Adding a JScrollPane to an overriden JPanel - java

I am trying to create a program that computes for the Round Robin algorithm. The logic works fine. My problem is with the overriden JPanel that I use to draw the timeline. The timeline goes on and on without definite line length. I want to add the overriden panel to a scroll pane so it can be scrollable.
SampleGPane.class
import java.awt.*;
import javax.swing.*;
public class
SampleGPane
{
/* Timeline elements */
Container timelineContainer;
JFrame timelineFrame = new JFrame ();
JPanel pnlDraw = new JPanel ();
JScrollPane timelineScroll;
public void
launchFrame ()
{
GPanel gpane = new GPanel ();
timelineContainer = timelineFrame.getContentPane ();
timelineScroll = new JScrollPane (gpane);
timelineContainer.add (timelineScroll);
timelineFrame.setSize (500, 250);
timelineFrame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
timelineFrame.setVisible (true);
}
private class
GPanel extends JPanel
{
#Override
public void
paintComponent (Graphics g)
{
super.paintComponent (g);
int runningLineX = 0;
int runningLineY = 0;
// g.drawLine (50, 50, orderCount * 5, 50);
runningLineX += 50;
runningLineY += 50;
for (int count = 0; count < 35; count++) {
g.drawString ("J" + (count + 1), runningLineX + 50, 25);
runningLineX += 50;
// runningLineY += 50;
g.drawLine (runningLineX, runningLineY, runningLineX + 50, runningLineY);
}
}
}
}
SampleGPane.class is called by SampleLaunch.class
public class
SampleLaunch
{
public static void main (String args[]) {
SampleGPane sgp = new SampleGPane ();
sgp.launchFrame ();
}
}
The problem is, the JScrollPane won't work. It doesn't seem to detect the line. How do I fix this?

You need to override the getPreferredSize() method of your custom panel to return a reasonable size.
The scrollbars will only appear when the preferred size of the component added to the viewport of the scroll pane is greater than the size of the scroll pane.
The timeline goes on and on without definite line length.
The line length will need to match your painting code. So you need parameters to control what to paint. These parameters will also be used in the calculation of the size of the component. In your example you iterate 35 times and increment the x by 50 so the width would be 1750 plus the starting x offset.

Related

Unable to drawimage on null layout swing

I want to draw some images on screen alongside some JButtons placed in different places of the screen. However whenever I have setLayout(null); the images do not show up on screen. If i don't set it to null I can make the images show up but I can't place my Jbuttons on the desired places.
How can i make so i have setLayout(null); and still be able to draw multiple images on screen while placing my buttons anywhere?
My Frame Class:
public class PFrame extends JFrame {
JPanel p;
public PFrame() {
p = new PPanel();
p.setBackground(Color.WHITE);
Container c = getContentPane();
c.setLayout(null);
c.add(p);
setSize(1200,700);
JRadioButton White = new JRadioButton("White");
ButtonGroup G1 = new ButtonGroup();
White.setBounds(1000, 30, 80, 50);
G1.add(White);
this.add(White);
//rest of buttons code here...
public class PPanel extends JPanel{
public void paintComponent(Graphics g) {
super.paintComponent(g);
Image [] vi = ImgArray();
int x = 0;
int y = 0;
int i;
for (i = 0; i < vi.length / 2; i++) {
g.drawImage(vi[i],x,y,240,310,null);
x+= 250;
}
y = 320;
x = 0;
for (i = vi.length / 2; i < vi.length; i++) {
g.drawImage(vi[i],x,y,240,310,null);
x+= 250;
}
}
}
Main method:
public static void main(String[] args) {
PersonagensFrame f =new PFrame();
f.setVisible(true);
f.repaint();
}
I would recomend using anything other then a null layout for swing. You should check out the documentation for layouts such as GridBagLayout and GridLayout; since they are much more friendly in terms of compatibility.
If that isn't what you are looking for, you should also try making two seperate panels, seperating your buttons and images.
Swing was specifically built to incorporate layouts in which they provide.
I hope you figure it out! :)

Adding buttons on a paintComponent drawn shape

My program is consist of two classes(test and paintClass) in different files. In the paintClass class I draw a 5x5 square board by using paintComponent method. I want to add buttons in each small square in the big square. When I run the code I don't get any buttons. I want to have 25(5x5) buttons by using jpanel on a shape drawn by paintComponent. Is this possible? If it is, how I can do it?
EDIT : The problem was the loop. Number had a default value of 0 so the loop didn't work. I defined number at the beginning. It solved the problem. Also one of the invervals were wrong. I changed j = 0 with j = 1.
import javax.swing.*;
import java.awt.*;
public class test
{
public static void main(String[] args)
{
JFrame frame = new JFrame("buttons");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(250,250);
PaintClass paint = new PaintClass();
paint.repaint();
f1.getContentPane().add(paint);
frame.pack();
frame.setVisible(true);
}
}
import javax.swing.*;
import java.awt.*;
public class PaintClass extends JPanel
{
private Graphics g;
private int interval,side,number;
private JButton button;
public PaintClass()
{
number = 5;
button = new JButton();
setLayout(new GridLayout(5,5));
for(int i = 0; i <= number - 1; i++)
{
for(int j = 1; j <= number - 1; j++)
{
button = new JButton();//ADDED
button.setBounds(i * interval, 0, interval, interval);
add(button);
}
button = new JButton();//ADDED
button.setBounds(0, i * interval, interval, interval);
add(button);
}
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
this.repaint();
side = 250;
number = 5;
interval = side / number;
g.drawRect(0,0, side, side);
for(int i = 0; i <= number - 1; i++)
{
for(int j = 0; j <= number - 1; j++)
{
g.drawLine(i * interval, 0, i * interval, side);
}
g.drawLine(0, i * interval, side, i * interval);
}
}
}
Choose one or the other: either add the buttons using the GridLayout, or paint the buttons using paintComponent. If the former, you should a) define the loop constraint (right now it is 0) b) create a new JButton for every loop (your code currently reuses the instance) and c) register the appropriate ActionListener to respond to events. If the latter, you need to register the appropriate listener (like MouseListener) to respond to user generated events.
private int interval,side,number;
Number has a default value of 0.
for(int i = 0; i <= number - 1; i++)
Since number is 0, your loop will never execute.
Once you do this the buttons will be added to the panel but they will cover your custom painting. To see background lines you just need to set the background of the panel to Color.BLACK and then create your GridLayout with a gap between the components. Read the API for the method to use.

Transferring JFrame to JPanel

I created a simple "elevator" program (it's still in the beginning stages) that goes up 1 floor when I click UP and vice versa.
I messed up pretty badly when I drew all my components into JFrame, and as expected, it flickers every time I click the button (repaints). I know the solution to be draw in the JPanel and put the said panel in the JFrame, but I have a problem translating my JFrame components into JPanel. I've tried extending JPanel, creating a JFrame object and then overriding the paintComponent() method and doing my drawing there, but when I compile it does not draw it at all. It only creates the frame.
Can anyone help me or give me tips on how to proceed "transferring" my programming from JFrame based to JPanel based? Thank you in advance!
My code is below:
import java.awt.*;
import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.Timer;
import java.math.*;
public class MyCanvas extends JFrame {
private int up = 0;
private int down = 0;
private int movefloorup = 0;
private int buildingType;//type of building (1 = Residential, 2 = Commercial)
private int totnumoffloors; //for the total number of floors
private int numofelevators; //for the number of elevators to be generated
private int floorlimit = 0; //to determine up until where the elevator will be moving
private int currenttime; //determine the time of the day the elevator is operating (1 = Morning, 2 = Lunch, 3 = Afternooon)
//For elevator resetting to bottom
private int rectX = 190;
private int switchmarker = 0;
//Lines and stuff
private int horizborder = 0;
private int bordercount = 0;
private class UpAction implements ActionListener //move the elevator up
{
public void actionPerformed(ActionEvent e)
{
if(movefloorup<780){
repaint();
up++;
movefloorup = movefloorup + 130;
//repaint();
}
else
{
switchmarker = 1;
movefloorup = 0;
repaint();
}
}
}
private class DownAction implements ActionListener //move the elevator down
{
public void actionPerformed(ActionEvent e)
{
if(movefloorup>0){
repaint();
down++;
movefloorup = movefloorup - 130;
//repaint();
}
else
{
switchmarker = 0;
movefloorup = 780;
repaint();
}
}
}
public MyCanvas(int buildingType, int totnumoffloors, int numofelevators, int currenttime){
this.buildingType = buildingType;
this.totnumoffloors = totnumoffloors;
this.numofelevators = numofelevators;
this.currenttime = currenttime;
String title;
if(this.buildingType == 1)
{
title = "Residential Building";
}
else
{
title = "Commercial Building";
}
setLayout(null);
horizborder = 500*((int)Math.ceil((double)totnumoffloors/7)); //calculating how wide the window should be
bordercount = ((int)Math.ceil((double)totnumoffloors/7)); //counts how many borders there will be
//NOTES
//A floor is 130 units in the Y-Direction
//Drawing the bulding layout
if(totnumoffloors>7)
{
setSize(horizborder, 1000);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle(title);
setLayout(new BorderLayout());
getContentPane().setBackground(Color.WHITE);
}
else{
setSize(500, 1000); //suitable for 7 floors
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle(title);
setLayout(new BorderLayout());
getContentPane().setBackground(Color.WHITE);
}
JButton upButton = new JButton("UP");
upButton.addActionListener(new UpAction());
add(upButton, BorderLayout.NORTH);
JButton downButton = new JButton("DOWN");
//downButton.setBounds(0, 0, 220, 30);
//downButton.setLocation(100, 100);
downButton.addActionListener(new DownAction());
add(downButton, BorderLayout.SOUTH);
}
public void paint(Graphics graphics){ //this is where you draw shit
super.paint(graphics);
//Floors
graphics.setColor(Color.RED);
int numoffloorsY = 830;
int numoffloorsX = 830;
int floorbeginning = 0;
int floorcounter = 1;
int floorflag = 0;
int rightedge = 500;
if(this.totnumoffloors>7) //drawing the floors
{
//Default number of floors -> 7
for(int i = 0;i<totnumoffloors;i++)
{
graphics.setColor(Color.RED);
graphics.drawLine(floorbeginning,numoffloorsX,rightedge,numoffloorsY); //FLOORS
graphics.setColor(Color.DARK_GRAY);
graphics.setFont(new Font("TimesRoman", Font.PLAIN, 15));
graphics.drawString(" "+floorcounter, floorbeginning+10, numoffloorsY+20); //SAVE THIS FOR DRAWING FLOORS
numoffloorsY = numoffloorsY - 130;
numoffloorsX = numoffloorsX - 130;
floorcounter++;
floorflag++;
if(floorflag==7)
{
floorbeginning = floorbeginning + 500;
rightedge = rightedge+500;
numoffloorsY = 830;
numoffloorsX = 830;
floorflag = 0;
}
}
//Every other floor past 7 will be added here.
/*for(int i = 0;i<totnumoffloors-7;i++)
{
//System.out.println("LOLOOLO");
graphics.setColor(Color.RED);
graphics.drawLine(floorbeginning,numoffloorsX,horizborder,numoffloorsY);
graphics.setColor(Color.DARK_GRAY);
graphics.setFont(new Font("TimesRoman", Font.PLAIN, 15));
graphics.drawString(" "+floorcounter, floorbeginning, numoffloorsY+20);
//graphics.setColor(Color.DARK_GRAY);
//graphics.drawLine(500,0,500,1000);
floorcounter++;
numoffloorsY = numoffloorsY - 130;
numoffloorsX = numoffloorsX - 130;
}*/
//DIVIDING LINE -> to determine the first 7 floors from the ones higher up.
for(int i=0;i<bordercount;i++)
{
graphics.setColor(Color.DARK_GRAY);
graphics.drawLine(500*i,0,500*i,1000);
}
}
else{
for(int i = 0;i<this.totnumoffloors;i++)
{
graphics.setColor(Color.RED);
graphics.drawLine(0,numoffloorsX,500,numoffloorsY);
graphics.setColor(Color.DARK_GRAY);
graphics.setFont(new Font("TimesRoman", Font.PLAIN, 15));
graphics.drawString(" "+floorcounter, floorbeginning+10, numoffloorsY+20); //SAVE THIS FOR DRAWING FLOOR
numoffloorsY = numoffloorsY - 130;
numoffloorsX = numoffloorsX - 130;
floorcounter++;
}
}
//Drawing the elevators
if(up>0 && movefloorup<1000){
graphics.setColor(Color.GRAY);
if(switchmarker==1)
{
System.out.println("ELSA");
rectX = 690;
//rectX = rectX + 190;
}
else
{
rectX = 190;
}
System.out.println(rectX);
graphics.fillRect(rectX, 850-movefloorup, 100, 100); //this needs to match the stats of the rectangle to fill it properly
graphics.drawRect(rectX, 850-movefloorup, 100, 100);
//Line for the door
graphics.setColor(Color.BLACK);
graphics.drawLine(rectX+50, 850-movefloorup, rectX+50, 950-movefloorup); //match the y-coordinate for the rectangle, add 100 for the y-coordinate of the other end
System.out.println(movefloorup);
System.out.println(switchmarker);
//drawLine(x1, y1, x2, y2); --From (x1,y1) to (x2,y2)
}
else if(down>0 && movefloorup>0)
{
graphics.setColor(Color.GRAY);
if(switchmarker==1) //This determines when the elevator should move to the next column of higher floors.
{
System.out.println("ELSA");
rectX = 500;
}
System.out.println(rectX);
graphics.fillRect(rectX, 850-movefloorup, 100, 100); //this needs to match the stats of the rectangle to fill it properly
//graphics.drawRect(190, 850 + movefloorup, 100, 100); //FIRST FLOOR
graphics.drawRect(rectX, 850-movefloorup, 100, 100); //SECOND FLOOR (135 units difference in Y-axis between floors)
//x-coordinate, y-coordinate, width, height
//Line for the door
graphics.setColor(Color.BLACK);
graphics.drawLine(rectX+50, 850-movefloorup, rectX+50, 950-movefloorup); //match the y-coordinate for the rectangle, add 100 for the y-coordinate of the other end
System.out.println(movefloorup);
System.out.println(switchmarker);
}
else
{
graphics.setColor(Color.GRAY);
graphics.fillRect(190, 850, 100, 100); //this needs to match the stats of the rectangle to fill it properly
graphics.drawRect(190, 850, 100, 100); //FIRST FLOOR
graphics.drawRect(190, 850, 100, 100); //SECOND FLOOR (135 units difference in Y-axis between floors)
//x-coordinate, y-coordinate, width, height
//Line for the door
graphics.setColor(Color.BLACK);
graphics.drawLine(240, 850, 240, 950); //match the y-coordinate for the rectangle, add 100 for the y-coordinate of the other end
//System.out.println("In else!");
}
}
}
The main class just gets input from the user, such as the number of floors, time of day, etc.
This is going to be a little messy.
Start by creating a custom component that extends from JPanel (I'll call it ElevatorPane).
Take the contents of the current paint method and place them within this components paintComponent method. This will involve moving the instance variables that the paintComponent method will need including, totnumoffloors, bordercount, up, down, movefloorup, switchmarker, rectX
This is where it gets a little messy...
You need to take the contents of your ActionListeners and translate these into methods within the ElevatorPane, this way you expose the functionality without exposing the details...
Create a constructor within ElevatorPane that takes the number of floors.
Override the getPrefferedSize method of ElevatorPane and return the size that the component needs to be to satisfy your needs...
Create an instance field of ElevatorPane in MyCanvas, instantiate it and add it to the frame.
Clean, build, run...

How to paint corners of a JButton with numbers?

I'm making a simple Kakuro application in Java Swing and I have used JButtons as cells. I've done everything from generating the grid (setBackground(Color.BLACK) and setBackground(Color.WHITE)) to filling with unique numbers.
But the problem is, I don't know how to paint the "clues" at the ends of JButtons. What I want is similar to:
Sometimes the numbers may appear on only 3 sides, 2 sides or even 1 side.
I thought of setting background images, but its not possible as the numbers are sums of dynamically generated numbers (the grid is dynamic).
So any idea how to get this kind of JButton? Or if its not possible, what other options do I have?
Thanks a lot in advance (I'm really stuck).
very simple and confortable way is add JLabels to the JButton by using BorderLayout,
import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public class FourLabelsInButton {
private JFrame frame;
private JButton myButton1;
private JLabel myButton1_Label_N;
private JLabel myButton1_Label_E;
private JLabel myButton1_Label_W;
private JLabel myButton1_Label_S = new JLabel();
public FourLabelsInButton() {
myButton1_Label_N = new JLabel("45");
myButton1_Label_N.setHorizontalAlignment(JLabel.CENTER);
myButton1_Label_N.setForeground(Color.red);
myButton1_Label_E = new JLabel("1");
myButton1_Label_E.setHorizontalAlignment(JLabel.CENTER);
myButton1_Label_E.setForeground(Color.red);
myButton1_Label_W = new JLabel("9");
myButton1_Label_W.setHorizontalAlignment(JLabel.CENTER);
myButton1_Label_W.setForeground(Color.red);
myButton1_Label_S = new JLabel("21");
myButton1_Label_S.setHorizontalAlignment(JLabel.CENTER);
myButton1_Label_S.setForeground(Color.red);
myButton1 = new JButton();
myButton1.setBackground(Color.black);
myButton1.setLayout(new BorderLayout());
myButton1.add(myButton1_Label_N, BorderLayout.NORTH);
myButton1.add(myButton1_Label_E, BorderLayout.EAST);
myButton1.add(myButton1_Label_W, BorderLayout.WEST);
myButton1.add(myButton1_Label_S, BorderLayout.SOUTH);
frame = new JFrame();
frame.add(myButton1);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
FourLabelsInButton ggg = new FourLabelsInButton();
}
});
}
}
I thought of setting background images, but its not possible as the numbers are sums of dynamically generated numbers (the grid is dynamic).
The images for the buttons can also be generated dynamically.
You may also use a custom component. For this case the painting can be implemented quite straightforward:
class KakuroComponent extends JComponent {
private final int[] numbers;
public KakuroComponent(int... numbers) {
this.numbers = numbers;
}
#Override
public void paintComponent(Graphics g) {
int w = getWidth();
int h = getWidth();
g.setColor(Color.black);
g.fillRect(0, 0, w, h);
g.setColor(Color.white);
g.drawLine(0, 0, w, h);
g.drawLine(w - 1, 0, 0, h - 1);
if (numbers[0] > 0) // if there is a top number
drawStringCentered(g, String.valueOf(numbers[0]), w / 2, h / 6);
if (numbers[1] > 0) // if there is a left number
drawStringCentered(g, String.valueOf(numbers[1]), w / 6, h / 2);
if (numbers[2] > 0) // if there is a right number
drawStringCentered(g, String.valueOf(numbers[2]), w * 5 / 6, h / 2);
if (numbers[3] > 0) // if there is a bottom number
drawStringCentered(g, String.valueOf(numbers[3]), w / 2, h * 5 / 6);
}
void drawStringCentered(Graphics g, String s, int x, int y) {
Rectangle2D bounds = g.getFontMetrics().getStringBounds(s, g);
g.drawString(s, (int) (x - bounds.getCenterX()), (int) (y - bounds.getCenterY()));
}
}
There shouldn't be any reason you can't simply draw anything you want in the JButton by overwriting the paint() method.
public class KakuroSquare extends JButton
{
/* ... */
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
/* Your paint logic. */
}
}

Placing component on Glass Pane

I have a subclass of JLabel that forms a component of my GUI. I have implemented the ability to drag and drop the component from one container to another, but without any visual effects. I want to have this JLabel follow the cursor during the drag of the item from one container to another. I figured that I could just create a glass pane and draw it on there. However, even after I add the component to the glass pane, set the component visible, and set the glass pane visible, and set the glass pane as opaque, I still so not see the component. I know the component works because I can add it to the content pane and have it show up.
How do I add a component to the glass pane?
Finally figured how to get the simple example working. Thanks, #akf. I was able to adapt this solution to my original problem, allowing me to remove ~60 lines of Java2D code that manually rendered a representation of the JLabel.
package test;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
public class MainFrame extends JFrame {
/**
* #param args
*/
public static void main(String[] args) {
MainFrame mf = new MainFrame();
mf.setSize(400, 400);
mf.setLocationRelativeTo(null);
mf.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
mf.setGlassPane(new JPanel());
JLabel l = new JLabel();
l.setText("Hello");
l.setBorder(new LineBorder(Color.BLACK, 1));
l.setBounds(10, 10, 50, 20);
l.setBackground(Color.RED);
l.setOpaque(true);
l.setPreferredSize(l.getSize());
//mf.add(l);
((JPanel)mf.getGlassPane()).add(l);
mf.getGlassPane().setVisible(true);
mf.setVisible(true);
}
}
The example code below shows how to drag a chess piece around a chess board. It uses JLayeredPane instead of a glass pane, but I'm sure the concepts would be the same. That is:
a) add the glass pane to the root pane
b) make the glass pane visible
c) add the component to the glass pane making sure the bounds are valid
d) use setLocation() to animate the dragging of the component
Edit: added code to fix SSCCE
JLabel l = new JLabel();
l.setText("Hello");
l.setBorder(new LineBorder(Color.BLACK, 1));
// l.setPreferredSize(l.getSize());
// l.setBounds(10, 10, 50, 20);
((JPanel)mf.getGlassPane()).add(l);
mf.setVisible(true);
mf.getGlassPane().setVisible(true);
When using layout managers you never use the setSize() or setBounds() methods. In your case you just set the preferred size to (0, 0) since this is the default size of all components.
It works when you add the label to the frame because the default layout manger for the content pane of the frame is a border layout, therefore the preferred size of the label is ignored and the label is made the size of the frame.
However, by default a JPanel uses a FlowLayout which does respect the preferred size of the component. Since the preferred size is 0, there is nothing to paint.
Also, the glass pane needs to made visible in order for it to be painted.
I suggest you read the Swing tutorial. There are section on how layout managers work and on how glass panes work and each section has working examples.
Edit: Example code added below:
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class ChessBoard extends JFrame implements MouseListener, MouseMotionListener
{
JLayeredPane layeredPane;
JPanel chessBoard;
JLabel chessPiece;
int xAdjustment;
int yAdjustment;
public ChessBoard()
{
Dimension boardSize = new Dimension(600, 600);
// Use a Layered Pane for this this application
layeredPane = new JLayeredPane();
layeredPane.setPreferredSize( boardSize );
layeredPane.addMouseListener( this );
layeredPane.addMouseMotionListener( this );
getContentPane().add(layeredPane);
// Add a chess board to the Layered Pane
chessBoard = new JPanel();
chessBoard.setLayout( new GridLayout(8, 8) );
chessBoard.setPreferredSize( boardSize );
chessBoard.setBounds(0, 0, boardSize.width, boardSize.height);
layeredPane.add(chessBoard, JLayeredPane.DEFAULT_LAYER);
// Build the Chess Board squares
for (int i = 0; i < 8; i++)
{
for (int j = 0; j < 8; j++)
{
JPanel square = new JPanel( new BorderLayout() );
square.setBackground( (i + j) % 2 == 0 ? Color.red : Color.white );
chessBoard.add( square );
}
}
// Add a few pieces to the board
ImageIcon duke = new ImageIcon("dukewavered.gif"); // add an image here
JLabel piece = new JLabel( duke );
JPanel panel = (JPanel)chessBoard.getComponent( 0 );
panel.add( piece );
piece = new JLabel( duke );
panel = (JPanel)chessBoard.getComponent( 15 );
panel.add( piece );
}
/*
** Add the selected chess piece to the dragging layer so it can be moved
*/
public void mousePressed(MouseEvent e)
{
chessPiece = null;
Component c = chessBoard.findComponentAt(e.getX(), e.getY());
if (c instanceof JPanel) return;
Point parentLocation = c.getParent().getLocation();
xAdjustment = parentLocation.x - e.getX();
yAdjustment = parentLocation.y - e.getY();
chessPiece = (JLabel)c;
chessPiece.setLocation(e.getX() + xAdjustment, e.getY() + yAdjustment);
layeredPane.add(chessPiece, JLayeredPane.DRAG_LAYER);
layeredPane.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
}
/*
** Move the chess piece around
*/
public void mouseDragged(MouseEvent me)
{
if (chessPiece == null) return;
// The drag location should be within the bounds of the chess board
int x = me.getX() + xAdjustment;
int xMax = layeredPane.getWidth() - chessPiece.getWidth();
x = Math.min(x, xMax);
x = Math.max(x, 0);
int y = me.getY() + yAdjustment;
int yMax = layeredPane.getHeight() - chessPiece.getHeight();
y = Math.min(y, yMax);
y = Math.max(y, 0);
chessPiece.setLocation(x, y);
}
/*
** Drop the chess piece back onto the chess board
*/
public void mouseReleased(MouseEvent e)
{
layeredPane.setCursor(null);
if (chessPiece == null) return;
// Make sure the chess piece is no longer painted on the layered pane
chessPiece.setVisible(false);
layeredPane.remove(chessPiece);
chessPiece.setVisible(true);
// The drop location should be within the bounds of the chess board
int xMax = layeredPane.getWidth() - chessPiece.getWidth();
int x = Math.min(e.getX(), xMax);
x = Math.max(x, 0);
int yMax = layeredPane.getHeight() - chessPiece.getHeight();
int y = Math.min(e.getY(), yMax);
y = Math.max(y, 0);
Component c = chessBoard.findComponentAt(x, y);
if (c instanceof JLabel)
{
Container parent = c.getParent();
parent.remove(0);
parent.add( chessPiece );
parent.validate();
}
else
{
Container parent = (Container)c;
parent.add( chessPiece );
parent.validate();
}
}
public void mouseClicked(MouseEvent e) {}
public void mouseMoved(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public static void main(String[] args)
{
JFrame frame = new ChessBoard();
frame.setDefaultCloseOperation( DISPOSE_ON_CLOSE );
frame.setResizable( false );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
}
Although tangential to the question, the JLayeredPane example cited by #camickr admits the following adaptation, which highlights the effect of mouseReleased() over an existing component.
public ChessBoard() {
...
// Add a few pieces to the board
addPiece(3, 0, "♛");
addPiece(4, 0, "♚");
addPiece(3, 7, "♕");
addPiece(4, 7, "♔");
}
static Font font = new Font("Sans", Font.PLAIN, 72);
private void addPiece(int col, int row, String glyph) {
JLabel piece = new JLabel(glyph, JLabel.CENTER);
piece.setFont(font);
JPanel panel = (JPanel) chessBoard.getComponent(col + row * 8);
panel.add(piece);
}
Besides the pointers to the LayerPane examples already provided, the issue with your original code centers around the setting of the preferred size of your label. You set it before the JLabel has been sized, so your:
l.setPreferredSize(l.getSize());
is ineffectual. If, on the other hand, you make that call after you make your call to setBounds, you will see your desired results. With that in mind, reorder this:
l.setPreferredSize(l.getSize());
l.setBounds(10, 10, 50, 20);
to look like this:
l.setBounds(10, 10, 50, 20);
l.setPreferredSize(l.getSize());
Since I had been following Romain Guy's blogs on Swing for a long time. I have a link that you might be interested in. He released the source - which used a GlassPane for DnD effects.
http://jroller.com/gfx/entry/drag_and_drop_effects_the
I myself never did use a fizzy animation/effect on DnD, so can't comment any further :-|

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