I search for a method, which gets called if the jpanel is shown on the display, because i have to fetch the real size of the panel.
Any suggestions?
Have you tried adding a ComponentListener to the JPanel? That would be where I would start with my code in the componentShown(...) method. For this to work, I think that you must call setVisible(true) on the JPanel after adding it to the display.
The other option is to simply query its size after calling pack(), or setVisible(true) on your GUI.
Edit
You state:
I added the panel to the gui designer.. when the window pops up, i wanna now the real size of the jpanel, because it can change it.
If you want to know the size of a component held by a window "when the window pops up", then add a WindowListener to the window and check the size of the component from the windowOpened(...) method.
Edit 2
Then you state:
after i have the real size, i add some subpanels, in relation to the size of this panel. so e.g. size/6 & the subpanel has now the size-height of size/6.
One Solution: Better not to set the sizes of anything but instead to use the right combination of layout managers and then let them set the proper sizes based on their rules.
Set the visibility using function setVisible(true);
Related
So basically, I am trying to get a JPanel window which will display all components inside dynamically. In other words, which will re-size the window, and display to fit its content.
I have been able to do it with help of JFrame and its pack() method which : "causes this Window to be sized to fit the preferred size and layouts of its subcomponents".
In my situation, I dont want to use JFrame because it will require much effort to make all changes.
Right now, I am able to make it work but only with the help of jscroll inside which wraps the text and or any new lines, so the window size is more static. So my JPanel is extending a TopComponent and am able to display it with:
jpanel.open();
jpanel.requestActive();
So the question is how to resize a window to fit its content upon actions in that window.
The JPanel has to be added to a Window in order to make sense. So I suggest you use layout managers correctly and you will get to a decent user interface.
When you add/remove components from a visible panel you need to use:
panel.revalidate();
panel.repaint();
Then the layout manager will lay out the components again.
I have a JPanel that uses FlowLayout. I add a number of JLabels to the JPanel, use setPreferedSize() to adjust their size and save them in a list, label_list. Everything works fine. Then I want to change their size:
for(JLabel c:label_list){
c.setPreferedSize(new Dimension(10,10));
}
And it doesn't work.
c.setBackground(Color.red)
and similar stuff works. Why can't I use setPreferedSize here?
c.setBounds(1,1,10,10) and c.setSize(10,10)
Works, but after i update the UI (resizeing the panel) every size goes back to normal.
Then I want to change their size:
for(JLabel c:label_list){ c.setPreferedSize(new Dimension(10,10)); }
And it doesn't work.
You need to call revalidate() on the parent of the labels so that it reperforms layout and enforces their preferred size.
c.setBounds(1,1,10,10) and c.setSize(10,10) Works, but after i update
the UI (resizeing the panel) every size goes back to normal.
Setting bounds/size/location manually conflicts with the LayoutManager of the parent container. The job of the LayoutManager is to position and size the child components.
Either set the layout to null and call yourself setSize-setLocation/setBounds, or use a LayoutManager (recommended) and never call setSize-setLocation/setBounds. At most, you can call setPreferred/setMaximum/setMinimum size but try to avoid this as it can causes cross L&F problems.
I have a problem when I try to resize a JLabel. In my application appears the next strucutre. Understand every list item like something inside the previous list item.
JFrame (Layout null, fixed size, not resizeable, used by different people).
JPanel (Layout null, with a size of all the window, the place were I put my work).
various JPanel with different Layouts (the areas of content inside the main panel, you can think about it like html divs...).
Inside one of this "divs" with Layout null there are extended Classes of JPanel with Flow Layout.
Inside every one of this extedend Classes are labels with preferredSizes.
The thing is that when after create all of this i call theFrame.setVisible(true); and all works propertly.
But in a moment of the flow of my application I have to change the size of one of the labels. Then, I simply call label.setPreferredSize(d) and the change doesn't change. The function works propertly if I call it before set visible the frame, but not after.
I have the feeling that the problem is that I don't use nothing like pack(), validate(), repaint(), etc. Because I don't know what it works. I try call repaint and validate to the jlabel, and repaint the main panel, but doesn't works.
I'm relative new with awt and swing, and this is for homework. Sorry for my bad use of English language, and thank you for your help.
After you change the size of your JLabel, call revalidate(). This will cause the JLabel to be resized without waiting for an event that triggers a re-layout (such as resizing the parent Frame, etc...).
JLabel lbl_test;
lbl_test.setPreferredSize(new Dimension(100, 100) );
lbl_test.revalidate();
One other thing to keep in mind, as I'm not certain which class you're having problems with. Null layouts (absolute positioning) mixed with layout managers are going to cause some strange things to happen.
I have a JFrame.
I also have a Box class which extends Component.
This box class has a paint method which makes a filled rectangle.
When I add multiple of these Box components to my JFrame, only the most recently added one is displayed when I call repaint on the JFrame.
I took a look at the layout managers, but I am not sure that's what I want. All I want is to be able to make an animation of whole bunch of rectangles wherever I want on the screen.
(I also tried creating a panel, adding the panel to the JFrame, and then adding all the Box components to the panel. This did not work either).
Thanks in advance!
You have 2 choices.
You can change the layout of your frame:
JFrame frame;
frame.setLayout(new FlowLayout());
Now, if you add more than one box, it will show up on the frame.
The other option is to do what you said you tried. (Adding a panel to the frame)
JPanel pane = new JPanel();
frame.add(pane);
(add the boxes to 'pane')
Also, you should be careful with the sizing of your Box. You will probably want a call to setPreferredSize() somewhere in the creation of the Box. This will tell Java what size to make the box when it is added to the layout.
You should also take a look at the Java Layout Manager Tutorials. There is lots of great info there.
And, one more thing. The reason only one box at a time was being displayed on the frame was because JFrame's layout manager is BorderLayout. And, when you call add on a component that has a BorderLayout, the component is automatically added to the center of the component. Subsequent calls to add will overwrite the center component, leaving only one component in the middle.
You do need to check out other layout managers. JFrame by default uses BorderLayout and without specifying the "place" a component is added, they get added to CENTER. Depending on what you want your UI to look like depends on the layout manager to use. I would suggest maybe using Netbeans GUI builder.
EDIT: Missed the part about what you want to add but the concept is still the same, if you just add these components to the default layout manager, they will get overwritten. Sounds like you may need to do your painting inside of just one of your Box components or create a JPanel and set the layout to null but then you would have to place them explicitly. Really depends on what you want to do with it exactly.
Do your layout on paper first, then read up on Swing layout managers.
Be aware that some Swing components only allow one component to be added to them. I've run across this when using Tabbed panes. Each tab can only accept one control (JPane?) so you have to create a separate panel with a layout to arrange the related controls and then as a unit add the pane to the tab. There are similar arrangements in the Swing library.
You could set the frame layout to null and then use setBounds() to position your boxes exactly where you want.
Thank you for all your answers.
Since I am using my own custom class, Box, I have the ability of setting the position of my the rectangle through the paint method.
I realized my Box class was extending the wrong thing. It should have been extending javax.swing.Jcomponent.
If I now use a panel with an OverlayLayout, add my components to that panel, they all show up properly.
I am trying to figure out why my JComponent refreshes when I manually drag my window, but it doesn't refresh when I call repaint or revalidate. The data is ready to be displayed, but it just won't show until I manually resize. Can anybody give some suggestions about what I can do or does this sound like it isn't a Swing problem since I tried repaint and revalidate?
One weird things I've noticed is that if I have this code:
sp.setSize(sp.getSize().width, sp.getSize().height+1);
sp.setSize(sp.getSize().width, sp.getSize().height-1);
If the first line is used, then the JComponent will refresh itself. If I use none or both of these lines it will not, which seems bizarre to me.
I am basically just putting a JPanel in a JInternalFrame in a JDesktopPane. There are two main functions for what I am trying to do. One adds the new JPanel and the other tries to refresh it so the new data will show:
public void addNewSP()
{
sp = new JInternalFrame("SP");
sp.setClosable(true);
sp.setLocation(700, 400); //this should be changed to something based on screen size
sp.setResizable(true);
sp.add(popUp);
this.parentContainer.add(sp, JLayeredPane.DRAG_LAYER);
sp.pack();
sp.show();
sp.setSize(500, 500);
sp.setPreferredSize(new Dimension(500, 500));
}
public void refreshSP()
{
sp.repaint();
sp.validate();
sp.repaint();
sp.validate();
parentContainer.validate();
parentContainer.repaint();
sp.setSize(sp.getSize().width, sp.getSize().height+1);
sp.setSize(sp.getSize().width, sp.getSize().height-1);
}
}
BTW parentContainer is the JDesktopPane
When changing the container's content, you have to call both:
revalidate() to make it recompute the layout for its content
repaint() to request a repaint for this container
but it just won't show until I manually resize.
We don't know the context of your question, which is why a SSCCE should always be posted as suggested earlier.
In general a JComponent, does not have a preferred size, so I'm guessing Swing doesn't think it needs to paint the component. When you resize the frame, chances are the component was added to the center of a BorderLayout so it automatically gets sized to fill the entire space of the frame.
The solution is to give your component a "preferred size" so that any layout manager can use this information to display the component properly.
if your are modifying container's subcomponents you should call jcomponent.validate();
I assume parentContainer is the JDesktopPane?
What kind of changes are you making to sp that are not showing up?
Changing the size of sp will cause Swing to repaint from scratch. That's why the setSize() is fixing the display.
Most likely, the changes you are making are either not happening on the EDT, or are not invalidating the right container. For example, if you change the visibility of a component in sp, you'll need to call sp.invalidate() to rerun the layout manager.
Have you checked that you're only changing components (or their models) on the EDT?
A quick test for that is to run with the Substance LAF as it will complain if you change things on another thread.