I'm trying to implement a quite simple UI using SpringLayout (partly because I, as opposed to most tutorial writers I find on the net, quite like the coding interface compared to other layout managers and partly because I want to learn how to use it). The UI basically looks like this:
This is all well. The UI resizes the way I want (keeping the welcome text centered and expanding the text area to fill all the new available space) if I increase the window size. However, below a certain point (more specifically when the window becomes too narrow for the welcome text):
I would like the window to not allow further shrinking, so that if the user tries to shrink the window to a size smaller than enough to house the components, it simply stops. How do I accomplish this, using the SpringLayout layout manager?
I know I could probably do this by handling some resize-event and checking if the minimum size is reach, and then just set the size to the minimum size. But this requires me to a) know, or know how to calculate, the minimum size of the window, even before it renders, b) write a bunch of event-handling code just to get some UI rendering right, and c) write a bunch of code for things that I expect a good layout manager to take care of ;)
you can override MinimumSize for TopLevelContainer
you have put JTextArea to the JScrollPane
easiest way is mixing LayoutManagers (called as NestedLayout) by spliting GUI to the parts (separated JPanels with same or different LayoutManager), rather than implements some most sofisticated LayoutManager (GridBagLayout or SpringLayout) for whole Container
some LayoutManagers pretty ignore setXxxSize
SpringLayout isn't my cup of Java
import java.awt.*;
import javax.swing.*;
public class MinSizeForContainer {
private JFrame frame = new JFrame("some frame title");
public MinSizeForContainer() {
JTextArea textArea = new JTextArea(15, 30);
JScrollPane scrollPane = new JScrollPane(textArea);
CustomJPanel fatherPanel = new CustomJPanel();
fatherPanel.setLayout(new SpringLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(fatherPanel, BorderLayout.CENTER);
frame.setLocation(20, 20);
frame.setMinimumSize(fatherPanel.getMinimumSize());
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
MinSizeForContainer Mpgp = new MinSizeForContainer();
}
});
}
}
class CustomJPanel extends JPanel {
private static final long serialVersionUID = 1L;
#Override
public Dimension getMinimumSize() {
return new Dimension(400, 400);
}
}
There are several issues to achieve a "real" (that is not shrinkable beyond) min size:
the child components must return some reasonable (based on their content) min size, many core components don't
the layoutManager must respect the compounded min of all children, no matter how little space is available
the top-level container (here the JFrame) must not allow shrinking beyond the min
The first is true for a JLabel, the second is met for SpringLayout (that's why the label is truncated) - which leaves the third as the underlying problem, the solution to which isn't obvious, actually I wasn't aware it's even possible before running #mKorbel's example. The relevant line indeed is
frame.setMinimumSize(someSize);
With that line in place, it's not possible to shrink the frame below. Without, it is. Starting from that observation, some digging turns out the doc for its override in Window
Sets the minimum size of this window to a constant value. [..] If
current window's size is less than minimumSize the size of the window
is automatically enlarged to honor the minimum size. If the setSize or
setBounds methods are called afterwards with a width or height less
[...] is automatically enlarged to honor the minimumSize value.
Resizing operation may be restricted if the user tries to resize
window below the minimumSize value. This behaviour is platform-dependent.
Looking at the code, there are two (implementation, don't rely on them :-) details related to the min size
Dimension minSize;
boolean minSizeSet;
and public api to access
public Dimension getMinimumSize()
public boolean isMininumSizeSet()
the first rather oldish (jdk1.1), the latter rather newish (jdk1.5) - implying that the first can't rely on the latter but internally has to check for a null minSize. The overridden sizing methods (with their guarantee to doing their best to respect a manually set minSize) on Window are the latest (jdk6) and do rely on the latter. Or in other words: overriding isMinimumSizeSet does the trick.
Some code snippet (beware: it's a hack, untested, might well be OS dependent with undesirable side-effects!):
// JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("some frame title") {
/**
* Overridden to tricks sizing to respect the min.
*/
#Override
public boolean isMinimumSizeSet() {
return true; //super.isMinimumSizeSet();
}
/**
* Overridden to adjust for insets if tricksing and not using
* LAF decorations.
*/
#Override
public Dimension getMinimumSize() {
Dimension dim = super.getMinimumSize();
// adjust for insets if we are faking the isMinSet
if (!super.isMinimumSizeSet() && !isDefaultLookAndFeelDecorated()) {
Insets insets = getInsets();
dim.width += insets.left + insets.right;
dim.height += insets.bottom + insets.top;
}
return dim;
}
};
// add a component which reports a content-related min
JLabel label = new JLabel("Welcome to my application!");
// make it a big min
label.setFont(label.getFont().deriveFont(40f));
frame.add(label);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
Related
I have multiple JTextAreas inside a JPanel. I am using a BoxLayout to make them align vertically and fill the width of the container.
It works, but they seem to expand to fill the entire height as well.
What I really want is simple - a text area that wraps text where I can control the width but allow the height to scale dynamically as more lines are added. The above method was just my best attempt at it. If there is a solution that uses a different layout manager, different text component, etc, that works.
minimal verifiable example below:
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setPreferredSize(new Dimension(300, 300));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel textAreas = new JPanel();
textAreas.setLayout(new BoxLayout(textAreas, BoxLayout.Y_AXIS));
JTextArea area1 = new JTextArea();
area1.append("this is a string");
area1.setLineWrap(true);
area1.setWrapStyleWord(true);
textAreas.add(area1);
JTextArea area2 = new JTextArea("and another that is much longer, so that it wraps to the next line");
area2.setLineWrap(true);
area2.setWrapStyleWord(true);
textAreas.add(area2);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(textAreas);
frame.add(scrollPane);
frame.pack();
frame.setVisible(true);
}
I have done research on this topic on my own, including looking at different layout managers (http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html), and checking other questions on the site, but I haven't had much luck.
TLDR: Can I make it so each element of a layout has a height that scales to its content but a fixed width? If so how?
What I really want is simple - a text area that wraps text where I can control the width but allow the height to scale dynamically as more lines are added.
The BoxLayout respects the maximum size so the text area grows to fill all the space available in the panel. You can override the getMaximumSize() method to return the preferred height by using something like:
JTextArea area1 = new JTextArea()
{
public Dimension getMaximumSize()
{
Dimension d = super.getMaximumSize();
d.height = getPreferredSize().height;
return d;
}
};
It works...
Not really. Make the frame wider and the text will unwrap. Then shrink the frame and the scrollbar will appear. That is the text will not wrap again
What you need to do is force the panel added to the scroll pane to be the same width as the viewport. This will allow wrapping to work properly.
You do this by implementing the Scrollable interface on the panel. Specifically you need to override the getScrollableTracksViewportWidth() method to return true.
Or an easier solution is to use the Scrollable Panel class which allows you to set properties of the panel to control this behaviour.
You can replace a JPanel with the ScrollablePanel:
//JPanel textAreas = new JPanel();
ScrollablePanel textAreas = new ScrollablePanel();
textAreas.setScrollableWidth( ScrollablePanel.ScrollableSizeHint.FIT );
Edit:
If there is a solution that uses a different layout manager
Without overriding the getMaximumSize() method of the text areas and when using the Scrollable Panel you should be able to use the following layout managers.
The GridBagLayout allows you to specify the "weightx" constraint. This will allow the component to fill all the available space in the panel.
Or if you don't like specifying all the constrains of the GridBagLayout you could use the Relative Layout which support vertical/horizontal layout of components at their preferred size.
You would just need to use the following to force the component to fill the horizontal space:
//textAreas.setLayout(new BoxLayout(textAreas, BoxLayout.Y_AXIS));
RelativeLayout rl = new RelativeLayout(RelativeLayout.Y_AXIS);
rl.setFill( true );
textAreas.setLayout(rl);
UPDATE: I have received justified criticism for posting non working code. I've taken that to heart and am updating this post with a complete working example. I'm also updating the description accordingly:
I have a very simple java swing GUI whose components take up what looks to be an equal amount of vertical (Y) space as is used by the largest Y extent component, but completely unnecessarily so. I have tried to shrink those components that don't need that much vertical space using preferredSize hints but to no avail.
The basic layout is simple: There's a main window and three vertical panels. The layout is a simple GridLayout (and I would prefer to keep it that way, unless someone shows me what I need cannot be done with GridLayout). All three panels seem to be occupying the same amount of vertical space, even though in the case of the sliders, this is massive waste of space. How can I get each of the sub-panes to only use as much space as they each need? i.e. I would like the two slider windows to be only as tall as the sliders and their description need to be.
The code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class test {
public static void main(String[] arg) {
JFrame mainWindow = new JFrame();
JSlider slider1 = new JSlider(0,100,50);
JSlider slider2 = new JSlider(0,100,50);
JPanel pnlSlider1 = new JPanel();
pnlSlider1.setLayout(new GridLayout(1,1)); // 1 row, 1 column
pnlSlider1.add(new JLabel("Description for slider1"));
pnlSlider1.add(slider1);
JPanel pnlSlider2 = new JPanel();
pnlSlider2.setLayout(new GridLayout(1,1)); // 1 row, 1 column
pnlSlider2.add(new JLabel("Description for slider2"));
pnlSlider2.add(slider2);
// label should now be to the left of slider
String content = "<html>Some rather long winded HTML content</html>";
JEditorPane ep = new JEditorPane("text/html", content);
// this is the main window panel
JPanel panel = new JPanel();
panel.setLayout(new GridLayout(3,1)); // 3 rows, 1 column
panel.add(ep);
panel.add(pnlSlider1);
panel.add(pnlSlider2);
// tie it all together and display the window
mainWindow.setPreferredSize(new Dimension(300, 600));
mainWindow.setLocation(100, 100);
mainWindow.getContentPane().add(panel);
mainWindow.pack();
mainWindow.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
mainWindow.setVisible(true);
}
}
(removed rant about not having seen any GUI coding advances in 30 years as that's not pertinent to the problem and likely won't be solved in this post either)
..components take up what looks to be an equal amount of vertical (Y) space as is used by the largest Y extent component, but completely unnecessarily so.
Yes, that is the way GridLayout is designed to work.
Use a GridBagLayout or BoxLayout or GroupLayout instead, each of which can do a single column or row of components of variable size (width and height).
I am trying to write a form in java, but after dynamically inserting JLabels to the current JDialog and doing a pack() the windows is resized to minimum. The JLabels are displayed, but I have to resize the window manually.
Here is the part where the JLabels are inserted:
public void displayQuizz(Test quiz){
int xLable = 44;
int yLable = 41;
int widthLable = 403;
int heightLable = 70;
int noOfQuestion = 1;
for(Question question : quiz.getQuestions()){
JLabel lblNewLabel = new JLabel(Integer.toString(noOfQuestion) + ". " + question.getStatement());
lblNewLabel.setBounds(xLable, yLable, widthLable, heightLable);
contentPanel.add(lblNewLabel);
contentPanel.revalidate();
contentPanel.repaint();
this.pack();
noOfQuestion++;
yLable += heightLable;
}
}
The pack() method sets the size of a Window (where JFrame and JDialog are subclasses from) to the preferred size.
The preferred size is determined by
The LayoutManager, which takes the arrangement of the components and
their preferred size into account
The component itself, if it does not have a layout manager
As you don't use a layout manager in your example (and set the bounds of the label manually), you also have to specify the preferred size yourself (see getPreferredSize(), the default is 0x0, that's the problem you encountered).
I'd encourage you to get used to always use layout managers (there's quite a lot of them, and you can easily write your own layout manager strategy if none suffices your needs).
I'm trying with Swing layouts to leave a gap above controls that's calculated from the current size of the window. It basically works, except that the control only moves when the window is resized horizontally - if I resize vertically, it stays where it is - then resizing 1 pixel horizontally, it snaps into the correct place. Can anyone explain why the resizing gets ignored when I'm only resizing vertically?
I've proved the at the componentResized () is still being called on vertical resizes, and that contentPane.getWidth () and contentPane.getHeight () still give the right values. So the size of the Dimension is being set correctly, just being ignored. Its like I need to put a call into contentPane.payAttentionToUpdatesSizesOfYourComponents (), but I can't find any method that does this. contentPane.invalidate () has no effect.
Also noticed if I strip out the BorderLayout, and set the BoxLayout directly in the contentPane, then it works as I want. However while that's fine for this tiny example, the real window I have this problem on has some components in a JPanel set at NORTH with a gap above, some components in another JPanel set at SOUTH with a gap below, and a BorderLayout was the only way I could get these to position correctly so I can't strip it out.
Any advice or suggestions would be welcome!
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.Box.Filler;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.WindowConstants;
public final class ResizeOnlyWorksHorizontally
{
public static final void main (final String [] args)
{
final JFrame frame = new JFrame ();
frame.setDefaultCloseOperation (WindowConstants.EXIT_ON_CLOSE);
final JPanel contentPane = new JPanel ();
frame.setContentPane (contentPane);
contentPane.setLayout (new BorderLayout ());
final JPanel top = new JPanel ();
top.setLayout (new BoxLayout (top, BoxLayout.Y_AXIS));
contentPane.add (top, BorderLayout.NORTH);
// Put a space, then a label below it
final Dimension startSpace = new Dimension (0, 0);
final Filler filler = new Filler (startSpace, startSpace, startSpace);
top.add (filler);
top.add (new JLabel ("Text"));
contentPane.addComponentListener (new ComponentAdapter ()
{
#Override
public final void componentResized (final ComponentEvent e)
{
// Just any calc based on contentPane width and height to demo problem
final int calc = (contentPane.getWidth () + contentPane.getHeight ()) / 2;
// Alter the size of the space above the label
final Dimension newSpace = new Dimension (0, calc);
filler.setMinimumSize (newSpace);
filler.setPreferredSize (newSpace);
filler.setMaximumSize (newSpace);
}
});
frame.pack ();
frame.setVisible (true);
}
}
To answer your question, you need the following after the sizes are changed to make sure the layout manager is invoked:
filler.revalidate();
However that is NOT a good solution as your entire approach to the problem is wrong. You should not be manually calculating sizes of components like that. That is the job of a layout manager. So you need to rethink your layout stategy. Don't forget you can nest panels with different layout managers.
For example if you need a changing gap in the frame then you should probably use a BoxLayout and you can add "glue" to the start and end. Or maybe you can use a GridBagLayout because you can control how components resize based on the space available.
Read the Swing tutorial on Layout Managers for more information.
It wouldn't let me put a long enough comment under your answer camickr :( I wanted to add that after posting this I also found this, similar but not identical problem with resizing BorderLayouts, and they describe a similar situation of NORTH/SOUTH positioned controls not paying attention to vertical sizing - Java Swing BorderLayout resize difficulties
I'd tried based on the replies to that to use GridBagLayout, and did get that to work after a bit of effort. Basically its a 1x5 grid layout then with cells containing (space I forcibly resize, controls, glue, more controls, space I forcibly resize), and this worked.
You should not be manually calculating sizes of components like that.
The only thing I'm manually setting the size of is the gap above+below the controls, all the controls themselves I'm letting the layout manager deal with. The size of those gaps has to match a background image on the frame which is sized to the frame but preserving aspect ratio, so the width of that border isn't something the layout manager can figure out, the real code for the 'calc' bit in my SSCCE above is:
final int edge = Math.min (contentPane.getWidth () / 4, contentPane.getHeight () / 3);
final int imgHeight = edge * 3;
final int borderSize = (contentPane.getHeight () - imgHeight) / 2;
So if the user resizes the window to be wide, there's black borders left+right of the image, and borderSize = 0. If the user resizes the window to be tall, there's black borders above+below the image, and I want the controls to avoid going there, so they always sit in the background image.
But thanks very much for the push in the right direction :)
I have a JFrame which contains just one JPanel.
I have tried setting the Panel's size and packing the frame, but that has no effect.
If I set the JFrame's size, it will change the size so it includes the title bar and borders.
How do I set the "actual size" so it doesn't include the title bar and borders?
Example:
Thanks in advance, guys
You could set the contentPane's preferredSize and call pack on the JFrame, but in general it's usually best to let components size themselves based on their preferred sizes as determined by their layout managers.
This is an example of setting JPanel's size and packing the frame:
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setPreferredSize(new Dimension(200, 200));
frame.add(panel);
frame.pack();
frame.setVisible(true);
Did you try something like this?
If you set the preferred size of the JPanel then the JFrame's pack() method will respect it.
Use the .getInsets method on JFrame which gives you the dimensions of the sizes around the non-client area.
Then add it up to your wanted size, and set the size using setSize.
If you want to get Frame border then first use pack on your frame and after that get Frame Insets like in this code bellow:
frame.pack();
Insets insets = frame.getInsets();
int frameLeftBorder = insets.left;
int frameRightBorder = insets.right;
int frameTopBorder = insets.top;
int frameBottomBorder = insets.bottom;
Is better to use the pack method right after your setResizable(boolean) method, because resizable for some reason changes your frame borders, but if you dont use resize method then use pack method right on the start of frame constructor.
Setting the actual size of the usable space in JFrame could be done through setting the preferred size of the container in
createComponents(Container container) method. Done in this way, you skip setting the size of
the whole JFrame through setPreferredSize(new Dimension (width, length) in the run() method. So, the code will look like this:
#Override
public void run() {
JFrame frame = new JFrame();
// other code ...
this.createCompoents(frame.getContentPane());
}
private void createCompoents(Container container) {
// other code ...
container.setPreferredSize(new Dimension(width, length));
}