java - オブジェクトをドラッグする方法

Question

ボックスをドラッグしたいのですが、四角形をドラッグしているときに四角形をクリックした場所にマウスカーソルを置きたいです。私はこのコードを試してみましたが、ドラッグしようとするとたくさんのエラーが発生しました。

import objectdraw.*;

import java.awt.*;

public class TouchWindow extends WindowController
{

    private FilledRect a;
    private boolean b;
    private Location c;
    private int x;
    private int y;
    public void begin()
    {
        b=false;
        a=new FilledRect(0,0,50,50,canvas);
    }
    public void onMouseClick(Location pt)
    {
        if(a.contains(pt))
        {
        b=true;
        pt=c;
        }
    }
    public void onMouseDrag(Location pt2)
    {
        if(b==true)
        {
        x=(int)c.getX()-(int)pt2.getX();
        y=(int)c.getY()-(int)pt2.getY();
        a.move(x,y);
        }
    }
}

Answer 1

うーん、これは私が横たわっていた例ですが、アプレットではありませんが、非常に簡単に移植できます。

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class ShapeMover {

    public ShapeMover() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Shape Mover");

        initComponents(frame);

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String s[]) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new ShapeMover();
            }
        });

    }

    private void initComponents(JFrame frame) {
        frame.getContentPane().add(new DragPanel());
    }
}

class DragPanel extends JPanel {

    Rectangle rect = new Rectangle(0, 0, 100, 50);
    int preX, preY;
    boolean isFirstTime = true;
    Rectangle area;
    boolean pressOut = false;
    private Dimension dim = new Dimension(400, 300);

    public DragPanel() {
        setBackground(Color.white);
        addMouseMotionListener(new MyMouseAdapter());
        addMouseListener(new MyMouseAdapter());
    }

    @Override
    public Dimension getPreferredSize() {
        return dim;
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g;
        if (isFirstTime) {
            area = new Rectangle(dim);
            rect.setLocation(50, 50);
            isFirstTime = false;
        }

        g2d.setColor(Color.black);
        g2d.fill(rect);
    }

    boolean checkRect() {
        if (area == null) {
            return false;
        }

        if (area.contains(rect.x, rect.y, rect.getWidth(), rect.getHeight())) {
            return true;
        }

        int new_x = rect.x;
        int new_y = rect.y;

        if ((rect.x + rect.getWidth()) > area.getWidth()) {
            new_x = (int) area.getWidth() - (int) (rect.getWidth() - 1);
        }
        if (rect.x < 0) {
            new_x = -1;
        }
        if ((rect.y + rect.getHeight()) > area.getHeight()) {
            new_y = (int) area.getHeight() - (int) (rect.getHeight() - 1);
        }
        if (rect.y < 0) {
            new_y = -1;
        }
        rect.setLocation(new_x, new_y);
        return false;
    }

    private class MyMouseAdapter extends MouseAdapter {

        @Override
        public void mousePressed(MouseEvent e) {
            preX = rect.x - e.getX();
            preY = rect.y - e.getY();

            if (rect.contains(e.getX(), e.getY())) {
                updateLocation(e);
            } else {
                pressOut = true;
            }
        }

        @Override
        public void mouseDragged(MouseEvent e) {
            if (!pressOut) {
                updateLocation(e);
            } else {
            }
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            if (rect.contains(e.getX(), e.getY())) {
                updateLocation(e);
            } else {
                pressOut = false;
            }
        }

        public void updateLocation(MouseEvent e) {
            rect.setLocation(preX + e.getX(), preY + e.getY());
            checkRect();

            repaint();
        }
    }
}