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();
}
});
}
}
Related
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Main {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setLayout(new FlowLayout());
frame.setSize(new Dimension(100, 100));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TestPanel panel = new TestPanel();
panel.setPreferredSize(new Dimension(50,50));
frame.add(panel);
frame.setVisible(true);
}
static class TestPanel extends JPanel implements ActionListener{
private static final long serialVersionUID = 8518959671689548069L;
public TestPanel() {
super();
Timer t = new Timer(1000, this);
t.setRepeats(true);
t.start();
}
int opacity = 10;
#Override
public void actionPerformed(ActionEvent e) {
if(opacity >= 250) {
opacity = 0;
}
else {
this.setBackground(new Color(255, 212, 100, opacity));
this.repaint();
opacity+=10;
System.out.println("opacity is " + opacity);
}
}
}
}
The rate the alpha changes is faster than it should be. After it reaches a certain point, the opacity drops, while the the opacity printed in the console is less than 250. Resizing the window "resets" it, making the alpha correct.
How do I make it actually draw the alpha correctly?
this.setBackground(new Color(255, 212, 100, opacity));
Swing does not support semi transparent backgrounds.
Swing expects a component to be either:
opaque - which implies the component will repaint the entire background with an opaque color first before doing custom painting, or
fully transparent - in which case Swing will first paint the background of the first opaque parent component before doing custom painting.
The setOpaque(...) method is used to control the opaque property of a component.
In either case this makes sure any painting artifacts are removed and custom painting can be done properly.
If you want to use tranparency, then you need to do custom painting yourself to make sure the background is cleared.
The custom painting for the panel would be:
JPanel panel = new JPanel()
{
protected void paintComponent(Graphics g)
{
g.setColor( getBackground() );
g.fillRect(0, 0, getWidth(), getHeight());
super.paintComponent(g);
}
};
panel.setOpaque(false); // background of parent will be painted first
Similar code would be required for every component that uses transparency.
Or, you can check out Background With Transparency for custom class that can be used on any component that will do the above work for you.
I've tried to research how Java's 2D rendering works, but I could never understand it. Here is the code in my main class:
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main{
public static void main(String args[]) {
JFrame frame = new JFrame();
frame.setSize(new Dimension(500,500));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("JFrame testing");
frame.setVisible(true);
Frame panel = new Frame();
frame.add(panel);
}
}
And then here is for the JPanel class:
import java.awt.Graphics;
import javax.swing.JPanel;
public class Frame extends JPanel{
private static final long serialVersionUID = 1L;
public Frame() {
Graphics g = this.getGraphics();
g.drawRect(0, 0, 100, 100);
this.paintComponent(g);
}
}
I am also getting this exception, but I'm not sure what it means:
Exception in thread "main" java.lang.NullPointerException
at Frame.<init>(Frame.java:10)
at Main.main(Main.java:18)
I'm basically just trying to draw a rectangle onto a panel to be shown on the frame I've created. I've heard about the paintComponent method, but I also don't fully understand that.
You should Never use getGraphics() of a Component.
Try below code
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(0, 0, 100, 100);
//this.paintComponent(g);
}
Edit
"why is super.paintComponent(g); called again inside the method?"
The documentation of paintComponent says it pretty well:
if you do not invoker super's implementation you must honor the opaque
property, that is if this component is opaque, you must completely
fill in the background in a non-opaque color. If you do not honor the
opaque property you will likely see visual artifacts.
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
I was wondering how you would get the color of the inset of a JTabbedPane. I cannot seem to get this color. Every attempt I make I get 236,236,236 which is the outside frame color, where the inside frame color is about 10 darker, 227,227,227 (using the built in apple color meter).
I am setting the look and feel using UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
You can see this in an image that I found on the internet. http://pagesofinterest.net/wordpress/wp-content/uploads/2009/06/Quaqua-Maven-Netbeans.jpg Where the words "Panel's Title" is the area that I am getting the lighter color that is not useful to me. Inside the round corners is the darker color I am trying to obtain. I tried getting the color of the content pane to no avail.
Thanks for all your help!
**EDIT:**Added code! As you see, I am trying to get the color of the area inside the rounded corners(if your on a mac) not the color of the frame or the tabs that say "1" "2". I have attached a photo and I am trying to get the background color of the portion that says "Here" Thanks!
import java.awt.Container;
import javax.swing.JFrame;
import javax.swing.JTabbedPane;
import javax.swing.UIManager;
public class main {
JFrame frame;
Container c1 = new Container();
Container c2 = new Container();
JTabbedPane top = new JTabbedPane();
static main GUI;
public void createGUI(){
frame = new JFrame();
Container c = frame.getContentPane();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
top = new JTabbedPane(JTabbedPane.TOP);
top.setFocusTraversalKeysEnabled(false);
top.setFocusable(false);
top.addTab("1", c1);
top.addTab("2", c2);
frame.setSize(315,450);
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setResizable(true);
c.add(top);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch(Exception e) {}
GUI = new main();
GUI.createGUI();
}
}
EDIT: camickr, Here is a screenshot of the UIManager Defaults. Unfortunately none of there colors in the are the correct color that the inset is.
You might be able to use UIMangaer Defaults to find the color.
You can override paintComponent() to use a GradientPaint in the tab's background, as shown below. A few notes,
Let the content adopt the preferred size of it contents, as shown here.
Construct the GUI in the event dispatch thread.
Use conventional Java names.
Addendum: the elements are not always in the same spot, so I do not know what place to get the color.
It sounds like you want to match a color used internally by the TabbedPaneUI delegate. One approach would be as follows:
Render a BufferedImage of the component, as shown here.
Determine the coordinates of a Point in top relative to the top of c1.
Point p = SwingUtilities.convertPoint(c1, 0, -1, top);
Obtain the color using getRGB(), as shown here; use Zoom to verify the result.
import java.awt.Color;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
/** #see https://stackoverflow.com/a/16625260/230513 */
public class Main {
JFrame frame;
Container c1 = new GradientPanel();
Container c2 = new GradientPanel();
JTabbedPane top = new JTabbedPane();
private static class GradientPanel extends JPanel {
public GradientPanel() {
this.add(new JLabel("Here"));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
GradientPaint p = new GradientPaint(0, 0, Color.white,
getWidth(), getHeight(), Color.gray);
g2d.setPaint(p);
g2d.fillRect(0, 0, getWidth(), getHeight());
}
}
public void createGUI() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
top = new JTabbedPane(JTabbedPane.TOP);
top.addTab("1", c1);
top.addTab("2", c2);
frame.add(top);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Main().createGUI();
}
});
}
}
The question I have is exactly same in requirement as How to pass mouse events to applications behind mine in C#/Vista? , but I need the same for a Transparent Java UI. I can easily create a transparent Java UI using 6.0 but couldn't get any info about passing events through the app to any applications(say a browser) behind.
I believe this will answer your question. To run it you will need Java 6 update 10 and above.
I tested it on Windows Vista
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class ClickThrough {
public static void main(String[] args) {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame f = new JFrame("Test");
f.setAlwaysOnTop(true);
Component c = new JPanel() {
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D)g.create();
g2.setColor(Color.gray);
int w = getWidth();
int h = getHeight();
g2.fillRect(0, 0, w,h);
g2.setComposite(AlphaComposite.Clear);
g2.fillRect(w/4, h/4, w-2*(w/4), h-2*(h/4));
}
};
c.setPreferredSize(new Dimension(300, 300));
f.getContentPane().add(c);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
com.sun.awt.AWTUtilities.setWindowOpaque(f,false);
}
}
Note that you need to either have an undecorated window or one that is decorated by Java alone (not the default OS decoration) otherwise the code won't work.
Savvas' answer helped me perfectly even on MacOS X 10.7.3 using Java 1.6.0_31. Thanks!
The only thing: I additionally had to set
f.setUndecorated(true);
This is not answer, but an update which corrects dangerous issues to the accepted answer as well as providing an example compatible with Java 7+
Per-Pixel alphering checks each pixel in the window to determine if it's transparent or not. If it's transparent, then the mouse events are allowed to pass through it, if its is not transparent, the mouse events will be caught by the window. This is generally an OS level issue.
The example is you provide is actually doing some very dangerous things, first it's painting a translucent color onto a opaque component, this means that Swing doesn't know that it should actually be painting anything under the component and could also result in a number of very nasty paint artifacts, as Swing only knows about opaque and transparent component, it doesn't know about semi-transparent components, so you need to trick the API.
When performing custom painting, you should always call super.paintComponent to ensure that the Graphics context is setup correctly before painting. In your case, you should also make the component transparent using setOpaque and passing it false
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class TestFrame {
public static void main(String[] args) {
new TestFrame();
}
public TestFrame() {
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.setUndecorated(true);
frame.setAlwaysOnTop(true);
frame.setBackground(new Color(0, 0, 0, 0));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setOpaque(false);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.BLUE);
g2d.setComposite(AlphaComposite.SrcOver.derive(0.5f));
g2d.fill(new Rectangle(0, 0, getWidth(), getHeight()));
g2d.dispose();
}
}
}
You could try using the Robot Class http://java.sun.com/javase/6/docs/api/java/awt/Robot.html which allows you to specify system events to the low level operating system, specifically things like mouse events.