Java JComponent paint --Almost working

Java JComponent paint --Almost working - java

I almost have the repaint() Jcomponent working. I had it working and then tried to make an absolute positioning and now it doesn't work.
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
public class DDHGenericFrame {
private static final long serialVersionUID = 1L;
DDHGenericPanel d = new DDHGenericPanel();
//DDHCircleOne o = new DDHCircleOne();
public DDHGenericFrame() {
initUI();
}
public final void initUI() {
JFrame frame = new JFrame("AbsoluteLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("Draw Circle");
frame.setBackground(Color.green);
frame.setLayout(null);
frame.setSize(300,425);
frame.add(d);
// frame.add(o);//didn't work neither
frame.setVisible(true);
}
public static void main(String[] args) {
DDHGenericFrame ex = new DDHGenericFrame();
}
}
Class 2: (This is the JComponent that I am trying to set)
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JComponent;
public class DDHTestDraw extends JComponent {
public DDHTestDraw () {
settPreferredSize();
}
public void settPreferredSize() {
Dimension d = new Dimension(25,25);
setPreferredSize(d);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawString("Text",20,20);
}
}
I added my component to the Container and then added the container to the JPanel and then the JPanel is added to the JFrame. I would think that this should work. I have a set preferred size. I had it working once and now it doesn't work.
I want to be able to make a component that is a circle. I want that circle to be able to be drawn any where on a Jframe, and then I want that circle to be able to move based on a a certain length of time. I am going to make a game that has circles dropping from the top and then falling to the bottom. When I had it working I did have the circle being written to the JPanel which is a complex piece of code. But I have had to go back to the old simple method of writing a single graphical word.

When you use null layout, you are completely responsible for making sure that components added have proper location and size (not preferredSize) set.
You should almost never use null layout.
Wouldn't this sort of thing work better by creating a logical class to represent the Circle, not a component? Then your drawing JPanel could hold a collection of logical circles, and the drawing JPanel could be responsible for drawing each Circle in its paintComponent method.
Edit
Your comments/my replies:
when you say never use an absolute layout, the company that I worked for always used a absolute layout only.
There are times when it is useful, but not for creating a typical component-filled GUI. Otherwise the GUI becomes very hard to modify and maintain.
When you mean a logical class you mean a class that just creates one circle.
Yes, and that holds all the necessary properties of that circle such as its Color, location, movement, etc..
Then the Jpanel would draw each circle.
Yes. I would imagine the drawing JPanel having an ArrayList<MyCircle> of them, and the paintComponent method iterating througgh this List.
when you say Size this is a property in JComponent.
I think that it is a property of Component, JComponent's parent. If you use null layout, then all components must have their size and location specified. Otherwise the component defaults to a location of [0, 0] and a size of [0, 0].
Edit 2
public Dimension Size(int a, int b) {
Dimension d = new Dimension();
d.width = a;
d.height = b;
return d;
}
This is the code that I used for the preferred size. I am at a lost why this doesn't work.
This code has no effect on either the size or the preferredSize properties of Component/JComponent. It doesn't surprise me that it will not help you. You would either have to override getSize() or getPreferredSize() or explicitly call setSize(...) or getPreferredSize(...) to change the state of the properties.
I am going to try it with a different layout manager and see but I would see the difference between one layout manager or another.
I'm not sure how to interpret this.
Edit 3
You state:
I worked at one company and we used absulute layouts all of the time. How would an absolute layout not work as good as, say BorderLayout(). To me the BorderLayout() are harder to implement. Or is it that you use a Jframe() with a BorderLayout, and then insert a Jpanel into an already existing position that is already also a BorderLayout(). I always have trouble getting my buttions and positions correct in a layout that is something different than a BorderLayout(). Can you post an example that would be easier to use than
I'm guessing you want an example of where use of layout managers is easier than using absolute positioning.
Let's take the example of a very simple calculator, one with buttons for numeric input and simple operations. Again this example is very basic, and is non-functional, but serves to illustrate the use of layouts. I could easily place my buttons in a GridLayout-using JPanel, and then place that button JPanel into a BorderLayout-using JPanel at the BorderLayout.CENTER position with the JTextField, display, placed in the same BorderLayout-using JPanel at the BorderLayout.PAGE_START position:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.*;
public class CalcEg {
private static final float BTN_FONT_SIZE = 20f;
private static final String[][] BTN_LABELS = {
{"7", "8", "9", "-"},
{"4", "5", "6", "+"},
{"1", "2", "3", "/"},
{"0", ".", " ", "="}
};
private static final int GAP = 4;
private JPanel mainPanel = new JPanel(new BorderLayout(GAP, GAP));
private JPanel buttonPanel = new JPanel();
private JTextField display = new JTextField();
public CalcEg() {
int rows = BTN_LABELS.length;
int cols = BTN_LABELS[0].length;
buttonPanel.setLayout(new GridLayout(rows, cols, GAP, GAP));
for (String[] btnLabelRow : BTN_LABELS) {
for (String btnLabel : btnLabelRow) {
if (btnLabel.trim().isEmpty()) {
buttonPanel.add(new JLabel());
} else {
JButton btn = createButton(btnLabel);
buttonPanel.add(btn);
}
}
}
display.setFont(display.getFont().deriveFont(BTN_FONT_SIZE));
display.setEditable(false);
display.setFocusable(false);
display.setBackground(Color.white);
mainPanel.setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
mainPanel.add(buttonPanel, BorderLayout.CENTER);
mainPanel.add(display, BorderLayout.PAGE_START);
}
private JButton createButton(String btnLabel) {
JButton button = new JButton(btnLabel);
button.setFont(button.getFont().deriveFont(BTN_FONT_SIZE));
return button;
}
public JComponent getMainComponent() {
return mainPanel;
}
private static void createAndShowGui() {
CalcEg mainPanel = new CalcEg();
JFrame frame = new JFrame("CalcEg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainComponent());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
This would result in a calculator that looks like so:
Now, sure you could say that you could produce this with null layout and setbounds(...), and that's all well and good, but now say that you're not satisfied with this calculator, and now desire that it has some scientific calculation functionality. Say you now want to add buttons for square, square root, exponential, and logarithm, but not only that, say you wish to add the buttons below the display and above the numeric and basic operations buttons. If you were to do this with null layout, you would have to reposition all the components below and to the right of any new components added, and you'd have to expand the size of the JTextField, all calculations that are tedious and prone to error.
If you used layout managers, you would instead only need to add one line of code, actually an additional row to an array:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.*;
public class CalcEg {
private static final float BTN_FONT_SIZE = 20f;
private static final String[][] BTN_LABELS = {
{"sqr", "sqrt", "exp", "log"}, // ******* Line Added Here *********
{"7", "8", "9", "-"},
{"4", "5", "6", "+"},
{"1", "2", "3", "/"},
{"0", ".", " ", "="}
};
private static final int GAP = 4;
private JPanel mainPanel = new JPanel(new BorderLayout(GAP, GAP));
private JPanel buttonPanel = new JPanel();
private JTextField display = new JTextField();
public CalcEg() {
int rows = BTN_LABELS.length;
int cols = BTN_LABELS[0].length;
buttonPanel.setLayout(new GridLayout(rows, cols, GAP, GAP));
for (String[] btnLabelRow : BTN_LABELS) {
for (String btnLabel : btnLabelRow) {
if (btnLabel.trim().isEmpty()) {
buttonPanel.add(new JLabel());
} else {
JButton btn = createButton(btnLabel);
buttonPanel.add(btn);
}
}
}
display.setFont(display.getFont().deriveFont(BTN_FONT_SIZE));
display.setEditable(false);
display.setFocusable(false);
display.setBackground(Color.white);
mainPanel.setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
mainPanel.add(buttonPanel, BorderLayout.CENTER);
mainPanel.add(display, BorderLayout.PAGE_START);
}
private JButton createButton(String btnLabel) {
JButton button = new JButton(btnLabel);
button.setFont(button.getFont().deriveFont(BTN_FONT_SIZE));
return button;
}
public JComponent getMainComponent() {
return mainPanel;
}
private static void createAndShowGui() {
CalcEg mainPanel = new CalcEg();
JFrame frame = new JFrame("CalcEg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainComponent());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
which would result in this GUI:
Again this is a very simplistic example, but the general principles apply to any GUI that holds components such as JButtons, JTextComponents, etc.

With Swing animation, the Timer class is an exceptional option.
//this class is a JPanel that implements ActionListener`
Timer t = new Timer(1000,this);//the first arg is how many times it repeats in milliseconds
//Then in the constructor...
t.start();
//the ActionPerformed function normally increments a variable then calls the repaint method.
rectangle_x++;
repaint(); //calls paintComponent
Another good idea is to cast g to a Graphics2D object- it's a lot safer and more capable.

Another way to use the Timer class:
Timer t = new Timer(510, new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
rectangle_x++;
repaint();
}
})
...
t.start();
You still need to override actionPerformed() in your main class though.

Related

Make the animation faster when there are thousands of components

I am trying to hide a JSplitPane with animation. By hide, I mean to setDividerLocation(0) so its left component is invisible (technically it is visible, but with zero width):
public class SplitPaneTest {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
JPanel leftPanel = new JPanel(new BorderLayout());
leftPanel.setBorder(BorderFactory.createLineBorder(Color.green));
JPanel rightPanel = new JPanel(new GridLayout(60, 60));
for (int i = 0; i < 60 * 60; i++) {
// rightPanel.add(new JLabel("s"));
}
rightPanel.setBorder(BorderFactory.createLineBorder(Color.red));
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel, rightPanel);
frame.add(splitPane);
JButton button = new JButton("Press me to hide");
button.addActionListener(e -> hideWithAnimation(splitPane));
leftPanel.add(button, BorderLayout.PAGE_START);
frame.setMaximumSize(new Dimension(800, 800));
frame.setSize(800, 800);
frame.setLocationByPlatform(true);
frame.setVisible(true);
});
}
private static void hideWithAnimation(JSplitPane splitPane) {
final Timer timer = new Timer(10, null);
timer.addActionListener(e -> {
splitPane.setDividerLocation(Math.max(0, splitPane.getDividerLocation() - 3));
if (splitPane.getDividerLocation() == 0)
timer.stop();
});
timer.start();
}
}
If you run it, will see that everything seems good, and the animation runs smooth.
However, in the real application the right of the JSplitPane is a JPanel with CardLayout and each card has a lot of components.
If you uncomment this line in order to simulate the number of components:
// rightPanel.add(new JLabel("s"));
and re-run the above example, you will see that the animation no longer runs smoothly. So, the question is, is is possible to make it smooth(-ier)?
I have no idea how to approach a solution - if any exists.
Based on my research, I registered a global ComponentListener:
Toolkit.getDefaultToolkit()
.addAWTEventListener(System.out::println, AWTEvent.COMPONENT_EVENT_MASK);
and saw the tons of events that are being fired. So, I think the source of the problem is the tons of component events that are being fired for each component. Also, it seems that components with custom renderers (like JList - ListCellRenderer and JTable - TableCellRenderer), component events are firing for all of the renderers. For example, if a JList has 30 elements, 30 events (component) will be fired only for it. It also seems (and that's why I mentioned it) that for CardLayout, events are taking place for the "invisible" components as well.
I know that 60*60 might sound crazy to you, but in a real application (mine has ~1500) as it makes sense, the painting is heavier.

I know that 60*60 might sound crazy to you, but in a real application (mine has ~1500) as it makes sense, the painting is heavier.
The layout manager is invoked every time the divider location is changed which would add a lot of overhead.
One solution might be to stop invoking the layout manager as the divider is animating. This can be done by overriding the doLayout() method of the right panel:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class SplitPaneTest2 {
public static boolean doLayout = true;
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
JPanel leftPanel = new JPanel(new BorderLayout());
leftPanel.setBorder(BorderFactory.createLineBorder(Color.green));
JPanel rightPanel = new JPanel(new GridLayout(60, 60))
{
#Override
public void doLayout()
{
if (SplitPaneTest2.doLayout)
super.doLayout();
}
};
for (int i = 0; i < 60 * 60; i++) {
rightPanel.add(new JLabel("s"));
}
rightPanel.setBorder(BorderFactory.createLineBorder(Color.red));
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel, rightPanel);
frame.add(splitPane);
JButton button = new JButton("Press me to hide");
button.addActionListener(e -> hideWithAnimation(splitPane));
leftPanel.add(button, BorderLayout.PAGE_START);
frame.setMaximumSize(new Dimension(800, 800));
frame.setSize(800, 800);
frame.setLocationByPlatform(true);
frame.setVisible(true);
});
}
private static void hideWithAnimation(JSplitPane splitPane) {
SplitPaneTest2.doLayout = false;
final Timer timer = new Timer(10, null);
timer.addActionListener(e -> {
splitPane.setDividerLocation(Math.max(0, splitPane.getDividerLocation() - 3));
if (splitPane.getDividerLocation() == 0)
{
timer.stop();
SplitPaneTest2.doLayout = true;
splitPane.getRightComponent().revalidate();
}
});
timer.start();
}
}
Edit:
I was not going to include my test on swapping out the panel full of components with a panel that uses an image of components since I fell the animation is the same, but since it was suggested by someone else here is my attempt for your evaluation:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.image.*;
public class SplitPaneTest2 {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
JPanel leftPanel = new JPanel(new BorderLayout());
leftPanel.setBorder(BorderFactory.createLineBorder(Color.green));
JPanel rightPanel = new JPanel(new GridLayout(60, 60));
for (int i = 0; i < 60 * 60; i++) {
rightPanel.add(new JLabel("s"));
}
rightPanel.setBorder(BorderFactory.createLineBorder(Color.red));
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT, leftPanel, rightPanel);
frame.add(splitPane);
JButton button = new JButton("Press me to hide");
button.addActionListener(e -> hideWithAnimation(splitPane));
leftPanel.add(button, BorderLayout.PAGE_START);
frame.setMaximumSize(new Dimension(800, 800));
frame.setSize(800, 800);
frame.setLocationByPlatform(true);
frame.setVisible(true);
});
}
private static void hideWithAnimation(JSplitPane splitPane) {
Component right = splitPane.getRightComponent();
Dimension size = right.getSize();
BufferedImage bi = new BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g = bi.createGraphics();
right.paint( g );
g.dispose();
JLabel label = new JLabel( new ImageIcon( bi ) );
label.setHorizontalAlignment(JLabel.LEFT);
splitPane.setRightComponent( label );
splitPane.setDividerLocation( splitPane.getDividerLocation() );
final Timer timer = new Timer(10, null);
timer.addActionListener(e -> {
splitPane.setDividerLocation(Math.max(0, splitPane.getDividerLocation() - 3));
if (splitPane.getDividerLocation() == 0)
{
timer.stop();
splitPane.setRightComponent( right );
}
});
timer.start();
}
}

#GeorgeZ. I think the concept presented by #camickr has to do with when you actually do the layout. As an alternative to overriding doLayout, I would suggest subclassing the GridLayout to only lay out the components at the end of the animation (without overriding doLayout). But this is the same concept as camickr's.
Although if the contents of your components in the right panel (ie the text of the labels) remain unchanged during the animation of the divider, you can also create an Image of the right panel when the user clicks the button and display that instead of the actual panel. This solution, I would imagine, involves:
A CardLayout for the right panel. One card has the actual rightPanel contents (ie the JLabels). The second card has only one JLabel which will be loaded with the Image (as an ImageIcon) of the first card.
As far as I know, by looking at the CardLayout's implementation, the bounds of all the child components of the Container are set during layoutContainer method. That would probably mean that the labels would be layed out inspite being invisible while the second card would be shown. So you should probably combine this with the subclassed GridLayout to lay out only at the end of the animation.
To draw the Image of the first card, one should first create a BufferedImage, then createGraphics on it, then call rightPanel.paint on the created Graphics2D object and finally dispose the Graphics2D object after that.
Create the second card such that the JLabel would be centered in it. To do this, you just have to provide the second card with a GridBagLayout and add only one Component in it (the JLabel) which should be the only. GridBagLayout always centers the contents.
Let me know if such a solution could be useful for you. It might not be useful because you could maybe want to actually see the labels change their lay out profile while the animation is in progress, or you may even want the user to be able to interact with the Components of the rightPanel while the animation is in progress. In both cases, taking a picture of the rightPanel and displaying it instead of the real labels while the animation takes place, should not suffice. So it really depends, in this case, on how dynamic will be the content of the rightPanel. Please let me know in the comments.
If the contents are always the same for every program run, then you could probably pre-create that Image and store it. Or even, a multitude of Images and store them and just display them one after another when the animation turns on.
Similarly, if the contents are not always the same for every program run, then you could also subclass GridLayout and precalculate the bounds of each component at startup. Then that would make GridLayout a bit faster in laying out the components (it would be like encoding a video with the location of each object), but as I am testing it, GridLayout is already fast: it just calculates about 10 variables at the start of laying out, and then imediately passes over to setting the bounds of each Component.
Edit 1:
And here is my attempt of my idea (with the Image):
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics2D;
import java.awt.GraphicsConfiguration;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Transparency;
import java.awt.image.BufferedImage;
import java.util.Objects;
import java.util.function.Consumer;
import java.util.function.IntBinaryOperator;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSplitPane;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class SplitPaneTest {
//Just a Timer which plays the animation of the split pane's divider going from side to side...
public static class SplitPaneAnimationTimer extends Timer {
private final JSplitPane splitPane;
private int speed, newDivLoc;
private IntBinaryOperator directionf;
private Consumer<SplitPaneAnimationTimer> onFinish;
public SplitPaneAnimationTimer(final int delay, final JSplitPane splitPane) {
super(delay, null);
this.splitPane = Objects.requireNonNull(splitPane);
super.setRepeats(true);
super.setCoalesce(false);
super.addActionListener(e -> {
splitPane.setDividerLocation(directionf.applyAsInt(newDivLoc, splitPane.getDividerLocation() + speed));
if (newDivLoc == splitPane.getDividerLocation()) {
stop();
if (onFinish != null)
onFinish.accept(this);
}
});
speed = 0;
newDivLoc = 0;
directionf = null;
onFinish = null;
}
public int getSpeed() {
return speed;
}
public JSplitPane getSplitPane() {
return splitPane;
}
public void play(final int newDividerLocation, final int speed, final IntBinaryOperator directionf, final Consumer<SplitPaneAnimationTimer> onFinish) {
if (newDividerLocation != splitPane.getDividerLocation() && Math.signum(speed) != Math.signum(newDividerLocation - splitPane.getDividerLocation()))
throw new IllegalArgumentException("Speed needs to be in the direction towards the newDividerLocation (from the current position).");
this.directionf = Objects.requireNonNull(directionf);
newDivLoc = newDividerLocation;
this.speed = speed;
this.onFinish = onFinish;
restart();
}
}
//Just a GridLayout subclassed to only allow laying out the components only if it is enabled.
public static class ToggleGridLayout extends GridLayout {
private boolean enabled;
public ToggleGridLayout(final int rows, final int cols) {
super(rows, cols);
enabled = true;
}
#Override
public void layoutContainer(final Container parent) {
if (enabled)
super.layoutContainer(parent);
}
public void setEnabled(final boolean enabled) {
this.enabled = enabled;
}
}
//How to create a BufferedImage (instead of using the constructor):
private static BufferedImage createBufferedImage(final int width, final int height, final boolean transparent) {
final GraphicsEnvironment genv = GraphicsEnvironment.getLocalGraphicsEnvironment();
final GraphicsDevice gdev = genv.getDefaultScreenDevice();
final GraphicsConfiguration gcnf = gdev.getDefaultConfiguration();
return transparent
? gcnf.createCompatibleImage(width, height, Transparency.TRANSLUCENT)
: gcnf.createCompatibleImage(width, height);
}
//This is the right panel... It is composed by two cards: one for the labels and one for the image.
public static class RightPanel extends JPanel {
private static final String CARD_IMAGE = "IMAGE",
CARD_LABELS = "LABELS";
private final JPanel labels, imagePanel; //The two cards.
private final JLabel imageLabel; //The label in the second card.
private final int speed; //The speed to animate the motion of the divider.
private final SplitPaneAnimationTimer spat; //The Timer which animates the motion of the divider.
private String currentCard; //Which card are we currently showing?...
public RightPanel(final JSplitPane splitPane, final int delay, final int speed, final int rows, final int cols) {
super(new CardLayout());
super.setBorder(BorderFactory.createLineBorder(Color.red));
spat = new SplitPaneAnimationTimer(delay, splitPane);
this.speed = Math.abs(speed); //We only need a positive (absolute) value.
//Label and panel of second card:
imageLabel = new JLabel();
imageLabel.setHorizontalAlignment(JLabel.CENTER);
imageLabel.setVerticalAlignment(JLabel.CENTER);
imagePanel = new JPanel(new GridBagLayout());
imagePanel.add(imageLabel);
//First card:
labels = new JPanel(new ToggleGridLayout(rows, cols));
for (int i = 0; i < rows * cols; ++i)
labels.add(new JLabel("|"));
//Adding cards...
final CardLayout clay = (CardLayout) super.getLayout();
super.add(imagePanel, CARD_IMAGE);
super.add(labels, CARD_LABELS);
clay.show(this, currentCard = CARD_LABELS);
}
//Will flip the cards.
private void flip() {
final CardLayout clay = (CardLayout) getLayout();
final ToggleGridLayout labelsLayout = (ToggleGridLayout) labels.getLayout();
if (CARD_LABELS.equals(currentCard)) { //If we are showing the labels:
//Disable the laying out...
labelsLayout.setEnabled(false);
//Take a picture of the current panel state:
final BufferedImage pic = createBufferedImage(labels.getWidth(), labels.getHeight(), true);
final Graphics2D g2d = pic.createGraphics();
labels.paint(g2d);
g2d.dispose();
imageLabel.setIcon(new ImageIcon(pic));
imagePanel.revalidate();
imagePanel.repaint();
//Flip the cards:
clay.show(this, currentCard = CARD_IMAGE);
}
else { //Else if we are showing the image:
//Enable the laying out...
labelsLayout.setEnabled(true);
//Revalidate and repaint so as to utilize the laying out of the labels...
labels.revalidate();
labels.repaint();
//Flip the cards:
clay.show(this, currentCard = CARD_LABELS);
}
}
//Called when we need to animate fully left motion (ie until reaching left side):
public void goLeft() {
final JSplitPane splitPane = spat.getSplitPane();
final int currDivLoc = splitPane.getDividerLocation(),
minDivLoc = splitPane.getMinimumDividerLocation();
if (CARD_LABELS.equals(currentCard) && currDivLoc > minDivLoc) { //If the animation is stopped:
flip(); //Show the image label.
spat.play(minDivLoc, -speed, Math::max, ignore -> flip()); //Start the animation to the left.
}
}
//Called when we need to animate fully right motion (ie until reaching right side):
public void goRight() {
final JSplitPane splitPane = spat.getSplitPane();
final int currDivLoc = splitPane.getDividerLocation(),
maxDivLoc = splitPane.getMaximumDividerLocation();
if (CARD_LABELS.equals(currentCard) && currDivLoc < maxDivLoc) { //If the animation is stopped:
flip(); //Show the image label.
spat.play(maxDivLoc, speed, Math::min, ignore -> flip()); //Start the animation to the right.
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
JPanel leftPanel = new JPanel(new BorderLayout());
leftPanel.setBorder(BorderFactory.createLineBorder(Color.green));
int rows, cols;
rows = cols = 60;
JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
final RightPanel rightPanel = new RightPanel(splitPane, 10, 3, rows, cols);
splitPane.setLeftComponent(leftPanel);
splitPane.setRightComponent(rightPanel);
JButton left = new JButton("Go left"),
right = new JButton("Go right");
left.addActionListener(e -> rightPanel.goLeft());
right.addActionListener(e -> rightPanel.goRight());
final JPanel buttons = new JPanel(new GridLayout(1, 0));
buttons.add(left);
buttons.add(right);
frame.add(splitPane, BorderLayout.CENTER);
frame.add(buttons, BorderLayout.PAGE_START);
frame.setSize(1000, 800);
frame.setMaximumSize(frame.getSize());
frame.setLocationByPlatform(true);
frame.setVisible(true);
splitPane.setDividerLocation(0.5);
});
}
}

Reordering labels

I'm creating labels dynamically from an array in a FlowLayout JPanel, storing them in a JLabel array for future reference. They are displayed from left to right as intended.
I want to move one of the labels to the beginning (leftmost) of the panel.
I don't mind if the whole array shifts or just two labels swap places:
apple orange pear cherry melon
|
cherry apple orange pear melon
or
cherry orange pear apple melon
I've swapped array entries, then revalidate() and repaint(), but nothing happens.
Is there an easy way to move swing components around without removing all and then re-adding them to the panel or copying all the properties from one label to the other (I have others defined, not just the text)?
Here is a stripped down version of my code:
import javax.swing.*;
public class Test extends JPanel {
public Test () {
String entries[] = { "apple", "orange", "pear", "cherry", "melon" };
JLabel[] lbls = new JLabel[entries.length];
for (int i = 0; i < entries.length; ++i) {
lbls[i] = new JLabel();
lbls[i].setText(entries[i]);
add(lbls[i]);
}
// swap array entries
JLabel tmplbl = new JLabel();
tmplbl = lbls[3];
lbls[3] = lbls[0];
lbls[0] = tmplbl;
revalidate();
repaint();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Test");
frame.setContentPane(new Test());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.pack();
}
});
}
}

I've swapped array entries
Swapping entries in an array does nothing. The Array has nothing to do with the panel.
So you need to adjust the components on the panel.
I want to move one of the labels to the beginning (leftmost) of the panel.
Well that is a different requirement than "swapping". It is also easier.
You can add a component to a panel and specify its position in the panel, so adding a component to the beginning is easy because its position will always be zero.
So to move the 3rd component to the beginning the code would be something like:
Component component = panel.getComponent(2);
panel.add(component, 0);
panel.revalidate();
panel.repaint();
If you really want a swap, then the code would be similar. You would get the component at both locations and then add the one component back to the lower location first and the add the other component back to the higher location.

There are a couple of things to fix before fixing your error:
Here are 2 errors in this line: public class Test extends JPanel {
Class name, do you know how many people call their classes Test? A LOT! Make it more descriptive, like SwapLabelsTest.
extends JPanel, you're not changing the behavior of the JPanel so there's no need to extend it in this case, just create a new instance of JPanel.
Don't put everything in the constructor, it's better to have an initialize() method or something like that (createAndShowGUI() in the code below) to handle GUI construction. It may seem like the easiest way, but separating that part will come handy later on when the project becomes bigger.
Move your variables to a bigger scope, for easier handling, unless those variables are local to the method, this will improve performance and readability.
Include a component that detects events, such as a JButton so that your swapping execution will happen when that event is triggered (a button click).
Your swapping logic seems a little bit odd, you have created new JLabels there and are trying to swap them, but it's better to have a MVC kind of pattern here, so that you swap the values in the array and then just update the UI after with those changes.
You may be asking, but how do I do that? Well like this:
String tmpString = entries[3];
entries[3] = entries[1];
entries[1] = tmpString;
The above code swaps the values in the entries array, all we have to do now is update each label with lbl[i].setText(entries[i]) inside of a for-loop.
So, you end up with something like this in the end:
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
private JFrame frame;
private JPanel panel;
private String entries[] = { "apple", "orange", "pear", "cherry", "melon" };
private JLabel[] lbls = new JLabel[entries.length];
JButton button;
private void createAndShowGUI() {
panel = new JPanel();
for (int i = 0; i < entries.length; ++i) {
lbls[i] = new JLabel();
lbls[i].setText(entries[i]);
panel.add(lbls[i]);
}
button = new JButton("Swap 1 and 3");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
String tmpString = entries[3];
entries[3] = entries[1];
entries[1] = tmpString;
reloadLabels();
}
});
frame = new JFrame("Test");
frame.add(panel);
frame.add(button, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.pack();
}
private void reloadLabels() {
for (int i = 0; i < entries.length; ++i) {
lbls[i].setText(entries[i]);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Test().createAndShowGUI();
}
});
}
}
Everytime you click the button, the items 1 & 3 (indexes) will be swapped and the UI will be updated (as .setText triggers an UI update).

Paint two overlaid JLabels

I want to paint a JLabel over another.
I override paint() so that a second JLabel is painted after calling super.paint().
However this second JLabel is not painted at all (because it is not showing, I think).
How can I achieve that effect?
public class OverlaidJLabel extends JLabel {
private String upperText;
public OverlaidJLabel(){
}
public void setUpperText(String upperText){
this.upperText = upperText;
}
#Override
public void paint(Graphics g){
super.paint(g);
JLabel upperLabel = new JLabel(upperText);
upperLabel.paint(g);
}
}

Some big problems here:
You don't want to override paint in this situation but rather paintComponent
You never want to create components within a painting method. These methods should be for painting and painting only as you'll be creating components many times (since painting methods can be called many times -- and completely out of your control) when they only should be created once, and you don't want to ever slow painting down since this hampers the perceived responsiveness of your GUI.
It makes no sense to create a component that is never added to the GUI, such as your upperLabel. Calling its paint method will achieve absolutely nothing (as you're finding out).
In general, you will want to favor composition over inheritance.
Much better:
If you want to have text on top of text, you could create two JLabels (separately), and place them on top of each other using an appropriate layout manager or using a JLayeredPane.
Or you can do your painting and your painting overlay in a single component, likely the paintComponent override of a JPanel.
For example, one possible overly can use a JLayeredPane that holds two JLabels. A simple example below uses JLabels that hold only text, although you could also implement with ImageIcons, and allow changing each JLabel's font, foreground color, etc...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagLayout;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class MyLabel extends JLayeredPane {
// labels to hold texts. label1 is the lower label
private JLabel label1 = new JLabel();
private JLabel label2 = new JLabel();
public MyLabel(String text1, String text2) {
// just so I can see the text separately:
label2.setForeground(Color.RED);
// set text
label1.setText(text1);
label2.setText(text2);
// JPanels to hold the labels. GridBagLayout will center the labels
JPanel baseComponent1 = new JPanel(new GridBagLayout());
JPanel baseComponent2 = new JPanel(new GridBagLayout());
// add labels to the JPanels
baseComponent1.add(label1);
baseComponent2.add(label2);
// have to be able to see through the JPanels
baseComponent1.setOpaque(false);
baseComponent2.setOpaque(false);
// add to the JLayeredPane label2 above label1
add(baseComponent1, JLayeredPane.DEFAULT_LAYER);
add(baseComponent2, JLayeredPane.PALETTE_LAYER);
// If the overall component resizes, resize the
// container base JPanels
addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
baseComponent1.setSize(MyLabel.this.getSize());
baseComponent2.setSize(MyLabel.this.getSize());
repaint();
}
});
}
// preferred size depends on the largest dimensions
// of the two JLabels
#Override
public Dimension getPreferredSize() {
Dimension size1 = label1.getPreferredSize();
Dimension size2 = label2.getPreferredSize();
int w = Math.max(size1.width, size2.width);
int h = Math.max(size1.height, size2.height);
return new Dimension(w, h);
}
}
and it can be tested like so:
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
#SuppressWarnings("serial")
public class MyLabelTest extends JPanel {
public MyLabelTest() {
add(new MyLabel("Test .............................. String 1", "Number 2"));
}
private static void createAndShowGui() {
MyLabelTest mainPanel = new MyLabelTest();
JFrame frame = new JFrame("MyLabelTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
My next iteration would be to add mutator methods to MyLabel to allow changing font, text, and foreground:
public void setFont1(Font font) {
label1.setFont(font);
}
public void setFont2(Font font) {
label2.setFont(font);
}
public void setText1(String text) {
label1.setText(text);
}
public void setText2(String text) {
label2.setText(text);
}
public void setForeground1(Color fg) {
label1.setForeground(fg);
}
public void setForeground2(Color fg) {
label2.setForeground(fg);
}

FlowLayout without linebreaks and/or in vertical direction

This is a follow-up to this question. Any viable answer will also answer that one.
What layout may be used with as little modification as possible to replicate the aligning nature of a FlowLayout, but never linebreak and also be available in a from-top-to-bottom flavour?
The obvious candidate, BoxLayout, does not work nicely with JPanels. Consider the following two examples:
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
class App
{
public static void main(String[] args)
{
JFrame window = new JFrame();
Box box = new Box(BoxLayout.Y_AXIS);
for(int i = 0; i < 5; ++i)
{
JLabel label = new JLabel("XX");
box.add(label);
}
box.add(Box.createVerticalGlue());
window.add(box);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
}
}
This will properly display a vertical line of labels, beginning at the top and stretching as far towards the bottom as the labels take space. Good.
Modifying this, however, just a tiny bit:
public static void main(String[] args)
{
JFrame window = new JFrame();
Box box = new Box(BoxLayout.Y_AXIS);
for(int i = 0; i < 5; ++i)
{
JLabel label = new JLabel("XX");
JPanel panel = new JPanel();
panel.add(label);
box.add(panel);
}
box.add(Box.createVerticalGlue());
window.add(box);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
}
This will stretch all components of the Box to the same height, placing the labels far away from each other. Bad.
Overriding the JPanel's getPreferredSize and getMaximumSize methods (with getMinimumSize) has no effect and would be a bad way to fix it, because it relied on the components rather than the container and its layout.
Addendum:
Here is an already pretty successful attempt using GroupLayout. Unfortunately it did not seem to occur to the designer that among DEFAULT_SIZE and PREFERRED_SIZE a choice MINIMUM_SIZE would have been a good idea.
Furthermore if it is possible to invert the sequence of GroupLayout.SequentialGroup, the API is no help to figure out how. I for one certainly have no clue how to even extend that class.
import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.Container;
import javax.swing.GroupLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
class LineLayout extends GroupLayout
{
public LineLayout(Container owner, int axis)
{
super(owner);
this.direction = axis;
this.direction |= owner.getComponentOrientation() != ComponentOrientation.LEFT_TO_RIGHT
? LineLayout.RIGHT_TO_LEFT : LineLayout.LEFT_TO_RIGHT;
this.setupGroups();
}
public LineLayout(Container owner, int axis, int orientation)
{
super(owner);
this.direction = axis;
this.direction |= orientation;
this.setupGroups();
}
#Override // to replicate FlowLayout functionality : this method is called from owner.add
public void addLayoutComponent(Component component, Object constraints)
{
if(constraints == null)
{
// REALLY surprised that this works, considering that overriding the JPanel's
// getMaximumSize method with getPreferredSize had no effect
this.horizontal.addComponent(component, GroupLayout.DEFAULT_SIZE,
GroupLayout.DEFAULT_SIZE,
GroupLayout.PREFERRED_SIZE);
this.vertical.addComponent (component, GroupLayout.DEFAULT_SIZE,
GroupLayout.DEFAULT_SIZE,
GroupLayout.PREFERRED_SIZE);
}
// TODO: else
}
protected void setupGroups()
{
super.setAutoCreateGaps(false); // does nothing
if((this.direction & LineLayout.AXIS) == LineLayout.Y_AXIS)
{
this.horizontal = super.createParallelGroup();
this.vertical = (this.direction & LineLayout.ORIENTATION) == LineLayout.RIGHT_TO_LEFT
? this.createSequentialInvertedGroup() : super.createSequentialGroup();
}
else
{
this.horizontal = (this.direction & LineLayout.ORIENTATION) == LineLayout.RIGHT_TO_LEFT
? this.createSequentialInvertedGroup() : super.createSequentialGroup();
this.vertical = super.createParallelGroup();
}
super.setHorizontalGroup(this.horizontal);
super.setVerticalGroup (this.vertical);
}
// How!?
// protected LineLayout.SequentialInvertedGroup createSequentialInvertedGroup() { return new LineLayout.SequentialInvertedGroup(); }
protected GroupLayout.SequentialGroup createSequentialInvertedGroup() { return super.createSequentialGroup(); } // placeholder
protected int direction;
protected GroupLayout.Group horizontal;
protected GroupLayout.Group vertical;
// not sure how reliable the constant field values of BoxLayout are, whether it's smart to assume them unchanging over the ages
public static final int AXIS = 0b1;
public static final int X_AXIS = 0b0; // = BoxLayout.X_AXIS;
public static final int Y_AXIS = 0b1; // = BoxLayout.Y_AXIS;
public static final int ORIENTATION = 0b10;
public static final int LEFT_TO_RIGHT = 0b00; // also top to bottom
public static final int RIGHT_TO_LEFT = 0b10; // also bottom to top
// No idea how; only has "add" methods; cannot actually do anything with the added components!?
//protected static class SequentialInvertedGroup extends GroupLayout.SequentialGroup
//{}
}
class Applikation
{
public static void main(String[] args)
{
JFrame window = new JFrame();
JPanel box = new JPanel();
box.setLayout(new LineLayout(box, LineLayout.Y_AXIS));
for(int i = 0; i < 5; ++i)
{
JLabel label = new JLabel("XX");
JPanel panel = new JPanel();
panel.add(label);
box.add(panel);
}
window.add(box);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
}
}
If you try this out, you will note that there are still notable border spaces between the "XX" labels, taking up about 2/3 of an extra label per gap. While already much better than in the BoxLayout example, I do not think there is a good way to improve this spacing further.

private static int MAX_HEIGHT = 40;
private static final Dimension DIMENSION = new Dimension(Integer.MAX_VALUE, MAX_HEIGHT);
public static void main(String[] args)
{
JFrame window = new JFrame();
Box box = new Box(BoxLayout.Y_AXIS){
private static final long serialVersionUID = 1L;
#Override
public Component add(Component comp) {
comp.setMaximumSize(DIMENSION);
return super.add(comp);
}
};
for(int i = 0; i < 5; ++i)
{
JLabel label = new JLabel("XX");
JPanel panel = new JPanel();
panel.add(label);
box.add(panel);
}
window.add(box);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.pack();
window.setVisible(true);
}

You are using a Box for adding your components into. And the Documentation says:
a Box can use only a BoxLayout.
Now lets look into the Documentation for BoxLayout. It says:
BoxLayout pays attention to a component's requested minimum, preferred, and maximum sizes.
Now we have found the reason for the different outputs of your two examples. In your first example you are adding JLabels directly to your Box. Since they have a default maximumSize depending on their content they are not scaled by the Box.
In your second example you are adding JPanels to the Box that have your JLabels in it. A JPanel does not have a default maximumSize and so it is scaled by the Box.
So if you want to get the same output with JPanels as without you need your JPanels to have a maximumSize depending on their content means the JLabels.
So you could set a maximumSize manually. Something like that:
panel.setMaximumSize(new Dimension(100,20));
Or you use a different LayoutManager with your JPanels. One that calculates its size depending on its components. One that pays attention to a component's requested minimum, preferred, and maximum sizes.
Does this sound familiar to you? Right its from the Documentation of BoxLayout. So try to use a BoxLayout on your JPanels and you will get exactly the same result as your first example.
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));

Centering components and resizing JFrame in swing

I am making a java GUI in which I have some vertical boxes. Inside those boxes, there are some buttons and Labels. I am trying to put the buttons and labels in the center but doesn't work!
I am using this code to set the label in the center.
JLabel update = new JLabel("update");
update.setHorizontalTextPosition(CENTER);
where update is the last component of my vertical box.
The other problem is that I need the window to resize automatically depending on the changes in my GUI (since it is a dynamic one)!
How can I make this too?

I am trying to put the buttons and labels in the center but doesn't work! I am using this code to set the label in the center.
There are several ways to do this, but the easiest for me is to use a GridBagLayout.
If the boxes/container (which hopefully extend from JPanel or JComponent) uses a GridBagLayout, and you add components into the container with GridBagConstraints: gridX and gridY set, but with weightX and weightY set to default of 0, those added components will center in the container.
I can't show code since I have no knowledge of the code you're currently using or the images of your observed/desired GUI's. If you need more help, please edit your question and provide more pertinent information.
The other problem is that I need the window to resize automatically depending on the changes in my GUI (since it is a dynamic one)! How can I make this too?
This will all depend on the layout managers that your GUI is using, something that we have no knowledge of as yet. Again, if you're still stuck, please create and post your Minimal, Complete, and Verifiable Example Program.
For example the following resizable GUI with centered buttons and JLabel texts:
Is created by the following code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import javax.swing.*;
#SuppressWarnings("serial")
public class VertBoxes extends JPanel {
private static final String[] LABEL_TEXTS = { "A", "One", "Two", "Monday",
"Tuesday", "January", "Fourth of July",
"Four score and seven years ago" };
public static final int PREF_W = 260;
public static final int PREF_H = 80;
public VertBoxes() {
setLayout(new GridLayout(0, 1, 5, 5));
setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
for (String labelTxt : LABEL_TEXTS) {
add(new InnerBox(labelTxt));
}
}
private class InnerBox extends JPanel {
public InnerBox(String labelTxt) {
setLayout(new GridBagLayout());
setBorder(BorderFactory.createLineBorder(Color.black, 4));
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
add(new JButton("Button"), gbc);
gbc.gridy++;
add(new JLabel(labelTxt), gbc);
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
}
private static void createAndShowGui() {
VertBoxes mainPanel = new VertBoxes();
JFrame frame = new JFrame("Vertical Boxes");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

Develop Reference

Java is a programming language and computing platform first released by Sun Microsystems in 1995.

Java JComponent paint --Almost working - java

Another way to use the Timer class: Timer t = new Timer(510, new ActionListener() { #Override public void actionPerformed(ActionEvent e) { rectangle_x++; repaint(); } }) ... t.start(); You still need to override actionPerformed() in your main class though.

Related

Make the animation faster when there are thousands of components

Reordering labels

Paint two overlaid JLabels

FlowLayout without linebreaks and/or in vertical direction

Centering components and resizing JFrame in swing

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