I am building a swing interface for drawing overlays over a particular image. I have found several examples of how to draw an image on a JPanel, and I am able to do this without difficulty. However, I would like to keep this image completely static while dynamically drawing overlays on top of it. With that in mind, it would be better if I could set the image as a permanent background of the panel, rather than having paintComponent() redraw the image every time. This would be particularly useful, as there will frequently be situations where I want to removeAll() graphics currently on the panel and redraw new ones.
So my question is this: is there a way to set a permanent background image in JPanel, or do I have to redraw the image every time paintComponent() is called?
put Image as Icon / ImageIcon to the JLabel
use this JLabel instread of JPanel
JLabel hasn't implemented any LayoutManager in compare with JFrame(BorderLayout) or JPanel(FlowLayout)
you have to define the proper LayoutManager, that accepting PreferredSize came its child(s)
then there are accesible (almost nearly) all methods as for JPanel, as container works
maybe you can try putting the Jpanel inside another Jpanel. You draw the image on the container JPanel. then make your inner JPanel a transparent one. this way, when there are no objects on it, you see the background of the parent JPanel which did not change.
Related
So I am trying to write for my project essentially a pokemon battle between 3 different pokemon using java swing. However the part which is stalling me is the animations. I tried using a null layout with setLocation so that I can move the imageicons based on a timer but the issue is, as you probably know, the imageicons won't show up in the null layout. Is there anyway to change it so that it will work this way.
This is how I have declared my pictures
java.net.URL torterraPic = getClass().getResource("torterra-1.gif");
ImageIcon torterra = new ImageIcon(new ImageIcon(torterraPic).getImage().getScaledInstance(100, 100, Image.SCALE_DEFAULT));
then I place my Image Icon in a JLabel which I add to the frame and then I do setLocation to chose where it goes.
I understand that it is discouraged to use absolute positioning but I feel that this is the best way to do this (assuming it is possible to add a picture) because that way I can manipulate the setLocation to make it move upwards during the attack. I have tried using gridbag and grid layout to try to do it but neither are as convenient for me.
So if there is someway to make this workout please tell me.
Thanks in advance!
No need to use null layouts and component absolute positioning since your image sprites shouldn't be JLabels or other components but rather create BufferedImage sprites and then draw them in a single drawing JPanel's paintComponent method as per the painting tutorials -- Lesson: Performing Custom Painting.
Draw the background image(s) first in a static position, and then move the position of the sprites via g.drawImage(...) override's x and y parameters. Drive the animation via a Swing Timer which uses an ActionListener or via other listeners such as Key Bindings.
I tried using a null layout with setLocation so that I can move the imageicons based on a timer but the issue is, as you probably know, the imageicons won't show up in the null layout.
Yes they will but you are now responsible to doing the layout manager functions, which means you need to set the location and size of the label.
Typically you would do something like:
label.setIcon(...);
label.setSize( label.getPreferredSize() ):
label.setLocation(...);
Then in your animation you just change the location as desired.
JLabel label=new JLabel("");
Image img=new ImageIcon(this.getClass().getResource("hancie.png")).getImage();
label.setIcon(new ImageIcon(img));
label.setBounds(10,50,200,200);
label.setBorder(new LineBorder(Color.BLACK,4));
frame.add(label);
I'm doing this project using Swing.
To add a more welcoming feel to the UI, I'm also adding a few Photoshopped images as the background.Here's where the problem begins...
I want the images to automatically resize themselves once the size of the window is increased or decreased, how can I make this happen ?
One way is to override the paintComponent(...) method of a JPanel to paint the image using the drawImage(....) method.
Another option is use a JLabel with an Icon as the background for the frame. Then you can use the Stretch Icon which will automatically scale based on the space available to the label. This is the most flexible solution since the StretchIcon can be used on any component that supports icons.
You can also check out the Background Panel which allows you to display an image. You can display the image at its actual size, scaled or tiled.
I have a setup that usually works, but I'm finding it a bit of a pain at the moment.
I have a JDialog (formerly a JFrame, but I've changed the UI flow recently to remove redundant JFrames) set to BorderLayout that contains three main JPanels, header, content and footer.
The header JPanel has a background image that is loading fine. However, I'm calling all manner of setMinimumSize / setPreferredSize / etc (I even tried setSize and setBounds out of desperation) and the JPanel isn't being sized correctly. The layout for that component is BoxLayout, and the children sit comfortably within it, but that shouldn't affect what I'm trying to do with the header panel itself.
The only thing that works is setting a size on the parent JDialog. But I don't want to do that / from what I've read it seems like bad design. I'd also have to maths out the potential width / height of all the children, add the margins, etc.
Advice I am not looking for: "use a different LayoutManager."
I want to understand if there's a reason for the child components not being respected.
I can provide code, but isolating a small, runnable segment is difficult given the amount of interlocked systems I'm juggling. Here is the relevant snippet to set the size of the JPanel. The image dimensions are 480 * 96.
public JPanelThemed(BufferedImage image) {
super();
this.backgroundImage = image;
setAllSimilarConstraints(new Dimension(image.getWidth(), image.getHeight()));
setOpaque(false);
}
// for use with BoxLayout as it requires explicit bounds to be set
public void setAllSimilarConstraints(Dimension dim) {
setPreferredSize(dim);
setMinimumSize(dim);
setMaximumSize(dim);
}
I would implement it a bit another way - to ensure that preferred/min/max/Size can not be changed from elsewhere:
public JPanelThemed(BufferedImage image) {
this.backgroundImage = image;
setOpaque(false);
}
public Dimension getPreferredSize() {
return new Dimension(this.backgroundImage.getWidth(), this.backgroundImage.getHeight());
}
If I don't define dimensions, how do I ensure the whole background I'm painting is displayed?
You could use a JLabel to display the ImageIcon. The size of the label will be the size of the image. You then set the layout manager of the label so you can add components to it.
Edit:
do you know why it's commonly-recommended to subclass JPanel when painting backgrounds in Java
When you use a JPanel the size of the panel is based on the components added to the panel and the layout manager you are using. Your custom painting code then needs to paint the image the way your want. That is you can paint the image from (0, 0), or you can center the image on the panel, you can scale the image to make it fit the pane, but the image in no way controls the size of the panel, unless you override the getPreferredSize() method of the panel to use custom code to base the size of the larger of the components or the image. So you are in full control.
When you use the JLabel approach suggested here, the size of the label is always the size of the image. Then components will be positioned based on the layout manager but can be truncated if the image is smaller than the space required by the components.
So based on your requirement that you want to make sure the entire image is displayed, I suggested the JLabel approach, since you don't need to write any custom code. I find this a simple approach when using popup non-resizable dialogs to display a background image and a few components and buttons to close the dialog.
You can also check out Background Panel which provides these common painting features in a reusable class.
I need to layer JPanels but I don't know how. I have 3 panels, the first is for the background, the second is for a Character/Sprite to move around and layers the first panel(background, and the third is a bar off to the side (Used for buttons and has nothing to do with they layers). How do I layer panel 1 and panel 2?
edit: The background is made up of a grid of 25x25 labels with an icon in each.
Some options:
Use a JLayeredPane which can layer components using a z-order Integer constant. Remember that when doing this, you are also essentially using a null layout, and so you will be fully responsible for setting the size and position of all components added to the JLayeredPane.
If all the background is doing is painting an image, you could use a single JPanel, and then simply paint the image as a BufferedImage that is displayed in the JPanel's paintComponent method. The sprite would also be painted but its location would vary.
See How to Use Layered Panes.
Don't forget to use:
panel.setOpaque(false);
Or you don't need to layer panels. You can just paint a background image on the panel. See Background Panel for an example of this.
We just recently worked on a top-down video game for my CSC class. All we did was draw the background and then all the sprites after it in the paint() method on the JPanel. We also used a Timer and an ActionListener to constantly update the JPanel.
Since JPanel and Canvas are both same-level components, the solution would probably be some sort of a 'hack'. This question says that you won't be able to add the lightweight component to the heavyweight canvas (I want JPanel transparent).
If this isn't posible, then would putting a transparent Component work? Also, is it feasible to add Swing components to the Component (it just has to work, even if it's bad). And how would I go about actually putting it over the canvas (since they are both same-level components)?
Note: I would never do something like this in a real app, I just need it in this case
One possiblity is to add the JPanel to whatever container the Canvas is on, then setting the color of the JPanel to have an alpha of 0. This should add it over the old one, without blocking out the Canvas. Is this what you want?
EDIT: Thinking about it, the JPanel's default color is transparent... You should just be able to add the JPanel the Canvas's parent, and lay it over it