Develop Reference

How can I use Graphics and Affinetransform draw a perspective picture

I want draw a picture with Java.
And I want rotate this picture along the X-axis or Y-axis to make the picture perspective.
It can make the image three-dimensional.
Do you know the function '3D rotation' in the PowerPoint? I just want to achieve this effect.
Can I use java to make it?
I am sorry that I have not describe my question carefully before.
This is the original image:
original image
I added a shear operation when I drew it
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.clearRect(0, 0, this.getWidth(), this.getHeight());
if (sourceImage != null) {
g2d.shear(0.5, 0);
g2d.drawImage(sourceImage, 0, 0, sourceImage.getWidth(), sourceImage.getHeight(), null);
}
}
And then it looks like this
The transformed image
But this is a linear transformation, I want perspective image, just like this
What I need to achieve
The AffineTransform in JAVA can only do linear transformations.
How can I use PerspectiveTransform, Do I need to use OpenGL or OpenCV to achieve it?
This is my complete code
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
public class ImagePanel extends JPanel{
private static final long serialVersionUID = 1L;
private BufferedImage sourceImage;
public ImagePanel() {
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.clearRect(0, 0, this.getWidth(), this.getHeight());
if (sourceImage != null) {
g2d.shear(0.5, 0);
g2d.drawImage(sourceImage, 0, 0, sourceImage.getWidth(), sourceImage.getHeight(), null);
}
}
public BufferedImage getSourceImage() {
return sourceImage;
}
public void setSourceImage(BufferedImage sourceImage) {
this.sourceImage = sourceImage;
}
}
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.filechooser.FileNameExtensionFilter;
public class MainUI extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
public static final String IMAGE_CMD = "choose image ... ";
private JButton imgBtn;
private ImagePanel imagePanel;
private BufferedImage srcImage;
public MainUI() {
setTitle("image demo");
imgBtn = new JButton(IMAGE_CMD);
JPanel btnPanel = new JPanel();
btnPanel.setLayout(new FlowLayout(FlowLayout.RIGHT));
btnPanel.add(imgBtn);
imagePanel = new ImagePanel();
getContentPane().setLayout(new BorderLayout());
getContentPane().add(imagePanel, BorderLayout.CENTER);
getContentPane().add(btnPanel, BorderLayout.SOUTH);
imgBtn.addActionListener(this);
}
#Override
public void actionPerformed(ActionEvent e) {
if(IMAGE_CMD.equals(e.getActionCommand())){
try {
JFileChooser chooser = new JFileChooser();
setFileTypeFilter(chooser);
chooser.showOpenDialog(null);
File f = chooser.getSelectedFile();
if (f != null) {
srcImage = ImageIO.read(f);
imagePanel.setSourceImage(srcImage);
imagePanel.repaint();
}
} catch (IOException e1) {
e1.printStackTrace();
}
imagePanel.repaint();
}
}
public void setFileTypeFilter(JFileChooser chooser){
FileNameExtensionFilter filter = new FileNameExtensionFilter("JPG & PNG Images", "jpg", "png");
chooser.setFileFilter(filter);
}
public void openView(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setPreferredSize(new Dimension(1280, 960));
pack();
setVisible(true);
}
public static void main(String[] args) {
MainUI ui = new MainUI();
ui.openView();
}
}

Drawing multiple graphic2d components into JPanel

I've read a lot of tutorials on drawing Graphics2D components and adding to JPanel/JFrame but I can't find how to add multiple these components into one JPanel simply. My code below adds only 1 component (line) and I can't find why it isn't possible to add more.
What am I doing wrong?
Desired behaviour: there should be 3 red lines.
My whole code:
package Examples;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example1 extends JFrame {
private final JPanel panel;
public Example1() {
// jpanel with graphics
panel = new JPanel();
panel.setPreferredSize(new Dimension(200, 200));
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
panel.setBackground(Color.WHITE);
add(panel);
// adding lines to jpanel
AddMyLine(); // 1st: this works well
AddMyLine(); // 2nd: this doesn't work
AddMyLine(); // 3rd: this doesn't work
setLayout(new FlowLayout(FlowLayout.LEFT));
setSize(250, 250);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
setLocationRelativeTo(null);
}
// add new line to jpanel
private void AddMyLine() {
MyLine c = new MyLine();
System.out.println(c);
panel.add(c);
}
// line component
private class MyLine extends JComponent {
public MyLine() {
setPreferredSize(new Dimension(200, 200));
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setColor(Color.red);
g2d.setStroke(new BasicStroke(1));
int x1 = (int)Math.round(Math.random()*200);
int y1 = (int)Math.round(Math.random()*200);
int x2 = (int)Math.round(Math.random()*200);
int y2 = (int)Math.round(Math.random()*200);
g2d.drawLine(x1,y1,x2,y2);
}
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Example1();
}
});
}
}

Your MyLine class should not be a Swing component and thus should not extend JComponent. Rather it should be a logical entity, and in fact can be something that implements Shape such as a Line2D, or could be your own complete class, but should know how to draw itself, i.e., if it does not implement Shape, then it should have some type of draw(Graphics2D g) method that other classes can call. I think instead you should work on extending your panel's JPanel class, such that you override its paintComponent method, give it a collection to hold any MyLine items added to it, and draw the MyLine items within the paintComponent.
Other options include drawing directly on to a BufferedImage, and then displaying that BufferedImage in your JPanel's paintComponent method. This is great for static images, but not good for images that need to change or move.
e.g.,
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class DrawChit extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
private List<Shape> shapes = new ArrayList<>();
public DrawChit() {
setBackground(Color.white);
}
public void addShape(Shape shape) {
shapes.add(shape);
repaint();
}
#Override // make it bigger
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (Shape shape : shapes) {
g2.draw(shape);
}
}
private static void createAndShowGui() {
DrawChit drawChit = new DrawChit();
drawChit.addShape(new Line2D.Double(10, 10, 100, 100));
drawChit.addShape(new Ellipse2D.Double(120, 120, 200, 200));
JFrame frame = new JFrame("DrawChit");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(drawChit);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Or an example using my own MyDrawable class, which produces a GUI that looks like this:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
#SuppressWarnings("serial")
public class DrawChit extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = PREF_W;
private List<MyDrawable> drawables = new ArrayList<>();
public DrawChit() {
setBackground(Color.white);
}
public void addMyDrawable(MyDrawable myDrawable) {
drawables.add(myDrawable);
repaint();
}
#Override
// make it bigger
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (MyDrawable myDrawable : drawables) {
myDrawable.draw(g2);
}
}
public void clearAll() {
drawables.clear();
repaint();
}
private static void createAndShowGui() {
final List<MyDrawable> myDrawables = new ArrayList<>();
myDrawables.add(new MyDrawable(new Line2D.Double(100, 40, 400, 400),
Color.red, new BasicStroke(40)));
myDrawables.add(new MyDrawable(new Ellipse2D.Double(50, 10, 400, 400),
Color.blue, new BasicStroke(18)));
myDrawables.add(new MyDrawable(new Rectangle2D.Double(40, 200, 300, 300),
Color.cyan, new BasicStroke(25)));
myDrawables.add(new MyDrawable(new RoundRectangle2D.Double(75, 75, 490, 450, 40, 40),
Color.green, new BasicStroke(12)));
final DrawChit drawChit = new DrawChit();
JFrame frame = new JFrame("DrawChit");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(drawChit);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener() {
private int drawCount = 0;
#Override
public void actionPerformed(ActionEvent e) {
if (drawCount >= myDrawables.size()) {
drawCount = 0;
drawChit.clearAll();
} else {
drawChit.addMyDrawable(myDrawables.get(drawCount));
drawCount++;
}
}
}).start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyDrawable {
private Shape shape;
private Color color;
private Stroke stroke;
public MyDrawable(Shape shape, Color color, Stroke stroke) {
this.shape = shape;
this.color = color;
this.stroke = stroke;
}
public Shape getShape() {
return shape;
}
public Color getColor() {
return color;
}
public Stroke getStroke() {
return stroke;
}
public void draw(Graphics2D g2) {
Color oldColor = g2.getColor();
Stroke oldStroke = g2.getStroke();
g2.setColor(color);
g2.setStroke(stroke);
g2.draw(shape);
g2.setColor(oldColor);
g2.setStroke(oldStroke);
}
public void fill(Graphics2D g2) {
Color oldColor = g2.getColor();
Stroke oldStroke = g2.getStroke();
g2.setColor(color);
g2.setStroke(stroke);
g2.fill(shape);
g2.setColor(oldColor);
g2.setStroke(oldStroke);
}
}

You shouldn't be drawing lines by adding components. Components are things like panels, buttons etc.
See this tutorial on how to draw with Graphics2D: https://docs.oracle.com/javase/tutorial/2d/geometry/primitives.html

Your code adds three components but the panel is not big enough to show the other two components
panel.setPreferredSize(new Dimension(200, 600));
setSize(250, 800);

Issue with addMouseMotionListener getting wrong coordinates

I borrowed the class below to make a selection area tool for a project. But it has a issue when I try to make a selection when the content is not aligned at top-left, it get my mouse coordinates related to the ScrollPane, but draws over the image - See this SS for better understanding:
sscce:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;
/** Getting a Rectangle of interest on the screen.
Requires the MotivatedEndUser API - sold separately. */
public class ScreenCaptureRectangle {
Rectangle captureRect;
ScreenCaptureRectangle(final BufferedImage screen) {
final BufferedImage screenCopy = new BufferedImage(screen.getWidth(), screen.getHeight(), screen.getType());
final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
JScrollPane screenScroll = new JScrollPane(screenLabel);
screenScroll.setPreferredSize(new Dimension((int)(screen.getWidth()*2), (int)(screen.getHeight()*2)));
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(screen, screenCopy);
screenLabel.repaint();
screenLabel.addMouseMotionListener(new MouseMotionAdapter() {
Point start = new Point();
#Override
public void mouseMoved(MouseEvent me) {
start = me.getPoint();
repaint(screen, 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(screen, 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 {
Robot robot = new Robot();
final Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
final BufferedImage screen = robot.createScreenCapture(new Rectangle(300,0,300,300));
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ScreenCaptureRectangle(screen);
}
});
}
}

I think you have problems because you are attempting to center the image in the panel.
The easiest solution is to make sure the image is painted from the top/left of the panel:
final JLabel screenLabel = new JLabel(new ImageIcon(screenCopy));
screenLabel.setHorizontalAlignment(JLabel.LEFT);
screenLabel.setVerticalAlignment(JLabel.TOP);

Basically, what's happening, is you are drawing directly to the image surface (which is held by the JLabel), so while, you drag at 2x2x36x36 on the screen, this then draws on the rectangle RELATIVE to the image itself
So even though the image is centered within the context of the JLabel, you are still rendering to the local context of the image (0x0), hence the disconnection between the two.
Depending on what it is you want to achieve, you change the way the painting works and take more direct control, for example...
import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class DrawimgExample {
public static void main(String[] args) {
try {
Robot robot = new Robot();
final Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
final BufferedImage screen = robot.createScreenCapture(new Rectangle(300, 0, 300, 300));
new DrawimgExample(screen);
} catch (AWTException exp) {
exp.printStackTrace();
}
}
public DrawimgExample(final BufferedImage screen) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new DrawingPane(screen));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class DrawingPane extends JPanel {
private BufferedImage img;
private Rectangle drawRect;
public DrawingPane(BufferedImage img) {
this.img = img;
MouseAdapter mouseHandler = new MouseAdapter() {
private Point startPoint;
#Override
public void mousePressed(MouseEvent e) {
startPoint = e.getPoint();
}
#Override
public void mouseDragged(MouseEvent e) {
Point endPoint = e.getPoint();
int startX = Math.min(startPoint.x, endPoint.x);
int startY = Math.min(startPoint.y, endPoint.y);
int width = Math.max(startPoint.x, endPoint.x) - startX;
int height = Math.max(startPoint.y, endPoint.y) - startY;
drawRect = new Rectangle(
startX,
startY,
width,
height
);
repaint();
}
};
addMouseListener(mouseHandler);
addMouseMotionListener(mouseHandler);
}
#Override
public Dimension getPreferredSize() {
return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int x = (getWidth() - img.getWidth()) / 2;
int y = (getHeight() - img.getHeight()) / 2;
g2d.drawImage(img, x, y, this);
if (drawRect != null) {
g2d.setColor(Color.RED);
g2d.draw(drawRect);
g2d.setColor(new Color(255, 255, 255, 150));
g2d.fill(drawRect);
}
g2d.dispose();
}
}
}
Having said that, where possible, you should avoid painting images directly, as JLabel already does a good job, but sometimes, if it doesn't meet your needs, you might need to take more direct control

How to Make a Splash Screen

I have a program which should has splash screen on JPanel, after button click should show another JPanel (object of the class) and draw shapes. I tried remove splash JPanel and after that add JPanel for drawing but it doeesn't work. How can I fix it? Two JLabel should be in the center of screen and it should be on 2 lines.
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.JComponent;
/**
*
* #author Taras
*/
public class MyComponent extends JComponent {
int i;
Color randColor;
public MyComponent()
{
this.i = i;
addMouseListener(new MouseHandler());
}
private ArrayList<Rectangle2D> arrOfRect=new ArrayList<>();
private ArrayList<Ellipse2D> arrOfEllipse=new ArrayList<>();
// private ArrayList<Color> randColor = new ArrayList<>();
Random rand = new Random();
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
for (Rectangle2D r : arrOfRect) {
g.setColor(new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat()));
g2.draw(r);
}
for (Ellipse2D e : arrOfEllipse) {
g.setColor(new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat()));
g2.draw(e);
}
}
public void add(Point2D p)
{
double x=p.getX();
double y=p.getY();
if (Pole.i == 1){
Ellipse2D ellipse = new Ellipse2D.Double(x, y, 100,100);
//randColor = new Color(randRed(), randGreen(), randBlue());
arrOfEllipse.add(ellipse);
}
if (Pole.i == 2){
Rectangle2D rectangls=new Rectangle2D.Double(x, y, 100, 100);
arrOfRect.add(rectangls);
}
if (Pole.i == 3){
Rectangle2D rectangls=new Rectangle2D.Double(x, y, 150, 100);
arrOfRect.add(rectangls);
}
if (Pole.i == 4){
Ellipse2D ellipse = new Ellipse2D.Double(x, y, 100,50);
arrOfEllipse.add(ellipse);
}
}
private class MouseHandler extends MouseAdapter {
public void mousePressed(MouseEvent event)
{
add(event.getPoint());
//Color rColor = new Color(randRed(), randGreen(), randBlue());
//randColor.add(rColor);
repaint();
}
}
private int randRed() {
int red;
Random randomNumber = new Random();
red = randomNumber.nextInt(255);
return red;
}
private int randGreen() {
int green;
Random randomNumber = new Random();
green = randomNumber.nextInt(255);
return green;
}
private int randBlue() {
int blue;
Random randomNumber = new Random();
blue = randomNumber.nextInt(255);
return blue;
}
}
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSeparator;
import javax.swing.JToolBar;
import javax.swing.SwingConstants;
import javax.swing.border.EmptyBorder;
import org.omg.CosNaming.NameComponent;
public class Pole extends JFrame {
public static int i;
public static JPanel nameContainer = new JPanel(new GridLayout(2, 1));
public static JFrame frame= new JFrame("Shape Stamper!");
public static void main(String[] args) {
JPanel container;
JButton circle = new JButton("Circle");
JButton square = new JButton("Square");
JButton rectangle = new JButton("Rectangle");
JButton oval = new JButton("Oval");
JLabel programName = new JLabel("Shape Stamper!");
JLabel programmerName = new JLabel("Progrramed by: ");
Font font = new Font("Serif", Font.BOLD, 32);
programName.setFont(font);
font = new Font("Serif", Font.ITALIC, 16);
programmerName.setFont(font);
programName.setHorizontalAlignment(JLabel.CENTER);
programmerName.setHorizontalAlignment(JLabel.CENTER);
//programmerName.setVerticalAlignment(JLabel.CENTER);
// nameContainer.setLayout(new BorderLayout());
nameContainer.add(programName);
nameContainer.add(programmerName);
//nameContainer.setLayout(new BoxLayout(nameContainer, BoxLayout.X_AXIS));
container = new JPanel(new GridLayout(1, 4));
container.add(circle);
container.add(square);
container.add(rectangle);
container.add(oval);
circle.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
i = 1;
frame.remove(nameContainer);
frame.repaint();
System.out.println(i);
}
});
square.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
i = 2;
}
});
rectangle.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
i = 3;
}
});
oval.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
i = 4;
}
});
MyComponent shape = new MyComponent();
frame.setSize(500, 500);
frame.add(shape, BorderLayout.CENTER);
frame.add(container, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

Here's an example of making a splash screen using an image.
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.*;
public class CircleSplashScreen {
public CircleSplashScreen() {
JFrame frame = new JFrame();
frame.getContentPane().add(new ImagePanel());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setUndecorated(true);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setBackground(new Color(0, 0, 0, 0));
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new CircleSplashScreen();
}
});
}
#SuppressWarnings("serial")
public class ImagePanel extends JPanel {
BufferedImage img;
public ImagePanel() {
setOpaque(false);
setLayout(new GridBagLayout());
try {
img = ImageIO.read(new URL("http://www.iconsdb.com/icons/preview/royal-blue/stackoverflow-4-xxl.png"));
} catch (IOException ex) {
Logger.getLogger(CircleSplashScreen.class.getName()).log(Level.SEVERE, null, ex);
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
}
}

JLabel unusable from other class

I got a problem with two problematics classes. One for drawing things, and other for implementing pan and zoom onto the previously drawn objects.
Imagine my interface as only two spitted panels, one empty(top) and one with a slider(bot):
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import java.awt.BorderLayout;
import javax.swing.JSplitPane;
import javax.swing.JPanel;
import javax.swing.BoxLayout;
import javax.swing.JLabel;
import javax.swing.JSlider;
import java.awt.FlowLayout;
public class Interface {
private JFrame mainFrame;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {Interface window = new Interface();window.mainFrame.setVisible(true);
} catch (Exception e) { e.printStackTrace();}
}
});
}
public Interface() {initialize();}
private void initialize() {
mainFrame = new JFrame();
mainFrame.setTitle("LXView");
mainFrame.setMinimumSize(new Dimension(800, 600));
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setExtendedState(mainFrame.getExtendedState()| JFrame.MAXIMIZED_BOTH);
mainFrame.getContentPane().setBackground(Color.WHITE);
mainFrame.getContentPane().setLayout(new BorderLayout(0, 0));
JSplitPane splitPane = new JSplitPane();
splitPane.setOrientation(JSplitPane.VERTICAL_SPLIT);
splitPane.setOneTouchExpandable(true);
splitPane.setBackground(Color.WHITE);
mainFrame.getContentPane().add(splitPane, BorderLayout.CENTER);
splitPane.setResizeWeight(0.99);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setEnabled(false);
splitPane.setLeftComponent(scrollPane);
Render topPane = new Render();
scrollPane.setViewportView(topPane);
topPane.setLayout(new BoxLayout(topPane, BoxLayout.X_AXIS));
JPanel botPane = new JPanel();
splitPane.setRightComponent(botPane);
botPane.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
JLabel zoomLevel = new JLabel("Zoom level:");
botPane.add(zoomLevel);
JSlider slider = new JSlider(JSlider.HORIZONTAL, 25, 100, 100);
slider.setMajorTickSpacing(15);
slider.setMinorTickSpacing(5);
slider.setPaintTicks(true);
slider.setPaintLabels(true);
slider.setPreferredSize(new Dimension(600,40));
botPane.add(slider);
PanAndZoom zoomer=new PanAndZoom(topPane.getLabel());
slider.addChangeListener(zoomer);
}
The top panel uses the render class which was made to draw graphics. Simplifying:
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Render extends JPanel {
JLabel envContainer;
Render() {
super();
ImageIcon imageIcon = new ImageIcon("/path/to/img1");
JLabel envContainer = new JLabel(imageIcon);
super.add(envContainer);
}
#Override
public void paint(Graphics g) {
super.paint(g);
/*Render stuff*/
}
public JLabel getLabel() {
return envContainer;
}
}
And the third class which is giving me the trouble, listens on the slider and sets the JLabel icon according to it:
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JSlider;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class PanAndZoom implements ChangeListener {
private JLabel label;
private BufferedImage image;
public PanAndZoom(JLabel lab){
this.label=lab;
try {
image = ImageIO.read(new File("/path/to/img1"));
} catch (IOException e) {
e.printStackTrace();
}
label.setIcon(new ImageIcon("/path/to/img2"));//To test another img. It gives runtime errors.
}
public void stateChanged(ChangeEvent e) {
int value = ((JSlider) e.getSource()).getValue();
double scale = value / 100.0;
BufferedImage scaled = getScaledImage(scale); // It also gives runtime errors.
System.out.println("Scale:"+scale+" Value:"+value);
label.setIcon(new ImageIcon(scaled));
label.revalidate();
}
private BufferedImage getScaledImage(double scale) {
int w = (int) (scale * image.getWidth());
int h = (int) (scale * image.getHeight());
BufferedImage bi = new BufferedImage(w, h, image.getType());
Graphics2D g2 = bi.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BICUBIC);
AffineTransform at = AffineTransform.getScaleInstance(scale, scale);
g2.drawRenderedImage(image, at);
g2.dispose();
return bi;
}
}
Why cant i use the JLabel if it was successfully returned by the getLabel method?

You're local version of envContainer in class Render's constructor is overriding the class instance envContainer.
public class Render extends JPanel {
JLabel envContainer; //<---- class instance
Render() {
super();
ImageIcon imageIcon = new ImageIcon("/path/to/img1");
JLabel envContainer = new JLabel(imageIcon); //<---- overriden by local instance, hence class instance remains null
super.add(envContainer);
}
My guess is that you didn't mean to make it a local version since you're not using it within the constructor for anything. Make the following change to your Render constructor.
Render() {
..
this.envContainer = new JLabel(imageIcon);
...
}