I am trying to create an image slideshow, the current code i have moves the image to the right and then moves it back to the left, but i want the image to move from left to the right and then come out from the left then go to the right and come out from the left.....that way repeatedly.
please help
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class MImage extends JPanel implements ActionListener {
Timer t = new Timer(10, this);
int x = 2, y = 2, velX = 2, velY = 2;
Image image;
int num = 0;
public void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon i = new ImageIcon("image/cartoon.jpg");
image = i.getImage();
g.drawImage(image, x, velY, null);
t.setRepeats(true);
t.start();
}
public void actionPerformed(ActionEvent e) {
if (x < 0 || x >= 1500) {
velX = -velX;
}
if (y < 0 || y >= 3000) {
velY = -velY;
}
x += velX;
y += velY;
repaint(x);
}
}
class SMimage
import javax.swing.JFrame;
public class SMImage {
public static void main(String[] args) {
MImage im = new MImage();
JFrame f = new JFrame();
f.add(im);
f.setVisible(true);
f.setSize(600, 400);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setTitle("Moving image");
}
}
it keeps moving to the right and and back to the left
The easiest way to accomplish what you want is to paint the image to the left, and to the right of the centered version of the image.
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, x - image.getWidth(this), velY, this);
g.drawImage(image, x, velY, this);
g.drawImage(image, x + image.getWidth(this), velY, this);
}
Related
I have a basic program that renders the position of the mouse on a java.awt.Canvas. However, the further away the mouse gets from the coordinates 0, 0 (top left of the window) the more inaccurate it becomes.
The box drawn on the screen (that represents the mouse position) seems to increasingly fall further and further behind where the actual mouse position is. Is there something I haven't done right or is this a problem with AWT or Swing.
Here's my code:
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;
import javax.swing.JFrame;
public class Main extends Canvas implements Runnable {
private static final long serialVersionUID = 1L;
private BufferedImage image;
private int[] pixels;
private static final MouseHandler handler = new MouseHandler();
public Main() {
image = new BufferedImage(640, 480, BufferedImage.TYPE_INT_RGB);
pixels = ((DataBufferInt)image.getRaster().getDataBuffer()).getData();
initWindow();
addMouseMotionListener(handler);
start();
}
private void initWindow() {
Dimension d = new Dimension(image.getWidth(), image.getHeight());
JFrame f = new JFrame("Mouse Pointer");
f.setPreferredSize(d);
f.setMinimumSize(d);
f.setMaximumSize(d);
f.setVisible(true);
f.setResizable(false);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void start() {
new Thread(this).start();
}
private void render() {
BufferStrategy bs = getBufferStrategy();
if(bs == null) {
createBufferStrategy(3);
return;
}
clearScreen();
drawMousePos();
Graphics g = bs.getDrawGraphics();
g.drawImage(image, 0, 0, getWidth(), getHeight(), null);
g.dispose();
bs.show();
}
public void run() {
while(true) {
render();
}
}
private void clearScreen() {
for(int i = 0; i < pixels.length; i++) pixels[i] = 0;
}
//draw 3 by 3 box around mouse position
private void drawMousePos() {
for(int y = -1; y <= 1; y++) {
for(int x = -1; x <= 1; x ++) {
if((handler.x + x) >= 0 &&
(handler.x + x) <= image.getWidth() &&
(handler.y + y) >= 0 &&
(handler.y + y) <= image.getHeight())
pixels[(handler.x + x) + (handler.y + y) * image.getWidth()] = 0xff00ff00;
}
}
}
public static void main(String[] args) {
new Main();
}
}
Mouse Handler class:
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
public class MouseHandler implements MouseMotionListener {
public int x, y;
public void mouseDragged(MouseEvent e) {
x = e.getX();
y = e.getY();
}
public void mouseMoved(MouseEvent e) {
x = e.getX();
y = e.getY();
}
}
Thanks for any help in advance.
The problem here is that you're setting size of the whole frame, ie 480 - it is the height of window with title bar, this is why actual size of content pane is smaller (~455), then during painting you're down scaling image.
To fix this - set content pane size to desired one:
f.getContentPane().setPreferredSize(d);
f.getContentPane().setMinimumSize(d);
f.getContentPane().setMaximumSize(d);
You also have small bug in drawMousePos:
(handler.x + x) <= image.getWidth() should use < instead of <=
I am just trying to make a simple aquarium type application. The fish moves from left to right. (the mouth of fish is faced towards right). When it reaches the end of the JFrame, it returns back. What I wanted is that it must face towards left when it returns.(goes back) So, I have decided to paint with a new image when the fish reaches at the specific coordinate. How to do it? Please.
image 1 = fish of image whose mouth is right faced
image 2 = fish of image whose mouth is left faced
package aquarium;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.util.Random;
import javax.swing.Timer;
public class Aquarium extends JPanel implements ActionListener{
Random r = new Random();
Timer t = new Timer(5, this);
int x = 0, y= 30;
int velX = 1 ,velY =1;
ImageIcon image = new ImageIcon(getClass().getResource("../res/aquarium.gif"));
ImageIcon image1 = new ImageIcon(getClass().getResource("../res/smallFish.gif"));
ImageIcon image2 = new ImageIcon(getClass().getResource("../res/new.gif"));
int numberFish = 12;
Aquarium() {
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
image.paintIcon(this, g, 0, 0);
image1.paintIcon(this, g, x, y);
t.start();
}
#Override
public void actionPerformed(ActionEvent e){
Graphics g = null;
if(x<0 || x>465) {
velX = -velX;
}
x += velX;
repaint();
}
public static void main(String[] args) {
Aquarium a = new Aquarium();
JFrame f = new JFrame();
f.setTitle("The Aquarium");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
f.setResizable(false);
f.setBounds(500,200,500,300); //left,top,width,height
f.add(a);
}
}
Use velX to check which fish it is and draw it:
public void paintComponent(Graphics g){
super.paintComponent(g);
image.paintIcon(this, g, 0, 0);
if (velX > 0) { // moving right
image1.paintIcon(this, g, x, y);
} else { // moving left
image2.paintIcon(this, g, x, y);
}
t.start();
}
I'm trying to create a simple panel where a 2-dimensional ball is bouncing up and down. I can't get it to work because for some reason I can't call the repaint method more than once a second. The design is basically that there is an object that can be given "an impulse" with the method move(). Everytime the evaluatePosition method is called, the current position will be calculated through the time that has passed, the velocity and the acceleration. The code for the panel is:
public class Display extends JPanel {
private MovableObject object = new MovableObject(new Ellipse2D.Double(5,5,50,50));
private static final int DELAY = 1000;
public Display(){
object.move(50,50);
Timer timer = new Timer(DELAY, new ActionListener(){
#Override
public void actionPerformed(ActionEvent e){
object.evaluatePosition();
repaint();
}
});
timer.start();
}
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g.drawOval((int)object.getPosition().getX(), (int)object.getPosition.getY()
(int)object.getShape().getWidth(), object.getShape().getHeight());
}
This code works for DELAY=1000 but not for DELAY=100 or DELAY=10 and so on. I read some example code here on SO but they all seem to me like what I already did. So why is my code not working?
EDIT (2016-01-30):
Since it really seems to be a performance issue, here's the code for the MovableObject (I just thought it would be irrelevant and you will probably see why):
public class MovableObject {
// I would really like to use Shape instead of Ellipse2D so that
// objects of any shape can be created
private Ellipse2D.Double shape;
private Point position;
// Vector is my own class. I want to have some easy vector addition and
// multiplication and magnitude methods
private Vector velocity = new Vector(0, 0);
private Vector acceleration = new Vector(0, 0);
private Date lastEvaluation = new Date();
public MovableObject(Ellipse2D.Double objectShape){
shape = objectShape;
}
public void evaluatePosition(){
Date currentTime = new Date();
long deltaTInS = (currentTime.getTime()-lastEvaluation.getTime())/1000;
// s = s_0 + v*t + 0.5*a*t^2
position = new Point((int)position.getX()+ (int)(velocity.getX()*deltaTInS) + (int)(0.5*acceleration.getX()*deltaTInS*deltaTInS),
(int)position.getY()+ (int)(velocity.getY()*deltaTInS) + (int)(0.5*acceleration.getY()*deltaTInS*deltaTInS));
lastEvaluation = currentTime;
}
}
public void move(Vector vector){
velocity = velocity.add(vector);
evaluatePosition();
}
public Point getPosition(){
return position;
}
public Ellipse2D.Double getShape(){
return shape;
}
My move method does not change position but velocity. Please notice that I just changed the shape Object from Shape to Ellipse2D for testing if my code has a performance issue because of the additional code. So if you think this is more complex than it needs to be: I actually want to add some complexity so that the MovableObject can have the shape of any subclass of shape. I've seen a lot of code that seemed more complex to me and rendered fast. So I'd like to know what's wrong with this (besides the fact that it's a bit too complex for just rendering an ellipse).
Okay, so this is a simple example, based on the out-of-context code snippet you left which doesn't seem to have any problems. It has variable speed controlled by a simple slider...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.geom.GeneralPath;
import java.awt.geom.PathIterator;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Display extends JPanel {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new Display());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
private MovableObject object = new MovableObject(new Ellipse2D.Double(5, 5, 50, 50));
private int delay = 40;
private Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
object.evaluatePosition(getSize());
repaint();
}
});
private JSlider slider = new JSlider(5, 1000);
public Display() {
object.move(50, 50);
slider = new JSlider(5, 1000);
slider.setSnapToTicks(true);
slider.setMajorTickSpacing(10);
slider.setMinorTickSpacing(5);
setLayout(new BorderLayout());
add(slider, BorderLayout.SOUTH);
// This is simply designed to put an artificate delay between the
// change listener and the time the update takes place, the intention
// is to stop it from pausing the "main" timer...
Timer delay = new Timer(250, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (timer != null) {
timer.stop();
}
timer.setDelay(slider.getValue());
timer.start();
}
});
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
delay.restart();
repaint();
}
});
slider.setValue(40);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g.create();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.draw(object.getTranslatedShape());
FontMetrics fm = g2.getFontMetrics();
String text = Integer.toString(slider.getValue());
g2.drawString(text, 0, fm.getAscent());
g2.dispose();
}
public class MovableObject {
private Shape shape;
private Point location;
private int xDelta, yDelta;
public MovableObject(Shape shape) {
this.shape = shape;
location = shape.getBounds().getLocation();
Random rnd = new Random();
xDelta = rnd.nextInt(8);
yDelta = rnd.nextInt(8);
if (rnd.nextBoolean()) {
xDelta *= -1;
}
if (rnd.nextBoolean()) {
yDelta *= -1;
}
}
public void move(int x, int y) {
location.setLocation(x, y);
}
public void evaluatePosition(Dimension bounds) {
int x = location.x + xDelta;
int y = location.y + yDelta;
if (x < 0) {
x = 0;
xDelta *= -1;
} else if (x + shape.getBounds().width > bounds.width) {
x = bounds.width - shape.getBounds().width;
xDelta *= -1;
}
if (y < 0) {
y = 0;
yDelta *= -1;
} else if (y + shape.getBounds().height > bounds.height) {
y = bounds.height - shape.getBounds().height;
yDelta *= -1;
}
location.setLocation(x, y);
}
public Shape getTranslatedShape() {
PathIterator pi = shape.getPathIterator(AffineTransform.getTranslateInstance(location.x, location.y));
GeneralPath path = new GeneralPath();
path.append(pi, true);
return path;
}
}
}
You could also have a look at
Swing animation running extremely slow
Rotating multiple images causing flickering. Java Graphics2D
Java Bouncing Ball
for some more examples...
I Have 3 Questing Regarding My Code
1==> How to remove Selected Shape in my code; when i right click every shape is deleted,
2==> I TOTALLY don't know how to highlight the overlapped are
3==> right now when i click on my JPanel, shape drawn from the point where mouse clicked, where as it should be the in the center of the mouse pointer
Thanks In advance
actually i'm new to Java. this is my code,
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import javax.swing.JPanel;
import javax.swing.JButton;
import Delete.Selection;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Area;
import java.util.ArrayList;
public class MyPanel extends JPanel {
ArrayList<MyRect> list = new ArrayList<MyRect>();
public MyPanel() {
addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON1) {
MyRect r = new MyRect(e.getX(), e.getY());
list.add(r);
repaint();
}
else {
list.clear();
repaint();
}
}
}
);
setPreferredSize(new Dimension(600, 400));
setBackground(Color.CYAN);
}
public void paintComponent(Graphics g){
super.paintComponent(g);
for (int i = 0; i < list.size(); i++) {
MyRect r = list.get(i);
g.fillRect(r.x, r.y, r.w, r.h);
}
}
class MyRect {
int x, y, w=100, h=100;
Color c = Color.BLACK;
public MyRect(int x, int y, int w, int h, Color color) {
this.x = x;
this.y = y;
this.w = w;
this.h = h;
this.c = color;
}
public MyRect(int x, int y) {
this.x = x;
this.y = y;
}
}}
how to highlight the overlapped area
You can use the intersection(...) method of the Rectangle class to get a Rectangle to paint:
import java.awt.*;
import javax.swing.*;
import java.awt.geom.*;
public class IntersectingRectangles extends JPanel
{
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
Dimension d = getSize();
int width = d.width * 3 / 4;
int height = d.height * 3 / 4;
Rectangle r1 = new Rectangle(0, 0, width, height);
g2d.setColor( Color.BLUE );
g2d.fill( r1 );
Rectangle r2 = new Rectangle(d.width - width, d.height - height, width, height);
g2d.setColor( Color.YELLOW );
g2d.fill( r2 );
// Specific solution when using Rectangles only
Rectangle r3 = r1.intersection(r2);
g2d.setColor(Color.GREEN);
g2d.fill(r3);
/*
// For a more generic solution using any Shape
Area area = new Area(r1);
area.intersect( new Area(r2) );
g2d.setColor(Color.GREEN);
g2d.fill(area);
*/
g2d.dispose();
}
#Override
public Dimension getPreferredSize()
{
return new Dimension(300, 300);
}
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Intersecting Rectangles");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new IntersectingRectangles());
frame.setLocationByPlatform( true );
frame.pack();
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowGUI();
}
});
}
}
How to remove Selected Shape in my code; when i right click every shape is deleted,
You need to iterate through the ArrayList containing the Rectangles. Then you can use the Rectangle.contains( yourMousePoint ) method to determine which Rectangle you clicked on. You will need to save the reference to the Rectangle. Then when the loop finishes executing you can remove the Rectangle from the ArrayList.
shape drawn from the point where mouse clicked, where as it should be the in the center of the mouse pointer
Then you need to change the x/y location of the Rectangle. It should be:
int x = mousePoint.x - (width / 2);
int y = mousePoint.y - (height / 2);
where width/height represent the size of the Rectangle you want to draw.
I'm trying to create a graphical component that allows me to draw one rectangle on a selected image (the rectangle must be drawn using drag-and-drop operations): the purpose of this component is to get the coordinates and the size of the rectangle drawn; the second goal is to provide a component which can be easily integrated in a graphical user interface.
The authors of this example created a subclass of JLabel in order to draw the image, then they added a MouseInputAdapter to the instance of this subclass in order to deal with the drawing of the rectangle.
I was inspired by that example, with the difference that I have created a subclass of JPanel class: I named it FigurePanel class. Then I made some changes in order to provide the following features:
if the image is larger than the instance of FigurePanel, then the scrollers must appear;
if the image is smaller than the instance of FigurePanel, then this image must be placed in the center of the panel;
while the user draws the rectangle, it should not extend beyond the limits of the image.
Here is the source code of FigurePanel class.
package imageselectionproject;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import javax.swing.JPanel;
import javax.swing.event.MouseInputAdapter;
public class FigurePanel extends JPanel
{
private Image backgroundImage = null;
private Rectangle imageLimits = new Rectangle(0, 0, getWidth(), getHeight());
private Rectangle currentRect = null;
private Rectangle rectToDraw = null;
private final Rectangle previousRectDrawn = new Rectangle();
public FigurePanel()
{
setOpaque(true);
SelectionListener listener = new SelectionListener();
addMouseListener(listener);
addMouseMotionListener(listener);
}
#Override
public Dimension getPreferredSize()
{
return backgroundImage == null ? super.getPreferredSize() : new Dimension(backgroundImage.getWidth(this), backgroundImage.getHeight(this));
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g); //paints the background and image
if (backgroundImage != null)
{
g.drawImage(backgroundImage, imageLimits.x, imageLimits.y, this);
}
// If currentRect exists, paint a box on top.
if (currentRect != null)
{
// Draw a rectangle on top of the image.
g.setXORMode(Color.white); // Color of line varies
// depending on image colors
g.drawRect(rectToDraw.x, rectToDraw.y,
rectToDraw.width - 1, rectToDraw.height - 1);
System.out.println(rectToDraw);
}
}
public void setImage(Image image)
{
int x = 0;
int y = 0;
if (image != null)
{
backgroundImage = image;
// The following instructions are used to center the image on the panel.
/*x = (getSize().width - image.getWidth(this)) / 2;
y = (getSize().height - image.getHeight(this)) / 2;
if (x < 0) x = 0;
if (y < 0) y = 0;*/
}
else
{
backgroundImage = null;
}
currentRect = null;
setSize(getPreferredSize());
imageLimits.setBounds(x, y, getWidth(), getHeight());
System.out.println("imageLimits = " + imageLimits);
repaint();
}
private void updateDrawableRect()
{
int x = currentRect.x;
int y = currentRect.y;
int width = currentRect.width;
int height = currentRect.height;
// Make the width and height positive, if necessary.
if (width < 0)
{
width = 0 - width;
x = x - width + 1;
if (x < 0)
{
width += x;
x = 0;
}
}
if (height < 0)
{
height = 0 - height;
y = y - height + 1;
if (y < 0)
{
height += y;
y = 0;
}
}
// The rectangle should not extend beyond the boundaries of the image.
if (x < imageLimits.x)
{
width -= (imageLimits.x - x);
x = imageLimits.x;
}
else if ((x + width) > imageLimits.x + imageLimits.width)
{
width = imageLimits.x + imageLimits.width - x;
}
if (y < imageLimits.y)
{
height -= (imageLimits.y - y);
y = imageLimits.y;
}
if ((y + height) > imageLimits.y + imageLimits.height)
{
height = imageLimits.y + imageLimits.height - y;
}
// Update rectToDraw after saving old value.
if (rectToDraw != null)
{
previousRectDrawn.setBounds(rectToDraw.x, rectToDraw.y,
rectToDraw.width, rectToDraw.height);
rectToDraw.setBounds(x, y, width, height);
}
else
{
rectToDraw = new Rectangle(x, y, width, height);
}
}
private class SelectionListener extends MouseInputAdapter
{
#Override
public void mousePressed(MouseEvent e)
{
int x = e.getX();
int y = e.getY();
currentRect = new Rectangle(x, y, 0, 0);
updateDrawableRect();
repaint();
}
#Override
public void mouseDragged(MouseEvent e)
{
updateSize(e.getX(), e.getY());
}
#Override
public void mouseReleased(MouseEvent e)
{
updateSize(e.getX(), e.getY());
}
/*
* Update the size of the current rectangle
* and call repaint. Because currentRect
* always has the same origin, translate it
* if the width or height is negative.
*
* For efficiency (though
* that isn't an issue for this program),
* specify the painting region using arguments
* to the repaint() call.
*
*/
void updateSize(int x, int y)
{
currentRect.setSize(x - currentRect.x, y - currentRect.y);
updateDrawableRect();
Rectangle totalRepaint = rectToDraw.union(previousRectDrawn);
repaint(totalRepaint.x, totalRepaint.y,
totalRepaint.width, totalRepaint.height);
}
}
}
The method setImage is used to set a new image, so it invokes the method repaint to redraw the graphical component. In the code shown above, I disabled (via comments) instructions to center the image: in this way, the component seems to work properly.
Instead, if I enable such instructions, the image is correctly positioned in the center of the panel when it is smaller than the panel itself, however, I encountered the following problem: suppose that it is currently displayed an image larger than the panel, if the new image that I decide to load is smaller than the currently displayed image, then the new image is not displayed; if I try to reload the new image, then it appears.
Why does this problem occur? How to solve it?
I also created the FigurePanelTest class in order to test the FigurePanel class.
package imageselectionproject;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Image;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
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.JScrollPane;
public class FigurePanelTest extends JFrame
{
public FigurePanelTest()
{
FigurePanel imagePanel = new FigurePanel();
JScrollPane imageScrollPane = new JScrollPane();
imageScrollPane.setPreferredSize(new Dimension(420, 250));
imageScrollPane.setViewportView(imagePanel);
JButton imageButton = new JButton("Load Image");
imageButton.addActionListener(
new ActionListener()
{
#Override
public void actionPerformed(ActionEvent evt)
{
JFileChooser fc = new JFileChooser();
int returnValue = fc.showOpenDialog(null);
if (returnValue == JFileChooser.APPROVE_OPTION) {
File selectedFile = fc.getSelectedFile();
System.out.println(selectedFile.getName());
try
{
Image image = ImageIO.read(selectedFile.getAbsoluteFile());
imagePanel.setImage(image);
imageScrollPane.getViewport().setViewPosition(new Point(0, 0));
}
catch(IOException e)
{
e.printStackTrace();
}
}
}
}
);
Container container = getContentPane();
container.setLayout(new FlowLayout());
container.add(imageScrollPane);
container.add(imageButton);
setSize(600, 400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Here is the main.
public static void main(String args[]) {
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new FigurePanelTest().setVisible(true);
}
});
}
For Andrew, a single program:
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
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.JScrollPane;
import javax.swing.event.MouseInputAdapter;
public class TestDrawPanel {
public static void main(String args[]) {
/* Create and display the form */
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new FigurePanelTest().setVisible(true);
}
});
}
}
class FigurePanelTest extends JFrame {
public FigurePanelTest() {
final FigurePanel imagePanel = new FigurePanel();
final JScrollPane imageScrollPane = new JScrollPane();
imageScrollPane.setPreferredSize(new Dimension(420, 250));
imageScrollPane.setViewportView(imagePanel);
JButton imageButton = new JButton("Load Image");
imageButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent evt) {
JFileChooser fc = new JFileChooser();
int returnValue = fc.showOpenDialog(null);
if (returnValue == JFileChooser.APPROVE_OPTION) {
File selectedFile = fc.getSelectedFile();
System.out.println(selectedFile.getName());
try {
Image image = ImageIO.read(selectedFile.getAbsoluteFile());
imagePanel.setImage(image);
imageScrollPane.getViewport()
.setViewPosition(new Point(0, 0));
} catch (IOException e) {
e.printStackTrace();
}
}
}
});
Container container = getContentPane();
container.setLayout(new FlowLayout());
container.add(imageScrollPane);
container.add(imageButton);
setSize(600, 400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
class FigurePanel extends JPanel {
private Image backgroundImage = null;
private Rectangle imageLimits = new Rectangle(0, 0, getWidth(), getHeight());
private Rectangle currentRect = null;
private Rectangle rectToDraw = null;
private final Rectangle previousRectDrawn = new Rectangle();
public FigurePanel() {
setOpaque(true);
SelectionListener listener = new SelectionListener();
addMouseListener(listener);
addMouseMotionListener(listener);
}
#Override
public Dimension getPreferredSize() {
return backgroundImage == null ? super.getPreferredSize()
: new Dimension(backgroundImage.getWidth(this),
backgroundImage.getHeight(this));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); // paints the background and image
if (backgroundImage != null) {
g.drawImage(backgroundImage, imageLimits.x, imageLimits.y, this);
}
// If currentRect exists, paint a box on top.
if (currentRect != null) {
// Draw a rectangle on top of the image.
g.setXORMode(Color.white); // Color of line varies
// depending on image colors
g.drawRect(rectToDraw.x, rectToDraw.y, rectToDraw.width - 1,
rectToDraw.height - 1);
System.out.println(rectToDraw);
}
}
public void setImage(Image image) {
int x = 0;
int y = 0;
if (image != null) {
backgroundImage = image;
// The following instructions are used to center the image on the
// panel.
/*
* x = (getSize().width - image.getWidth(this)) / 2; y =
* (getSize().height - image.getHeight(this)) / 2;
*
* if (x < 0) x = 0; if (y < 0) y = 0;
*/
} else {
backgroundImage = null;
}
currentRect = null;
setSize(getPreferredSize());
imageLimits.setBounds(x, y, getWidth(), getHeight());
System.out.println("imageLimits = " + imageLimits);
repaint();
}
private void updateDrawableRect() {
int x = currentRect.x;
int y = currentRect.y;
int width = currentRect.width;
int height = currentRect.height;
// Make the width and height positive, if necessary.
if (width < 0) {
width = 0 - width;
x = x - width + 1;
if (x < 0) {
width += x;
x = 0;
}
}
if (height < 0) {
height = 0 - height;
y = y - height + 1;
if (y < 0) {
height += y;
y = 0;
}
}
// The rectangle should not extend beyond the boundaries of the image.
if (x < imageLimits.x) {
width -= (imageLimits.x - x);
x = imageLimits.x;
} else if ((x + width) > imageLimits.x + imageLimits.width) {
width = imageLimits.x + imageLimits.width - x;
}
if (y < imageLimits.y) {
height -= (imageLimits.y - y);
y = imageLimits.y;
}
if ((y + height) > imageLimits.y + imageLimits.height) {
height = imageLimits.y + imageLimits.height - y;
}
// Update rectToDraw after saving old value.
if (rectToDraw != null) {
previousRectDrawn.setBounds(rectToDraw.x, rectToDraw.y,
rectToDraw.width, rectToDraw.height);
rectToDraw.setBounds(x, y, width, height);
} else {
rectToDraw = new Rectangle(x, y, width, height);
}
}
private class SelectionListener extends MouseInputAdapter {
#Override
public void mousePressed(MouseEvent e) {
int x = e.getX();
int y = e.getY();
currentRect = new Rectangle(x, y, 0, 0);
updateDrawableRect();
repaint();
}
#Override
public void mouseDragged(MouseEvent e) {
updateSize(e.getX(), e.getY());
}
#Override
public void mouseReleased(MouseEvent e) {
updateSize(e.getX(), e.getY());
}
/*
* Update the size of the current rectangle and call repaint. Because
* currentRect always has the same origin, translate it if the width or
* height is negative.
*
* For efficiency (though that isn't an issue for this program), specify
* the painting region using arguments to the repaint() call.
*/
void updateSize(int x, int y) {
currentRect.setSize(x - currentRect.x, y - currentRect.y);
updateDrawableRect();
Rectangle totalRepaint = rectToDraw.union(previousRectDrawn);
repaint(totalRepaint.x, totalRepaint.y, totalRepaint.width,
totalRepaint.height);
}
}
}
The problem is calculating the x and y in the setImage().It's not calculating the center of panel correctly.I'm saying this by checking the values of x and y after loading small and large images many times
However I tried putting the centering the image inside paintComponent and it worked perfectly
if (backgroundImage != null) {
imageLimits.x = (this.getWidth() - backgroundImage.getWidth(this)) / 2;
imageLimits.y = (this.getHeight() - backgroundImage.getHeight(this)) / 2;
g.drawImage(backgroundImage, imageLimits.x, imageLimits.y, this);
}