So ive been doing a bit of java recently and i have run into a bit of a problem. I have been playing around with 2d drawing and added an image to the project.
The problem is that when the window gets resized, it redraws and duplicates the image. I have made a little workaround, but its not ideal... So why does the image duplicate?
Before:
http://i.imgur.com/PmHRZBQ.png
(window is resized)
After:
http://i.imgur.com/bhsvVZz.png
Code
main.java
import javax.swing.JFrame;
public class main
{
public static void main(String [] args) throws InterruptedException
{
JFrame f = new JFrame("Title");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Canvas testing = new Canvas();
f.add(testing);
f.setSize(800, 600);
f.setVisible(true);
}
}
canvas.java
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Canvas extends JPanel
{
public void paintComponent (Graphics g)
{
super.paintComponent(g);
this.setBackground(Color.WHITE);
g.setColor(Color.BLACK);
g.fillRect(25, 25, 100, 30);
g.setColor(new Color(190,81,215));
g.fillRect(25, 68, 10, 10);
g.setColor(Color.RED);
g.drawString("Matt is da best", 100, 10);
try
{
BufferedImage image = ImageIO.read(new File("C:/face.png"));
JLabel picLabel = new JLabel(new ImageIcon(image));
System.out.println("Added pic");
add(picLabel);
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
Don't load the image in the paintComponent(Graphics) method! It could be declared as a class attribute and loaded in the constructor.
Don't add components in the paintComponent method either! It will trigger a repaint.
This should work more reliably..
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class main
{
public static void main(String [] args) throws InterruptedException
{
JFrame f = new JFrame("Title");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Canvas testing = new Canvas();
f.add(testing);
f.setSize(800, 600);
f.setVisible(true);
}
}
class Canvas extends JPanel
{
BufferedImage image;
Canvas() {
image = new BufferedImage(200,200,BufferedImage.TYPE_INT_RGB);
JLabel picLabel = new JLabel(new ImageIcon(image));
System.out.println("Added pic");
add(picLabel);
}
public void paintComponent (Graphics g)
{
super.paintComponent(g);
this.setBackground(Color.WHITE);
g.setColor(Color.BLACK);
g.fillRect(25, 25, 100, 30);
g.setColor(new Color(190,81,215));
g.fillRect(25, 68, 10, 10);
g.setColor(Color.RED);
g.drawString("Matt is da best", 100, 10);
}
}
Other tips
Have the Canvas return a preferred size and pack() the frame rather than set a size to it.
Start and update a Swing GUI on the EDT.
Don't give your custom class the same name as a J2SE class. That can get confusing. Maybe call it JCanvas.
Take a look at your paintComponent method...
Each time paintComponent is called, you are creating a new JLabel and adding it back to the panel...
try
{
BufferedImage image = ImageIO.read(new File("C:/face.png"));
JLabel picLabel = new JLabel(new ImageIcon(image));
System.out.println("Added pic");
add(picLabel);
}
catch (IOException e)
{
e.printStackTrace();
}
This in turn will produce another repaint request and the sync will begin all over again.
NEVER modify the state of any component from within any paint method. This will simple...blow up in your face...
You should load your image and add the label within the constructor or some other method (that paintXxx doesn't call)
The important thing to remember about painting in Swing is, you don't control it. The repaint engine may update your component at any time, with or without your interaction, based on it's own needs. You can encourage a paint by calling repaint, but there is no guarantee of when or what will be repainted.
Related
This question already has an answer here:
Can't draw to JPanel with getGraphics
(1 answer)
Closed 4 years ago.
I'm having trouble getting the graphics of my JPanel to work. It refuses to draw anything, regardless of anything I've tried and anything I can find on the internet.
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.Timer;
import java.util.*;
import java.io.*;
public class Mandelbrot{
public static void main(String[] args){
JFrame win=new JFrame();
JPanel dis=new JPanel();
win.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
win.setResizable(false);
win.setVisible(true);
win.add(dis);
dis.setPreferredSize(new Dimension(1000,500));
win.pack();
Graphics g=dis.getGraphics();
g.setColor(Color.red);
g.fillRect(0, 0, 100, 100);
}
}
Posting as an answer because I ran out of comment room:
Note:
If you need to be constantly changing things, then a JPanel is probably not your best option. I recommend you rethink what you are trying to do because you should probably use a Canvas or paint to a bunch of different labels/glass panes and overlay them however you want, this will allow you to have moving components/animations in a foreground item, and make different changes to the background item.
Alternatively, you can make the JPanel draw a buffered image, or you can store a list of items to paint, and you can paint them each time. For the buffered image method you can directly edit and draw to the buffered image every time you need to make a change.
Below is an example of how to use the buffered image method.
First create a custom JPanel in a new class:
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JPanel;
public class DrawPanel extends JPanel{
public BufferedImage canvas = new BufferedImage(panelWidth, panelHeight, BufferedImage.TYPE_INT_ARGB);
#Override
public void paintComponent(Graphics g){
//Draw the canvas
g.drawImage(canvas, 0, 0, this);
}
}
Now in your main method you can replace JPanel dis=new JPanel() with this:
DrawPanel dis = new DrawPanel();
Graphics g=dis.canvas.getGraphics();
g.setColor(Color.red);
g.fillRect(0, 0, 100, 100);
Note how I use dis.canvas to get the graphics of the bufferedImage instead of the graphics of the JPanel.
It's as simple as that.
As per Andrews comment. You should consider extending a JLabel instead of a JPanel, it is much more lightweight, and easier to update using label.repaint();.
public static void main(String... args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
JPanel panel = new JPanel() {
#Override
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.red);
g.fillRect(0, 0, 100, 100);
}
};
panel.setPreferredSize(new Dimension(640, 480));
frame.add(panel);
frame.setVisible(true);
frame.pack();
}
Just an example - you should create a new Class subclassing JPanel, see Painting in AWT and Swing.
A gif that I tried to put into a JPanel isn't showing up after clicking the button that triggers it until I resize the window. When it does show up, it does not fit the JPanel and is not animated. I looked at several posts that dealt with this but I don't understand how to use them in my case.
/*
* Author: Raymo111
* Date: 13/04/2018
* Description: Wishes happy birthday to a special someone
*/
//Imports java GUI classes
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
// Main class with JFrame and ActionListener enabled
public class Happy_Birthday_GUI extends JFrame implements ActionListener {
// Class variables
private static JButton startButton = new JButton("CLICK TO START");
private static JPanel startPanel = new JPanel(), gifPanel = new JPanel();
private static Color blue = new Color(126, 192, 238), pink = new Color(255, 192, 203);
private static GridLayout grid1 = new GridLayout(1, 1);
// Constructor
public Happy_Birthday_GUI() {
// Initial screen
startButton.addActionListener(this);
startButton.setFont(new Font("Comic Sans MS", Font.PLAIN, 50));
startPanel.setLayout(grid1);
startPanel.add(startButton);
startPanel.setBorder(BorderFactory.createLineBorder(blue, 100));
startButton.setBackground(pink);
getContentPane().add(startPanel);
// Sets title, size, layout (grid 1x1), and location of GUI window (center)
setTitle("Happy Birthday from Dolphin");
setSize(840, 840);
setLayout(grid1);
setLocationRelativeTo(null);
setVisible(true);
}
// Main method
public static void main(String[] args) {
new Happy_Birthday_GUI();
}
// Action Performed method
public void actionPerformed(ActionEvent event) {
// Proceed to gif and song
if (startButton == event.getSource()) {
getContentPane().removeAll();
BufferedImage dolphin;
gifPanel.setLayout(grid1);
gifPanel.setBorder(BorderFactory.createLineBorder(pink, 100));
try {
dolphin = ImageIO.read(new File("C:\\Users\\raymo\\Pictures\\dolphin.gif"));
JLabel gifLabel = new JLabel(new ImageIcon(dolphin));
gifPanel.add(gifLabel);
} catch (IOException e) {
e.printStackTrace();
}
getContentPane().add(gifPanel);
}
}
}
Here is dolphin.gif. It's cute.
How do I get it to show up immediately after clicking the start button as an animated gif that fits the JPanel? Thanks in advance.
BufferedImage doesn't support painting animated Gifs, instead, you'll need to make use of Image (or preferably, ImageIcon).
This could then be applied directly to a JLabel, which will perform the animation operation itself.
animated gif that fits he JPanel?
Okay, that's a much more complex problem. One approach would be to convert the Gif to the required size, but needless to say, that's very, very complex.
A simpler solution might be to use a AffineTransform and scale the image to meet the requirements of the component itself. This would require a custom component, capable of calculating the scale and painting each frame of the image.
Luckily for you, JPanel is an ImageObserver, this means it's capable of painting the gif animation
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
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 TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private ImageIcon image;
public TestPane() {
image = new ImageIcon("/Users/swhitehead/Downloads/NbENe.gif");
}
#Override
public Dimension getPreferredSize() {
return new Dimension(600, 600);
}
#Override
protected void paintComponent(Graphics g) {
int imageWidth = image.getIconWidth();
int imageHeight = image.getIconHeight();
if (imageWidth == 0 || imageHeight == 0) {
return;
}
double widthScale = (double)getWidth() / (double)imageWidth;
double heightScale = (double)getHeight() / (double)imageHeight;
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawImage(image.getImage(), AffineTransform.getScaleInstance(widthScale, heightScale), this);
g2d.dispose();
}
}
}
I tried to put into a JPanel isn't showing up after clicking the button
When you add (or remove) components from a visible GUI the basic code is:
panel.add(...);
panel.revalidate();
panel.repaint();
The revalidate() is need to invoke the layout manager so the component is given a size.
is not animated.
Use a JLabel with an ImageIcon to display images. A JLabel will animated the gif.
When it does show up, it does not fit the JPanel and
You can try the Stretch Icon which is designed to fill the space available to the label.
I ended up doing:
gifPanel.add(new TestPane());
getContentPane().add(gifPanel);
revalidate();
repaint();
using camickr's revalidate and repaint, and MadProgrammer's TestPane class,
which worked very well to get the gif to animate, resize correctly and display immediately.
Why doesn't JPanel (panel) get drawn on the green background (the jpanel)? I want to be able to do this without extending j panel to...
Furthermore, for java games should i use keybindings or keylistener in java.
import javax.swing.*;
import java.awt.event.*;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
public class Game {
JFrame window;
JPanel panel;
int charPosX = 0;
int charPosY = 0;
public Boolean createGui() {
window = new JFrame("Game");
window.setSize(1000,500);
window.setResizable(false);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
panel = new JPanel();
panel.setVisible(true);
panel.setLayout(null);;
panel.setBackground(new Color(65,130,92));
window.add(panel);
return true; //returns true if ran and will be ran by check status in Main.
}
public void paintComponent(Graphics g) {
panel.paintComponents(g);
g.setColor(Color.RED);
g.drawRect(100,10,30,40);
g.fillRect(10, 10, 20, 10);
}
}
Let's take your code for a second and add #Override to your paintComponent method...
public class Game {
//...
#Override
public void paintComponent(Graphics g) {
panel.paintComponents(g);
g.setColor(Color.RED);
g.drawRect(100, 10, 30, 40);
g.fillRect(10, 10, 20, 10);
}
}
And now we have a compiler error! This is because Game extends Object and does not have a paintComponent method. This means that there is no way that the method could be called by any part of the existing painting system, so, it never gets called.
Components make poor "game" entities, they have a lot of "plumbing" which doesn't make them very efficient for this kind of work, you're generally better off heading down a complete custom painting route
import javax.swing.*;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
public class Game {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Game().createGui();
}
});
}
JFrame window;
GamePanel panel;
int charPosX = 0;
int charPosY = 0;
public Boolean createGui() {
window = new JFrame("Game");
window.setSize(1000, 500);
window.setResizable(false);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new GamePanel();
panel.setBackground(new Color(65, 130, 92));
window.add(panel);
window.setVisible(true);
return true; //returns true if ran and will be ran by check status in Main.
}
public class GamePanel extends JPanel {
private Rectangle entity = new Rectangle(100, 10, 30, 40);
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
g2d.draw(entity);
g2d.setColor(Color.BLUE);
g2d.fill(entity);
g2d.dispose();
}
}
}
Also note, I called window.setVisible(true); only after I had added the panel to the window, this is because Swing is lazy when it comes to adding/removing components. If you want to add/remove components after the UI has been realized on the screen, you'll need to call revalidate and repaint on the container to trigger a layout and paint pass
Also, beware, there is a difference between paintComponent and paintComponents ;)
I would highly recommend having a look at Painting in AWT Swing and Performing Custom Painting to gain a better understanding of how painting works in Swing and how you can take advantage of it
Here is my code:
package trialruns;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class TransparentFrame extends JFrame
{
JButton b1;
public TransparentFrame()
{
setTitle("Transparent Frame Demo");
setSize(400,400);
setLayout(new GridBagLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
setUndecorated(true);
setVisible(true);
setResizable(true);
setOpacity(0.4f);
}
public static void main(String args[])
{
new TransparentFrame();
}
}
The problem is if I setOpacity<1.0 i get an error :
The frame is decorated at java.awt.Frame.setOpacity(Frame.java:960)
And if I make do setUndecorated(true) then I cant resize the Jframe
I need to be able to resize a transparent JFrame
I also need to be able to access the folders under the transparent frame
I mean if the transparent window is sitting on the desktop and I want to open a particular folder placed under the window then I should be able to do so without the jframe getting minimized.
Is there any way to do this??
I searched online but couldn't find a suitable solution.
Resizing of the frame is handled by the frame itself. When you remove the Border decorations you lose the resizing functionality.
So, you need to manage the resizing of the frame yourself. Check out Component Resizer for a class that will allow you to resize any component.
The change to your code would be:
//setResizable(true); // not needed as this is the default anyway
setOpacity(0.4f);
new ComponentResizer( this );
But is it possible to keep the border opaque
Yes, but you will only get the Swing decorated Border, not the platform Border and decorations:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class TransparentFrame2 extends JFrame
{
public TransparentFrame2()
{
setTitle("Transparent Frame Demo");
setUndecorated(true);
getRootPane().setWindowDecorationStyle(JRootPane.FRAME);
setBackground( new Color(0, 0, 0, 0) );
setSize(400,400);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
}
public static void main(String args[])
{
new TransparentFrame2();
}
}
Also it is still not possible to access the content behind the frame
Yes, but you need full transparency. If you don't use full transparency then the mouse event is passed to the frame, not the component underneath the frame.
If you what semi transparency then theoretically you could add a MouseListener to the frame to intercept the MouseEvent. Then you can make your frame invisible. Then you could use a Robot to generate a new MouseEvent which will now be dispatched to the screen. You would next to use the frames locationOnScreen(...) method to convert the mouse point from the frames coordinates. I have never tried this approach.
try this.. working for me..
import java.awt.*;
import static java.awt.GraphicsDevice.WindowTranslucency.PERPIXEL_TRANSLUCENT;
import javax.swing.*;
class TransparentFrame extends JFrame {
JButton b1;
public TransparentFrame() {
setTitle("Transparent Frame Demo");
setSize(400, 400);
setAlwaysOnTop(true);
setLayout(new GridBagLayout());
setDefaultCloseOperation(EXIT_ON_CLOSE);
setVisible(true);
setResizable(true);
JPanel panel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
if (g instanceof Graphics2D) {
final int R = 255;
final int G = 255;
final int B = 255;
Paint p =
new GradientPaint(0.0f, 0.0f, new Color(R, G, B, 0),
0.0f, getHeight(), new Color(R, G, B, 0), true);
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(p);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
};
setContentPane(panel);
JButton button = new JButton("Button");
setBackground(new Color(0,0,0,0));
panel.add(button);
}
public static void main(String args[]) {
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gd = ge.getDefaultScreenDevice();
boolean isPerPixelTranslucencySupported = gd.isWindowTranslucencySupported(PERPIXEL_TRANSLUCENT);
//If translucent windows aren't supported, exit.
if (!isPerPixelTranslucencySupported) {
System.err.println("PerPixel Translucency is not supported");
System.exit(0);
}
JFrame.setDefaultLookAndFeelDecorated(true);
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
TransparentFrame tw = new TransparentFrame();
tw.setVisible(true);
}
});
}
}
referenced from this
I was trying to use XOR mode in Graphics to draw a 1bit texture in color against a flat background, when I encountered a behaviour in Graphics I don't understand.
Here is an example of what I mean, isolated:
package teststuff;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
public class XORTest extends JFrame {
public XORTest() {
super("Test");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(500, 400);
setIgnoreRepaint(true);
setResizable(false);
setVisible(true);
createBufferStrategy(2);
Graphics graphics = getBufferStrategy().getDrawGraphics();
graphics.setColor(Color.black);
graphics.fillRect(0, 0, getWidth(), getHeight());
graphics.setColor(Color.green);
graphics.fillRect(30, 40, 100, 200);
graphics.setXORMode(Color.white); // (*)
graphics.fillRect(60, 80, 100, 200);
graphics.dispose();
getBufferStrategy().show();
}
public static void main(String[] args) {
XORTest test = new XORTest();
}
}
If I uncomment the line marked with (*), two green rectangles are drawn as expected. If I leave it, nothing is drawn into the component, not even the black background or green rectangle that is drawn beforehand. Even more odd, it worked once. I had the color as Color.green instead of white before. After I changed it, it drew as expected. But when I closed the application and started it again, it didn't work anymore and it hasn't since.
Is this a bug in java? In my jre? Undocumented behaviour for Graphics? I'm on Windows and running the example on the jdk7.
Screenshots: Imgur album because it won't let me post 3 links
The third screenshot is the code as it is above, the first with (*) commented and the second is how it looked the one time it worked (I created that in GIMP because I didn't take a screenshot then).
Without a compelling reason to the contrary, it's easier and more reliable to override paintComponent() in JPanel, which is double buffered by default. With a compelling reason, follow the guidelines in BufferStrategy and BufferCapabilities. Also note,
Override getPreferredSize() to specify the preferred size of a component.
Swing GUI objects should be constructed and manipulated only on the event dispatch thread.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* #see https://stackoverflow.com/a/16721780/230513
*/
public class Test {
private void display() {
JFrame f = new JFrame("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new XORPanel());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static class XORPanel extends JPanel {
#Override
public Dimension getPreferredSize() {
return new Dimension(190, 320);
}
#Override
protected void paintComponent(Graphics graphics) {
super.paintComponent(graphics);
graphics.setColor(Color.black);
graphics.fillRect(0, 0, getWidth(), getHeight());
graphics.setColor(Color.green);
graphics.fillRect(30, 40, 100, 200);
graphics.setXORMode(Color.white);
graphics.fillRect(60, 80, 100, 200);
}
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Test().display();
}
});
}
}