问题：

拖动绘制的形状

金伟

2023-03-14

图形界面允许您使用不同的类创建图形。

在下面的代码中，我使用3个不同的类创建形状：

GeneralPath barBell = new GeneralPath();
barBell.append(new Ellipse2D.Double(100, 100, 75, 100), true);
barBell.append(new Rectangle2D.Double(150, 125, 175, 50), true);
barBell.append(new Ellipse2D.Double(300, 100, 75, 100), true);
shapePanel.addShape(barBell, Color.RED);

shapePanel.addShape(new Rectangle2D.Double(100, 300, 75, 150), Color.BLUE);

Polygon triangle = new Polygon();
triangle.addPoint(0, 0);
triangle.addPoint(100, 0);
triangle.addPoint(50, 100);
triangle.translate(400, 250);
shapePanel.addShape(triangle, Color.GREEN);

产生屏幕图像：

不幸的是，Shape接口不提供任何用于转换Shape的功能。

例如，要将形状移动到新位置，我使用以下方法：

if (dragShape instanceof Path2D)
    ((Path2D)dragShape).transform(AffineTransform.getTranslateInstance(deltaX, deltaY));
else if (dragShape instanceof Polygon)
    ((Polygon)dragShape).translate(deltaX, deltaY);
else if (dragShape instanceof RectangularShape)
{
    RectangularShape rs = (RectangularShape)dragShape;
    Rectangle r = rs.getBounds();
    r.x += deltaX;
    r.y += deltaY;
    rs.setFrame( r );
}

我不喜欢逻辑的实例。

是否有一种更通用的方法可以在不使用instanceof逻辑的面板周围拖动任何形状？

完整示例：

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import javax.swing.*;

public class ShapePanel2 extends JPanel
{
    private ArrayList<ColoredShape> coloredShapes = new ArrayList<ColoredShape>();

    public ShapePanel2()
    {
        DragListener dl = new DragListener();
        addMouseListener(dl);
        addMouseMotionListener(dl);
    }

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

        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        for (ColoredShape cs : coloredShapes)
        {
            g2.setColor( cs.getForeground() );
            g2.fill( cs.getShape() );
        }
    }

    @Override
    public Dimension getPreferredSize()
    {
        return new Dimension(600, 500);
    }

    public void addShape(Shape shape, Color color)
    {
        ColoredShape cs = new ColoredShape(color, shape);
        coloredShapes.add( cs );
        repaint();
    }

    class ColoredShape
    {
        private Color foreground;
        private Shape shape;

        public ColoredShape(Color foreground, Shape shape)
        {
            this.foreground = foreground;
            this.shape = shape;
        }

        public Color getForeground()
        {
            return foreground;
        }

        public void setForeground(Color foreground)
        {
            this.foreground = foreground;
        }

        public Shape getShape()
        {
            return shape;
        }
    }

    class DragListener extends MouseAdapter
    {
        private Shape dragShape;
        private Point pressed;

        @Override
        public void mousePressed(MouseEvent e)
        {
            if (SwingUtilities.isLeftMouseButton(e))
            {
                pressed = e.getPoint();

                for (int i = coloredShapes.size() - 1; i >= 0; i--)
                {
                    ColoredShape cs = coloredShapes.get(i);

                    if (cs.getShape().contains( pressed ))
                    {
                        coloredShapes.remove(i);
                        coloredShapes.add(cs);
                        repaint();
                        dragShape = cs.getShape();
                        break;
                    }
                }
            }
        }

        @Override
        public void mouseDragged(MouseEvent e)
        {
            if (dragShape != null)
            {
                int deltaX = e.getX() - pressed.x;
                int deltaY = e.getY() - pressed.y;

                if (dragShape instanceof Path2D)
                    ((Path2D)dragShape).transform(AffineTransform.getTranslateInstance(deltaX, deltaY));
                else if (dragShape instanceof Polygon)
                    ((Polygon)dragShape).translate(deltaX, deltaY);
                else if (dragShape instanceof RectangularShape)
                {
                    RectangularShape rs = (RectangularShape)dragShape;
                    Rectangle r = rs.getBounds();
                    r.x += deltaX;
                    r.y += deltaY;
                    rs.setFrame( r );
                }

                pressed = e.getPoint();
                repaint();
            }
        }

        @Override
        public void mouseReleased(MouseEvent e)
        {
            dragShape = null;
        }
    }

    private static void createAndShowGUI()
    {
        ShapePanel2 shapePanel = new ShapePanel2();

        GeneralPath barBell = new GeneralPath();
        barBell.append(new Ellipse2D.Double(100, 100, 75, 100), true);
        barBell.append(new Rectangle2D.Double(150, 125, 175, 50), true);
        barBell.append(new Ellipse2D.Double(300, 100, 75, 100), true);
        shapePanel.addShape(barBell, Color.RED);

        shapePanel.addShape(new Rectangle2D.Double(100, 300, 75, 150), Color.BLUE);

        Polygon triangle = new Polygon();
        triangle.addPoint(0, 0);
        triangle.addPoint(100, 0);
        triangle.addPoint(50, 100);
        triangle.translate(400, 250);
        shapePanel.addShape(triangle, Color.GREEN);

        JFrame frame = new JFrame("ShapePanel2");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(shapePanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        java.awt.EventQueue.invokeLater( () -> createAndShowGUI() );
    }
}

共有1个答案

姜经武

2023-03-14

一种方法可能是在将形状添加到面板时，将每个形状转换为通用路径。

现在拖动逻辑只需要支持实现Shape接口的单个类：

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import javax.swing.*;

public class ShapePanel extends JPanel
{
    private ArrayList<ColoredShape> coloredShapes = new ArrayList<ColoredShape>();

    public ShapePanel()
    {
        DragListener dl = new DragListener();
        addMouseListener(dl);
        addMouseMotionListener(dl);
    }

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

        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        for (ColoredShape cs : coloredShapes)
        {
            g2.setColor( cs.getForeground() );
            g2.fill( cs.getShape() );
        }
    }

    @Override
    public Dimension getPreferredSize()
    {
        return new Dimension(600, 500);
    }

    public void addShape(Shape shape, Color color)
    {
        // Convert the Shape to a GeneralPath so the Shape can be translated
        // to a new location when dragged

        ColoredShape cs = new ColoredShape(color, new GeneralPath(shape));
        coloredShapes.add( cs );
        repaint();
    }

    class ColoredShape
    {
        private Color foreground;
        private GeneralPath shape;

        public ColoredShape(Color foreground, GeneralPath shape)
        {
            this.foreground = foreground;
            this.shape = shape;
        }

        public Color getForeground()
        {
            return foreground;
        }

        public void setForeground(Color foreground)
        {
            this.foreground = foreground;
        }

        public GeneralPath getShape()
        {
            return shape;
        }
    }

    class DragListener extends MouseAdapter
    {
        private GeneralPath dragShape;
        private Point pressed;

        @Override
        public void mousePressed(MouseEvent e)
        {
            //  the clicked Shape will be moved to the end of the List
            //  so it is painted on top of all other shapes.

            if (SwingUtilities.isLeftMouseButton(e))
            {
                pressed = e.getPoint();

                for (int i = coloredShapes.size() - 1; i >= 0; i--)
                {
                    ColoredShape cs = coloredShapes.get(i);

                    if (cs.getShape().contains( pressed ))
                    {
                        coloredShapes.remove(i);
                        coloredShapes.add(cs);
                        repaint();
                        dragShape = cs.getShape();
                        break;
                    }
                }
            }
        }

        @Override
        public void mouseDragged(MouseEvent e)
        {
            if (dragShape != null)
            {
                int deltaX = e.getX() - pressed.x;
                int deltaY = e.getY() - pressed.y;

                dragShape.transform(AffineTransform.getTranslateInstance(deltaX, deltaY));

                pressed = e.getPoint();
                repaint();
            }
        }

        @Override
        public void mouseReleased(MouseEvent e)
        {
            dragShape = null;
        }
    }

    private static void createAndShowGUI()
    {
        ShapePanel shapePanel = new ShapePanel();

        GeneralPath barBell = new GeneralPath();
        barBell.append(new Ellipse2D.Double(100, 100, 75, 100), true);
        barBell.append(new Rectangle2D.Double(150, 125, 175, 50), true);
        barBell.append(new Ellipse2D.Double(300, 100, 75, 100), true);
        shapePanel.addShape(barBell, Color.RED);

        shapePanel.addShape(new Rectangle2D.Double(100, 300, 75, 150), Color.BLUE);

        Polygon triangle = new Polygon();
        triangle.addPoint(0, 0);
        triangle.addPoint(100, 0);
        triangle.addPoint(50, 100);
        triangle.translate(400, 250);
        shapePanel.addShape(triangle, Color.GREEN);

        JFrame frame = new JFrame("ShapePanel");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(shapePanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        java.awt.EventQueue.invokeLater( () -> createAndShowGUI() );
    }
}

类似资料：

绘制形状

通过 Entity 添加形状先来看一个添加立方体的例子 var viewer = new Cesium.Viewer('cesiumContainer'); var redBox = viewer.entities.add({ name : 'Red box with black outline', position: Cesium.Cartesian3.fromDegrees(-107
绘制矩形

使用closePath()闭合图形首先我们用上节课的方法绘制一个矩形。 <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title></title> </head> <body> <!DOCTYPE html> <html lang="zh"> <head> <meta charset="UT
如何在MPAndroidChart中绘制可拖动的限制线

我已经使用MP Android chart创建了一个折线图，并希望创建一条可拖动的线来设置限制。因此，如果该值超过行值，则用户会收到警报。我的用例类似于Android系统数据使用限制。我遇到了LimitLines-https://github.com/PhilJay/MPAndroidChart/wiki/The-Axis，还使用触摸事件回调拖动https://github.com/PhilJa
如何使用鼠标拖动事件在Java Applet上绘制矩形

问题内容：我正在使用Java。我想根据mousedrag事件绘制矩形。如果用户拖动鼠标，则小程序上的矩形应根据当前鼠标坐标增加或减少。我有以下代码。在下面的代码中，我使用[b] SelectionArea [/ b]类扩展了在其上执行绘制操作的画布。我在此类中使用[b] image [/ b]变量进行双缓冲，以减少闪烁并保存小程序的先前状态（即，绘制小程序的内容）但如果我画第一个矩形，代码工
OpenCV绘制圆形

可以使用包的相应方法在图像上绘制各种形状，如圆形，矩形，线条，椭圆，多段线，凸起，多段线，多段线。可以使用类的方法在图像上绘制一个圆形。以下是这种方法的语法 - 该方法接受以下参数 - mat - Mat对象，表示要在其上绘制圆的图像。 point - 代表圆中心的对象。 radius - 表示圆的半径的整型变量。 scalar - 表示圆的颜色的标量对象(BGR)。 thickness -
6.1.4绘制矩形

绘制矩形点击菜单栏中的“绘制矩形”按钮可以绘制矩形，绘制矩形在数据下载的时候经常要用到，绘制矩形操作及信息与绘制面相同。修改矩形添加后可以使用“选中对象”后双击更改面的样式，也可右键“属性”修改线的属性信息。点击属性信息框下方的整体移动（单点修改）键对面进行位置的更改。在“空间信息”栏修改矩形的节点坐标后，需要注意的是修改完可能就不是标准矩形了，要调整。删除矩形

拖动绘制的形状

共有1个答案

相关问答

相关文章

相关阅读

相关工具

相关文档