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 :)
Related
I have a label with an unknown amount of text. I need to display this label in a panel. The panel must have a fixed width, but the height needs to be changed to adjust to perfectly wrap whatever the text turns out to be.
So, suppose I have a limit on width of 400 pixels. The text it has to display turns out be 80 words. I need to make this text wrap onto new lines, so its basically a paragraph that is 400 pixels wide, and a previously unknown height. The height of the container needs to be no bigger than is necessary to display the paragraph.
I would love to be able to do this with some sort of layout manager that will work when I resize the frame, so if the width limit changes to say 500 pixels, the height of the label containing the existing paragraph will resize so that there is never more height that is necessary to display the label.
Think of it like someone posting an answer to this question on Stack Overflow. The width of your response is limited to the width of the div in the HTML of this site, but it's going to adjust the height of your div so that it fits your entire answer, no more and no less. I feel like I'm going crazy here; this seems like such basic functionality there has to be a simple way of doing it in Java Swing.
Here is an example of what I'm talking about. Here is a long sentence in a single line without any width restriction.
However, that's too wide because there's a 400 pixel width restriction. It needs to look like this:
Is there a way I can accomplish this wrapping + fitting height to contents with a layout manager, hopefully a box manager? Could you please give an example of the code? It needs to give the correct height for the label based on the amount of text, and I'd really like it to work when the frame gets resized as well.
Here is what I have. It doesn't work because it specifies the height based on the example text, but I need to be able to deal with a variable amount of text, so I can plug in any paragraph and the height of the label will be correct.
public class Playground {
public static void main(String[] args) {
JFrame myFrame = new JFrame();
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setBackground(Color.red);
myFrame.setSize(new Dimension(400, 600));
JPanel groupPanel = new JPanel();
myFrame.add(groupPanel);
groupPanel.setLayout(new BoxLayout(groupPanel, BoxLayout.Y_AXIS));
groupPanel.setBackground(Color.green);
JPanel itemPanel = new JPanel();
groupPanel.add(itemPanel);
itemPanel.setLayout(new GridLayout(1,1));
String msg = "<html><p>This is going to be a really long message that says a lot of words but doesnt really say anything. ";
msg += "We want label containing the message (and the itemPanel that contains it) to always have as much height as necessary ";
msg += "to display the message given the width of the frame</p></html>";
JLabel testLabel = new JLabel(msg);
testLabel.setBackground(Color.yellow);
testLabel.setOpaque(true);
itemPanel.setPreferredSize(new Dimension(400, 64));
itemPanel.setMinimumSize(new Dimension(400, 64));
itemPanel.setMaximumSize(new Dimension(400, 64));
itemPanel.add(testLabel);
myFrame.pack();
myFrame.setVisible(true);
}
}
This was a previous answer that helped by getting the frame to pack around a 400px paragraph:
If the only reason you need HTML is for wrapping, then maybe you can
use a JTextArea instead:
//JLabel testLabel = new JLabel(msg);
JTextArea testLabel = new JTextArea();
testLabel.setText(msg);
testLabel.setLineWrap( true );
testLabel.setWrapStyleWord( true );
testLabel.setSize(400, 1);
The setSize(...) statement will provide the hint for the text area on
when to wrap so it can calculate its actual preferred size.
You can always set the properties of the text area to make is look
like a label.
It helps when the frame is initialized, but when I resize the frame the height of the label doesn't change, so maybe I just have to keep calling pack? I'm not sure how I would place that in an event handler though.
Back to the JLabel and HTML:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Playground {
public static void main(String[] args) {
JFrame myFrame = new JFrame();
myFrame.setAlwaysOnTop(true);
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setPreferredSize(new Dimension(350, 130));
JPanel groupPanel = new JPanel();
groupPanel.setLayout(new GridLayout(1,1));
String msg = "<html><p align='justify'>This is going to be a really long "
+ "message that says a lot of words but doesnt really say anything. "
+ "We want label containing the message (and the itemPanel that "
+ "contains it to always have as much height as necessary to display "
+ "the message given the width of the frame.</p></html>";
JLabel testLabel = new JLabel(msg);
testLabel.setBackground(Color.yellow);
testLabel.setVerticalAlignment(JLabel.TOP);
testLabel.setOpaque(true);
groupPanel.add(testLabel);
myFrame.add(groupPanel);
myFrame.pack();
myFrame.setVisible(true);
myFrame.setLocationRelativeTo(null);
}
}
And here is what the code does:
This is definitely a noob question. How do I resize two JTextArea panels so they look something like this:
aaaaaaaaaaaaaa
a a a
a a a
a a a
aaaaaaaaaaaaaa
With the first area about a tenth of the width of the second. I must also enclose this in a new scroll pane, but I've taken care of that. the resize function doesn't seem to be working.
When you create the text areas you use something like:
JTextArea textArea1 = new JTextArea(10, 10);
JTextArea textArea2 = new JTextArea(10, 80);
The two numbers provide a suggestion for the number of rows and characters in each row.
Then you add them to a scroll pane:
JPanel panel = new JPanel();
panel.add(textArea1);
panel.add(textArea2);
JScrollPane scrollPane = new JScrollPane( panel );
frame.add(scrollPane):
The above code will give you fixed size text areas.
Or, if you really want to do it by percentage and allow the text areas to dynamically grow/shrink you would use:
JTextArea textArea1 = new JTextArea(10, 1);
JTextArea textArea2 = new JTextArea(10, 1);
And then add them to a JPanel using a GridBagLayout with the appropriate constraints. You would need to use:
1. the "fill" constraint which would allow the text areas to grow as the space available grows.
2. the "weightx" contstraint. This will allow you to allocate extra space in the percentage that you desire.
Read the section from the Swing tutorial on How to Use GridBagLayout for more information and working examples.
You can use a JSplitPane to split horizontally (or vertically) the two components (text areas). This approach lets the user to freely move the divider (ie the vertical separator of the two areas) to a location he/she prefers.
As for the preference on the allocation of space of each component, you can use the setResizeWeight method which will distribute the new space allocated for the split pane (each time the user resizes the window) according to the value you specify. For example calling this method with a value of 0.5 will distribute the new size equally to both left and right components. A value of 0 will give all the extra space at the right component. A value of 1 will give it to the left component. A value of 1.0 / 3.0 will split the new space to three and then reserve the first third to the left component and the other two thirds to the right component. And so on...
This should be good user-experience, although if you don't want the user to relocate the divider by himself/herself, then use camickr's answer.
Here's a working example:
import java.awt.Component;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class Main {
private static Component buildTextAreaContainer() {
final JTextArea txt = new JTextArea();
final JScrollPane scroll = new JScrollPane(txt);
return scroll;
}
public static void main(final String[] args) {
SwingUtilities.invokeLater(() -> {
final JSplitPane split = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, buildTextAreaContainer(), buildTextAreaContainer());
//split.setContinuousLayout(true);
//split.setOneTouchExpandable(true);
split.setResizeWeight(1d / 3d); //one third for left component, two thirds for right component.
split.setPreferredSize(new Dimension(1000, 600));
final JFrame frame = new JFrame("Splitted text areas test.");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(split);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}
To learn more about how to use the JSplitPane you can read the corresponding tutorial or the docs themselves.
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'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);
I'm working on building a chess game in Java, and I'm currently having a bit of trouble getting the GUI exactly the way I want it with Swing. I'm using a GridLayout to organize a grid of 8x8 ChessButtons (which override the JButton so that I can store extra information inside of them such as coordinates). Originally, the ChessButtons wouldn't appear unless I moused over them, but I solved that problem by placing each ChessButton inside a separate JPanel and setting each button's setPreferredSize() to a set height and width.
Now, my problem is that there seems to be a small margin or padding above (and/or below?) each button. I've made sure to set setHgap(0) and setVgap(0) for the GridLayout, so I'm pretty sure the mysterious margin is coming from either the buttons or the JPanels. But, I can't seem to get rid of them, and they seem to be causing each ChessButton to shift a little bit up/down whenever I mouse of them.
I realize this description of the problem might be a little hard to visualize, so I've taken a screenshot (using JButtons rather than ChessButtons so the gaps are slightly easier to recognize): http://img3.imageshack.us/img3/6656/jbuttonmargins.png
Here is the code I used to initialize each ChessButton:
chessBoard = new JPanel(new GridLayout(8, 8, 0, 0));
chessBoard.setBorder(BorderFactory.createEmptyBorder());
for (int i = 0; i <= 65; i++) {
//Create a new ChessButton
ChessButton button = new ChessButton("hi");
button.setBorder(BorderFactory.createEmptyBorder());
button.setPreferredSize(new Dimension(75, 75));
button.setMargin(new Insets(0, 0, 0, 0));
//Create a new JPanel that the ChessButton will go into
JPanel buttonPanel = new JPanel();
buttonPanel.setPreferredSize(new Dimension(75, 75));
buttonPanel.setBorder(BorderFactory.createEmptyBorder());
buttonPanel.add(button);
//Add the buttonPanel to the grid
chessBoard.add(buttonPanel);
}
So, how can I get rid of these vertical spaces between buttons? I'm relatively new to Swing, so I'm sorry if the answer is extremely obvious, but I'd appreciate any help anyone might have to offer! Thanks in advance!
Don't add an empty border; do use setBorderPainted(false).
Addendum: As #camickr notes, the panel's layout may include default gaps. The example below uses no-gap GridLayout accordingly.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
/** #see http://stackoverflow.com/questions/4331699 */
public class ButtonBorder extends JPanel {
private static final int N = 8;
private static final int SIZE = 75;
public ButtonBorder() {
super(new GridLayout(N, N));
this.setPreferredSize(new Dimension(N * SIZE, N * SIZE));
for (int i = 0; i < N * N; i++) {
this.add(new ChessButton(i));
}
}
private static class ChessButton extends JButton {
public ChessButton(int i) {
super(i / N + "," + i % N);
this.setOpaque(true);
this.setBorderPainted(false);
if ((i / N + i % N) % 2 == 1) {
this.setBackground(Color.gray);
}
}
}
private void display() {
JFrame f = new JFrame("ButtonBorder");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ButtonBorder().display();
}
});
}
}
Originally, the ChessButtons wouldn't appear unless I moused over them, but I solved that problem by placing each ChessButton inside a separate JPanel and setting each button's setPreferredSize() to a set height and width
That is not the proper solution. There is no reason to use a JPanel to hold the buttons. In fact, this is probably the cause of the problem. The buttons should show up when you add them to a GridLayout. If they don't show up its probably because you added the buttons to the GUI after making the GUI visible. Components should be added to the GUI BEFORE it is made visible.
Now, my problem is that there seems to be a small margin or padding above (and/or below?) each button
I don't understand why there also isn't a horizontal gap. When you create a JPanel, by default it uses a FlowLayout which also contains a horizontal/vertical gap of 5 pixels. So I understand why you might have the vertical gap of 10 pixels. I don't understand why there is no horizontal gap.
If you need more help post your SSCCE demonstrating the problem. And the SSCCE should use regular JButtons. Get the basics working with standard components before you start playing with custom components. That way you know if the problem is with your custom code or not.
Try adding chessBoard.setPreferredSize(600, 600) to create a JPanel for the board that only has room to fit the buttons (8 buttons each way * 75 size each way on the buttons).