Is there any function which can be replaced with paint() and repaint()in java.
I have a scenario.
There is a triangle (Triangle 1). when user will click in triangle another triangle (Triangle 2) will appear and 1st (Triangle 1) will be removed from screen. (coded using JFrame, paint() and repaint())
I have achieved it so far. but problem is when I minimize or change size of window with mouse the output window, it just paint again Triangle 1 rather than Triangle 2. OR Clear the whole screen if i call g2d.clearRect(0, 0, 1000, 1000);
triangle.reset();
Note: These both functions are to remove previous triangle (Triangle 1).
Is there any function that state should not be changed on minimize or when window size changed ?
or can we override repaint() or anything helping according to scenario.
Here is the Working code. Execute it, Click in triangle then minimize and see again. You will get the problem more clearly.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Triangle_shape extends JFrame implements ActionListener {
public static JButton btnSubmit = new JButton("Submit");
public Triangle_shape() {
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setLayout(new BorderLayout());
frame.add(new TrianglePanel(), BorderLayout.CENTER);
frame.add(btnSubmit, BorderLayout.PAGE_END);
frame.pack();
frame.repaint();
frame.setTitle("A Test Frame");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
#Override
public void actionPerformed(ActionEvent e) {
throw new UnsupportedOperationException("Not supported yet.");
}
public static class TrianglePanel extends JPanel implements MouseListener {
private Polygon triangle, triangle2;
public TrianglePanel() {
//Create triangle
triangle = new Polygon();
triangle.addPoint(400, 550); //left
triangle.addPoint(600, 550); //right
triangle.addPoint(500, 350); //top
//Add mouse Listener
addMouseListener(this);
//Set size to make sure that the whole triangle is shown
setPreferredSize(new Dimension(300, 300));
}
/**
* Draws the triangle as this frame's painting
*/
#Override
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
g2d.draw(triangle);
}
//Required methods for MouseListener, though the only one you care about is click
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
/**
* Called whenever the mouse clicks. Could be replaced with setting the
* value of a JLabel, etc.
*/
public void mouseClicked(MouseEvent e) {
Graphics2D g2d = (Graphics2D) this.getGraphics();
Point p = e.getPoint();
if (triangle.contains(p)) {
System.out.println("1");
g2d.clearRect(0, 0, 1000, 1000);
triangle.reset();
g2d.setColor(Color.MAGENTA);
triangle2 = new Polygon();
triangle2.addPoint(600, 550); // left
triangle2.addPoint(700, 350); //top
triangle2.addPoint(800, 550); //right
g2d.draw(triangle2);
} else {
System.out.println("Triangle dont have point");
}
}
}
}
paint() and repaint() work fine, but you are not using them as they are designed to be used. The window system doesn't keep a persistent image of what a component looks like. It expects your component to be able to repaint its entire appearance on demand (such as when the window is resized or un-minimized).
If you grab a Graphics object with getGraphics() and draw something on the component, the stuff you draw will indeed be lost if/when the entire component needs to be repainted. So you should not do that, but instead make sure your paintComponent method has all the information it needs to completely repaint the component.
If you only want one triangle on the screen at once, do not create a separate variable triangle2. Just replace the one triangle you have by altering your mouse click handler as follows:
public void mouseClicked(MouseEvent e) {
Point p = e.getPoint();
if (triangle.contains(p)) {
triangle = new Polygon();
triangle.addPoint(600, 550); // left
triangle.addPoint(700, 350); //top
triangle.addPoint(800, 550); //right
repaint();
} else {
System.out.println("Point not in triangle");
}
}
Your paintComponent method should call super.paintComponent to ensure the background is painted, but otherwise you do not need to change it:
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.draw(triangle);
}
Alternatively if you are trying to keep multiple triangles on the screen, for example, to add a new one at every click, you should add them into a list of shapes which will be drawn whenever the component needs to be repainted:
private final List<Shape> shapes = new ArrayList<>();
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
for (Shape s : shapes)
g2d.draw(s);
}
Then to control the set of shapes that is on screen, manipulate the contents of the list, and call repaint();.
For instance, to add a new shape to the ones on screen:
Polygon triangle = new Polygon();
triangle.addPoint(200, 300);
triangle.addPoint(200, 200);
triangle.addPoint(300, 200);
shapes.add(triangle);
repaint();
To remove all shapes from the screen:
shapes.clear();
repaint();
You should also make sure that you switch to the Swing thread at the start of the program, because it is not safe to interact with Swing components from the main thread. In main:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
.
.
.
frame.setVisible(true);
}
});
}
Your mouseClicked method should not create a new Triangle object. After resetting triangle just add new points to it. Also don't draw in this method but call repaint:
public void mouseClicked(MouseEvent e) {
Point p = e.getPoint();
if (triangle.contains(p)) {
System.out.println("1");
triangle.reset(); // change the current triangle
triangle.addPoint(600, 550); // new left
triangle.addPoint(700, 350); // new top
triangle.addPoint(800, 550); // new right
repaint(); // force repainting
} else {
System.out.println("Triangle dont have point");
}
}
Now if you want many triangles you should have a collection of Polygons. Like this :
public static class TrianglePanel extends JPanel implements MouseListener {
private Vector<Polygon> triangles;
public TrianglePanel() {
n = 0;
// Create an empty collection
triangles = new Vector<Polygon>();
//Create first triangle
Polygon triangle = new Polygon();
triangle.addPoint(400, 550); //left
triangle.addPoint(600, 550); //right
triangle.addPoint(500, 350); //top
// Add the triangle to the collection
triangles.add(triangle);
//Add mouse Listener
addMouseListener(this);
//Set size to make sure that the whole triangle is shown
setPreferredSize(new Dimension(300, 300));
}
/**
* Draws the triangles as this frame's painting
*/
#Override
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
for (Polygon p : triangles) // Draw all triangles in the collection
g2d.draw(p);
}
//Required methods for MouseListener, though the only one you care about is click
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
/**
* Called whenever the mouse clicks. Could be replaced with setting the
* value of a JLabel, etc.
*/
public void mouseClicked(MouseEvent e) {
Graphics2D g2d = (Graphics2D) this.getGraphics();
Point p = e.getPoint();
// Do what you want with p and the collection
// For example : remove all triangles that contain the point p
ListIterator<Polygon> li = triangles.listIterator();
while (li.hasNext()) {
if (li.next().contains℗) li.remove();
}
// Do what you want to update the list
// For example: Add a new triangle...
Polygon triangle = new Polygon();
triangle.addPoint(600+n, 550); // left
triangle.addPoint(700+n, 350); //top
triangle.addPoint(800+n, 550); //right
triangles.add(triangle); // add the new triangle to the list
n += 10; // next new triangle will be "moved" right
repaint();
}
private int n;
}
Related
Hi I am trying to get my program to move the shapes I create across the screen and for some reason its not working Im not sure whats happening? It has to be something small can anyone point me in the right direction.
public class MultipleObs extends JFrame {
private JPanel paintPanel;
public MultipleObs() {
setDefaultCloseOperation(EXIT_ON_CLOSE);
setMinimumSize(new Dimension(300, 300));
paintPanel = new PaintPanel();
getContentPane().add(paintPanel, BorderLayout.CENTER);
pack();
}
class PaintPanel extends JPanel implements ActionListener {
private java.util.List<Shape> shapes;
private Shape mouseOverShape=null;
int x=0, velX=2;
javax.swing.Timer tm = new javax.swing.Timer(5,this);
public PaintPanel(){
super();
shapes = new ArrayList<Shape>();
shapes.add(new Rectangle2D.Float(x,25,25,25));
shapes.add(new Ellipse2D.Float(x, 15, 60, 30));
shapes.add(new Ellipse2D.Float(x, 35, 60, 30));
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
for (Shape s : shapes){
g2.draw(s);
}
tm.start();
}
#Override
public void actionPerformed(ActionEvent e) {
x = x+ velX;
repaint();
}
}
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new MultipleObs().setVisible(true);
}
});
}
}
Two issues:
Do not ever start a Swing Timer inside of paintComponent. That method should be for painting and painting only. Instead start the Timer in the constructor.
When you create an Ellipse2D object, its position is fixed. Changing one of the variables used to create it will have no effect on the already created object.
A possible solution is to not use Ellipse2D's but instead draw ovals using Graphics#drawOval(...) inside of paintComponent and use the changing x field in that method call. If you must use Ellipse2D's, then you will need to translate them some way, perhaps by using an AffineTransform, but this way is a bit more complicated since I think that you'd have to wrap your Ellipse2D into a Path2D for this to work.
Another option: create a BufferedImage sprite, draw your complex shapes into the BufferedImage using a Graphics2D object obtained from the BufferedImage, and then draw that within paintComponent via drawImage(myImage, imageX, imageY, null), and change the imageX in your Timer.
I'm resolving an excercise about to create a closest pair of points. The first satge i'm doing is trying to make a points(cricles) with my mouse. But i got no respons with the left button (just one circle in (0,0)), the others buttons 2 and 3 work fine. I'm stuck in why and how to resolve that? Any hint or help is appreciate.
Here is the code:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ClosestPairOfPoints extends JFrame {
// Create a canvas
private Circle canvas = new Circle();
public ClosestPairOfPoints() {
// Create a panel
JPanel p = new JPanel();
// Add canvas and panel
add(canvas, BorderLayout.CENTER);
// add(p);
canvas.addMouseListener(new MouseAdapter() {
#Override
// Handle mouse clicked event
public void mouseClicked(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1)
canvas.createCircle();
else if (e.getButton() == MouseEvent.BUTTON2)
System.out.println("Try again with the left button");
else if (e.getButton() == MouseEvent.BUTTON3)
System.out.println("Try again with the left button");
}
});
}
public static void main(String[] args) {
JFrame frame = new ClosestPairOfPoints();
frame.setTitle("Closest pair of Ppoints");
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 300);
frame.setVisible(true);
}
static class Circle extends JPanel { // Inner class
private int x;
private int y;
private int radius = 10; // Default circle radius
// Create a circle
public void createCircle() {
}
// paint the component
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawOval(x, y, radius, radius);
}
}
}
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class ClosestPairOfPoints extends JFrame {
// Create a canvas
private Circle canvas = new Circle();
public ClosestPairOfPoints() {
// Add canvas and panel
add(canvas, BorderLayout.CENTER);
canvas.addMouseListener(new MouseAdapter() {
#Override
// Handle mouse clicked event
public void mouseClicked(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1){
canvas.createCircle(e.getX(), e.getY());
}else if (e.getButton() == MouseEvent.BUTTON2){
System.out.println("Try again with the left button");
}else if (e.getButton() == MouseEvent.BUTTON3){
System.out.println("Try again with the left button");
}
}
});
}
public static void main(String[] args) {
JFrame frame = new ClosestPairOfPoints();
frame.setTitle("Closest pair of Ppoints");
frame.setLocationRelativeTo(null); // Center the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 300);
frame.setVisible(true);
}
static class Circle extends JPanel { // Inner class
private int x;
private int y;
private int radius = 10; // Default circle radius
// Create a circle
public void createCircle(int x, int y) {
this.x = x;
this.y = y;
repaint();
}
// paint the component
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawOval(x, y, radius, radius);
}
}
}
It should work now. You needed to call createCircle and pass it the position of the mouseClick, and then call repaint so the paint component can be called again and the circle redrawn in the correct position.
Haha it seems like another person has posted an answer while I was typing this. As mentioned the event object "e" contains information about the mouse click, so using the getX() and getY() methods, you can get the x and y position of the mouse click.
Also, you don't need the JPanel p = new JPanel(); in your code either.. because "canvas" is already a JPanel and the one you added to the JFrame.
Hope this helps
The left mouse button is responding normally (did a System.out.println with the left mouse button), but, as Hovercraft Full of Eels stated, your createCircle() method is empty. That's your problem.
In terms of actually drawing the circle, I won't write the entire code for you, but I'll tell you that e.getX() and e.getY() will come in handy when figuring out where the mouse is when the mouse click occurred.
I'm trying to figure out how to redraw a panel on mouse click. I can capture the mouse clicks just fine, but cannot for the life of me get the component to draw. This is a simplified test class I setup for simplicity. My Test class exteds JComponent.
Any ideas?
Here's my main:
public static void main(String[] args) {
JFrame frame = new JFrame("Point Capture Test");
frame.setContentPane(new Test().panelMain);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
Here's my Test constructor:
public Test() {
mPanel.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
JOptionPane.showMessageDialog(panelMain, e.getPoint());
JOptionPane.showMessageDialog(panelMain, "clicked "+ e.getSource() + " at " + e.getPoint());
//removed a bunch of stuff here that captures the clicked coordinates so I can use them to draw lines on the panel
repaint();
}
});
}
Here's my Test paintComponent method:
public void paintComponent(Graphics g){
Graphics2D g2 = (Graphics2D) g;
if (this.mClicks > 2) { //draw polygon
Polygon polyTest = new Polygon();
for (Point point : this.mPntPoints){
polyTest.addPoint(point.x, point.y);
}
g2.setColor(Color.RED);
g2.fill(polyTest);
g2.draw(polyTest);
}
//just added this as a test and it doesn't draw either
g2.drawLine(10, 30, 20, 40);
}
My gaol is to draw several images using 2D graphics in a paintComponent() method. However, I'm not sure how I could add a MouseListener such that each image would know if it was selected.
My solution thus far is too simply record the coordinates of the mouse click, and see if they are contained within the boundaries of each of the images. However this will be difficult with images that have more complex boundaries.
Another option would be too create simple shapes and place them over the images, but again images with more complex boundaries will be difficult. In another discussion on SO found
here, someone mentioned using GeneralPath to draw more complex shapes. I have never played with is, but this seems encouraging.
Of these 2 options, what seems to be the best solution, or are there other recommendations
Are you images painted on top of one another or are they drawn separately.
If they are drawn separately, then you should do the custom painting on a JComponent. Then you can do the drawing by using the GeneralPath. You will also need to implement the contains(...) method by checking if the mouseclick is contained in the GeneralPath. If the contains() method is implemented properly then the MouseListener will respond properly.
Here is a simpler example:
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
public class RoundButton extends JButton {
public RoundButton(String label) {
super(label);
// These statements enlarge the button so that it
// becomes a circle rather than an oval.
Dimension size = getPreferredSize();
size.width = size.height = Math.max(size.width, size.height);
setPreferredSize(size);
// This call causes the JButton not to paint the background.
// This allows us to paint a round background.
setContentAreaFilled(false);
}
// Paint the round background and label.
protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
// You might want to make the highlight color
// a property of the RoundButton class.
g.setColor(Color.lightGray);
} else {
g.setColor(getBackground());
}
g.fillOval(0, 0, getSize().width-1, getSize().height-1);
// This call will paint the label and the focus rectangle.
super.paintComponent(g);
}
// Paint the border of the button using a simple stroke.
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width-1, getSize().height-1);
}
// Hit detection.
Shape shape;
public boolean contains(int x, int y) {
// If the button has changed size, make a new shape object.
if (shape == null || !shape.getBounds().equals(getBounds())) {
shape = new Ellipse2D.Float(0, 0, getWidth(), getHeight());
}
return shape.contains(x, y);
}
// Test routine.
public static void main(String[] args) {
// Create a button with the label "Jackpot".
JButton button = new RoundButton("Jackpot");
button.setBackground(Color.green);
button.setBounds(0, 0, 100, 100);
JButton button2 = new RoundButton("Jackpot2");
button2.setBackground(Color.red);
button2.setBounds(50, 50, 100, 100);
// Create a frame in which to show the button.
JFrame frame = new JFrame();
frame.getContentPane().setBackground(Color.yellow);
frame.getContentPane().setLayout(null);
frame.getContentPane().add(button);
frame.getContentPane().add(button2);
// frame.getContentPane().setLayout(new FlowLayout());
frame.setSize(200, 200);
frame.setVisible(true);
MouseListener mouseListener = new MouseAdapter() {
public void mouseEntered( MouseEvent e )
{}
public void mouseExited( MouseEvent e )
{}
public void mouseClicked( MouseEvent e )
{
System.out.println( "clicked " );
}
public void mousePressed( MouseEvent e )
{
System.out.println( "pressed " );
}
public void mouseReleased( MouseEvent e )
{
System.out.println( "released " );
}
};
button.addMouseListener( mouseListener );
}
}
We have a swing application which displays a lot of rectangles. We use Rectangle2D.double class to draw the rectangles on a JPanel.
My requirement is this. Upon clicking the rectangle, I have to pick an image from the local filesystem and show it in a popup window or a frame.
My question is how can I provide a hyperlink or button inside that Rectangle2D.double rectangle.
Please let me know.
Thanks
-Jad.
I hope this is what you mean:
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
public class RectButton extends JPanel {
Rectangle2D.Double rect;
public RectButton() {
this.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
Point point = e.getPoint();
System.out.println(checkRectArea(point));
// Do whatever else you want here.
}
});
}
public boolean checkRectArea(Point point) {
return rect.contains(point);
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
rect = new Rectangle2D.Double(10, 10, 50, 50);
g2.draw(rect);
}
public static void main(String[] args) {
JFrame frame = new JFrame();
RectButton r = new RectButton();
frame.add(r);
frame.setSize(new Dimension(300, 300));
frame.setVisible(true);
}
}
This program draws a rectangle and print true if you clicked inside the rectangle, false otherwise.
You want to put a MouseListener on the panel, that will catch all clicks anywhere on the panel. You can then get the location of the click from the event and determine which rectangle the click happened in, and then call up the code appropriate for that event and location.