clear();
isClear = true;
repaint();
}
Here is my trick to clear image on the panel, it is accomplished by re-drawing canvas(jPanel at this time) with some specific color(gray).
The main method, paintComponent as following..
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if(isClear)
{
Graphics2D g2d = (Graphics2D) g.create();
Rectangle2D rectangle = new Rectangle2D.Double(0,0,getWidth(),getHeight());
g2d.setPaint(Color.GRAY);
g2d.fill(rectangle);
g2d.dispose();
isClear = false;
return;
}
if (imageList.size() > 0) {
BufferedImage img = null;
for(int i = 0; i < imageList.size(); i++)
{
img = imageList.get(i);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
Finally, you read the code below how to handle action commands along with java's component,
#Override
public void actionPerformed(ActionEvent e) {
if(e.getActionCommand().equals("draw"))
{
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.drawImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurrio un error al guardar la imagen");
}
}
}
else if(e.getActionCommand().equals("pick"))
{
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.addImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurrio un error al guardar la imagen");
}
}
}
else if(e.getActionCommand().equals("clear"))
{
drawPan.clearImage();
}
}
As you see the code, picking a file is required every time you click both the pick or draw me button.
Full source code
package com.tobee.ui.test;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class JFileChooserTest {
static Runnable doRun = new Runnable()
{
final class DrawAction implements ActionListener
{
final ImagePane drawPan;
DrawAction(final ImagePane drawPan)
{
this.drawPan = drawPan;
}
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand());
if(e.getActionCommand().equals("draw"))
{
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.drawImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurriò un error al guardar la imàgen");
}
}
}
else if(e.getActionCommand().equals("pick"))
{
JFileChooser navegador = new JFileChooser();
if (navegador.showOpenDialog(null) == 0) {
try {
BufferedImage imagenAbrir = ImageIO.read(navegador.getSelectedFile());
//drawPan.paintComponents(imagenAbrir.getGraphics());
drawPan.addImage(imagenAbrir);
} catch (IOException ie) {
JOptionPane.showMessageDialog(null, "Ocurriò un error al guardar la imàgen");
}
}
}
else if(e.getActionCommand().equals("clear"))
{
drawPan.clearImage();
}
}
}
final class ImagePane extends JPanel {
private static final long serialVersionUID = 1L;
private boolean isClear;
private List<BufferedImage> imageList;
public ImagePane()
{
imageList = new ArrayList<BufferedImage>();
isClear = false;
}
public void clearImage() {
imageList.clear();
isClear = true;
repaint();
}
public void addImage(BufferedImage imagenAbrir) {
imageList.add(imagenAbrir);
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(240, 220);
}
public void drawImage(BufferedImage img)
{
if (imageList.size() > 0) imageList.clear();
imageList.add(img);
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if(isClear)
{
Graphics2D g2d = (Graphics2D) g.create();
Rectangle2D rectangle = new Rectangle2D.Double(0,0,getWidth(),getHeight());
g2d.setPaint(Color.GRAY);
g2d.fill(rectangle);
g2d.dispose();
isClear = false;
return;
}
if (imageList.size() > 0) {
BufferedImage img = null;
for(int i = 0; i < imageList.size(); i++)
{
img = imageList.get(i);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
}
#Override
public void run() {
final JFrame frame = new JFrame();
JPanel lienzo = new JPanel();
lienzo.setLayout(new BorderLayout());
JPanel optionPan = new JPanel();
ImagePane drawPan = new ImagePane();
JButton drawMe = new JButton("draw me");
JButton pickMe = new JButton("pick me");
JButton clearMe = new JButton("clear me");
DrawAction drawAct = new DrawAction(drawPan);
optionPan.add(drawMe);
optionPan.add(pickMe);
optionPan.add(clearMe);
lienzo.add(optionPan, BorderLayout.NORTH);
lienzo.add(drawPan, BorderLayout.CENTER);
frame.add(lienzo);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
drawMe.addActionListener(drawAct);
drawMe.setActionCommand("draw");
pickMe.addActionListener(drawAct);
pickMe.setActionCommand("pick");
clearMe.addActionListener(drawAct);
clearMe.setActionCommand("clear");
}
};
public static void main(String[] args)
{
SwingUtilities.invokeLater(doRun);
}
}

switching images dynamically on jframe

I have an assignment to create a GUI that switches images when a menu item is selected (ex. file, new picture) and also contains buttons for zooming in and out on the images. When I try switching images with my code, the image only partly loads. When I minimize the window and then reopen it, the image is fully loaded. I'm wondering why this is happening.
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
public class ImageZoom extends JPanel {
private Image image;
int x, y;
private JButton zoomIn;
private JButton zoomOut;
private JMenuBar bar;
private JMenu file;
private JMenuItem choosePic = new JMenuItem("New Picture");
private String pics[] = {"waterfall.jpg", "mountains.jpg"};
private int picIndex = 1;
int imageHeight = getHeight();
int imageWidth = getWidth();
int zoom = 1;
Image images[] = new Image[2];
public ImageZoom() {
try {
images[0] = ImageIO.read(new File("waterfall.jpg"));
images[1] = ImageIO.read(new File("mountains.jpg"));
} catch (IOException e) {}
zoomIn = new JButton("+");
zoomOut = new JButton("-");
JPanel panel = new JPanel();
bar = new JMenuBar();
file = new JMenu("File");
file.add(choosePic);
bar.add(file);
choosePic.addActionListener (new ActionListener() {
public void actionPerformed (ActionEvent e) {
if (e.getSource() == choosePic) {
repaint();
}
}
});
zoomIn.addActionListener (new ActionListener() {
public void actionPerformed (ActionEvent e) {
if (e.getSource() == zoomIn) {
if (zoom < 6) {
zoom += 1;
repaint();
}
}
}
});
zoomOut.addActionListener( new ActionListener() {
public void actionPerformed (ActionEvent e) {
if (e.getSource() == zoomOut) {
if (zoom > 1) {
zoom -= 1;
repaint();
}
}
}
});
}
public JPanel getButtonPanel () {
JPanel panel = new JPanel();
panel.add(zoomIn);
panel.add(zoomOut);
return panel;
}
public Image getImage() {
try {
image = ImageIO.read(new File(pics[picIndex % 2]));
picIndex++;
}
catch (IOException e){}
return image;
}
protected void paintComponent (Graphics g) {
imageHeight = getHeight() * zoom;
imageWidth = getWidth() * zoom;
super.paintComponent(g);
g.drawImage(getImage(), 0, 0, imageWidth, imageHeight, null);
}
public void createJFrame () {
JFrame frame = new JFrame();
ImageZoom imgZoom = new ImageZoom();
frame.setJMenuBar(bar);
frame.add(imgZoom);
frame.add(getButtonPanel(), BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(650, 650);
frame.setResizable(false);
frame.setVisible(true);
}
}
class Test {
public static void main (String[] args) {
ImageZoom zoom = new ImageZoom();
zoom.createJFrame();
}
}

For simplicity, you should just be using a JLabel and calling its setIcon method to switch the images. You could dynamically scale the images as required (just maintain a reference to the original)
Problem #1
You should be passing this to drawImage, this will allow the component to act as the ImageObserver and schedule additional reprints as required based on events from the image's state, which leads to
Problem #2
You should not be calling getImage from within the paintComponent method, paintComponent could be called for any number of reasons, many of which you don't control or even know about and paintComponent should simply paint the current state of the component and never, ever try and change the state
Side Note: Instead of repeatedly trying to load the images, it would be better to load them once and continue to reuse the loaded reference

How to set imageicon fix on jlabel

I am trying to make a java desktop application. I have a JLabel where I am shuffling image but all image sizes are different so I want to fix size of the image on JLabel.
How can I do this?
Here is my code :
public class ImageShuffle1 extends JPanel {
private List<Icon> list = new ArrayList<Icon>();
private List<Icon> shuffled;
private JLabel label = new JLabel();
private Timer timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
update();
}
});
public ImageShuffle1() {
this.setLayout(new GridLayout(1, 0));
list.add(new ImageIcon("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\e.jpg"));
list.add(new ImageIcon("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\d.jpg"));
list.add(new ImageIcon("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\yellow.png"));
list.add(new ImageIcon("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\f.jpg"));
list.add(new ImageIcon("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\l.jpg"));
//label.setIcon(UIManager.getIcon("OptionPane.informationIcon"));
for(Icon icon: list){
Image img = icon.getImage() ;
// put here the size properties
Image newimg = img.getScaledInstance( 45, 34, java.awt.Image.SCALE_SMOOTH ) ;
icon = new ImageIcon(newimg);
}
shuffled = new ArrayList<Icon>(list);
Collections.shuffle(shuffled);
timer.start();
}
private void update() {
if (shuffled.isEmpty()) {
shuffled = new ArrayList<Icon>(list);
Collections.shuffle(shuffled);
}
Icon icon = shuffled.remove(0);
label.setIcon(icon);
}
private void display() {
JFrame f = new JFrame("ImageShuffle");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.add(label);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ImageShuffle1().display();
}
});
}
}
I am getting error herein this.
line/variable getimage can not found mage img = icon.getImage() ;
Thanks in advance

Use BufferedImage in place of Icon that has a functionality to re size it.
Here is the code
import java.awt.EventQueue;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
public class ImageShuffle1 extends JPanel {
private List<BufferedImage> list = new ArrayList<BufferedImage>();
private List<BufferedImage> shuffled;
private JLabel label = new JLabel();
private int width = 50;
private int height = 100;
private Timer timer = new Timer(1000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
update();
}
});
public ImageShuffle1() {
try {
list.add(resizeImage(ImageIO.read(new File("resources/1.png"))));
list.add(resizeImage(ImageIO.read(new File("resources/2.png"))));
list.add(resizeImage(ImageIO.read(new File("resources/6.png"))));
list.add(resizeImage(ImageIO.read(new File("resources/Tulips.jpg"))));
} catch (IOException e) {
e.printStackTrace();
}
shuffled = new ArrayList<BufferedImage>(list);
Collections.shuffle(shuffled);
timer.start();
}
private BufferedImage resizeImage(BufferedImage originalImage) throws IOException {
BufferedImage resizedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = resizedImage.createGraphics();
g.drawImage(originalImage, 0, 0, width, height, null);
g.dispose();
return resizedImage;
}
private void update() {
if (shuffled.isEmpty()) {
shuffled = new ArrayList<BufferedImage>(list);
Collections.shuffle(shuffled);
}
BufferedImage icon = shuffled.remove(0);
label.setIcon(new ImageIcon(icon));
}
private void display() {
JFrame f = new JFrame("ImageShuffle");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.add(label);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ImageShuffle1().display();
}
});
}
}

Lets start with this...
for(Icon icon: list){
Image img = icon.getImage() ;
Icon does not have a method getImage, there is actually no way to get the "image" data maintained by the Icon class without first rendering it to something (like a BufferedImage)
A better solution might be to load the images into a List that supports BufferedImage. BufferedImage is a more versatile starting point and because it extends from Image, it can be used with ImageIcon. For example...
private List<BufferedImage> list = new ArrayList<BufferedImage>();
//...
list.add(ImageIO.read("E:\\SOFTWARE\\TrainPIS\\res\\drawable\\e.jpg"));
Take a look at Reading/Loading an Image
For scaling you might like to take a look at
The Perils of Image.getScaledInstance
Java: maintaining aspect ratio of JPanel background image
Quality of Image after resize very low -- Java

First you resize every image to a fixed size and it must be fit in JLabel
public static Boolean resizeImage(String sourceImage, String destinationImage, Integer Width, Integer Height) {
BufferedImage origImage;
try {
origImage = ImageIO.read(new File(sourceImage));
int type = origImage.getType() == 0? BufferedImage.TYPE_INT_ARGB : origImage.getType();
//*Special* if the width or height is 0 use image src dimensions
if (Width == 0) {
Width = origImage.getWidth();
}
if (Height == 0) {
Height = origImage.getHeight();
}
int fHeight = Height;
int fWidth = Width;
//Work out the resized width/height
if (origImage.getHeight() > Height || origImage.getWidth() > Width) {
fHeight = Height;
int wid = Width;
float sum = (float)origImage.getWidth() / (float)origImage.getHeight();
fWidth = Math.round(fHeight * sum);
if (fWidth > wid) {
//rezise again for the width this time
fHeight = Math.round(wid/sum);
fWidth = wid;
}
}
BufferedImage resizedImage = new BufferedImage(fWidth, fHeight, type);
Graphics2D g = resizedImage.createGraphics();
g.setComposite(AlphaComposite.Src);
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g.drawImage(origImage, 0, 0, fWidth, fHeight, null);
g.dispose();
ImageIO.write(resizedImage, "png", new File(destinationImage));
...

Image Capture in BufferedImage

I am new here and also quite new to Java.
I am making an app where one can select an area of image and it simply returns the selected coordinates. The problem is that, instead of displaying the image, it displays a black area instead of the image.
Also tried with BufferedImage.TYPE_INT_ARGB and now it shows a blank area.
Here is the code. Please help.
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class ScreenCaptureRectangle {
Rectangle captureRect;
ScreenCaptureRectangle(final Image im) {
final BufferedImage screenCopy = new BufferedImage(
im.getWidth(null),
im.getHeight(null),
BufferedImage.TYPE_INT_ARGB);
final BufferedImage screenCopy1 = new BufferedImage(
im.getWidth(null),
im.getHeight(null),
BufferedImage.TYPE_INT_ARGB);
final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
JScrollPane screenScroll = new JScrollPane(screenLabel);
screenScroll.setPreferredSize(new Dimension(
(int)(im.getWidth(null)),
(int)(im.getHeight(null))));
JPanel panel = new JPanel(new BorderLayout());
panel.add(screenScroll, BorderLayout.CENTER);
final JLabel selectionLabel = new JLabel(
"Drag a rectangle in the screen shot!");
panel.add(selectionLabel, BorderLayout.SOUTH);
repaint(screenCopy1, screenCopy);
screenLabel.repaint();
screenLabel.addMouseMotionListener(new MouseMotionAdapter() {
Point start = new Point();
#Override
public void mouseMoved(MouseEvent me) {
start = me.getPoint();
repaint(screenCopy1, screenCopy);
selectionLabel.setText("Start Point: " + start);
screenLabel.repaint();
}
#Override
public void mouseDragged(MouseEvent me) {
Point end = me.getPoint();
captureRect = new Rectangle(start,
new Dimension(end.x-start.x, end.y-start.y));
repaint(screenCopy1, screenCopy);
screenLabel.repaint();
selectionLabel.setText("Rectangle: " + captureRect);
}
});
JOptionPane.showMessageDialog(null, panel);
System.out.println("Rectangle of interest: " + captureRect);
}
public void repaint(BufferedImage orig, BufferedImage copy) {
Graphics2D g = copy.createGraphics();
g.drawImage(orig,0,0, null);
if (captureRect!=null) {
g.setColor(Color.RED);
g.draw(captureRect);
g.setColor(new Color(255,255,255,150));
g.fill(captureRect);
}
g.dispose();
}
public static void main(String[] args) throws Exception {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
try {
new ScreenCaptureRectangle(ImageIO.read(new File("Desert.jpg")));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
}
}

Your problem is that you never paint the original image (im, read from "Desert.jpg") into any of your screenCopy or screenCopy1 images, you only create empty BufferedImages of the same size. These "copies" will always stay blank.