没有使用mouseMoved（）调用PaintComponent（）方法

Question

I am trying to write a program that allows the user to create squares or circles by clicking on a JButton in a window, and then by clicking somewhere in the window (not on the button).

I currently am using two actionListeners for the different buttons that add a Square or Circle to an arrayList of type Shape (an interface that both square and circle implement). I have a class called frameListener which implements MouseListener and MouseMotionListener, which updates the location of the square or circle when the mouse is moved, deletes the square or circle if the mouse leaves the window, or stops updating it when the mouse is clicked (making it permanent).

I also have a class called MyPanel, which extends JPanel, and uses the paintComponent(Graphics g) method to paint the squares and circles on the background.

package smys01;

import java.util.ArrayList;
import java.text.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;




public class SMYS01 extends JFrame {

    private Color c = new Color(0, 0, 0);
    private static ArrayList<Shape> shapes = new ArrayList();
    private static ArrayList<Shape> deleted = new ArrayList();

    private Point a;
    private boolean makeSquare = false, makeCircle = false, makeSquiggle = false;

    public static void main(String[] args) {
        SMYS01 window = new SMYS01();

    }
    //good main

    //0 is empty for making things, 1 is having a square selected to change, 2 is background;

    private JButton makeSquareB = new JButton("New Square" /*, add icon later*/);

    private JButton makeCircleB = new JButton("New Circle");

    private Color background = new Color(0, 150, 0);



    public SMYS01() {
        makeSquareB.addActionListener(new ActionListener(){
            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("making square");
                if(!makeCircle&&!makeSquare){
                    makeSquare = true;

                    shapes.ensureCapacity(shapes.size());
                    shapes.add(new Square((int) a.getX(), (int) a.getY(), c));
                }else if(makeSquare){

                }else if(makeCircle){
                    makeCircle=false;
                    makeSquare=true;
                    shapes.remove(shapes.size()-1);
                    shapes.ensureCapacity(shapes.size());
                    shapes.add(new Square((int) a.getX(), (int) a.getY(), c));
                }
            }
        });


        makeCircleB.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                System.out.println("making circle");
                if(!makeCircle&&!makeSquare){
                    makeCircle = true;
                    shapes.ensureCapacity(shapes.size());
                    shapes.add(new Circle((int) a.getX(), (int) a.getY(), c));
                }else if(makeCircle){

                }else if(makeSquare){
                    makeSquare=false;
                    shapes.remove(shapes.size()-1);
                    shapes.ensureCapacity(shapes.size());
                    shapes.add(new Circle((int) a.getX(), (int) a.getY(), c));
                }
            }
        });
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane();
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
        MyPanel thing = new MyPanel();


        frame.addMouseListener(new FrameListener());
        frame.setContentPane(thing);

        frame.setSize(thing.getPreferredSize());

        frame.setTitle("Art!");

        frame.addMouseMotionListener(new FrameListener());
    }


    private class MyPanel extends JPanel {

        public MyPanel() {

            GroupLayout layout = new GroupLayout(this);
            layout.setHorizontalGroup(
                    layout.createSequentialGroup()
                    .addComponent(makeCircleB)
                    .addComponent(makeSquareB)
            );
            layout.setVerticalGroup(
                    layout.createSequentialGroup()
                    .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                            .addComponent(makeCircleB)
                            .addComponent(makeSquareB)
                    )
            );

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(500, 500);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(background);
            g.drawRect((int)g.getClipBounds().getX(),(int)g.getClipBounds().getY(),(int)g.getClipBounds().getWidth(),(int)g.getClipBounds().getHeight());
            g.fillRect((int)g.getClipBounds().getX(),(int)g.getClipBounds().getY(),(int)g.getClipBounds().getWidth(),(int)g.getClipBounds().getHeight());


            System.out.println(shapes.size());
            for (Shape i : shapes) {

                int[] a = i.getDim();
                g.setColor(new Color(a[4], a[5], a[6], a[7]));

                if(i instanceof Square){
                    g.drawRect(a[0], a[1], a[2], a[3]);
                    g.fillRect(a[0], a[1], a[2], a[3]);
                }else if(i instanceof Circle){
                    g.drawOval(a[0], a[1], a[2], a[3]);
                    g.fillOval(a[0], a[1], a[2], a[3]);
                }

            }

        }
    }


    class FrameListener implements MouseListener, MouseMotionListener {


        public void mousePressed(MouseEvent e) {
            System.out.println("pressed");
            a = new Point(e.getPoint());
            if (makeSquare) {
                makeSquare = false;
                System.out.println("square made!");
            }
            if (makeCircle) {
                makeCircle = false;
                System.out.println("cirlce made!");
            }

            //use this for sliders, nothing else. 

        }

        public void mouseReleased(MouseEvent e) {
            System.out.println("released");
            a = new Point(e.getPoint());
            //use for sliders, nothing else.

        }

        public void mouseClicked(MouseEvent e) {
            System.out.println("clicked");
            a = new Point(e.getPoint());
            //don't need this
            //makeSquare = false;
            //makeCircle = false;

            //makeSquiggle too.
        }

        public void mouseMoved(MouseEvent e) {

            //showing up as false atm
            a = new Point(e.getPoint());
            System.out.println(a);
            if (makeSquare||makeCircle) {
                Shape b = shapes.get(shapes.size()-1);
                b.updateLocation((int) a.getX(), (int) a.getY());

            }


        }

        public void mouseDragged(MouseEvent e) {
            //only check if over a JSlider
        }

        //complete methods:
        public void mouseEntered(MouseEvent e) {
            System.out.println("entered");
            //nothing, Mouse re-entering doesn't effect the program. 
        }

        public void mouseExited(MouseEvent e) {
            System.out.println("exited");
            makeSquare = false;
            makeCircle = false;
            makeSquiggle = false;
            //if mouse leaves the window while trying to make one of these, stop it. 

        }
    }



}

code for the Shape interface:

package smys01;

public interface Shape {
    public void updateLocation(int newXPos, int newYPos);
    public void updateDimensions(int newXDim, int newYDim);
    public void delete();
    public void purge();
    public void restore();
    public int[] getDim();
}

Code for Square: Note! this code was written a bit back, and has some parts that are not relevant at all or even complete (but are completely unused). This is for the constructor, updateDimensions() method, and the updateLocation() method

package smys01;
import java.awt.Color;
public class Square implements Shape{
    //tbr=to be returned.
    boolean deleted=false;
    boolean purged=false;
    private int xPos, yPos, xDim, yDim;
    private int saveXPos, saveYPos, saveXDim, saveYDim, saveR, saveG, saveB, saveA;
    private Color fill;
    public Square(int initX, int initY, Color a){
        xPos=initX;
        yPos=initY;
        xDim=50;
        yDim=50;
        fill=a;
    }
    public void updateDimensions(int newXDim, int newYDim){
        if(purged||deleted)
            return;
        if(newXDim<=2){
            xDim=2;
        }else{
            xDim=newXDim;
        }
        if(newYDim<=2){
            yDim=2;
        }else{
            yDim=newYDim;
        }

    }
    public void updateLocation(int newXPos, int newYPos){
        if(purged){
            return;
        }
        if(newXPos<=5){
            xPos=5;


        }else{
            xPos=newXPos;

        }
        if(newYPos<=25){
            yPos=25;
        }else{
            yPos=newYPos;
        }


                }
        public void delete(){
        if(!deleted){
            saveXPos=xPos;
            saveYPos=yPos;
            saveXDim=xDim;
            saveYDim=yDim;
            saveR=fill.getRed();
            saveB=fill.getBlue();
            saveG=fill.getGreen();
            saveA=fill.getAlpha();
            deleted=true;
            xPos=-5;
            yPos=-5;
            xDim=1;
            yDim=1;
                        }
    }
    public void purge(){
        saveXPos=-10;
        saveYPos=-10;
        saveXDim=3;
        saveYDim=3;
        //use in an if statement, and if true (will be, set the square value to null, so this reference will go away, preventing data overflow
    }
    public void restore(){
        xPos=saveXPos;
        yPos=saveYPos;
        xDim=saveXDim;
        yDim=saveYDim;
        deleted=false;
    }
    public int[] getDim(){
        int[] tbr={xPos,yPos, xDim, yDim,fill.getRed(), fill.getBlue(), fill.getGreen(), fill.getAlpha()};
        return tbr;
    }
    public String toString(){
        String tbr="Square: ("+xPos+", "+yPos+"); ("+xDim+", "+yDim+"); ("+fill.toString();
        return tbr;
    }

}

The code for the Circle class is the exact same, but the object type allows the paintComponent method to distinguish them.

I am trying to get this to call paintComponent when mouseMoved is called, however I cannot seem to get it to do this. I have tried using repaint(), and I have looked for a few hours trying to figure this out.

So far, I have seen that, basically, Swing will call paintComponent when it needs to (when window size is changed, or window is minimized and re-opened).

However, I am unsure how to call it upon pressing the button or moving the mouse, and repaint() won't work for this.

I apologize if some of the code is sloppy, I have rewritten it a few times, and some parts are unnecessary but still there.

Is there a way to actively call the paintComponent method from within the anonymous action classes or the FrameListener class?

Answer 1

After some input from @MadProgrammer, I figured out what was not working. The mouseListener was attached to the JFrame rather than the JPanel, so the events were being triggered, but paintComponent (by repaint()) was not. I added it to the panel and added repaint() to the end of the mouseMoved() method, and it is working perfectly.