I am new to making GUIs so I decided to try the the windows builder for eclipse, and while great I do have some doubts. I have been searching but I cannot seen to find a good way to add a background image to my "menu". For example I tried this:
public Menu() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(50, 50, 300, 250); //Dimensiones
contentPane = new JPanel() { //Imagen de Fondo
public void paintComponent(Graphics g) {
Image img = Toolkit.getDefaultToolkit().getImage(
Menu.class.getResource("/imgs/rotom.jpg"));
g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
}
};
And adding the following classes:
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
But to no avail the window remains with its dull grey color, so far my code is just the standard one WindowsBuilder cooks for you plus 4 buttons but I doubt they're of importance here. Shouldn't the code I added override the paintComponent() method of the jPanel and draw the image in it?
The class for the menu is in a package within my project and the image is within a imgs package is within the same project as well.
Thanks a lot in advance.
A simple method, if you're not interested in resizing the background image or applying any effects is to use a JLabel...
BufferedImage bg = ImageIO.read(Menu.class.getResource("/imgs/rotom.jpg"));
JLabel label = new JLabel(new ImageIcon(bg));
setContentPane(label);
setLayout(...);
There are limitations to this approach (beyond scaling), in that the preferred size of the label will always be that of the image and never take into account it's content. This is both good and bad.
The other approach, which you seem to be using, is to use a specialised component
public class BackgroundPane extends JPanel {
private BufferedImage img;
public BackgroundPane(BufferedImage img) {
this.img = img;
}
#Override
public Dimension getPreferredSize() {
return img == null ? super.getPreferredSize() : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, this);
}
}
You should avoid trying to perform any task in the paintComponent method which may take time to complete as paintComponent may be called often and usually in quick succession....
Getting the image to scale when the component is resized is an entire question into of it self, for some ideas, you could take a look at...
Java: maintaining aspect ratio of JPanel background image
Java: JPanel background not scaling
Quality of Image after resize very low -- Java
Reading/Loading images
Oh, and, you should avoid extending directly from top level containers, like JFrame, they reduce the reusability for your components and lock you into a single container
Related
I am writing a program that consists of three different panels.
This is part of my bottom panel. I display an image using BufferedImage, and I would like to create some text that will appear around 350px into the image, and 15px down. I cannot manage to get this to work and overlay over the bufferedImage.
My current code is as follows (For the bottom panel):
public class BtmPanel extends JPanel {
BtmPanel(){
try {
JLabel imgLabel = new JLabel();
final BufferedImage img = ImageIO.read(new File("image.png"));
ImageIcon icon = new ImageIcon(img);
imgLabel.setIcon(icon);
this.add(imgLabel);
}
catch(IOException ie){
System.out.println("image does not exist");
}
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("Y: " + MiddlePanel.y ,350,15);
}
}
There are a couple of ways you might achieve this, depending on your needs and desires.
For example, rather than using a JLabel to display the image, you could paint it directly yourself, for example...
public class BtmPanel extends JPanel {
private BufferedImage image;
BtmPanel(){
try {
image = ImageIO.read(new File("image.png"));
}
catch(IOException ie){
System.out.println("image does not exist");
}
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image != null) {
g.drawImage(0, 0, image, this);
}
g.drawString("Y: " + MiddlePanel.y ,350,15);
}
}
The reason for doing it this way is you don't (really) control the placement of the image within a JLabel (lots of things can affect it's positioning).
Another solution would be to draw the text directly onto the BufferedImage itself. Which you would use would depend on how dynamic the text might be and a bunch of other factors
A way to do this is doing the exact inverse of your example, overriding the JPanel's paint method painting a BufferedImage (creating a background with your image), and then you can normally add the JLabel with text on your JPanel extension.
Please note that if JPanel is resized and you don't want to have a bad quality background, you'll have to manually create a resized version to adapt the container, or, at least, resize your buffered image with a little logic to keep Width/Height ratio... not that easy!
For the basic version you can try something like the following (taken from a working example) paintComponent overridden function:
#Override
protected void paintComponent(Graphics g) {
Image background = backgroundImage.getScaledInstance(this.getWidth(), this.getHeight(), Image.SCALE_DEFAULT);
super.paintComponent(g);
if (backgroundImage != null) {
g.drawImage(background, 0, 0, null);
}
}
Hope this helps ;)
I am creating a wrapper for Notch's "Prelude of the Chambered", and I wish to make it so that you can resize the window. I can not figure out how I could make the contents scale, I have tried to override onPaint. I can not modify the Jar to get this done.
onPaint attempt:
package com.gudenau.pc.poc;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import javax.swing.JFrame;
public class JScaledFrame extends JFrame {
private static final long serialVersionUID = 4044340683411982494L;
public JScaledFrame(String title) {
super(title);
}
#Override
public void paint(Graphics graphics){
Dimension min = getMinimumSize();
Dimension size = getSize();
BufferedImage image = new BufferedImage(min.width, min.height, BufferedImage.TYPE_4BYTE_ABGR);
Graphics subGraphics = image.getGraphics();
super.paint(subGraphics);
subGraphics.dispose();
graphics.drawImage(image, 0, 0, size.width, size.height, null);
}
}
Scaling the content is very difficult. What you want to is change the scaling context of the Graphics context painting the underlying component.
Typically, what you would do, is override the paint method of the offending component and apply the scaling factor you want...
public class MyExtendedClass extends ... {
#Override
public void paint(Graphics g) {
Graphics2D g2d = (Graphics2D)g.create();
double scaleFactor = 1d;
// Calculate the scaling factor to apply
// based on the "default" size and the
// current size...
g2d.scale(scaleFactor, scaleFactor);
super.paint(g2d);
g2d.dispose();
}
}
This could introduce all kinds of weirdness and frankly a more robust solution might be to use JXLayer/JLayer, for example...
Zooming JLayeredPane via JLayer and the LayerUI
How to add MouseListener to item on Java Swing Canvas
You may also find using an AffineTransform easier...
Do not paint on top level container such as JFrame. Use JComponent or JPanel. Override paintComponent() for painting rather than paint() and don't forget to call super.paintComponent(g).
Do painting in paintComponent nothing else. Avoid putting extra program logic or unnecessary allocations into that method. Painting operations should be fast and optimized for better performance and user experience.
Also, avoid null image observers when calling drawImage. JPanel for instance implements ImageObserver, so you can pass this if extending JPanel.
See Performing Custom Painting for more information. Also see Painting in AWT and Swing.
Since it seems as though this will be hard to do with normal Java I will implement some dark magic with the ASM libraries. I was hoping it would not need to be done this way, but it seems as though scaling a canvas that is loaded from an external jar is not possible.
I'm having problems with putting a stable image background.
I successfully create/draw an image background but when I consecutively run it many times, the image is not showing. The background image seems to be not stable. When I drag the frame to a side of my laptop screen, the image is being erased. How do I create/draw a stable background image that doesn't flicker or erased when dragged?
This code below is what I used for my background image:
public void paint( Graphics g ) {
super.paint(g);
g.drawImage(img, -30, 0, null); //draw image to background
}
Use the JLabel.setIcon(Icon icon) method.
The benefit of this is you don't need to overwrite any method to put a background.
Indeed you can also use JLabel in alternative to JPanel, if you want a container that has an image background. Below can explain this trick in code:
public class JPanelWithBackground extends JLabel {
public JPanelWithBackground() {
add(new JButton("I can attached to JLabel? Isn't cool? "));
setBackgroundImage("path_to_image.png");
}
public void setBackgroundImage(String imagePath) {
setIcon(new ImageIcon(imagePath));
}
}
I am new in Java and I am currently creating a game with graphics. I have this class that extends from JFrame. In this class, I have many JPanels that needs an image as background. As I know, to be able to paint images in the JPanel, I need to have a separate class that extends from JPanel and that class's paintComponent method will do the work. But I don't want to make separate classes for each JPanel, I have too many of them; and with the fact that I am only concerned with the background. How can I do this? is it with an anonymous inner class? How?
For better understanding I provided some code:
public GUI extends JFrame {
private JPanel x;
...
public GUI() {
x = new JPanel();
// put an image background to x
}
Why not make a single class that takes a Image??
public class ImagePane extends JPanel {
private Image image;
public ImagePane(Image image) {
this.image = image;
}
#Override
public Dimension getPreferredSize() {
return image == null ? new Dimension(0, 0) : new Dimension(image.getWidth(this), image.getHeight(this));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.drawImage(image, 0, 0, this);
g2d.dispose();
}
}
You would even provide hints about where it should be painted.
This way, you could simply create an instance when ever you needed it
Updated
The other question is, why?
You could just use a JLabel which will paint the icon for you without any additional work...
See How to use labels for more details...
This is actually a bad idea, as JLabel does NOT use it's child components when calculating it's preferred size, it only uses the size of the image and the text properties when determining it's preferred size, this can result in the component been sized incorrectly
You don't have to make another class for it? You could just do:
x = new JPanel(){
public void paintComponent(Graphics g){
super.paintComponent(g);
//draw background image
}
};
You can do this in single line:
panelInstance.add(new JLabel(new ImageIcon(ImageIO.read(new File("Image URL")))));
I hope it will work for you.
I am using the JScrollNavigator component described here, in order to provide a navigation window onto a large "canvas-like" CAD component I have embedded within a JScrollPane.
I have tried to adapt the JScrollNavigator to draw a thumbnail image of the canvas to provide some additional context to the user. However, the action of doing this causes the rendering of my application's main frame to become corrupted. Specifically, it is the action of calling paint(Graphics) on the viewport component (i.e. my main canvas), passing in the Graphics object created by the BufferedImage that causes subsequent display corruption; if I comment this line out everything works fine.
Below is the JScrollNavigator's overridden paintComponent method:
#Override
protected void paintComponent(Graphics g) {
Component view = jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
// Paint JScrollPane view to off-screen image and then scale.
// It is this action that causes the display corruption!
view.paint(g2d);
g2d.drawImage(img, 0, 0, null);
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
super.paintComponent(g);
g.drawImage(scaled, 0, 0, null);
}
Does anyone have any suggestions as to the cause of the corruption? I would have thought that painting to an offscreen image should have no effect on existing paint operations.
EDIT
To provide some additional detail: The JScrollNavigator forms a sub-panel on the left-hand side of a JSplitPane. The JScrollPane associated with the navigator is on the right-hand side. The "corruption" causes the splitter to no longer be rendered and the scrollbars to not be visible (they appear white). If I resize the JFrame, the JMenu section also becomes white. If I attempt to use the navigator or interact with the scrollbars, they become visible, but the splitter remains white. It's as if the opaque settings of the various components has been affected by the rendering of the viewport view to an offscreen image.
Also, if I make the JScrollNavigator appear in a completely separate JDialog, everything works correctly.
EDIT 2
I can reproduce the problem consistently by doing the following:
Add a JMenuBar to the mFrame:
JMenuBar bar = new JMenuBar();
bar.add(new JMenu("File"));
mFrame.setJMenuBar(bar);
In the main() method of JScrollNavigator replace:
jsp.setViewportView(textArea);
... with:
jsp.setViewportView(new JPanel() {
{
setBackground(Color.GREEN);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 5));
}
});
Ensure that the JScrollNavigator is embedded as a panel within mFrame, rather than appearing as a separate JDialog:
mFrame.add(jsp, BorderLayout.CENTER);
mFrame.add(nav, BorderLayout.NORTH);
Now when the application runs the JMenuBar is no longer visible; the act of painting the view (i.e. a green JPanel with thick black border) to the Graphics2D returned by BufferedImage.createGraphics() actually appears to be rendering it onscreen, possibly from the top-left corner of the JFrame, thus obscuring other components. This only seems to happen if a JPanel is used as the viewport view, and not another component such as JTextArea, JTable, etc.
EDIT 3
Looks like this person was having the same problem (no solution posted though): http://www.javaworld.com/community/node/2894/
EDIT 4
Here's the main and paintComponent methods that result in the reproducible error described in Edit 2:
public static void main(String[] args) {
JScrollPane jsp = new JScrollPane();
jsp.setViewportView(new JPanel() {
{
setBackground(Color.GREEN);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 5));
}
});
JScrollNavigator nav = new JScrollNavigator();
nav.setJScrollPane(jsp);
JFrame mFrame = new JFrame();
JMenuBar bar = new JMenuBar();
bar.add(new JMenu("File"));
mFrame.setJMenuBar(bar);
mFrame.setTitle("JScrollNavigator Test");
mFrame.setSize(800, 600);
mFrame.setLayout(new GridLayout(1, 2));
mFrame.add(jsp);
mFrame.add(nav);
Dimension screenDim = Toolkit.getDefaultToolkit().getScreenSize();
mFrame.setLocation((screenDim.width - mFrame.getSize().width) / 2, (screenDim.height - mFrame.getSize().height) / 2);
mFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mFrame.setVisible(true);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Component view = jScrollPane.getViewport().getView();
if (img == null) {
GraphicsConfiguration gfConf = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
}
Graphics2D g2d = img.createGraphics();
view.paint(g2d);
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
g.drawImage(scaled, 0, 0, null);
}
EDIT 5
It seems like others are having trouble recreating the exact problem. I would ask people to run the code pasted here. When I first run this example I see the following:
Neither the JScrollNavigator or the JMenuBar have been painted; these frame areas are transparent.
After resizing I see the following:
The JMenuBar has still not been painted and it appears that the JPanel was at some point rendered at (0,0) (where the JMenuBar should be). The view.paint call within paintComponent is the direct cause of this.
Summary: The original JScrollNavigator uses the Swing opacity property to render a convenient green NavBox over a scaled thumbnail of the component in an adjacent JScrollPane. Because it extends JPanel, the (shared) UI delegate's use of opacity conflicts with that of the scrollable component. The images seen in edit 5 above typify the associated rendering artifact, also shown here. The solution is to let NavBox, JScrollNavigator and the scrollable component extend JComponent, as suggested in the second addendum below. Each component can then manage it's own properties individually.
I see no unusual rendering artifact with your code as posted on my platform, Mac OS X, Java 1.6. Sorry, I don't see any glaring portability violations.
A few probably irrelevant, but perhaps useful, observations.
Even if you use setSize(), appropriately in this case, you should still pack() the enclosing Window.
f.pack();
f.setSize(300, 200);
For convenience, add() forwards the component to the content pane.
f.add(nav, BorderLayout.WEST);
Prefer StringBuilder to StringBuffer.
Consider ComponentAdapter in place of ComponentListener.
Addendum: As suggested here, I got somewhat more flexible results using RenderingHints instead of getScaledInstance() as shown below. Adding a few icons makes it easier to see the disparate effect on images and text.
editPane.insertIcon(UIManager.getIcon("OptionPane.errorIcon"));
editPane.insertIcon(UIManager.getIcon("OptionPane.warningIcon"));
...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Component view = jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(),
view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D off = img.createGraphics();
off.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
off.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
view.paint(off);
Graphics2D on = (Graphics2D)g;
on.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
on.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
on.drawImage(img, 0, 0, getWidth(), getHeight(), null);
}
Addendum secundum: It looks like the JPanel UI delegate is not cooperating. One workaround is to extend JComponent so that you can control opacity. It's only slightly more work to manage the backgroundColor. NavBox and JScrollNavigator are also candidates for a similar treatment.
jsp.setViewportView(new JComponent() {
{
setBackground(Color.red);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 16));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
});
I am also not sure what you mean by corruption, but I noticed that the resampled image is much nicer if you specify Image.SCALE_SMOOTH as the rescaling hint:
Image scaled = img.getScaledInstance(getWidth(), getHeight(), Image.SCALE_SMOOTH);
Maybe this is what you are looking for...
I was able to reproduce your problem and get you the result your looking for. The problem is that the drawing of the image wasn't complete by the time you were repainting again, so only portions of the image were being painted. To fix this, add this field to your JScrollNavigator class (as a lock):
/** Lock to prevent trying to repaint too many times */
private boolean blockRepaint = false;
When we repaint the component, this lock will be activated. It won't be released until we have been able to successfully paint the panel - then another paint can be executed.
The paintComponent needs to be changed to abide by the lock and use a ImageObserver when painting your navigation panel.
#Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
if(!blockRepaint){
final Component view = (Component)jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// Paint JScrollPane view to off-screen image and then scale.
// It is this action that causes the display corruption!
view.paint(g2d);
ImageObserver io = new ImageObserver() {
#Override
public boolean imageUpdate(Image img, int infoflags, int x, int y,int width, int height) {
boolean result = true;
g.drawImage(img, 0, 0, null);
if((infoflags & ImageObserver.FRAMEBITS) == ImageObserver.FRAMEBITS){
blockRepaint = false;
result = false;
}
return result;
}
};
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
blockRepaint = g.drawImage(scaled, 0, 0, io);
}
}