So I have an image being drawn inside a JPanel which itself is added to a JFrame. However when the Image is first drawn it appears to be very small. I'm not sure if this is a problem with the panel or a problem with the image. It is illustrated below:
![enter image description here][1]
I have drawn a rectangle around the image.
Now the JPanel is supposed to be contained within the JFrame. The JFrame is not supposed to be coloured in as is seen above. The JPanel is meant to be about a quarter of the size of the JFrame and the image is supposed to take up almost all of the JPanel.
Could you please tell me if it's the image which is the problem or the Panel. Sorry if it seems obvious.
Awaiting SSCCE
I have no idea what you are doing based on the few random lines of code you posted. Nowhere in the code do you actually create/read an image.
As far as I know a Mandelbrot Set is actually done by painting code. If so the problem is probably that you did not override the getPreferredSize() (don't use the setSize() method) of you painting panel to return the size of the image you are painting. Read the section from the Swing tutorial on Custom Paining for more information.
Or if you are actually using an existing image then read the section from the Swing tutorial on How to Use Icons for working examples of using images.
Also, components should be added to the frame BEFORE you make the frame visible.
If you need more help then post a proper SSCCE that demonstrates the problem.
BufferedImage image = ImageIO.read(file); //Read image through BufferedReader
labelimage.setIcon(new ImageIcon(image.getScaledInstance(labelimage.getWidth(), labelimage.getHeight(), image.SCALE_SMOOTH))); // This line will automaticallically set Image size equal to size of Jlabel
how about adding a label inside the panel, and draw the image using setIcon(..)
usually I use the following class to make the image fit to the label size (I make my label has static size - not resizable).. you might wanna modify it to suit your need..
import java.awt.Component;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.net.URL;
import javax.swing.ImageIcon;
public class CustomImageIcon extends ImageIcon {
private BufferedImage dest;
public CustomImageIcon(String filename) {
super(filename);
}
public CustomImageIcon(Image image) {
super(image);
}
public CustomImageIcon(URL location) {
super(location);
}
#Override
public synchronized void paintIcon(Component c, Graphics g, int x, int y) {
if(c!=null)
dest = new BufferedImage(c.getWidth(), c.getHeight(), BufferedImage.TYPE_INT_ARGB);
else dest = new BufferedImage(getIconWidth(), getIconHeight(), BufferedImage.TYPE_INT_ARGB);
ImageObserver imgObs = getImageObserver();
if(imgObs==null) imgObs = c;
int width;
int height;
if(c!=null)
{
width = c.getWidth();
height = c.getHeight();
}
else
{
width = getIconWidth();
height = getIconHeight();
}
g.drawImage(dest, 0, 0, c);
g.drawImage(
getImage(),
0,
0,
width,
height,
imgObs);
}
}
Related
I am making my chess game with javax.swing.
I am using gridLayout(8,8) filled with JButtons, with background color
set to brown and lightBrown as usual on chess boards.
Now I want to put ImageIcon (king , rock , ect..) on that Buttons which I got from google images and edit them in paint.net .
white king on gray background
But most of the pieces can move from gray buttons to light gray buttons.
so I can either make all pieces on light gray background
white king on light gray background
and just swich ImageIcon depending which JButton piece is landing on (but I would rather not),
Or make background color on that image transparent, but I have no idea how to do that (for example is there some color which swing making transparent automaticly)
Thank you for help.
You should take a look to RGBA color model.
In this model the A stands for alpha channel, which is generally used as an opacity channel.
This means that you can have a "transparent" color by setting the alpha value of your color to 0.
The java.awt.Color class provides some constructors where you can specify the alpha value of your Color, for example :
Color(int r, int g, int b, int a) Creates an sRGB color with the
specified red, green, blue, and alpha values in the range (0 - 255).
You can make the background color of your image transparent by yourself, if you can't find a program which gave you this option.
For example this code i wrote tries to remove the background colour from your "white king on gray background" image.
If you try to compile and run, you should get this result:
As you can see not all the background has been removed from your image, this is due to the fact that the background is made by different colours.
But this example shows you that you can manipulate your images pixels in order to obtain transparency.
I think that the best option would be to search online some chess images that have already a transparent background.
For example, i can post some links here (i don't know if there are some copyright issues, take care of this), you could easily get all the images if you check URLs :
Black Rook
White Queen
Example Code :
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
public class TransparentTest
{
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
try {
BufferedImage image = ImageIO.read(new File("KING.jpg"));
BufferedImage transparentImage = removeColors(image,new Color(245,222,180));
createAndShowGUI(image,transparentImage);
}
catch(IOException ex) {
JOptionPane.showMessageDialog(null,"Please check your file image path","Error",JOptionPane.ERROR_MESSAGE);
}
}
});
}
public static void createAndShowGUI(BufferedImage image,BufferedImage transparentImage) {
JPanel pane = new JPanel(new FlowLayout(FlowLayout.CENTER,40,10));
pane.setBackground(Color.BLUE);
pane.add(new JLabel(new ImageIcon(image)));
pane.add(new JLabel(new ImageIcon(transparentImage)));
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(pane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static BufferedImage removeColors(BufferedImage image,Color... colorsBlackList) throws IOException {
int height = image.getHeight(), width=image.getWidth();
BufferedImage transparentImage = new BufferedImage(width,height,BufferedImage.TYPE_INT_ARGB);
for(int y=0;y<height;y++) {
for(int x=0;x<width;x++) {
int pixel = image.getRGB(x,y);
int red = (pixel>>16) &0xff;
int green = (pixel>>8) &0xff;
int blue = (pixel>>0) &0xff;
int alpha = 255;
// Settings opacity to 0 ("transparent color") if the pixel color is equal to a color taken from the "blacklist"
for(Color color : colorsBlackList) {
if(color.getRGB() == pixel) alpha = 0;
}
transparentImage.setRGB(x,y,(alpha&0x0ff)<<24 | red<<16 | green<<8 | blue);
}
}
return transparentImage;
}
}
So, I am trying to create a monopoly game. I am trying to load an image (of the board) onto a JPanel.
I first want to scale the image to a 1024*1024 image.
I already got the image to appear on the JPanel (so the file address works).
But whenever I use the getScaledInstance() method, the image doesn't appear
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.SystemColor;
//a class that represent the board (JFrame) and all of it components
public class Board extends JFrame {
private final int SCALE;
private JPanel panel;
public Board(int scale) {
getContentPane().setBackground(SystemColor.textHighlightText);
// SCALE = scale;
SCALE = 1;
// set up the JFrame
setResizable(false);
setTitle("Monopoly");
// set size to a scale of 1080p
setSize(1920 * SCALE, 1080 * SCALE);
getContentPane().setLayout(null);
panel = new JPanel() {
public void paint(Graphics g) {
Image board = new ImageIcon(
"C:\\Users\\Standard\\Pictures\\Work\\Monopoly 1.jpg")
.getImage();
board = board.getScaledInstance(1022, 1024, java.awt.Image.SCALE_SMOOTH);
g.drawImage(board, 0, 0, null);
}
};
panel.setBounds(592, 0, 1024, 1024);
getContentPane().add(panel);
}
public static void main(String[] args) {
Board board = new Board(1);
board.setVisible(true);
board.panel.repaint();
}
}
Whenever I remove the board.getScaledInstance() line of code, the image appears (though not scaled), but when I add the line of code, the image doesn't appear at all.
Why does this happen?
You're doing several things wrong:
You're overriding paint, not paintComponent. This is dangerous as you're overriding an image that does too much and has too much responsibility. Doing this without care can lead to significant image side effects, and will also lead to slow perceived animation due to paint not double buffering.
You're not calling the super painting method within your override, something that will lead to accumulation of painting artifacts and breaking of the Swing component painting chain.
You're reading in an image potentially multiple times and within a painting method, a method that must be as fast as possible since it's a major determinant in the perceived responsiveness of your application. Read it in once only, and then save it to a variable.
You're using null layouts and setBounds. While null layouts and setBounds() might seem to Swing newbies like the easiest and best way to create complex GUI's, the more Swing GUI'S you create the more serious difficulties you will run into when using them. They won't resize your components when the GUI resizes, they are a royal witch to enhance or maintain, they fail completely when placed in scrollpanes, they look gawd-awful when viewed on all platforms or screen resolutions that are different from the original one.
You're scaling the image within the paint method, again doing something that will slow down the perceived responsiveness of the GUI. Instead, scale the image once only, and save that scaled image to a variable.
Importantly, you're using the same variable, board, for both the original image and the scaled image, and this will lead to re-scaling of the image every time that paint is called.
As Mad points out, you should pass in this to your g.drawImage(...) method call, so that you don't draw an image before it's completely read in.
Also, don't read the image in as a File or as an ImageIcon when you're not using it as an ImageIcon. Use ImageIO to read it in as a BufferedImage, and use resources, not Files.
I would also simplify things, for example:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class MyBoard extends JPanel {
private static final String IMG_PATH = "http://ecx.images-amazon.com/"
+ "images/I/81oC5pYhh2L._SL1500_.jpg";
// scaling constants
private static final int IMG_WIDTH = 1024;
private static final int IMG_HEIGHT = IMG_WIDTH;
// original and scaled image variables
private BufferedImage initialImg;
private Image scaledImg;
public MyBoard() throws IOException {
URL url = new URL(IMG_PATH);
initialImg = ImageIO.read(url); // read in original image
// and scale it *once* and store in variable. Can even discard original
// if you wish
scaledImg = initialImg.getScaledInstance(IMG_WIDTH, IMG_HEIGHT,
Image.SCALE_SMOOTH);
}
// override paintComponent, not paint
#Override // and don't forget the #Override annotation
protected void paintComponent(Graphics g) {
super.paintComponent(g); // call the super's painting method
// just to be safe -- check that it's not null first
if (scaledImg != null) {
// use this as a parameter to avoid drawing an image before it's
// ready
g.drawImage(scaledImg, 0, 0, this);
}
}
// so our GUI is sized the same as the image
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet() || scaledImg == null) {
return super.getPreferredSize();
}
int w = scaledImg.getWidth(this);
int h = scaledImg.getHeight(this);
return new Dimension(w, h);
}
private static void createAndShowGui() {
MyBoard mainPanel = null;
try {
mainPanel = new MyBoard();
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
JFrame frame = new JFrame("My Board");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
I'm implementing a simple chat application, using Java. I want my chat application to have the "bubble" message style like modern message apps, so I've built 2 classes LeftArrowBubble and RightArrowBubble which extend JPanel to illustrate sender & receiver bubbles, like this:
This is the code for my LeftArrowBubble class (quite alike for RightArrowBubble):
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Polygon;
import java.awt.RenderingHints;
import java.awt.geom.Area;
import java.awt.geom.RoundRectangle2D;
import javax.swing.JPanel;
/**
* #author harsh
*/
public class LeftArrowBubble extends JPanel {
private static final long serialVersionUID = -5389178141802153305L;
private int radius = 10;
private int arrowSize = 12;
private int strokeThickness = 3;
private int padding = strokeThickness / 2;
#Override
protected void paintComponent(final Graphics g) {
final Graphics2D g2d = (Graphics2D) g;
g2d.setColor(new Color(0.5f, 0.8f, 1f));
int x = padding + strokeThickness + arrowSize;
int width = getWidth() - arrowSize - (strokeThickness * 2);
int bottomLineY = getHeight() - strokeThickness;
g2d.fillRect(x, padding, width, bottomLineY);
g2d.setRenderingHints(new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON));
g2d.setStroke(new BasicStroke(strokeThickness));
RoundRectangle2D.Double rect = new RoundRectangle2D.Double(x, padding, width, bottomLineY, radius, radius);
Polygon arrow = new Polygon();
arrow.addPoint(20, 8);
arrow.addPoint(0, 10);
arrow.addPoint(20, 12);
Area area = new Area(rect);
area.add(new Area(arrow));
g2d.draw(area);
}
}
Now I have a JFrame window with a JScrollPane on it, which looks like this:
What I want to do now is when I click on that CreateNewBubble button, a new Left(or Right)ArrowBubble JPanel will be created & displayed inside that JScrollPane (and this JScrollPane will be vertical scrollable if there're more bubbles inside of it). I've already tried this way:
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
BubbleTest.LeftArrowBubble leftArrowBubble = new BubbleTest.LeftArrowBubble();
jScrollPane1.add(leftArrowBubble);
}
But it didn't work as I expected: nothing shows up in the JScrollPane after clicking the button!
I've been stuck at this problem for hours, really appreciate if you guys can help!
You can't use .add that way on a JScrollPane. A JScrollPane can only scroll a single component, which is set by either passing it to its constructor, or by calling .setViewportView.
Instead, create a separate container for the bubbles, such as a vertical Box, and set that as the single component scrolled by the scroll pane:
Box box = new Box(BoxLayout.Y_AXIS);
JScrollPane jScrollPane1 = new JScrollPane(box);
When you add a bubble, add it to the box (and call .revalidate() to lay it out):
box.add(leftArrowBubble);
box.revalidate();
Edit: Also, your bubbles will not, by default, have any size, unless you give them a size such as by calling setPreferredSize or by overriding getPreferredSize or by putting components inside them.
With JScrollPane you should always add components to the scroll pane's JViewPort. Look at the documentation here, it explains the concept behind the class rather well.
Short summary: A JScrollPane holds the scroll bars and a view port. The view port is a component that displays only a portion of its content - in this case the part that is visible on screen. The scroll bars tell the view port which portion to show.
I have the following code. Basically I have a frame which has a background image. I also have three panels within the frame: panels 1, 2 and 3. 2 & 3 work fine as I haven't subclassed them. However, panel 1 as soon as I subclassed it i.e. put the logic inside the paintComponent method of JPanel stopped working as that method is never called and foo is never printed. I'm not able to figure out why. Would appreciate your help. I've tried a few suggestions from other similar threads and they haven't helped.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) throws IOException {
JFrame.setDefaultLookAndFeelDecorated(true);
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
int fooPanelX = 5;
int fooPanelY = 160;
int fooPanelWidth = 470;
int fooPanelHeight = 305;
int bar0PanelX = 5;
int bar0PanelY = 550;
int bar0PanelWidth = 230;
int bar0PanelHeight = 210;
int bar1PanelX = bar0PanelX * 2 + bar0PanelWidth + bar0PanelX;
int bar1PanelY = bar0PanelY;
int bar1PanelWidth = bar0PanelWidth;
int bar1PanelHeight = bar0PanelHeight;
JPanel panel1 = new Panel1(fooPanelX, fooPanelY, fooPanelWidth, fooPanelHeight);
JPanel panel2 = new JPanel();
panel2.setBackground(Color.WHITE);
panel2.setLocation(bar0PanelX, bar0PanelY);
panel2.setSize(bar0PanelWidth, bar0PanelHeight);
panel2.setOpaque(false);
panel2.setBorder(BorderFactory.createLineBorder(Color.WHITE));
panel2.setBounds(bar0PanelX, bar0PanelY, bar0PanelWidth, bar0PanelHeight);
JPanel panel3 = new JPanel();
panel3.setBackground(Color.WHITE);
panel3.setLocation(bar1PanelX, bar1PanelX);
panel3.setSize(bar1PanelWidth, bar1PanelHeight);
panel3.setOpaque(false);
panel3.setBorder(BorderFactory.createLineBorder(Color.WHITE));
panel3.setBounds(bar1PanelX, bar1PanelY, bar1PanelWidth, bar1PanelHeight);
JLabel imagePanel = new JLabel(new ImageIcon(ImageIO.read(new File("image.png"))));
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == 27) {
System.exit(0);
}
}
});
frame.setContentPane(imagePanel);
frame.getContentPane().add(panel1);
frame.getContentPane().add(panel2);
frame.getContentPane().add(panel3);
frame.setLocation((int) (screenSize.getWidth() * 0.75),
(int) (screenSize.getHeight() * 0.25));
frame.pack();
frame.setVisible(true);
}
#SuppressWarnings("serial")
static class Panel1 extends JPanel {
int x, y, w, h;
public Panel1(int x, int y, int w, int h) {
this.x = x;
this.y = y;
this.w = w;
this.h = h;
}
#Override
public void paintComponent(Graphics graphics) {
System.out.println("foo");
super.paintComponents(graphics);
setBackground(Color.WHITE);
setLocation(x, y);
setSize(w, h);
setOpaque(true);
setBorder(BorderFactory.createLineBorder(Color.WHITE));
}
}
}
Update: If you aren't able to find the issue then please could you provide me with an alternative way of doing the following. I need a frame with a background image and three panels on top of the background image. The three panels have to have pixel perfect locations and sizes on the background image to look right. That's it pretty much. I'll be repainting the three panels but the background image will remain the same.
Well, the problem is that you are not using an appropriate LayoutManager.
JLabel does not come with any LayoutManager by default. So when you add your Panel1, it has a size of 0x0 and is located in (0,0) and since no LayoutManager will change that, it will keep that size and location. With empty bounds, your component is never painted, hence your paintComponent method is never called.
Now, you should NEVER do this in paintComponent:
setBackground(Color.WHITE);
setLocation(x, y);
setSize(w, h);
setOpaque(true);
setBorder(BorderFactory.createLineBorder(Color.WHITE));
Do that in the constructor or some other method. paintComponent is meant for "painting a component", not changing its properties.
I decided to tackle the problem in a very different way. This is how I did it. I startedc completely from scratch with my code. I created a JFrame instance and a Canvas instance (the canvas was subclassed). In the canvas I used drawImage() to apply the background image. Then for each of the three areas that I wanted to animate on the background image, instead of creating three JPanels, I simply used fillRect() within the canvas to fill the right areas on the image. That's it. Nice and simple. The repaint() every second does flickr on the three areas and that's the next challenge. I'm guessing I have to use double buffering but it's not something I've used before so I'll look into that next. Anyway, using a single canvas in place of three JPanels proved a heck of a lot simpler and the reason I was able to do that was because the background image provided everything else visually. All I had to do was drawImage() and fillRect(). Thanks for all contributions.
Update: I have now completed this task. There was one thing I changed about the above. While attempting to double buffer with Canvas I had a few issues: the usual "component must have valid peer" exception. While looking into that I learnt that one should not use Canvas in Swing and that the practice of using it was mixing AWT and Swing. So I swapped it out for JComponent (as I didn't need anything that JPanel offered). And as Swing is double buffered by default my work was complete. No flicker and simplified code.
I'm trying to create an image (screen-shot) of a non-visible AWT component. I can't use the Robot classes' screen capture functionality because the component is not visible on the screen. Trying to use the following code:
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
component.paintAll(g);
Works sometimes, but does not work if the component contains things such as a text box or button, or some sort of OpenGL / 3D component (these things are left out of the image!). How can I take a proper screenshot of the whole thing?
(disclamer: woops.. this doesn't seem to work for AWT )-:
I can't believe no one has suggested SwingUtilities.paintComponent or CellRendererPane.paintComponent which are made for this very purpose. From the documentation of the former:
Paints a component to the specified Graphics. This method is primarily useful to render Components that don't exist as part of the visible containment hierarchy, but are used for rendering.
Here is an example method that paints a non-visible component onto an image:
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class ComponentPainter {
public static BufferedImage paintComponent(Component c) {
// Set it to it's preferred size. (optional)
c.setSize(c.getPreferredSize());
layoutComponent(c);
BufferedImage img = new BufferedImage(c.getWidth(), c.getHeight(),
BufferedImage.TYPE_INT_RGB);
CellRendererPane crp = new CellRendererPane();
crp.add(c);
crp.paintComponent(img.createGraphics(), c, crp, c.getBounds());
return img;
}
// from the example of user489041
public static void layoutComponent(Component c) {
synchronized (c.getTreeLock()) {
c.doLayout();
if (c instanceof Container)
for (Component child : ((Container) c).getComponents())
layoutComponent(child);
}
}
}
Here is a snippet of code that tests the above class:
JPanel p = new JPanel();
p.add(new JButton("Button 1"));
p.add(new JButton("Button 2"));
p.add(new JCheckBox("A checkbox"));
JPanel inner = new JPanel();
inner.setBorder(BorderFactory.createTitledBorder("A border"));
inner.add(new JLabel("Some label"));
p.add(inner);
BufferedImage img = ComponentPainter.paintComponent(p);
ImageIO.write(img, "png", new File("test.png"));
And here is the resulting image:
Component has a method paintAll(Graphics) (as you already have found). That method will paint itself on the passed graphics. But we have to pre-configure the graphics before we call the paint method. That's what I found about the AWT Component rendering at java.sun.com:
When AWT invokes this method, the
Graphics object parameter is
pre-configured with the appropriate
state for drawing on this particular
component:
The Graphics object's color is set to the component's foreground property.
The Graphics object's font is set to the component's font property.
The Graphics object's translation is set such that the coordinate (0,0) represents the upper left corner of the component.
The Graphics object's clip rectangle is set to the area of the component that is in need of repainting.
So, this is our resulting method:
public static BufferedImage componentToImage(Component component, Rectangle region)
{
BufferedImage img = new BufferedImage(component.getWidth(), component.getHeight(), BufferedImage.TYPE_INT_ARGB_PRE);
Graphics g = img.getGraphics();
g.setColor(component.getForeground());
g.setFont(component.getFont());
component.paintAll(g);
g.dispose();
if (region == null)
{
return img;
}
return img.getSubimage(region.x, region.y, region.width, region.height);
}
This is also the better way instead of using Robot for the visible components.
EDIT:
A long time ago I used the code I posted here above, and it worked, but now not. So I searched further. I have a tested, working way. It is dirty, but works. The Idea of it is making a JDialog, put it somewhere out of the Screen bounds, set it visible, and then draw it on the graphics.
Here is the code:
public static BufferedImage componentToImageWithSwing(Component component, Rectangle region) {
BufferedImage img = new BufferedImage(component.getWidth(), component.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics g = img.createGraphics();
// Real render
if (component.getPreferredSize().height == 0 && component.getPreferredSize().width == 0)
{
component.setPreferredSize(component.getSize());
}
JDialog f = new JDialog();
JPanel p = new JPanel();
p.add(component);
f.add(p);
f.pack();
f.setLocation(-f.getWidth() - 10, -f.getHeight() -10);
f.setVisible(true);
p.paintAll(g);
f.dispose();
// ---
g.dispose();
if (region == null) {
return img;
}
return img.getSubimage(region.x, region.y, region.width, region.height);
}
So, this will work also on Windows and Mac. The other answer was to draw it on a virtual screen. But this doesn't need it.
Excellent question, I've thought about this myself from time to time!
As you already have written, that rending heavy weight components such as 3D and AWT onto an image is a big problem. These components are (almost) directly transferred to the graphic card so they cannot be re-rendered to an image using the normal paintComponent stuff, you need help from the operative system or doing your own rendering of these components.
1. Making your own to image renderer
For each component that does not have a to image rendering method you need to create your own. For example using jogl you can take a off-screen screenshot using this method (SO post).
2. Rendering onto a virtual screen
Prerequisites:
Can you start the program/component in a headless environment?
Are you using Linux?
Then you can use Xvfb to render the whole program onto a virtual screen and then taking a screenshot from that virtual screen like this:
Xvfb :1 &
DISPLAY=:1 java YourMainClass
xwd -display :1 -root -out image.xwd
Maybe you need to tweek Xvfb a little bit by passing the size of the program you want to render to it (-screen 0 1024x768x24).
The Screen Image class shows how this can be done for Swing components. I've never tried it with AWT components, buy I could guess the concept would be the same.
How about something like this. The JFrame that holds all of the components is not visible.
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
/**
* Captures an invisible awt component
* #author dvargo
*/
public class ScreenCapture
{
private static List<String> types = Arrays.asList( ImageIO.getWriterFileSuffixes() );
/**
* Build GUI
* #param args
*/
public static void main(String [] args)
{
JFrame invisibleFrame = new JFrame();
invisibleFrame.setSize(300, 300);
JPanel colorPanel = new JPanel();
colorPanel.setBackground(Color.red);
colorPanel.setSize(invisibleFrame.getSize());
JTextArea textBox = new JTextArea("Here is some text");
colorPanel.add(textBox);
invisibleFrame.add(colorPanel);
JButton theButton = new JButton("Click Me");
colorPanel.add(theButton);
theButton.setVisible(true);
textBox.setVisible(true);
colorPanel.setVisible(true);
//take screen shot
try
{
BufferedImage screenShot = createImage((JComponent) colorPanel, new Rectangle(invisibleFrame.getBounds()));
writeImage(screenShot, "filePath");
}
catch (IOException ex)
{
Logger.getLogger(ScreenCapture.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* Create a BufferedImage for Swing components.
* All or part of the component can be captured to an image.
*
* #param component component to create image from
* #param region The region of the component to be captured to an image
* #return image the image for the given region
*/
public static BufferedImage createImage(Component component, Rectangle region) {
// Make sure the component has a size and has been layed out.
// (necessary check for components not added to a realized frame)
if (!component.isDisplayable()) {
Dimension d = component.getSize();
if (d.width == 0 || d.height == 0) {
d = component.getPreferredSize();
component.setSize(d);
}
layoutComponent(component);
}
BufferedImage image = new BufferedImage(region.width, region.height, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = image.createGraphics();
// Paint a background for non-opaque components,
// otherwise the background will be black
if (!component.isOpaque()) {
g2d.setColor(component.getBackground());
g2d.fillRect(region.x, region.y, region.width, region.height);
}
g2d.translate(-region.x, -region.y);
component.paint(g2d);
g2d.dispose();
return image;
}
public static void layoutComponent(Component component) {
synchronized (component.getTreeLock()) {
component.doLayout();
if (component instanceof Container) {
for (Component child : ((Container) component).getComponents()) {
layoutComponent(child);
}
}
}
}
/**
* Write a BufferedImage to a File.
*
* #param image image to be written
* #param fileName name of file to be created
* #exception IOException if an error occurs during writing
*/
public static void writeImage(BufferedImage image, String fileName)
throws IOException
{
if (fileName == null) return;
int offset = fileName.lastIndexOf( "." );
if (offset == -1)
{
String message = "file suffix was not specified";
throw new IOException( message );
}
String type = fileName.substring(offset + 1);
if (types.contains(type))
{
ImageIO.write(image, type, new File( fileName ));
}
else
{
String message = "unknown writer file suffix (" + type + ")";
throw new IOException( message );
}
}
}