java - 在一个 JFrame 中拖动并移动两个形状

Question

我有一个程序，可以在 JFrame 中绘制 2 个矩形。我希望当我拖动和移动(用于调整大小)时，其中一个矩形和第二个矩形同时移动。因此，当您移动上方矩形的下边框时，下方矩形的上边框也会沿相同方向移动。

编辑:我是 Java 编程的初学者，我根本不知道如何做到这一点。

import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;

class Resizing extends JPanel {
Rectangle rect = new Rectangle(100,100,150,150);
Rectangle rect2 = new Rectangle(100,250,150,100);

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D)g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
    g2.setColor(new Color(0, 0, 200));
    g2.fill(rect);
    g2.setColor(new Color(0, 0, 100));
    g2.fill(rect2);

}

public static void main(String[] args) {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Resizing test = new Resizing();
    Resizing test2 = new Resizing();

    Resizer resizer = new Resizer(test);
    Resizer2 resizer2 = new Resizer2(test2);

    test.addMouseListener(resizer);
    test2.addMouseListener(resizer2);

    test.addMouseMotionListener(resizer);
    test2.addMouseMotionListener(resizer2);

    f.add(test);
    f.add(test2);

    f.setSize(400,400);
    f.setLocation(100,100);
    f.setVisible(true);
}
}
class Resizer extends MouseAdapter {
Resizing component;
boolean dragging = false;
// Give user some leeway for selections.
final int PROX_DIST = 3;

public Resizer(Resizing r) {
    component = r;
}

public void mousePressed(MouseEvent e) {
    if(component.getCursor() != Cursor.getDefaultCursor()) {
        // If cursor is set for resizing, allow dragging.
        dragging = true;
    }
}

public void mouseReleased(MouseEvent e) {
    dragging = false;
}

public void mouseDragged(MouseEvent e) {
    if(dragging){
        Point p = e.getPoint();
        Rectangle r = component.rect;
        int type = component.getCursor().getType();
        int dx = p.x - r.x;
        int dy = p.y - r.y;
        switch(type) {
            case Cursor.N_RESIZE_CURSOR:
                int height = r.height - dy;
                r.setRect(r.x, r.y+dy, r.width, height);
                break;
            case Cursor.S_RESIZE_CURSOR:
                height = dy;
                r.setRect(r.x, r.y, r.width, height);
                break;
            default:
                System.out.println("unexpected type: " + type);
        }
        component.repaint();
    }
}

public void mouseMoved(MouseEvent e) {
    Point p = e.getPoint();
    if(!isOverRect(p)) {
        if(component.getCursor() != Cursor.getDefaultCursor()) {
            // If cursor is not over rect reset it to the default.
            component.setCursor(Cursor.getDefaultCursor());
        }
        return;
    }
    // Locate cursor relative to center of rect.
    int outcode = getOutcode(p);
    Rectangle r = component.rect;
    switch(outcode) {
        case Rectangle.OUT_TOP:
            if(Math.abs(p.y - r.y) < PROX_DIST) {
                component.setCursor(Cursor.getPredefinedCursor(
                                    Cursor.N_RESIZE_CURSOR));
            }
            break;
        case Rectangle.OUT_BOTTOM:
            if(Math.abs(p.y - (r.y+r.height)) < PROX_DIST) {
                component.setCursor(Cursor.getPredefinedCursor(
                                    Cursor.S_RESIZE_CURSOR));
            }
            break;
        default:    // center
            component.setCursor(Cursor.getDefaultCursor());
    }
}

/**
 * Make a smaller Rectangle and use it to locate the
 * cursor relative to the Rectangle center.
 */
private int getOutcode(Point p) {
    Rectangle r = (Rectangle)component.rect.clone();
    r.grow(-PROX_DIST, -PROX_DIST);
    return r.outcode(p.x, p.y);
}

/**
 * Make a larger Rectangle and check to see if the
 * cursor is over it.
 */
private boolean isOverRect(Point p) {
    Rectangle r = (Rectangle)component.rect.clone();
    r.grow(PROX_DIST, PROX_DIST);
    return r.contains(p);
}
}

class Resizer2 extends MouseAdapter {
Resizing component2;
boolean dragging2 = false;
// Give user some leeway for selections.
final int PROX_DIST2 = 3;

public Resizer2(Resizing r2) {
    component2 = r2;
}

    @Override
public void mousePressed(MouseEvent e2) {
    if(component2.getCursor() != Cursor.getDefaultCursor()) {
        // If cursor is set for resizing, allow dragging.
        dragging2 = true;
    }
}

    @Override
public void mouseReleased(MouseEvent e2) {
    dragging2 = false;
}

    @Override
public void mouseDragged(MouseEvent e2) {
    if(dragging2) {
        Point p2 = e2.getPoint();
        Rectangle r2 = component2.rect2;
        int type = component2.getCursor().getType();
        int dx2 = p2.x - r2.x;
        int dy2 = p2.y - r2.y;
        switch(type) {
            case Cursor.N_RESIZE_CURSOR:
                int height = r2.height - dy2;
                r2.setRect(r2.x, r2.y+dy2, r2.width, height);
                break;
            case Cursor.S_RESIZE_CURSOR:
                height = dy2;
                r2.setRect(r2.x, r2.y, r2.width, height);
                break;
            default:
                System.out.println("unexpected type: " + type);
        }
        component2.repaint();
    }
}

public void mouseMoved(MouseEvent e2) {
    Point p2 = e2.getPoint();
    if(!isOverRect(p2)) {
        if(component2.getCursor() != Cursor.getDefaultCursor()) {
            // If cursor is not over rect reset it to the default.
            component2.setCursor(Cursor.getDefaultCursor());
        }
        return;
    }
    // Locate cursor relative to center of rect.
    int outcode = getOutcode(p2);
    Rectangle r2 = component2.rect2;
    switch(outcode) {
        case Rectangle.OUT_TOP:
            if(Math.abs(p2.y - r2.y) < PROX_DIST2) {
                component2.setCursor(Cursor.getPredefinedCursor(
                                    Cursor.N_RESIZE_CURSOR));
            }
            break;
        case Rectangle.OUT_BOTTOM:
            if(Math.abs(p2.y - (r2.y+r2.height)) < PROX_DIST2) {
                component2.setCursor(Cursor.getPredefinedCursor(
                                    Cursor.S_RESIZE_CURSOR));
            }
            break;
        default:    // center
            component2.setCursor(Cursor.getDefaultCursor());
    }
}

/**
 * Make a smaller Rectangle and use it to locate the
 * cursor relative to the Rectangle center.
 */
private int getOutcode(Point p2) {
    Rectangle r2 = (Rectangle)component2.rect2.clone();
    r2.grow(-PROX_DIST2, -PROX_DIST2);
    return r2.outcode(p2.x, p2.y);
}

/**
 * Make a larger Rectangle and check to see if the
 * cursor is over it.
 */
private boolean isOverRect(Point p2) {
    Rectangle r2 = (Rectangle)component2.rect2.clone();
    r2.grow(PROX_DIST2, PROX_DIST2);
    return r2.contains(p2);
}
}

Answer 1

在这个基本example ，mouseDragged()处理程序计算 dx和dy ，当鼠标拖动时应用于对象的相对偏移。在您的情况下，您将对两个矩形应用相同的偏移量。在更详细的例子中引用here ，一个List<Node>命名selected保存当前选定的节点，并且 Node.updatePosition()更新所有选定节点的位置。

附录:我是 Java 编程的初学者，我根本不知道如何做到这一点。

当使用新语言或不熟悉的图形库时，我发现从小示例开始很有帮助。您可以查看引用的一些替代方法 here和 here .