I'm a somewhat novice programmer and I'm have some trouble adding an image to my frame. While I know how to add images generally, this specific case it does not work.
public class Tutorial extends JFrame{
Tutorial(){
JFrame frame = new JFrame("ImageTutorial");
frame.setVisible(true);
frame.setSize(750,850);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(null);
ImageIcon image = new ImageIcon(getClass().getResource("Green Block.png"));
JLabel imagelabel = new JLabel(image);
imagelabel.setBounds(10, 10, 75, 75);
imagelabel.setOpaque(true);
frame.add(imagelabel);
Now, I've located the problem but I don't understand 'why' its a problem. When I remove
frame.setSize(750,850);
the image shows, but when its there it doesn't. How can the frame's size impact the image showing and how can I get around it?
Just curious, logically, what makes you think a frame should be visible before you add any components? Logically speaking, wouldn't it seem right to add your components first, then make the frame visible. It's like displaying a painting in an art gallery even before the painter has painted anything on it. It just makes no sense. I highly doubt setting the size has anything to do with it. IF you don't set the size of the frame, then the frame appears as small as possible. When you resize the frame, it causes a repaint, then showing the label you add. But generally, you want to always set frame visible after all you components are added, to avoid this problem.
Side note: You should stay away from null layouts. You need to learn to use Layout Managers and let them do the dynamic sizing and locating for you.
Related
First, to get it out of the way, I absolutely NEED to use heavyweight AWT component with a swing application. I need features from both of them.
The task is simple - render a heavyweight AWT Canvas (or any other element), render OpenGL scene directly onto it, then display Swing buttons above it for the UI.
My problem is that it works half-way.
I don't seem to have problems with Z-ordering. I am using jLayeredPanes for it, and I can move Canvas between layers and it actually works, popping on top or below other elements.
The problems are with transparency.
The thing is, Swing elements have Opaque parameter, and when it's set to false (non-opaque) - it should basically be transparent and you should see the next element below it. In my case, however, the AWT Canvas gets ignored, and you instead only see the next underlying SWING element.
Here are a couple of screenshots. They are taken from a standalone test project of mine. The canvas is stretched to the size of the frame, and in the upper left there is a JLayeredPane dummy element that is a simplified version of the menu.
On the first screenshot, the JLayeredPane's Opaque setting is set to true, and you can see that it's background property is set to Blue color.
On the second screenshot, everything is exactly the same but Opaque is set to false. Instead of displaying whatever is on the Canvas - what gets drawn in empty grey jFrame background.
Lastly, on the third screenshot I have put Canvas into a jPanel instead of leaving it on its own. As you can see, the Panel's orange color is seen through the transparent jLayeredPane, but the Canvas is yet again hidden.
Here's the code for the Frame layout. I would not post my rendering/context code right now
frame = new JFrame("AWT test");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(width, height));
canvas = new Canvas();
canvas.setSize(width,height);
//this part exists only in the third example
JPanel p = new JPanel();
p.setSize(width,height);
p.setBackground(Color.orange);
p.add(canvas);
// third example end
JLayeredPane pane = new JLayeredPane();
JLayeredPane paneMenu = new JLayeredPane();
JButton button = new JButton();
button.setSize(20,20);
paneMenu.setSize(200,200);
paneMenu.add(button, new Integer(1));
paneMenu.setBackground(Color.BLUE);
paneMenu.setOpaque(false); //True for the first example
pane.add(p, new Integer(1)); // canvas for the first two examples
pane.add(paneMenu, new Integer(2));
pane.setOpaque(false);
frame.add(pane);
frame.pack();
frame.setVisible(true);
frame.transferFocus();
Could anyone please explain me what is going on and how to do what I need to do.
I will repeat again - I have to use heavyweight component as render target. I am aware of solutions like JOGL's GLPanel which is a lightweight Swing-compatible component. But I tried that method and the performance is really slow, because instead of directly rendering onto it as a context target - it reads FrameBuffer from memory, flips it, and then paints it as BufferedImage. This path is not fitting for the limited resources of an embedded system that I'll be running on.
c0der said: Please post minimal reproducible example
Errrrm.... Didn't I?
Here, you can have it in complete java class form if you want, but I literally changed some variables for constants.
import javax.swing.*;
import java.awt.*;
public class Main
{
public static void main(String[] args)
{
JFrame frame = new JFrame("AWT test");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setPreferredSize(new Dimension(500, 500));
Canvas canvas = new Canvas();
canvas.setSize(500,500);
canvas.setBackground(Color.RED);
//this part exists only in the third example
JPanel p = new JPanel();
p.setSize(500,500);
p.setBackground(Color.orange);
p.add(canvas);
// third example end
JLayeredPane pane = new JLayeredPane();
JLayeredPane paneMenu = new JLayeredPane();
JButton button = new JButton();
button.setSize(20,20);
paneMenu.setSize(200,200);
paneMenu.add(button, new Integer(1));
paneMenu.setBackground(Color.BLUE);
paneMenu.setOpaque(false); //True for the first example
pane.add(p, new Integer(1)); // canvas for the first two examples
pane.add(paneMenu, new Integer(2));
pane.setOpaque(false);
frame.add(pane);
frame.pack();
frame.setVisible(true);
frame.transferFocus();
}
}
A little update:
I initially suspected that because Swing elements delegate all their drawing to the underlying heavyweight element (In my case JFrame), then what happens is that the frame generates a single frameBuffer for itself and then displays on top of Canvas. Canvas itself is not handled in this generation and thus the frame "covers" over the canvas.
That doesn't seem to be the case. I tried making the JFrame undecorated, all panels non-opaque, and display the picture. The result - canvas is still "cut", and through the hole you can see the underlying IDE menu.
This makes me think that somewhere during Drawing, the Canvas itself detects that it is obscured by another element, and that it doesn't need to draw that area. So it "optimizes" itself and doesn't update these pixels.
Maybe I'm wrong. But here's another screenshot. This is the same example as before, but I took out 3d rendering and simply trying to display Canvas with background set to Red.
Once again, going to reply to my own question.
It turned out that I need to do
setComponentMixingCutoutShape(paneMenu, new Rectangle());
for the menu pane that lies underneath the button. That essentially tells java not to cut out the element from the heavyweight underlying component.
I am new to the java (and programming in general) and I am trying to make my very first program. I'm stuck on the same problem for about 5 hours now, so I've decided to ask for help.
Basically I'm trying to make a program (2d game) that has about 20 positions on the board. Each position is either blue (owned by player1), red(owned by player2) or black(not owned by anyone).
The way I'm going about this is in main I've put a method that calls setup game, and then a method that plays game. I am working on the setup game, basically all it does is it makes an object of class Background (extends JPanel, and overrides paintComponent()) and 20 objects of class Position(extends JPanel, and overrides paintComponent()).
So far I'm stuck on putting those Position objects on top of Background object.
When I do:
Background background= new Background();
frame.getContentPane().add(background);
Position position1= new Position;
frame.getContentPane().add(position1);
frame.setVisible(true);
it shows only a circle and no background as I was hoping, if I first add position and then background, I only have background and no circle.
Anyway I'm new to the java and I am still having trouble founding my way around, however I've tried to search for solutions, and I've found many different solutions to this problem (such as adding position to background first, and then adding background to frame, etc.) but I couldn't make any of them to work.
I am aware that the way I am adding them both to frame is (very likely) completely wrong, but I wrote it that way so you would (hopefully) be sure that what I've wrote actually does show you that my code for each of those classes draws something on the screen.
PS: I didn't copy my code here as most of variable and method names aren't in English so it's fairly hard to read, but if you still think its needed, I will add it. Also I'm sorry for my probably stupid question, but I'm kinda hitting a wall here and I've no idea what else to try.
Basically I'm trying to make a program (2d game) that has about 20
positions on the board. Each position is either blue (owned by
player1), red(owned by player2) or black(not owned by anyone).
Painting in Swing by default never returns PreferredSize, is required to override getPreferedSize()
JPanel has implemented FlowLayout in API, this LayoutManager accepting only PreferredSize came from JComponents added to this container
after a.m. changes to post an SSCCE, short, runnable, compilable
Background background= new Background();
frame.getContentPane().add(background);
Position position1= new Position;
frame.getContentPane().add(position1);
A JFrame uses a BorderLayout by default. Also by default when you add a component to a Container that uses a BorderLayout the comopnent is added to the CENTER. Only one comonent can be added to the CENTER so your Position comonent replaces the Background component.
You want to add the Position to the Background and then add the Background to the frame. Something like:
Background background= new Background();
Position position1= new Position;
background.add(position1);
frame.add(background);
Note: there is no need to uses getContentPane() when adding a component to the frame.
The root panel should be a JFrame with a Container class underneath. When you call someRoot.window.container = yourJPanel, that loads the JPanel as the main component view of the JFrame. Note, a JFrame can only hold one JPanel but other JPanels can hold other JPanels. Just as you add the initial JPanel to the JFRam, a JPanel's own container can be another JPanel. Hope this helps.
Like this:
JPanel temp = new JPAnel();
frame.getContentPane().add(temp);
temp.getContentPane().add(new JPanel());
After these additions, there is a command that is illuding me but you call on JFrame to get it to refresh in real time. I think it is something like:
frame.validate(); //thanks #SMT
or something,
Try using something like
jPanelExampleName.validate();
jPanelExampleName.repaint();
after adding your JPanels.
It sounds like you want to use one JFrame and attach JPanels to it. This is how I personally would do it.
Declare your JFrame and JPanels
JFrame frame1 = new JFrame( "App Name");
JPanel panel1 = new JPanel();
JPanel panel2 = new JPanel();
JPanel panel3 = new JPanel();
JPanel panel4 = new JPanel();
Set the Background (I'm using colors but you get the idea)
panel1.setBackground(Color.orange);
panel2.setBackground(Color.orange);
panel3.setBackground(Color.orange);
panel4.setBackground(Color.orange);
Set your layout for the JFrame (I'm using BoxLayout not sure which would be best for you) You can find the best one for you and some sample code here. Also just set the default close operation.
frame1.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame1.setLayout( new BoxLayout( frame1.getContentPane(), BoxLayout.Y_AXIS ) );
Then Just attach your JPanels
frame1.add( panel1);
frame1.add( panel2);
frame1.add( panel3);
frame1.add( panel4);
frame1.pack();
frame1.setVisible( true );
This will allow you to use the JPanels you created and then change the colors via other methods.
I'm struggling with two Java GUI things at the moment.
This is the situation: I'm designing a word game using Swing components. I have a main JFrame where everything is placed (my GUI class extends JFrame). There are two things I want to do:
1st: I would like to set an image as the background image of the main frame, it has to be displayed behind all components. i've searched around but haven't found a working solution. I tried making an extended BackGroundPanel class but when I create an instance of BackGroundPanel I have no idea how to make it the background of the frame... I also haven't find a good way to load in an image from an 'images' directory in my src folder...
2nd: when the program starts the user is greeted with an undecorated JDialog, the main frame needs to be disabled, which I figured out, but I would also like to make it a bit darker. I believe it should be possible with the GlassPane, but I have no idea how to set the GlassPane to cover the panel with one color...
Help will be much appreciated, I don't think I have any helpful code to share, but I think the situation explained above gives a general idea? I would just like someone to get me on track with this so I can further work this out! Thanks!
My Main class extends JFrame and it has a BorderLayout.
Add your BorderLayout to a JPanel having, e.g. GridLayout().
This AnimationTest illustrates painting a background image behind components.
This Translucent example illustrates using an AlphaComposite; see also this AlphaTest.
Well for your first question, you can use a label and set the icon of it:
JLabel lblimage = new JLabel("");
lblimage.setIcon(new ImageIcon(Main.class.getResource("/img/background.png")));
lblimage.setBounds(0, 0, 794, 711); //size of frame
contentPane.add(lblimage); //bottom
contentPane.add(component1); //middle low
contentPane.add(component2); //middle top
contentPane.add(component3); //top
as for your second question.. you could possibly do the same thing, just use an image with a solid color and lower the transparency, and place on top of your other components (not sure on this solution though).
I think I solved my problem, but I don't know why it works this way, so I'm hoping someone can explain it to me so I don't do the same mistake again in the future.
Here's a quick example that is compilable of what I'm trying to do:
public class BoxLayoutTest extends JFrame
{
public BoxLayoutTest()
{
setSize(400,300);
JPanel mainPanel = new JPanel(new FlowLayout());
setContentPane(mainPanel);
JPanel subPanel = new JPanel();
subPanel.setLayout(new BoxLayout(subPanel, BoxLayout.PAGE_AXIS));
subPanel.setBackground(Color.BLUE);
JLabel labelTest = new JLabel("This is a test");
subPanel.add(labelTest);
labelTest.setPreferredSize(new Dimension(150, 20));
mainPanel.add(subPanel);
System.out.println(mainPanel.getSize());
}
public static void main( String[] args )
{
BoxLayoutTest testFrame = new BoxLayoutTest();
testFrame.setVisible(true);
}
}
At first, I had problems with the panel containing the JLabel not resizing like it should with the preferred size. I found out that it was because I was using some variation of mainPanel.getSize() as a preferred size for my subpanels. In this example, I'm using actual number values, which work.
The reason why it didn't work the old way (and that's actually the thing I'd like someone to explain), is why, as seen in the SOP line, mainPanel.getSize() returns a width and a height of 0 while it clearly takes the whole screen, which is 400x300.
Thanks #camickr for telling me I shouldn't set a preferredSize for my Panels, this helped me figure out where the problem was coming from.
Why [does] mainPanel.getSize() returns a width and a height of 0?
Until pack() "causes this Window to be sized to fit the preferred size and layouts of its subcomponents," the dimensions will be zero.
System.out.println(mainPanel.getSize());
this.pack();
System.out.println(mainPanel.getSize());
Console:
java.awt.Dimension[width=0,height=0]
java.awt.Dimension[width=160,height=30]
Its hard to say why your code doesn't work, since you didn't post your code. A few random lines of code does not give us the context of how the code is used in your program.
When you post a question you need to post your SSCCE which demonstrates the problem.
The glue should not have fixed the problem. The panel should still display, its just that it may not display in the position you expect it to be. A BoxLayout will attempt to resize components added to it to fill up the entire space available to it.
You should not be using setPreferredSize() on a panel. It is the job of the layout manager to calculate the preferred size of the panel based on the preferred size of all the components added to it. So I would say your code is still wrong.
is there a difference between typing this and this.getContentPane()
Certain methods calls are automatically forwarded to the content pane of the frame, which is why the end result is the same. Read the JFrame API. This is addressed in the API description or for the method in question.
I am writting a simple application which has a button that opens a new window then display a simple GUI/Text to acccept inputs from a user. but for some reason, I can get JLabel to be displayed on the new window. The application has following structure:
+mainFrame - JFrame
+newFrame - JFrame
-+newPanel - JPanel
----title - JLabel
----submitButton -JButton
...
Buttons and textfields all display fine, but Jlabels won't show up at all. I have tried using different layouts and all but I still can't get it shown. JLabels inside mainFrame tree, works fine.. so it seems like the problem is due to newFrame declaration or something, but then button should not be displayed either. Well, I am kindda lost and can someone suggest me what I should check?
Thanks : )
Make sure you do frame.pack() before you make it visible.
It can also help to set borders on different components (in different colours) for debugging just to see which components are/aren't turning out with size 0, in order to narrow down your problem. Logging, or breakpointing the component's setSize method, can help too.
Apart from that, maybe post some sample code? At the moment, you're question is fairly vague to answer.
Firstly, do you know about JDialog, and JOptionPane - these classes are often a better way of showing another popup window. It is quite rare to use 2 JFrames, (though sometimes a sensible thing to do).
Secondly have you done pack() and setVisible(true)?
The code below works fine for me. Either this breaks for you and it is something about your Java implementation, or you must be doing something different, in which case can you tell us what it is:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class JLabelShower {
public static void main(String [] args) {
JFrame mainFrame = new JFrame("main frame");
JButton popup = new JButton("start new frame");
mainFrame.getContentPane().add(popup);
mainFrame.pack();
mainFrame.setVisible(true);
popup.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JFrame newFrame = new JFrame("new frame");
JPanel newPanel = new JPanel();
JLabel title = new JLabel("title");
newPanel.add(title);
newFrame.setContentPane(newPanel);
newFrame.pack();
newFrame.setVisible(true);
}
});
}
}
In case you are using the JLabel as a placeholder, i.e. initialize it with an empty string and set the text later:
Since the JLabel's size gets calculated when the panel gets layed out (i.e. early on) and is based on the contained text, you'll probably end up with a label thinking it has a preferred size of (0, 0).
In this case you should tell the label what size it should ask for by calling setPreferredSize with an appropriate value.
And another cause might be the layoutmanager you are using in the surrounding panel. Maybe you are adding the label and the button in the same place, e.g. BorderLayout.CENTER. That would explain why only one of the two gets displayed.
Set the opacity of the JLabel object to true using title.setOpaque(true) . It will paint every pixel within bound of the JLabel object. This solved my problem of same type.