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Java swing how to layer custom paintings

BACKGROUND
I'm currently working on a project where I want to be able to draw a triangle, circle and a rectangle on a JPanel and move them around.
When a figure is moved, it should end up "at the top" so that it covers other figures that are in an overlapping position and when a figure is moved, the "top" is selected; if several figures cover the position of the mouse pointer, the top one is selected.
MY PROBLEM
I cannot figure out how to fix the issue of my shapes not ending up on top of each other if I drag them to the same position. They just stay in the same layers and if i stack them all on top of each other I still pick up the rectangle first.

They just stay in the same layers...
That's because of the order in which you are drawing them:
drawRec.paintComponent(g);
drawCirc.paintComponent(g);
drawTri.paintComponent(g);
Which will result in the drawTri to always be painted on top of the others (because you always paint it last). In a similar way, drawRec will be painted on the bottom of the others (since you are painting it always first). Then drawCirc will be painted in the middle. There is no dynamic order (let me put it) of the painting here. It doesn't matter what you drag or not, they are always going to be painted in that sequence.
A solution might be to have them in a list or array of some sort where when you drag one shape, you put it last in the list, and move the others before it. If you combine that with painting all shapes sequentialy from the list, then you will have your desired result.
...if i stack them all on top of each other I still pick up the rectangle first.
That's because of how your mousePressed in the ClickListener class works: it first of all checks if the rectangle is clicked and then the others. That means that if the rectangle overlaps another shape, then the rectangle is always going to be prioritized.
One solution might again be putting all your shapes in a data structure where you can modify their selection order. For example a list or array where let's say that the closer to the top is a shape then the later it will appear in the list. Then, when the user clicks somewhere, you will check the shapes starting from the last one in the list going to first one. If you find something, you immediately break the loop and select what you found. If you don't find anything, then the user clicked the panel somewhere where there are no shapes currently.
I am almost certain there must be more efficient data structures than a list or array for this problem (because you have to iterate in linear time all shapes to find the one clicked), but I am not an expert on collision detection, so, in order to keep things simple, I am going to stick with it. But there is also one other operation we want to do: change the painting and the selection order of the clicked shape. Long story short, we can use a LinkedHashSet for the job, because:
It maintains an order of the shapes.
We can quickly and efficiently change the order by first removing the clicked shape from its current postion (constant time) and then adding it back to the LinkedHashSet (also constant time), essentialy placing it last in the insertion order. So that automatically means that we have to use the last element in the set as the top most one. And that's good, because when painting we can iterate over all shapes in the set in the order in which they are found in it, so the last shape will be painted last (which means on top of all others). The same stands for the selection of a shape when clicking: we iterate over all elements, and select the last one which we found containing the user's click point. If LinkedHashSet had a descending iterator (by insertion order) then we could also optimize a little the searching of shapes at a given click point, but it doesn't (at least for Java 8 in which the following demonstration/example code applies), so I will stick with iterating from the start, checking all shapes every time and keeping the last one found containing the click point.
Finally, I would advise you to use the API class java.awt.Shape for the shapes since this enables you to create arbitrary shapes and get the contains method to check if a point lies inside them, the drawing/filling capability, the bounds, the path iterator, and so on...
Summarizing all the above, with an example code:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Paint;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Objects;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class NonComponentMain {
public static Shape createRectangle(final double width,
final double height) {
return new Rectangle2D.Double(0, 0, width, height);
}
public static Shape createEllipse(final double width,
final double height) {
return new Ellipse2D.Double(0, 0, width, height);
}
public static Shape createCircle(final double radius) {
return createEllipse(radius + radius, radius + radius);
}
public static class MoveableShapeHolder {
private final Shape shape;
private final Paint paint;
private final Rectangle2D originalBounds;
private double offsetX, offsetY;
public MoveableShapeHolder(final Shape shape,
final Paint paint) {
this.shape = Objects.requireNonNull(shape);
this.paint = paint;
offsetX = offsetY = 0;
originalBounds = shape.getBounds2D();
}
public void paint(final Graphics2D g2d) {
final AffineTransform originalAffineTransform = g2d.getTransform();
final Paint originalPaint = g2d.getPaint();
g2d.translate(offsetX, offsetY);
if (paint != null)
g2d.setPaint(paint);
g2d.fill(shape);
g2d.setPaint(originalPaint);
g2d.setTransform(originalAffineTransform);
}
public void moveTo(final double newBoundsCenterX,
final double newBoundsCenterY) {
offsetX = newBoundsCenterX - originalBounds.getCenterX();
offsetY = newBoundsCenterY - originalBounds.getCenterY();
}
public void moveBy(final double dx,
final double dy) {
offsetX += dx;
offsetY += dy;
}
public boolean contains(final Point2D pt) {
return shape.contains(pt.getX() - offsetX, pt.getY() - offsetY);
}
public Point2D getTopLeft() {
return new Point2D.Double(offsetX + originalBounds.getX(), offsetY + originalBounds.getY());
}
public Point2D getCenter() {
return new Point2D.Double(offsetX + originalBounds.getCenterX(), offsetY + originalBounds.getCenterY()); //Like 'getTopLeft' but with adding half the size.
}
public Point2D getBottomRight() {
return new Point2D.Double(offsetX + originalBounds.getMaxX(), offsetY + originalBounds.getMaxY()); //Like 'getTopLeft' but with adding the size of the bounds.
}
}
public static class DrawPanel extends JPanel {
private class MouseDrag extends MouseAdapter {
private MoveableShapeHolder current;
private Point origin;
private Point2D center;
#Override
public void mousePressed(final MouseEvent e) {
current = null;
center = null;
final Point evtLoc = e.getPoint();
for (final MoveableShapeHolder moveable: moveables)
if (moveable.contains(evtLoc))
current = moveable; //Keep the last moveable found to contain the click point! It's important to be the last one, because the later the moveable appears in the collection, the closer to top its layer.
if (current != null) { //If a shape was clicked...
//Initialize MouseDrag's state:
origin = e.getPoint();
center = current.getCenter();
//Move to topmost layer:
moveables.remove(current); //Remove from its current position.
moveables.add(current); //Move to last (topmost layer).
//Rapaint panel:
repaint();
}
}
#Override
public void mouseDragged(final MouseEvent e) {
if (current != null) { //If we are dragging something (and not empty space), then:
current.moveTo(center.getX() + e.getX() - origin.x, center.getY() + e.getY() - origin.y);
repaint();
}
}
#Override
public void mouseReleased(final MouseEvent e) {
current = null;
origin = null;
center = null;
}
}
private final LinkedHashSet<MoveableShapeHolder> moveables;
public DrawPanel() {
moveables = new LinkedHashSet<>();
final MouseAdapter ma = new MouseDrag();
super.addMouseMotionListener(ma);
super.addMouseListener(ma);
}
/**
* Warning: all operations on the returned value must be made on the EDT.
* #return
*/
public Collection<MoveableShapeHolder> getMoveables() {
return moveables;
}
#Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
moveables.forEach(moveable -> moveable.paint((Graphics2D) g)); //Topmost moveable is painted last.
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet())
return super.getPreferredSize();
final Dimension preferredSize = new Dimension();
moveables.forEach(moveable -> {
final Point2D max = moveable.getBottomRight();
preferredSize.width = Math.max(preferredSize.width, (int) Math.ceil(max.getX()));
preferredSize.height = Math.max(preferredSize.height, (int) Math.ceil(max.getY()));
});
return preferredSize;
}
}
private static void createAndShowGUI() {
final DrawPanel drawPanel = new DrawPanel();
final Collection<MoveableShapeHolder> moveables = drawPanel.getMoveables();
MoveableShapeHolder moveable = new MoveableShapeHolder(createRectangle(100, 50), Color.RED);
moveable.moveTo(100, 75);
moveables.add(moveable);
moveable = new MoveableShapeHolder(createCircle(40), Color.GREEN);
moveable.moveTo(125, 100);
moveables.add(moveable);
moveable = new MoveableShapeHolder(createRectangle(25, 75), Color.BLUE);
moveable.moveTo(125, 75);
moveables.add(moveable);
final JFrame frame = new JFrame("Click to drag");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(drawPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(final String[] args) {
SwingUtilities.invokeLater(NonComponentMain::createAndShowGUI);
}
}
All the above apply in the case you want to work with a single custom component painting all shapes. If instead you want, you can create a custom component for each shape and use a JLayeredPane for positioning them on top of each other. But then you would probably need a custom LayoutManager too (in order to handle the location of each component).

I created the following GUI.
I created a Shape class. I used a java.awt.Point to hold the center point and a java.awt.Polygon to hold the actual shape. I was able to use the Polygon contains method to see if I was mouse clicking inside the polygon.
I created a ShapeModel class to hold a java.util.List of Shape instances. Creating the proper application model is so important when creating a Swing GUI.
I created a JFrame and a drawing JPanel. The drawing JPanel draws the List of Shape instances. Period. The MouseAdapter will take care of recalculating the polygon and repainting the JPanel.
The trick is in the MouseAdapter mousePressed method. I delete the selected Shape instance and add the selected Shape instance back to the List. This moves the selected shape to the top of the Z-order.
Here's the complete runnable code. I made all the classes inner classes so I could post this code as one block.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class MoveShapes implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new MoveShapes());
}
private final DrawingPanel drawingPanel;
private final ShapeModel shapeModel;
public MoveShapes() {
this.shapeModel = new ShapeModel();
this.drawingPanel = new DrawingPanel();
}
#Override
public void run() {
JFrame frame = new JFrame("Move Shapes");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(drawingPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public void repaint() {
drawingPanel.repaint();
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawingPanel() {
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(600, 500));
MoveListener listener = new MoveListener();
this.addMouseListener(listener);
this.addMouseMotionListener(listener);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (Shape shape : shapeModel.getShapes()) {
g2d.setColor(shape.getColor());
g2d.fillPolygon(shape.getShape());
}
}
}
public class MoveListener extends MouseAdapter {
private Point pressedPoint;
private Shape selectedShape;
#Override
public void mousePressed(MouseEvent event) {
this.pressedPoint = event.getPoint();
this.selectedShape = null;
List<Shape> shapes = shapeModel.getShapes();
for (int i = shapes.size() - 1; i >= 0; i--) {
Shape shape = shapes.get(i);
if (shape.getShape().contains(pressedPoint)) {
selectedShape = shape;
break;
}
}
if (selectedShape != null) {
shapes.remove(selectedShape);
shapes.add(selectedShape);
}
}
#Override
public void mouseReleased(MouseEvent event) {
moveShape(event.getPoint());
}
#Override
public void mouseDragged(MouseEvent event) {
moveShape(event.getPoint());
}
private void moveShape(Point point) {
if (selectedShape != null) {
int x = point.x - pressedPoint.x;
int y = point.y - pressedPoint.y;
selectedShape.incrementCenterPoint(x, y);
drawingPanel.repaint();
pressedPoint = point;
}
}
}
public class ShapeModel {
private final List<Shape> shapes;
public ShapeModel() {
this.shapes = new ArrayList<>();
this.shapes.add(new Shape(100, 250, Color.BLUE, ShapeType.TRIANGLE));
this.shapes.add(new Shape(300, 250, Color.RED, ShapeType.RECTANGLE));
this.shapes.add(new Shape(500, 250, Color.BLACK, ShapeType.CIRCLE));
}
public List<Shape> getShapes() {
return shapes;
}
}
public class Shape {
private final Color color;
private Point centerPoint;
private Polygon shape;
private final ShapeType shapeType;
public Shape(int x, int y, Color color, ShapeType shapeType) {
this.centerPoint = new Point(x, y);
this.color = color;
this.shapeType = shapeType;
createPolygon(shapeType);
}
public void incrementCenterPoint(int x, int y) {
centerPoint.x += x;
centerPoint.y += y;
createPolygon(shapeType);
}
private void createPolygon(ShapeType shapeType) {
this.shape = new Polygon();
switch (shapeType) {
case TRIANGLE:
int angle = 30;
int radius = 100;
for (int i = 0; i < 3; i++) {
Point point = toCartesianCoordinates(angle, radius);
shape.addPoint(point.x, point.y);
angle += 120;
}
break;
case RECTANGLE:
angle = 45;
radius = 100;
for (int i = 0; i < 4; i++) {
Point point = toCartesianCoordinates(angle, radius);
shape.addPoint(point.x, point.y);
angle += 90;
}
break;
case CIRCLE:
radius = 75;
for (angle = 0; angle < 360; angle++) {
Point point = toCartesianCoordinates(angle, radius);
shape.addPoint(point.x, point.y);
}
break;
}
}
private Point toCartesianCoordinates(int angle, int radius) {
double theta = Math.toRadians(angle);
int x = (int) Math.round(Math.cos(theta) * radius) + centerPoint.x;
int y = (int) Math.round(Math.sin(theta) * radius) + centerPoint.y;
return new Point(x, y);
}
public Color getColor() {
return color;
}
public Point getCenterPoint() {
return centerPoint;
}
public Polygon getShape() {
return shape;
}
}
public enum ShapeType {
TRIANGLE, RECTANGLE, CIRCLE
}
}

I cannot figure out how to fix the issue of my shapes not ending up on top of each other if I drag them to the same position
Components on a panel are painted based on the components ZOrder. The component with the lowest ZOrder is painted last.
So in the mousePressed metthod of your MouseListener when you select a component to drag you can change its ZOrder:
Component child = e.getComponent();
child.getParent().setComponentZOrder(child, 0);
Edit:
drawRec.paintComponent(g);
drawCirc.paintComponent(g);
drawTri.paintComponent(g);
I didn't notice that code before.
Never invoke paintComponent() directly.
Swing has a parent/child relationship. You just need to add each of the 3 shape panels to the parent panel. The parent panel will then paint the child components based on the ZOrder I described above. Get rid of those 3 lines of code.

How can I add objects to the screen when I press the mouse button?

I am currently making a tile based game. Everything so far is working fine. However, I want the player to be able to add objects, like stone or wood to the screen when he/she presses the mouse button. I attempted this myself but it is not working. Here is what I have done, but is not working:
This is my KeyInput class, where all the keyboard and mouse events take place.
public static ArrayList<StoneTile> sTile = new ArrayList<StoneTile>();
public KeyInput(Handler handler) {
this.handler = handler;
}
public void tick(LinkedList<Square> object) {}
public void mousePressed(MouseEvent e){
int mx = e.getX();
int my = e.getY();
System.out.println("Pressed (X,Y): " + mx + " " + my);
sTile.add(new StoneTile(1,mx,my));
if(sTile.add(new StoneTile(1,mx,my))){
System.out.println("ADDED");
}
}
public void mouseReleased(MouseEvent e){
System.out.println("Released");
}
Here is my StoneTile class, this is what I want to add to screen:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.util.LinkedList;
public class StoneTile extends Tile {
Textures tex;
public StoneTile(int id,int x,int y) {
super(Textures.stoneArray[0], id);
Tile.x = x;
Tile.y = y;
}
public static void main(String[] args) {
}
public Rectangle getBounds(){
return new Rectangle(x,y,Tile.TILEWIDTH,Tile.TILEHEIGHT);
}
}
The Textures.stoneArray[0] is simply the image that I want to add to the screen.
The Tile.(instance variable, like x, y, TILEWIDTH, and TILEHEIGHT) is simply a Tile class that contains all the render methods for the tiles (grass, stone, etc). If anything is unclear I will clarify or if you need any code provided, then I will add it in.
Note - The ArrayList was just an idea that I had in mind, if there are more efficient ways of doing this or any better ideas, I am open to all of them.
Here is where I set the MouseListener. I set it in an init() method and then called in a run() method (last line):
private void init() {
BufferedImageLoader loader = new BufferedImageLoader();
level = loader.loadImage("level.png");
world = new worldLoader("res/worlds/world1.txt");
handler = new Handler();
WIDTH = getWidth();
HEIGHT = getHeight();
cam = new Camera(handler, Game.WIDTH / 2, Game.HEIGHT / 2);
setWIDTH(getWidth());
setHEIGHT(getHeight());
tex = new Textures();
//backGround = loader.loadImage("/background.jpg");
handler.addObject(new Coin(100, 100, handler, ObjectId.Coin));
handler.addObject(new newStoneTile(20,20,ObjectId.newStoneTile));
handler.addObject(new player_Square(100,100, handler, ObjectId.player_Square));
//handler.addObject(new OneUp(300, 150, handler, ObjectId.OneUp));
this.addKeyListener(new KeyInput(handler));
this.addMouseListener(new KeyInput(handler));
}
jcomponent, is this what you meant?
public class Window {
private static final long serialVersionUID = -6482107329548182911L;
static final int DimensionX = 600;
static final int DimensionY = 600;
public Window(int w, int h, String title, Game game) {
game.setPreferredSize(new Dimension(w, h));
game.setMaximumSize(new Dimension(w, h));
game.setMinimumSize(new Dimension(w, h));
JFrame frame = new JFrame();
frame.add(game);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
game.start();
}
}

Perhaps the best way to try and answer this question is to give a small example.
Essentially what needs to happen is the following (assuming my understanding of the problem is correct):
User clicks on the JComponent/JPanel to determine where to place a Tile. This will cause a MouseEvent that needs to be listened for and handled.
The JComponent/JPanel needs a MouseListener implementation which will create a new Tile object and add it to the List of the Tile objects. Once this is complete the JComponent/JPanel needs to know to repaint(). You do not override repaint() but rather paintComponent(Graphics g), which will be called by repaint() (eventually).
The paintComponent(Graphics g) method will iterate over the List of Tile objects, drawing them to the JComponent/JPanel using the Graphics context for the component.
To illustrate this I have simplified your problem. Note this isn't the best way to solve the problem since the Model (game logic) and the GUI should be separated, ideally using Model View Controller / Observer pattern.
First and most importantly is the GamePanel class, which extends JPanel. It's sole role in this example is to display the game graphically and handle mouse clicks. i.e. handling the list of tasks noted above.
GamePanel
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JPanel;
public class GamePanel extends JPanel {
private List<Tile> tiles; // Stores the Tile objects to be displayed
/**
* Sole constructor for GamePanel.
*
* #param width the width of the game panel
* #param height the height of the game panel
*/
public GamePanel(int width, int height) {
tiles = new ArrayList<>();
setPreferredSize(new Dimension(width, height));
// Implement mouse events for when the JPanel is 'clicked', only using the
// mouse released operation in this case.
addMouseListener(new MouseListener() {
#Override
public void mouseReleased(MouseEvent e) {
// On mouse release, add a StoneTile (in this case) to the tiles List
tiles.add(new StoneTile(e.getX(), e.getY()));
// Repaint the JPanel, calling paint, paintComponent, etc.
repaint();
}
#Override
public void mouseClicked(MouseEvent e) {
// Do nothing
}
#Override
public void mousePressed(MouseEvent e) {
// Do nothing
}
#Override
public void mouseEntered(MouseEvent e) {
// Do nothing
}
#Override
public void mouseExited(MouseEvent e) {
// Do nothing
}
});
}
/**
* Draws the Tiles to the Game Panel.
*
* #param g the Graphics context in which to paint
*/
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g); // Make sure you do this
// For this example, using black as the color to draw
g.setColor(Color.BLACK);
// Iterate over the tile list and draw them to the JPanel
for (Tile tile : tiles) {
Rectangle tileRect = tile.getBounds();
g.fillRect(tileRect.x, tileRect.y, tileRect.width, tileRect.height);
}
}
}
Second is the GameFrame, which extends JFrame. This is just a basic JFrame which adds a GamePanel object. I've also included the main method which will ensure the GUI is initialized on the Event Dispatch Thread.
GameFrame
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class GameFrame extends JFrame {
private static final String TITLE = "Tile Game"; // Game Frame Window Title
private final JPanel gamePanel;
/**
* Sole constructor for GameFrame.
*
* #param width the width of the game in pixels
* #param height the height of the game in pixels
*/
public GameFrame(int width, int height) {
gamePanel = new GamePanel(width, height);
}
/**
* Performs final configuration and shows the GameFrame.
*/
public void createAndShow() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle(TITLE);
add(gamePanel);
pack();
setVisible(true);
}
/**
* Entry point for the program.
*
* #param args not used
*/
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
GameFrame gameFrame = new GameFrame(640, 480);
gameFrame.createAndShow();
}
});
}
}
Finally, the other classes used in the example for completeness, Tile and StoneTile. Personally I don't see much benefit from using Rectangle inside the model, but each to their own and I wanted to keep the example somewhat similar to your currently implementation.
Tile
import java.awt.Rectangle;
public abstract class Tile {
private int x, y, width, height;
public Tile(int x, int y, int width, int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
}
public Rectangle getBounds() {
return new Rectangle(x, y, width, height);
}
}
StoneTile
public class StoneTile extends Tile {
public StoneTile(int x, int y) {
super(x, y, 100, 100);
}
}
One final comment. I notice that your sTile ArrayList is static, this should probably not be the case as it belongs to the class rather than a particular instance of the class.

Drawing circle at centre of JFrame doesn't update after `repaint()`

I am writing a program which involves creating a JFrame and drawing a circle inside it using drawOval() from the Graphics class. I have reached a problem where I am trying to create a point at the centre of the JFrame, and then draw my circle with this pont being the x and y coordinates of the circle. Here is my code so far:
import java.awt.Graphics;
import javax.swing.JFrame;
import java.awt.event.*;
import java.awt.geom.Point2D;
import java.awt.Point;
class MouseJFrameMotion extends JFrame implements MouseMotionListener{
int circleXcenter;
int circleYcenter;
int circleRadius = 50;
boolean show = false;
public MouseJFrameMotion(){
addMouseMotionListener(this);
}
public void paint(Graphics g){
super.paint(g);
if(show){
g.drawOval(circleXcenter,circleYcenter, circleRadius*2,circleRadius*2);
}
}
public void mouseDragged(MouseEvent e){
}
Point frameCenter = new Point((this.getWidth()/2), (this.getHeight()/2));
public void mouseMoved(MouseEvent e){
int xLocation = e.getX();
int yLocation = e.getY();
show = true;
circleXcenter = (int) frameCenter.getX();
circleYcenter = (int) frameCenter.getY();
repaint();
}
}
public class GrowingCircle {
public static void main(String[] args) {
MouseJFrameMotion myMouseJFrame = new MouseJFrameMotion();
myMouseJFrame.setSize(500, 500);
myMouseJFrame.setVisible(true);
}
}
As you can see in the main() function, I set the size of the JFrame to 500x500. However, when the circle is drawn, it's x and y coordinates are (0,0) when I expect them to be (250, 250) based on Point frameCenter after repaint() is called. Where am I going wrong?

So two things...
Don't override paint of JFrame, there a JRootPane, contentPane and other components between the user and the frames surface which can interfere with the painting. Instead, use a JPanel and override its paintComponent method
At the time Point frameCenter = new Point((this.getWidth()/2), (this.getHeight()/2)); is evaluated, the frame's size is 0x0, you need to reevaluate the frameCenter before you paint the circle. When you do this will depend on how dynamic you want the change to be

I think you need both repaint() and revalidate() method

When you are constructing the class MouseJFrameMotion, the variable frameCenter is defined and set width and height 0 and it will never change. So what you can do is to calculate the frame center when you are drawing.
public void mouseMoved(MouseEvent e) {
int xLocation = e.getX();
int yLocation = e.getY();
show = true;
Point frameCenter = new Point((this.getWidth() / 2), (this.getHeight() / 2));
circleXcenter = (int) frameCenter.getX();
circleYcenter = (int) frameCenter.getY();
repaint();
}

Draw in my JPanel calling a function in the "main"

I have an informatic project with JAVA langage for class and it's rated to graduate from high school.
Btw my program consists in drawing geometrical forms in the JPanel with clic control but I don't know how to put, in my main program, fonctions which draw figures as I want like drawSquare(x,y,length). For the moment the program show this window (it's a JFrame with my JPanel inside):
http://i.imgur.com/YetG3VB.png
I have a method readClick() which give to a Point point the coordinates point.x and point.y in the frame but I don't know how, in my main, I can do to call a graphical drawing.
"My problem is that I want to put in my main program something like
Point clic;
clic= Fenetre.readClick() ; // I have this method which wait me to clic on the frame
x = clic.x ; //and give to point the coordonates
y= clic.y; // point.x && point.y
clic = Fenetre.readClick();
a = clic.x ;
b = clic.y ;
"Function which draws rectangle for example"(x,y,a,b);
//It's this fonction I want to create and
// I want it to draw the rectangle in the JPanel
But I don't know how to make the function which adds a drawing in the JPanel "
My main program :
public class Geogebra {
#SuppressWarnings("unused")
public static void main(String args[]){
Fenetre fen = new Fenetre();
}}
My window class :
import java.awt.Color;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.concurrent.SynchronousQueue;
import javax.swing.JFrame;
#SuppressWarnings({ "unused", "serial" })
public class Fenetre extends JFrame {
static Panneau component = null;
private final static SynchronousQueue<MouseEvent> clicks = new SynchronousQueue<MouseEvent>();
public Fenetre(){
JFrame frame = new JFrame();
component = new Panneau();
frame.setTitle("ISNOGEBRA");
frame.setSize(900, 700); // Taille initiale de la fenetre : 900 * 700
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(component);
frame.setVisible(true);
component.addMouseListener( new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
clicks.offer(e);
}
});
}
public static MouseEvent readMouse() {
try {
return clicks.take();
}
catch (InterruptedException e) {
throw new AssertionError();
}
}
public static Point readClick() {
return readMouse().getPoint();
}
}
My JPanel class (the two class Mathwrapper and Menu just draw the interface, I'll show them if needed but it's really long) :
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Shape;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.util.concurrent.ConcurrentLinkedQueue;
import javax.swing.JPanel;
#SuppressWarnings({ "serial", "unused" })
public class Panneau extends JPanel implements MouseListener {
Menu menu;
MathWrapper mw;
public Panneau(){
super();
this.setBackground(Color.WHITE);
menu = new Menu(20, 20);
mw = MathWrapper.getInstance(0, 80);
this.setOpaque(true);
this.addMouseListener(this);
}
#Override
public void paintComponent(Graphics g){
menu.draw(g);
mw.draw(g);
}
public void mouseClicked(MouseEvent e) {
//That shows a blue square behind the icon in the menu I click on
//and draws a black one on the one which was selected
if((e.getX() > 20 && e.getX() < 60) && (e.getY()) > 20 && e.getY() < 60){
menu.btns[menu.activeTool].toggleClicked();
menu.btns[0].toggleClicked();
menu.activeTool = 0;
}else if((e.getX() > 80 && e.getX() < 120) && (e.getY()) > 20 && e.getY() < 60){
menu.btns[menu.activeTool].toggleClicked();
menu.btns[1].toggleClicked();
menu.activeTool = 1;
}else if((e.getX() > 140 && e.getX() < 180) && (e.getY()) > 20 && e.getY() < 60){
menu.btns[menu.activeTool].toggleClicked();
menu.btns[2].toggleClicked();
menu.activeTool = 2;
}else if((e.getX() > 200 && e.getX() < 240) && (e.getY()) > 20 && e.getY() < 60){
menu.btns[menu.activeTool].toggleClicked();
menu.btns[3].toggleClicked();
menu.activeTool = 3;
}else if((e.getX() > 260 && e.getX() < 300) && (e.getY()) > 20 && e.getY() < 60){
menu.btns[menu.activeTool].toggleClicked();
menu.btns[4].toggleClicked();
menu.activeTool = 4;
}
mw.setActiveTool(menu.activeTool);
this.repaint();
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
}
Please help me I've read plents of documents about JPanel and drawing but I still don't understand ..

If I understand your question, you basically want some function from which you can
wait for user interaction and get information about it
draw something to your window
(I'm ignoring right now that you want to do it from the main method, since I'm pretty sure you'll be happy to do it from another method as well)
Basically you are facing two obstacles in that project:
Drawing in most windowing systems is event driven, i. e. if the user puts the window to front, it has to know how to draw its current state
User interaction is also event driven, i. e. you will get callbacks when the user clicks.
The first obstacle is easy to solve: Create a BufferedImage somewhere that both your UI code and the function can access, and draw inside it. (BufferedImage has a createGraphics method you can use to draw inside the image's buffer). Then the paintComponent method just draws the image whenever somebody puts the window to foreground.
The second obstacle is a bit harder. Basically you'll need threading and synchronization for it. It used to be a lot of tweaking with wait and notify and synchronized calls up to Java 1.4, but since Java 1.5 the synchronization (for this special case) can be handled by BlockingQueue class. So your UI code waits (with MouseListener) for a mouse click and adds the coordinates (as a java.awt.Point) to BlockingQueue, and your UI code will just have to wait for the next point whenever it needs one. You will still have a bit of experience using multithreaded applications (so you should know how to start a Thread and that a Thread cannot interact directly with the UI), so depending on your experience of Java it may be a steep learning curve - but certainly doable.
EDIT: I see you are already using some kind of synchronization for the mouse events, so probably the only parts you still need is starting a thread and drawing to a BufferedImage instead of the real window itself.
EDIT2: Here is a very simplified example that shows you how you can draw to a BufferedImage from a second thread. It will ask for coordinates and colors from the console (standard input) and paint them to the image, which will show in the JPanel. It is your task to combine this example with what you already have to move the mouse position across etc.
import java.awt.*;
import javax.swing.*;
import java.awt.image.BufferedImage;
import java.util.Scanner;
public class BufferedImagePainting extends JFrame {
public static void main(String[] args) {
BufferedImage img = new BufferedImage(800, 600, BufferedImage.TYPE_3BYTE_BGR);
JPanel drawPanel = new DrawPanel(img);
new InteractionThread(img, drawPanel).start();
new BufferedImagePainting(drawPanel);
}
public BufferedImagePainting(final JPanel drawPanel) {
super();
setLayout(new GridLayout(1, 1));
add(drawPanel);
pack();
setVisible(true);
}
private static class DrawPanel extends JPanel {
private BufferedImage img;
public DrawPanel(BufferedImage img) {
this.img = img;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(img.getWidth(), img.getHeight());
}
}
private static class InteractionThread extends Thread {
private BufferedImage img;
private JPanel drawPanel;
public InteractionThread(BufferedImage img, JPanel drawPanel) {
this.img = img;
this.drawPanel = drawPanel;
}
#Override
public void run() {
#SuppressWarnings("resource")
Scanner s = new Scanner(System.in);
while (true) {
System.out.println("Enter a draw color and a fill color, separated by spaces");
System.out.println("Enter colors as 6-digit hex number, i. e. 000000 = black, ffffff = white");
Color drawColor = new Color(Integer.parseInt(s.next(), 16));
Color fillColor = new Color(Integer.parseInt(s.next(), 16));
System.out.println("Enter coordinates in form x y width height, separated by spaces");
int x = s.nextInt();
int y = s.nextInt();
int w = s.nextInt();
int h = s.nextInt();
Graphics g = img.createGraphics();
g.setColor(fillColor);
g.fillRect(x, y, w, h);
g.setColor(drawColor);
g.drawRect(x, y, w, h);
g.dispose();
drawPanel.repaint();
}
}
}
}

You must set visibility of your JFrame. Try this in your main class.
public class Geogebra {
#SuppressWarnings("unused")
public static void main(String args[]){
Fenetre fen = new Fenetre();
fen.setVisible(true);
}}

Java Draw Three Shapes Based on Mouse Clicks?

I'm new to drawing in Java and have been having some trouble working with the mouse listener event. What I am trying to do is draw a point on click, then draw a line that extends from that point on click, and finally the last point on click connects to make a triangle. As of now I am just working on getting the point and line to work. The way I have it now is close I think; a circle is drawn in the top corner instead of where the user clicks but on click a line is drawn from where the circle is. Tried using a boolean to decide when something should be drawn but have been unsuccessful..Thanks for any help.
Main Class
package TriangleDraw;
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class TriangleDrawMain {
public static void main(String[] args) {
//create a frame or window
JFrame frame = new JFrame();
//set window size
frame.setSize(500, 500);
//set the title
frame.setTitle("Triangle Draw");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//add panel to frame and make it visible
MouseComponent component = new MouseComponent();
frame.add(component);
frame.setVisible(true);
}
}
Drawing Class
package TriangleDraw;
import java.util.*;
import java.awt.*;
import java.awt.event.MouseListener;
import java.awt.event.MouseEvent;
import javax.swing.*;
import java.awt.geom.*;
public class MouseComponent extends JPanel implements MouseListener{
boolean drawPoint = true;
boolean drawLine = false;
boolean drawTriangle = false;
public MouseComponent(){
super();
pointX = 0;
pointY = 0;
oldX = 0;
oldY = 0;
addMouseListener(this);
}
int pointX, pointY, oldX,oldY;
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
if(drawPoint == true){
g.drawOval(pointX,pointY,10,10);
drawPoint = false;
drawLine = true;
oldX = pointX;
oldY = pointY;
}
if(drawLine == true){
g.drawLine(pointX, pointY, oldX, oldY);
}
}
public void mouseClicked(MouseEvent mouse){
pointX = mouse.getX();
pointY = mouse.getY();
repaint();
}
public void mouseEntered(MouseEvent mouse){ }
public void mouseExited(MouseEvent mouse){ }
public void mousePressed(MouseEvent mouse){ }
public void mouseReleased(MouseEvent mouse){ }
}

I wouldn't change state in paintComponent, you don't know when that will be called (where you assign oldX and oldY). I suggest creating two Point objects, and switch between the two point objects in every other mouseClicked event.
If paintComponent is called more than once between mouseClicked, you'll end up having oldX and OldY equal to pointX and pointY.

Start drawPoint as false. And the change the names of your variables to save points.
Then you'll want something like this in your click:
public void mouseClicked(MouseEvent mouse){
if(!drawPoint)
{
pointX = mouse.getX();
pointY = mouse.getY();
drawPoint = true;
}
else if(!drawLine)
{
lineX = mouse.getX();
lineY = mouse.getY();
drawLine = true;
}
repaint();
}
And then your paint is simple:
public void paintComponent(Graphics g){
super.paintComponent(g);
if(drawLine){
g.drawLine(pointX, pointY, lineX, lineY);
}
else if(drawPoint){
g.drawOval(pointX-5,pointY-5,10,10);
}
}
It's actually important that in your paint loop, you check drawLine first, and in your mouseClicked you check drawPoint first.
Once you've grasped what's happening here, you can attempt the drawTriangle yourself!