I have a container in which components can be dragged. The problem I encountered is whenever I picked up a component and it was automatically added to a window, the component would stop firing drag events even if the mouse was still dragging on the handle. Then the next time I would click and drag on the handle (now in the floating window) it would continue dragging. Here's some basic code:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.Box.Filler;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.SwingUtilities;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;
/**
*
*/
#SuppressWarnings("serial")
public class DraggableDemo extends JPanel {
private class DraggablePanel extends JPanel {
private class MyMouseAdapter extends MouseAdapter {
private DraggablePanel floater;
private Point dragOffset;
#Override
public void mouseDragged(MouseEvent e) {
if (floater == null) {
startDragging(e);
}
Point transformedEventPoint = SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), owner);
updateWindowLocation(transformedEventPoint);
}
private void startDragging(MouseEvent e) {
Component component = e.getComponent();
floater = (DraggablePanel) SwingUtilities.getAncestorOfClass(DraggablePanel.class, component);
Point floaterAbsoluteLocation = SwingUtilities.convertPoint(floater.getParent(), floater.getLocation(), owner);
Point transformedEventPoint = SwingUtilities.convertPoint(component, e.getPoint(), owner);
// designate a drag offset so the component's corner doesn't teleport to mouse location
dragOffset = new Point(transformedEventPoint.x - floaterAbsoluteLocation.x, transformedEventPoint.y - floaterAbsoluteLocation.y);
swapComponents(getFiller(), floater);
// place the floating component in a window
window.add(floater);
window.pack();
floater.setBorder(new LineBorder(Color.YELLOW));
updateWindowLocation(transformedEventPoint);
window.setVisible(true);
}
private void updateWindowLocation(Point point) {
Point p = new Point(point.x - dragOffset.x, point.y - dragOffset.y);
SwingUtilities.convertPointToScreen(p, owner);
window.setLocation(p);
}
private JComponent getFiller() {
Dimension dimension = floater.getSize();
JComponent filler = (JComponent) Box.createRigidArea(dimension);
// border
Border dashedBorder = BorderFactory.createDashedBorder(Color.gray, 3f, 3f, 2f, true);
filler.setBorder(dashedBorder);
filler.setOpaque(true);
return filler;
}
#Override
public void mouseReleased(MouseEvent e) {
Point transformedEventPoint = SwingUtilities.convertPoint(e.getComponent(), e.getPoint(), owner);
Component compDroppedOn = SwingUtilities.getDeepestComponentAt(owner, transformedEventPoint.x, transformedEventPoint.y);
if (compDroppedOn instanceof Filler) {
window.remove(floater);
swapComponents(floater, compDroppedOn);
window.setVisible(false);
floater = null;
}
}
}
private JWindow window;
private MyMouseAdapter mouseAdapter;
private DraggableDemo owner;
DraggablePanel(DraggableDemo owner) {
this.owner = owner;
JPanel smallPanel = new JPanel();
smallPanel.setPreferredSize(new Dimension(200, 100));
smallPanel.setBackground(Color.green);
JPanel bigPanel = new JPanel();
bigPanel.setPreferredSize(new Dimension(200, 400));
bigPanel.setBackground(Color.red);
setLayout(new BorderLayout());
add(smallPanel, BorderLayout.NORTH);
add(bigPanel, BorderLayout.CENTER);
setBorder(new LineBorder(Color.blue));
mouseAdapter = new MyMouseAdapter();
smallPanel.addMouseListener(mouseAdapter);
smallPanel.addMouseMotionListener(mouseAdapter);
owner.addMouseListener(mouseAdapter);
owner.addMouseMotionListener(mouseAdapter);
window = new JWindow();
window.setAlwaysOnTop(true);
}
}
private GridBagConstraints gbc;
/**
*
*/
public DraggableDemo() {
setLayout(new GridBagLayout());
gbc = new GridBagConstraints();
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.weightx = 1;
for (int i = 0; i < 2; i++) {
add(new DraggablePanel(this), gbc);
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DraggableDemo newContentPane = new DraggableDemo();
newContentPane.setOpaque(true);
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowGUI();
}
});
}
/**
*/
private void swapComponents(Component toAdd, Component toRemove) {
Container parent = toRemove.getParent();
int index = parent.getComponentZOrder(toRemove);
parent.remove(toRemove);
parent.add(toAdd, gbc, index);
revalidate();
repaint();
}
}
What I've tried:
The original container holds a few components per column, each firing different mouse events.
Initially I registered the mouse listener to the main container and got and moved the component based on coordinates, but that didn't satisfy the condition of mouse entering / exiting smaller components firing events themselves.
After this I attempted to register multiple mouse listeners, each doing its own thing, but I've learned that these would eat up events that would happen in the hierarchy.
Finally, I decided to register a single listener to every single component I needed to register to and based on the component instance returned from events, I would delegate these events to an appropriate mouse 'adapter'.
How can I fix the component in order to drag correctly when it is picked up? Like I've said, I can't register only to the main container, because then I wouldn't have access to events fired by smaller components, and I can't register multiple listeners because events would then be eaten up by the first one that fired.
whenever I picked up a component and it was automatically added to a window, the component would stop firing drag events
It is not just the component that stops firing the drag event. It appear that no drag event is generated for any component:
In your createAndShowGUI() method, after the frame is visible, I added:
long eventMask = AWTEvent.MOUSE_MOTION_EVENT_MASK + AWTEvent.MOUSE_EVENT_MASK;
Toolkit.getDefaultToolkit().addAWTEventListener( new AWTEventListener()
{
public void eventDispatched(AWTEvent e)
{
System.out.println(e.getID());
}
}, eventMask);
Which should display all mouse events generated for any component. However, once the Window is displayed, no further events are generated for any component, confirming your problem.
Next I removed the above code and replaced it with a custom EventQueue to simply display every event that is generated:
EventQueue queue = new EventQueue()
{
protected void dispatchEvent(AWTEvent event)
{
System.out.println(event);
super.dispatchEvent(event);
}
};
Toolkit.getDefaultToolkit().getSystemEventQueue().push(queue);
Now I do see all the mouse drag events.
So maybe you can create a custom EventQueue that handles mouse events that are generated on your DraggablePanel?
Related
Hello first of all when I run the program a button appear , when I press the button the image will go from top to down.
I try the code when the image go from top to down , it work very well
BUT when I put all the codes together there is an error in ( frame.add(new AnimationPane() ); )
Question : How to add AnimationPane() to the frame ???
because this is my problem.
The idea that I want to make two scenes , the first one have a button to make go to the second scene which will have an image (it must be pushed from top until reach down ).
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package maincontentpaneswitching;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class MainContentPaneSwitching {
private static class ChangeContentPaneListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
// I want to put the image here
JPanel newFrameContents = new JPanel(); //Uses FlowLayout by default.
newFrameContents.add(new JLabel("You have successfully changed the content pane of the frame!", JLabel.CENTER));
/*We assume that the source is a JButton and that the Window is of type JFrame, hence
the following utility method call is possible without letting any errors appear:*/
JFrame frame = (JFrame) SwingUtilities.getWindowAncestor((JButton) e.getSource());
frame.setSize(600, 300);
frame.setContentPane(newFrameContents); //Change the content pane of the frame.
frame.revalidate(); //Notify the frame that the component hierarchy has changed.
frame.add(new AnimationPane() );
frame.pack(); //Resize the frame as necessary in order to fit as many contents as possible in the screen.
frame.setLocationRelativeTo(null); //Place the frame in the center of the screen. As you can tell, this needs its size to calculate the location, so we made sure in the previous line of code that it is set.
frame.repaint(); //Repaint frame with all its contents.
}
}
public class AnimationPane extends JPanel {
private BufferedImage boat;
private int yPos = 0;
private int direction = 1;
public AnimationPane() {
try {
boat = ImageIO.read(new URL("https://i.stack.imgur.com/memI0.png"));
Timer timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
yPos += direction;
if (yPos + boat.getHeight() > getHeight()) {
yPos = getHeight() - boat.getHeight();
direction *= +1;
} else if (yPos < 0) {
yPos = 0;
direction *= +1;
}
repaint();
}
});
timer.setRepeats(true);
timer.setCoalesce(true);
timer.start();
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
public Dimension getPreferredSize() {
return boat == null ? super.getPreferredSize() : new Dimension(boat.getHeight()*2 , boat.getWidth() *2);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
int x = getWidth() - boat.getWidth();
g.drawImage(boat, x, yPos, this);
}
}
private static class MainRunnable implements Runnable {
#Override
public void run() {
JButton changeContentPaneButton = new JButton("Click to go to the next image!");
changeContentPaneButton.addActionListener(new ChangeContentPaneListener());
JPanel frameContents = new JPanel(); //Uses FlowLayout by default.
frameContents.add(changeContentPaneButton);
JFrame frame = new JFrame("My application");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Tells the frame that when the user closes it, it must terminate the application.
frame.setContentPane(frameContents); //Add contents to the frame.
frame.pack(); //Resize the frame as necessary in order to fit as many contents as possible in the screen.
frame.setLocationRelativeTo(null); //Place the frame in the center of the screen. As you can tell, this needs its size to calculate the location, so we made sure in the previous line of code that it is set.
frame.setVisible(true);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new MainRunnable()); //Swing code must always be used in the Event Dispatch Thread.
}
}
Introduction
As I said in my comment, I couldn't get the image animation to work properly. At least this code would give you a solid foundation to start with.
Here's the GUI I came up with.
Here's the GUI after you left-click on the button.
If you're going to add comments to your code, put the comments on separate lines from the code. Not everyone has a large monitor and can read 200+ character lines of code.
Explanation
Oracle has a rad tutorial, Creating a GUI With Swing. Skip the Netbeans section.
When I create a Swing GUI, I use the model/view/controller (MVC) pattern. This pattern allows me to separate my concerns and focus on one part of the application at a time.
In Swing, the MVC pattern means:
The view reads information from the model
The view may not update the model
The controller updates the model and repaints/revalidates the view.
There's usually not one controller to "rule them all". Each listener controls its portion of the model and the view.
When I put together an application, I code one tiny tiny piece of it, then run tests. I probably ran two to three dozen tests, and this was mostly coded by you.
Model
I created a BoatImage class to read the boat image. It's a separate class, so I can read the image before I start to construct the GUI.
View
I created a JFrame. I created a main JPanel with a CardLayout.
I use a CardLayout to layout the button JPanel and the image JPanel. This way, the JFrame is not constantly changing size.
I create the JFrame and JPanels as separate methods/classes. This makes it much easier for people, including yourself, to read and understand the view code.
Controller
I coded the ChangeContentPaneListener to change from the button JPanel to the image JPanel. This is where you would put your image animation code.
Code
Here's the complete runnable code. I made all the additional classes inner classes so I could post this code as one block.
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class MainContentPaneSwitching implements Runnable {
public static void main(String[] args) {
// Swing code must always be used in the Event Dispatch Thread.
SwingUtilities.invokeLater(new MainContentPaneSwitching());
}
private AnimationPane animationPane;
private BoatImage boatImage;
private CardLayout cardLayout;
private JPanel mainPanel;
public MainContentPaneSwitching() {
this.boatImage = new BoatImage();
}
#Override
public void run() {
JFrame frame = new JFrame("My application");
// Tells the frame that when the user closes it, it
// must terminate the application.
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.mainPanel = createMainPanel();
frame.add(mainPanel, BorderLayout.CENTER);
// Resize the frame as necessary in order to fit as many contents
// as possible in the screen.
frame.pack();
// Place the frame in the center of the screen. As you can tell, this
// needs its size to calculate the location, so we made sure in the
// previous line of code that it is set.
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private JPanel createMainPanel() {
cardLayout = new CardLayout();
JPanel panel = new JPanel(cardLayout);
panel.add(createButtonPanel(), "button");
animationPane = new AnimationPane(boatImage);
panel.add(animationPane, "image");
return panel;
}
private JPanel createButtonPanel() {
JPanel panel = new JPanel(new FlowLayout());
panel.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
JButton changeContentPaneButton = new JButton(
"Click to go to the next image!");
changeContentPaneButton.addActionListener(
new ChangeContentPaneListener(this, boatImage));
panel.add(changeContentPaneButton);
return panel;
}
public JPanel getAnimationPane() {
return animationPane;
}
public void repaint() {
animationPane.repaint();
}
public class AnimationPane extends JPanel {
private static final long serialVersionUID = 1L;
private BoatImage boat;
public AnimationPane(BoatImage boat) {
this.boat = boat;
BufferedImage image = boat.getBoat();
this.setPreferredSize(new Dimension(image.getWidth(),
image.getHeight()));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
BufferedImage image = boat.getBoat();
int x = getWidth() - image.getWidth();
g.drawImage(image, x, boat.getyPos(), this);
}
}
private class ChangeContentPaneListener implements ActionListener {
private int direction, yPos;
private final MainContentPaneSwitching view;
private final BoatImage model;
public ChangeContentPaneListener(MainContentPaneSwitching view,
BoatImage model) {
this.view = view;
this.model = model;
this.direction = 1;
this.yPos = 0;
}
#Override
public void actionPerformed(ActionEvent e) {
cardLayout.show(mainPanel, "image");
}
}
public class BoatImage {
private int yPos;
private BufferedImage boat;
public BoatImage() {
try {
URL url = new URL("https://i.stack.imgur.com/memI0.png");
boat = ImageIO.read(url); // boat.jpg
} catch (MalformedURLException e) {
e.printStackTrace();
boat = null;
} catch (IOException e) {
e.printStackTrace();
boat = null;
}
this.yPos = 0;
}
public BufferedImage getBoat() {
return boat;
}
public void setyPos(int yPos) {
this.yPos = yPos;
}
public int getyPos() {
return yPos;
}
}
}
Using LayerUI to add labels to the upper corner of a tabbed pane. Would like to allow these labels to display as hyperlinks, so I set the color blue, the cursor to a hand and I added a mouselistener.
Howev,er when I paint the component the cursor customization and mouse listener are not not working.
sample image
Sample Application:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JLayer;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.SwingUtilities;
import javax.swing.plaf.LayerUI;
public class TopRightCornerLabelLayerUITest {
public static JPanel makeUI() {
JPanel resultPanel = new JPanel();
resultPanel.setLayout( new BorderLayout());
resultPanel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
JTabbedPane tabbedPane = new JTabbedPane();
tabbedPane.add("Tab 1", new JPanel());
tabbedPane.add("Tab 2", new JPanel());
resultPanel.add(new JLayer<JComponent>(tabbedPane, new TopRightCornerLabelLayerUI()), BorderLayout.CENTER);
return resultPanel;
}
private static void initandShow()
{
JDialog dialog = new JDialog();
dialog.getContentPane().add(makeUI());
dialog.setSize(520, 240);
dialog.setLocationRelativeTo(null);
dialog.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
initandShow();
}
});
}
}
class TopRightCornerLabelLayerUI extends LayerUI<JComponent> {
private JPanel rubberStamp = new JPanel();
#Override public void paint(Graphics g, JComponent c) {
super.paint(g, c);
JLabel layoutHyperlink = new JLabel("<html><a href=''>File Layout and Descriptions</a></html>");
JLabel templateHyperlink = new JLabel("<html><a href=''>Download Template</a></html>");
layoutHyperlink.setForeground(Color.BLUE.darker());
layoutHyperlink.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
layoutHyperlink.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// the user clicks on the label
System.err.println("clicked");
}
});
templateHyperlink.setForeground(Color.BLUE.darker());
templateHyperlink.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
templateHyperlink.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// the user clicks on the label
System.err.println("clicked");
}
});
// Add components
Dimension templateDimension = templateHyperlink.getPreferredSize();
int x = c.getWidth() - templateDimension.width - 5;
SwingUtilities.paintComponent(g, templateHyperlink, rubberStamp, x, 2, templateDimension.width , templateDimension.height);
Dimension layoutDimension = layoutHyperlink.getPreferredSize();
x = c.getWidth() - layoutDimension.width - 15 - templateDimension.width;
SwingUtilities.paintComponent(g, layoutHyperlink, rubberStamp, x, 2, layoutDimension.width, templateDimension.height);
}
}
I was actually unaware of class JLayer until I read your question. I don't have a complete answer but I think it's enough to give you a push in the right direction. I was helped by the lesson in Oracle's Java tutorial: How to Decorate Components with the JLayer Class. That lesson has a section entitled Responding to Events which helped me to figure out how to partially solve your issue. Basically you are just painting the labels and not actually adding them as components and therefore they will not respond to mouse events. Since the labels can be considered part of the JLayer component that is added as a component, you can configure that JLayer to respond to mouse events. As stated in the tutorial lesson, you need to override some other methods in your TopRightCornerLabelLayerUI class. The code below contains two of those methods. Add them to your code and see if they give you the expected result.
public void installUI(JComponent c) {
super.installUI(c);
((JLayer<?>) c).setLayerEventMask(AWTEvent.MOUSE_EVENT_MASK);
}
protected void processMouseEvent(MouseEvent e, JLayer l) {
if (e.getID() == MouseEvent.MOUSE_CLICKED) {
Point pt = e.getPoint();
if (pt.x >= xTemplateHyperlink && pt.x <= (xTemplateHyperlink + widthTemplateHyperlink)) {
System.out.println("clicked");
}
}
}
EDIT:
Forgot to mention that I added the following members to your TopRightCornerLabelLayerUI class...
private int xTemplateHyperlink;
private int yTemplateHyperlink;
private int widthTemplateHyperlink;
private int heightTemplateHyperlink;
And set their values in method paint() like so...
Dimension templateDimension = templateHyperlink.getPreferredSize();
xTemplateHyperlink = c.getWidth() - templateDimension.width - 5;
yTemplateHyperlink = 2;
widthTemplateHyperlink = templateDimension.width;
heightTemplateHyperlink = templateDimension.height;
which explains the code in method processMouseEvent().
Simply; I have a JPanel inside a JScrollPane;
As expected; JScrollPane by default listens to MouseWheelEvent so that scrolling is working well for when the wheel is rotating and while the cursor is hovering over the JPanel.
But After that; I just updated JPanel so that it implements MouseWheelListener, and I added this mouse wheel listener for the JPanel itself.
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
if (e.isControlDown()) {
if (e.getWheelRotation() < 0) {
System.out.println("mouse wheel Up");
} else {
System.out.println("mouse wheel Down");
}
}
}
The JPanel responds to this implementation for when both; the Ctrl is pressed down and the wheel is rotating and while the cursor is hovering over the JPanel. But the default behaviour of the JScrollPane is unexpectedly lost!!!
When I rotate the wheel while the cursor is hovering over the JPanel the scrolls of the JScrollPane is not responding!!!
It seems that; this implementation of MouseWheelListener breaks the default of a JPanel.
So; How to implement MouseWheelListener for JPanel without breaking its default implementation?
MouseWheelEvents and the scrolling behavior have some subtle caveats.
For example, when you open this page (I mean THIS one, which you are currently reading), place the mouse in the middle, and start srolling down with the wheel, you will scroll over the code snippets. Note that although the code snippets are contained in code blocks that have a scrollbar, continuously rotating the mouse wheel will not trigger a scrolling in the code blocks, but only in the whole page. But when you once move the mouse while it is inside a code block, and afterwards roll the mouse wheel, then you will scroll in the code block only - and not the whole page.
Similarly, rotating the mouse wheel may not affect the hovered scrollable. I think it depends on the Window Manager and the Look & Feel, but in some cases, you will scroll the scroll pane that contains the focussed component - even if the mouse cursor is outside of this component, and even if it is over a scollable component (you can also observe this, for example, in the Windows Explorer)!
However, some of these mechanisms and subtleties can be found in the Swing components as well. For example, the redispatching mechanism that passes MouseWheelEvents to the ancestors if they are not handled by the component itself.
Following this pattern, a solution (that is conceptually similar to the one that LuxxMiner proposed, but may be a tad more generic) may be to simply re-dispatch the MouseWheelEvent to the parent component:
package stackoverflow;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
public class MouseWheelListenerForPanelInScrollpane
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
#Override
public void run()
{
createAndShowGUI();
}
});
}
private static void createAndShowGUI()
{
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.getContentPane().setLayout(new GridLayout(1,2));
MouseWheelListenerPanel m = new MouseWheelListenerPanel();
m.setPreferredSize(new Dimension(100,4000));
JScrollPane scrollPane = new JScrollPane(m);
f.getContentPane().add(scrollPane);
f.setSize(500,500);
f.setLocationRelativeTo(null);
f.setVisible(true);
}
}
class MouseWheelListenerPanel extends JPanel implements MouseWheelListener
{
MouseWheelListenerPanel()
{
addMouseWheelListener(this);
}
#Override
public void mouseWheelMoved(MouseWheelEvent e)
{
if (e.isControlDown())
{
if (e.getWheelRotation() < 0)
{
System.out.println("mouse wheel Up");
}
else
{
System.out.println("mouse wheel Down");
}
}
else
{
getParent().dispatchEvent(e);
}
}
}
Add an else to re-dispatch the event directly to the scroll pane if ctrl is not down:
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
if (e.isControlDown()) {
if (e.getWheelRotation() < 0) {
System.out.println("mouse wheel Up");
} else {
System.out.println("mouse wheel Down");
}
} else {
// pass the event on to the scroll pane
getParent().dispatchEvent(e);
}
}
I don't know if this really qualifies as an proper answer, since it's kind of a workaround, but I came up with the following solution: Just invoke the mouseWheelMoved method of the scrollPane only when Ctrl isn't being pressed:
if (e.isControlDown()) {
if (e.getWheelRotation() < 0) {
infoLabel.setText("Mouse Wheel Up");
} else {
infoLabel.setText("Mouse Wheel Down");
}
} else {
scrollPane.getListeners(MouseWheelListener.class)[0].mouseWheelMoved(e);
}
Full Example:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.border.TitledBorder;
public class Example {
public Example() {
JFrame frame = new JFrame();
frame.setLayout(new BorderLayout());
frame.add(new ScrollPanePanel());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 400);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Example();
}
});
}
}
class ScrollPanePanel extends JPanel implements MouseWheelListener {
private JLabel infoLabel;
private JScrollPane scrollPane;
public ScrollPanePanel() {
JPanel panel = new JPanel(new GridLayout(0, 1));
for (int i = 1; i <= 100; i++) {
panel.add(new JLabel("Label " + i));
}
panel.addMouseWheelListener(this);
scrollPane = new JScrollPane(panel);
infoLabel = new JLabel(" ");
JPanel infoPanel = new JPanel();
infoPanel.add(infoLabel);
setLayout(new BorderLayout());
add(scrollPane);
add(infoPanel, BorderLayout.SOUTH);
}
#Override
public void mouseWheelMoved(MouseWheelEvent e) {
if (e.isControlDown()) {
if (e.getWheelRotation() < 0) {
infoLabel.setText("Mouse Wheel Up");
} else {
infoLabel.setText("Mouse Wheel Down");
}
} else {
scrollPane.getListeners(MouseWheelListener.class)[0].mouseWheelMoved(e);
}
}
}
I'm trying to make a program that lets the user manually place and resize components within a JScrollPane, a bit of a special-case UI Builder. I managed to make a custom JPanel class that allows the user to move it around manually however when it's added to the JScrollPane and moved around, if it goes outside of the visual bounds of the JScrollPane the scrollbars don't appear or adjust.
Here is my main class that includes the JFrame and JScrollPane.
package quickscrolltest;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class QuickScrollTest {
JFrame wnd;
JScrollPane scroll;
JPanel pnl;
MovablePanel pnl1;
public QuickScrollTest() {
wnd = new JFrame();
scroll = new JScrollPane();
pnl = new JPanel();
pnl.setLayout(null);
scroll.setViewportView( pnl );
wnd.setContentPane(scroll);
wnd.pack();
pnl1 = new MovablePanel();
Dimension dim1 = new Dimension( 300, 400 );
pnl1.setSize( dim1 );
pnl1.setPreferredSize(dim1);
pnl1.setBackground( Color.CYAN );
pnl1.setLocation( 10, 10 );
/*scroll.getViewport().add(pnl1,null);*/
pnl.add(pnl1);
wnd.setSize( 800, 600 );
wnd.setLocationRelativeTo(null);
wnd.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
wnd.setVisible(true);
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
new QuickScrollTest();
}
}
Here is the MovablePanel class
package quickscrolltest;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JPanel;
public class MovablePanel extends JPanel implements MouseListener, MouseMotionListener {
Color bg = Color.GRAY;
Point clickPoint;
public MovablePanel() {
addMouseListener(this);
addMouseMotionListener(this);
}
#Override
public void setBackground( Color col ) {
super.setBackground(col);
bg = col;
}
#Override
public void mouseClicked(MouseEvent e) {}
#Override
public void mousePressed(MouseEvent e) {
clickPoint = e.getPoint();
}
#Override
public void mouseReleased(MouseEvent e) {
setCursor( Cursor.getDefaultCursor() );
}
#Override
public void mouseEntered(MouseEvent e) {
setCursor( Cursor.getPredefinedCursor(Cursor.HAND_CURSOR) );
super.setBackground( Color.RED );
}
#Override
public void mouseExited(MouseEvent e) {
setCursor( Cursor.getDefaultCursor() );
super.setBackground( bg );
}
#Override
public void mouseDragged(MouseEvent e) {
setCursor( Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR) );
int lastX = getX() - (int) clickPoint.getX();
int lastY = getY() - (int) clickPoint.getY();
setLocation(lastX + e.getX(), lastY + e.getY() );
}
#Override
public void mouseMoved(MouseEvent e) {}
}
How can I make it so that users can freely move components around in the JScrollPane and have the scrollbars update as required?
My final code will have a standalone mouselistener/mousemotionlistener class that generically works on a given JComponent but I coded the listeners directly into the JPanel for simplicity.
Thanks
Scrollbars automatically appear/disappear when the preferred size of the component displayed in the viewport of the scroll panes changes.
You can use the Drag Layout. This class is a custom layout manager and will automatically recalculate the preferred size of the panel as components are dragged around the panel.
You will need to handle the mouseReleased event so you can revalidate() the panel, and invoke the DragLayout once you are finished dragging the component so the preferred size can be reset. Or you could use the ComponentMover class which is referenced in the blog article to do the dragging of the component for you. It supports an auto resize property which will do the revalidate() for you.
I am very new to Java AWT. My question header must seem ridiculous to you, sorry about that. In my application I have three buttons which display different threads when clicked on. Now I want to add maybe a button or checkboxes or choicelist, etc when clicked on a particular button. For eg, if I click on yes button, it should display a choice list, something like that. How do I achieve something like that? Here is my code so far:
import java.awt.Button;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class AppWindow extends Frame implements ActionListener{
String keymsg = "Test message";
String mousemsg = "Nothing";
int mouseX=30, mouseY=30;
String msg;
public AppWindow(){
//addKeyListener(new MyKeyAdapter(this));
//addMouseListener(new MyMouseAdapter(this));
addWindowListener(new MyWindowAdapter());
}
public void paint(Graphics g){
g.drawString(msg, 150, 100);
}
//Here the window is created:
public static void main(String args[]){
AppWindow appwin = new AppWindow();
appwin.setSize(new Dimension(300,200));
appwin.setTitle("My first AWT Application");
appwin.setLayout(new FlowLayout(FlowLayout.LEFT));
appwin.setVisible(true);
Button yes,no,maybe;
yes = new Button("yes");
no = new Button("no");
maybe = new Button("maybe");
appwin.add(yes);
appwin.add(no);
appwin.add(maybe);
yes.addActionListener(appwin);
no.addActionListener(appwin);
maybe.addActionListener(appwin);
}
#Override
public void actionPerformed(ActionEvent ae) {
// TODO Auto-generated method stub
String str = ae.getActionCommand();
if(str.equals("yes")){
msg = "You pressed Yes";
}
if(str.equals("no")){
msg = "You pressed No";
}
if(str.equals("maybe")){
msg = "You pressed Maybe";
}
repaint();
}
}
class MyWindowAdapter extends WindowAdapter {
public void windowClosing(WindowEvent we){
System.exit(0);
}
}
Points describing what you should be doing :
As already mentioned by others, better to use Swing over AWT, since Swing is more advanced.
As much as possible, always try to Paint on top of a JPanel or a
JComponent, instead of Painting right on top of your JFrame, by
overriding the paintComponent(Graphics g) method of the said
JComponent/JPanel
Never call setVisible(true) on the JFrame until and unless it's
size has been established. So in general terms, this has to be the
last call, once you are done adding components to the JFrame and
the size of the JFrame has been realized by the LayoutManager.
Inside your actionPerformed(...), instead of writing all if
statement blocks, you should adhere to the if-else if statement
blocks. The benefit of this, over the former is that, at any given
time, only one event will be fired, hence once the said condition is
satisfied, you don't want your code to keep checking other
conditions, which in general is really not a good programming
practice, IMHO.
MOST IMPORTANT THING : Never make calls like pack()/setVisible(...) from within the main method, such calls belong
to the Event Dispatch Thread, and must be done on the same. Please
read Concurrency in Swing for more detail.
Have a look at the example program, for better understanding.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class ComponentExample
{
private CustomPanel drawingBoard;
private JPanel contentPane;
private JButton yesButton;
private JButton noButton;
private JButton maybeButton;
private JComboBox cbox;
private ActionListener buttonAction = new ActionListener()
{
#Override
public void actionPerformed(ActionEvent ae)
{
JButton button = (JButton) ae.getSource();
if (cbox.isShowing())
contentPane.remove(cbox);
if (button == yesButton)
{
drawingBoard.setText("You Pressed YES.");
contentPane.add(cbox, BorderLayout.PAGE_END);
}
else if (button == noButton)
drawingBoard.setText("You Pressed NO.");
else if (button == maybeButton)
drawingBoard.setText("You Pressed MAYBE.");
/*
* revalidate()/repaint() is needed
* when the JComponent is added or
* removed from the already
* visible Container.
*/
contentPane.revalidate();
contentPane.repaint();
}
};
public ComponentExample()
{
cbox = new JComboBox(
new String[]{"I GOT IT"
, "I STILL HAD DOUBT"});
}
private void displayGUI()
{
JFrame frame = new JFrame("Component Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
contentPane = new JPanel();
contentPane.setOpaque(true);
contentPane.setBackground(Color.DARK_GRAY);
contentPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(5, 5));
JPanel buttonPanel = new JPanel();
buttonPanel.setOpaque(true);
buttonPanel.setBackground(Color.WHITE);
yesButton = new JButton("YES");
yesButton.addActionListener(buttonAction);
noButton = new JButton("NO");
noButton.addActionListener(buttonAction);
maybeButton = new JButton("MAY BE");
maybeButton.addActionListener(buttonAction);
buttonPanel.add(yesButton);
buttonPanel.add(noButton);
buttonPanel.add(maybeButton);
contentPane.add(buttonPanel, BorderLayout.PAGE_START);
drawingBoard = new CustomPanel();
contentPane.add(drawingBoard, BorderLayout.CENTER);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new ComponentExample().displayGUI();
}
});
}
}
class CustomPanel extends JPanel
{
private String msg;
public CustomPanel()
{
msg = "";
setOpaque(true);
setBackground(Color.WHITE);
}
public void setText(String msg)
{
this.msg = msg;
repaint();
}
#Override
public Dimension getPreferredSize()
{
return (new Dimension(300, 300));
}
#Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawString(msg, getWidth() / 3, getHeight() / 3);
}
}
I don't know if I have understood the question well but... couldn't you create those elements and call their setVisible(boolean) methods to make them not visible at first, and them make them visible when user pushes buttons?