I want to capture mouse events in Swing Component, like MouseDrag Event etc, but I have found there are some events missing when I move my mouse very quickly,
It seems not all of the events are captured. The trace of mouse I captured is discrete but I want to the trace of mouse and the precision is 1 pixel.
Could you help me please? Thanks a lot.
You can't do this. Not even the mouse itself reports every single pixel (or whatever unit it uses) to the computer.
You'll have to interpolate the missing points. A single linear interpolation should do the trick.
If you only want to capture mouse movement on a certain Component, then the MouseDrag event etc will be all you need. As Matti Virkkunen said, you have to do point-to-point interpolation if you want to have a continuous line.
If you are asking about capturing all events that happen inside a Container and its sub-components, then you might consider accessing the EventQueues.
However, I have no actual knowledge of that, but a search on google might get you where u need.
One really easy solution - especially when it comes to painting - is using the provided Graphics and Graphics2D objects:
static class MyPanel extends JPanel {
private static final long serialVersionUID = -5482850214654836564L;
private int lastX = -1;
private int lastY = -1;
public MyPanel() {
super(true); // activate double buffering
addMouseListener(new MouseAdapter() {
#Override public void mousePressed(final MouseEvent pE) {
final int newX = pE.getX();
final int newY = pE.getY();
final Graphics g = getGraphics();
if (g == null) return; // panel not visible
g.drawLine(lastX, lastY, newX, newY); // or add to list
lastX = newX;
lastY = newY;
}
});
}
}
public static void main(final String[] args) {
final JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setBounds(200, 200, 400, 400);
f.add(new MyPanel());
f.setVisible(true);
}
For a more consistent system take a look into Java Shapes (RoundRectangle, Polygon) etc.
Those could be created in the listener part, then stored in a list, and inside the paint()/paintComponent() method you could draw those shapes with g.fill() or g.drawPolygon(p).
Related
As the title suggests, my problem is that I want to be able to drag an image.
In this specific case, I want to drag an image from one JPanel (or rather my own subclass) into another (different) subclass of JPanel. Therefore, I added an MouseListener to my JPanel subclass, so that upon clicking a certain area in the panel, an image is chosen to be painted on the JFrame (subclass). Here's some code so you'll understand my problem:
public void mousePressed(MouseEvent e) {
int x = e.getX();
int y = e.getY();
if (x >= 10 && x < 42 && y >= 10 && y < 42) {
image = barracks; //barracks is a predefined image, created in the constructor
dragBuilding = true;
PixelMain.pixelMain.repaint(); //pixelMain is an instance of the JFrame subclass
}
}
//irrelevant code, e.g mouseMoved, ...
public void mouseDragged(MouseEvent e) {
if (dragBuilding) {
//System.out.println("GPanel mouseDragged");
PixelMain.pixelMain.repaint();
}
}
the JFrame subclass only contains the constructor and the following code:
public void paint(Graphics g) { //i would have used paintComponent, but it seems like JFrame does not have this method ...?
super.paint(g);
if (PixelMain.panelOffense.getDragBuilding()) { //panelOffense is an instance of the JPanel subclass, getDragBuilding returns a boolean that depends on whether the mouse is held down at the moment
Graphics2D g2 = (Graphics2D) g;
Rectangle2D tr = new Rectangle2D.Double((int)getMousePosition().getX(), (int)getMousePosition().getY(), 16, 16); //size of the texture
TexturePaint tp = new TexturePaint(PixelMain.panelOffense.getImg(), tr);
g2.setPaint(tp);
Rectangle2D r = (Rectangle2D) new Rectangle((int)getMousePosition().getX(), (int)getMousePosition().getY(), 16, 16); //area to fill with texture
g2.fill(r);
System.out.println("test");
}
}
Before you ask - I did move some code to other classes so it's called less often, but that's not the problem. Even if the paint method only draws a rectangle (directly on Graphics g, not Graphics2D), the rectangle flickers.
If anyone could help me figure out a solution, I'd be very thankful!
Note: I know it's probably not very elegant to draw on a JFrame or a subclass of JFrame, but I personally don't know an alternative.
Note 2: According to google/stackoverflow results or threads that I read, I should use a JPanel, which seems to be double-buffered (whatever that is, I didn't really understand that. but then again, it's almost 11 pm here). Hence, I could probably move all my components to a JPanel to solve the issue, but I wanted to try to solve the problem without doing that.
Note 3: Yes, the code belongs to a (strategy) game I'm writing, but considering that the problem is not really related to game development exclusively, I decided to post it here and not at game development stack exchange.
This question already has answers here:
Adding Image to a Polygon
(2 answers)
Closed 8 years ago.
I'm trying to basically remake Asteroids in java, but I'm going to use a bald eagle as a ship that shoots down Soviet flags. Right now, my bald eagle image is a square with a white outline around the eagle. I would like to remove this, is there any way to map this in a one-to-one fashion to a polygon of sorts?
Here's my code, though I don't know exactly how this will help anything:
public class Main {
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException {
GameTest t = new GameTest();
}
public static class GameTest extends JFrame {
private static final int WINDOW_WIDTH = 800;
private static final int WINDOW_HEIGHT = 500;
private GamePanel gamePanel;
public GameTest() throws IOException {
super("Deep Fried Freedom");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
setLayout(new BorderLayout());
gamePanel = new GamePanel();
add(gamePanel);
center(this);
setVisible(true);
}
public static void center(JFrame frame) {
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
Point center = ge.getCenterPoint();
int w = frame.getWidth();
int h = frame.getHeight();
int x = center.x - w / 2, y = center.y - h / 2;
frame.setBounds(x, y, w, h);
frame.validate();
}//end of center method
}
}
public class GamePanel extends JPanel {
public static BufferedImage baldEagleImage;
public GamePanel() throws IOException {
super();
baldEagleImage = ImageIO.read(new File("baldeagleimage.jpg"));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.black);// set color black
g.fillRect(0, 0, getWidth(), getHeight()); // paint background
g.drawImage(baldEagleImage, 350, 175, null);//paint the launcher
}//end paintComponent method
}//end GamePanel class
You have several ways that you can achieve this effect. Your best bet would be to use the alpha channel of your image. Just open your image in an image editing tool such as Gimp. In this set the background of your image to transparent around your image.
Another option (which is not the best) but fulfils your request is to use a paint stroke in Java2D. Have a look at using the java2d clipping feature. You can get a tutorial on this here
Usually you will have a Java object that represents the ship, and it has x and y coordinates called something like centerX and centerY. That gives you the center of the ship on your screen within the bounds of the viewable area. You modify these values when you want the ship to move up and down, and you g.drawImage the image you want to use at these coordinates as well (plus any offsets as needed to make the image appear centered to your liking).
A common method is to have a thread started upon initialization, and in that thread is a while(true) block that does an update() method on all objects that need to be updated, and then a Thread.sleep(17) that mimics a framerate of about 60 frames per second. In this method, your ship has its X and Y coords updated and then the image drawn at that location every 17 milliseconds, and that's how you get a ship (and any other object for that matter) to appear like they are moving around on the screen.
I am creating lines and other components and want them to respond like a Swing button events as a line would be clickable :
class CustomLine extends JComponent {
private int destx = 100;
private int desty = 100;
private int startx = 0;
private int starty = 0;
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawLine(startx, starty, destx, desty);
}
}
how this works?
It would be a math problem. You need to find the equation of the line and then find the distance from point (mouse click).
The math is done for you, for example here
You will also need to figure out handling mouse events.
What about extending it from JButton?
Just overrive the paint-Method like you did with JComponent and use it like a normal Button.
I'm not sure, if you need to alter the Border, too. I'm not familiar with altering GUI-Elements, but maybe this should do the trick.
How can I mousedrag different BufferedImages in Java2D?
For instance, if I have ten or more images, how can I move that images which my mouse is over?
Now I'm importing an BufferedImage with
BufferedImage img = new BufferdImage(new File("filename"));
And I'm painting this with Graphics2D with
public void paintComponent(Graphics g) {
super.paintComponent(g);
g2d = (Graphics2D) g;
g2d.drawImage(img, x1, y1, null);
g2d.drawImage(img2, x2, y2,null);
}
Everytime I'm moving on a image I'm repaint()-ing the entire screen.
My mousemove class is as follows
class MouseMotionHandler extends MouseMotionAdapter {
#Override
public void mouseDragged(MouseEvent e) {
x1 = e.getX() - (img.getWidth() / 2);
y1 = e.getY() - (img.getHeight() / 2);
repaint();
}
}
With this method I'm able to "drag" one picture, but what to do when I will drag more individually?
Use the BufferedImage to create an ImageIcon which you use to create a JLabel. Then you add the JLabel to the panel that uses a null layout. No custom painting code is required to do this.
Now if you want to drag the label around you can use the Component Mover.
You can try making a custom component that contains only a single image. Along with your painting and mouse motion handling code, the component overrides the contains method so that it returns true only if the coordinates are within the image.
These components are then stacked in a JLayeredPane, (hopefully) only moving the images that the mouse is on top of.
From what you ask I suppose that your current repainting logic is global. You need to apply it to every image you have. So, if you for instance display every image in JPanel attach MouseMotionListener to every such panel and make this logic happen in JPanel.
If you post more code - especially of the component you show your images in - I will be able to go into more details.
Here's is a simple example that implements dragging for either single- or multiple-selections. The object Node would correspond roughly to your object Card.
Addendum: Also considered the Overlap Layout mentioned in this answer to a related question. Instead of List<Node>, your program would manage a List<Card>, where each Card is a JLabel having a card image.
I should make tree arrays:
one for the x-values
one for the y-values
one for the BufferedImages
So, something like this:
int[] xValues = new int[10];
int[] yValues = new int[10];
BufferedImage[] imgs = new BufferedImage[10];
Then the
class MouseMotionHandler extends MouseMotionAdapter {
#Override
public void mouseDragged(MouseEvent e) {
for (int i = 0; i < 10; i++)
{
xValues[i] = e.getX() - (imgs[i].getWidth() / 2);
yValues[i] = e.getY() - (imgs[i].getHeight() / 2);
}
repaint();
}
}
Then paint them like this:
public void paintComponent(Graphics g) {
super.paintComponent(g);
g2d = (Graphics2D) g;
for (int i = 0; i < 10; i++)
{
g2d.drawImage(imgs[i], xValues[i], yValues[i], null);
}
}
I think something like this is what you need.
Here's the code for my JLayeredPane init. My problem here is that my images don't show up...
layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new java.awt.Dimension(500, 410));
layeredPane.setBorder(javax.swing.BorderFactory.createTitledBorder(
"Center deck"));
for(BufferedImage imgs : images){
JLabel label = new JLabel(new ImageIcon(imgs));
layeredPane.add(label, JLayeredPane.DEFAULT_LAYER);
}
add(layeredPane);
I'm doing these iTunes Stanford classes, and I've been learning beginning Java. Things are going great, but they recently introduced events-and specifically MouseEvents. I've been reading the chapters in the book, and pouring through the example code, and something is just not clicking right for me...it's always that asynchronous stuff that gives me trouble :-D
Earlier, some people mentioned it was important that I mention that the "addMouseListener" is a class in the Graphics import. As far as I can tell, that just adds a blanket mouse listener to the canvas.
I'm still real new to this, so I may not be describing things as well as I should.
This is a piece of code that I have been trying to simplify in order to better understand it. Currently, it will build a red rectangle, and I can click on it and drag it along the x axis. Great!!!
import java.awt.*;
import java.awt.event.*;
import acm.graphics.*;
import acm.program.*;
/** This class displays a mouse-draggable rectangle and oval */
public class DragObject extends GraphicsProgram {
/* Build a rectangle */
public void run() {
GRect rect = new GRect(100, 100, 150, 100);
rect.setFilled(true);
rect.setColor(Color.RED);
add(rect);
addMouseListeners();
}
/** Called on mouse press to record the coordinates of the click */
public void mousePressed(MouseEvent e) {
lastX = e.getX();
lastY = e.getY();
gobj = getElementAt(lastX, lastY);
}
/** Called on mouse drag to reposition the object */
public void mouseDragged(MouseEvent e) {
if((lastX) > 100){
gobj.move(e.getX() - lastX, 0);
lastX = e.getX();
lastY = e.getY();
}
}
/** Called on mouse click to move this object to the front */
public void mouseClicked(MouseEvent e) {
if (gobj != null) gobj.sendToFront();
}
/* Instance variables */
private GObject gobj; /* The object being dragged */
private double lastX; /* The last mouse X position */
private double lastY; /* The last mouse Y position */
}
If I drag the mouse off the canvas, I want the rectangle to stay within the canvas, and not move off it (the same behavior that a horizontal scroll bar would do if you moved beyond the scroll area with the mouse button still clicked). How can I do that?
I've been trying something along these lines, but it's not working right:
if ( ( lastX > (getWidth() - PADDLE_WIDTH) ) || ( lastX < PADDLE_WIDTH ) ) {
gobj.move(0, 0);
} else {
gobj.move(e.getX() - lastX, 0);
}
Your code is moving the rectangle relative to the last position of the mouse. This works fine when you are simply moving things, but for your needs when you want it to stop at the borders, you need to use absolute positioning.
// When the mouse is pressed, calculate the offset between the mouse and the rectangle
public void mousePressed(MouseEvent e) {
lastX = e.getX();
lastY = e.getY();
gobj = getElementAt(lastX, lastY);
}
public void mouseDragged(MouseEvent e) {
double newX;
// Assuming you can get the absolute X position of the object.
newX = gobj.getX() + e.getX() - lastX;
// Limit the range to fall within your canvas. Adjust for your paddle width as necessary.
newX = Math.max( 0, Math.min( newX, getWidth() ) );
// Set the new position of the paddle, assuming you can set the absolute position.
gobj.setX( newX );
lastX = e.getX();
lastY = e.getY();
}
}
This may not be quite what you want because as soon as you go off the edge, the object will stop moving, but then once you move back toward the canvas, your paddle will move immediately instead of waiting for the mouse to reach the same relative position to the paddle at which it started.
You can probably experiment to get it to do what you want.
In order to do this you will need to know the width of the Canvas object, i'm sure there will be a method that will provide this value. You can then check the current x location of the MouseEvent against the width of the canvas, and not increment the x coordinates of the shape object once you are past the width of the canvas. Depending on how much of the shape you want to remain in the canvas, you may need to take into account the width of the shape object as well.
One thing that helps me when dealing w/ animation and moving objects in a gui is drawing out a few scenarios on paper, and noting how the coordinates change.