如何在java中绘制菱形？

Question

所以我必须画一个菱形。不是静态钻石，而是我自己拖动和绘制的钻石。我已经使用通用路径来做到这一点，但它正在绘制一个不直的钻石；钻石向左弯曲，它没有被吸引到我的鼠标指向的地方。

这是我创建菱形的代码。有人可以帮我解决这个问题吗？

 private GeneralPath drawDiamond(int x1, int y1, int x2, int y2){
            
            int x = Math.min(x1, x2);
            int y = Math.min(y1, y2);

            // Gets the difference between the coordinates and

            int width = Math.abs(x1 - x2);
            int height = Math.abs(y1 - y2);
            
            Rectangle2D.Double diamond = new Rectangle2D.Double(x1,y1,width,height);
            
            GeneralPath connectedDiamond = new GeneralPath(GeneralPath.WIND_EVEN_ODD);
            
            connectedDiamond.append(diamond, true);
            
            AffineTransform at = new AffineTransform();
            at.rotate(Math.toRadians(20));
            connectedDiamond.transform(at);
            
            return connectedDiamond;
        }

这是我的绘画方法：

public void paint(Graphics g) {           

            graphSettings = (Graphics2D) g;           

            graphSettings.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON);

            graphSettings.setStroke(new BasicStroke(4));
           
            Iterator<Color> strokeCounter = shapeStroke.iterator();
            for (NamedShape s : shapes) {

                graphSettings.draw(s.getShape());

            }

            if (drawStart != null && drawEnd != null) {
                
                graphSettings.setComposite(AlphaComposite.getInstance(
                        AlphaComposite.SRC_OVER, 0.40f));

                graphSettings.setPaint(Color.LIGHT_GRAY);

                Shape aShape = null;
                    
                if(currentAction == 7){
                    
                    aShape = drawDiamond(drawStart.x, drawStart.y, drawEnd.x, drawEnd.y);
                }

                graphSettings.draw(aShape);
            }
        }

有人可以帮我做这件事吗？

Answer 1

将菱形创建为具有顶点的多边形会更简单

(x + Width/2, y)
(x + Width, y + Height/2)
(x + Width/2, y + Height)
(x, y + Height/2)

Answer 2

2D Shape API 实际上非常强大，我最喜欢的类之一是Path2D，它允许您简单地“绘制”虚拟形状，例如

public class Diamond extends Path2D.Double {

    public Diamond(double width, double height) {
        moveTo(0, height / 2);
        lineTo(width / 2, 0);
        lineTo(width, height / 2);
        lineTo(width / 2, height);
        closePath();
    }

}

现在，您需要使用 AffineTransformation 或翻译 Graphics 上下文来定位它，但这并不难

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Path2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class JavaApplication251 {

    public static void main(String[] args) {
        new JavaApplication251();
    }

    public JavaApplication251() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private Diamond diamond;

        public TestPane() {
            diamond = new Diamond(100, 100);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int x = (getWidth() - diamond.getBounds().width) / 2;
            int y = (getHeight()- diamond.getBounds().height) / 2;
            AffineTransform at = AffineTransform.getTranslateInstance(x, y);
            Shape shape = at.createTransformedShape(diamond);
            g2d.setColor(Color.YELLOW);
            g2d.fill(shape);
            g2d.setColor(Color.RED);
            g2d.draw(shape);
            g2d.dispose();
        }

    }

    public class Diamond extends Path2D.Double {

        public Diamond(double width, double height) {
            moveTo(0, height / 2);
            lineTo(width / 2, 0);
            lineTo(width, height / 2);
            lineTo(width / 2, height);
            closePath();
        }

    }

}

Answer 3

不如不旋转矩形，而是在矩形内的 4 个点之间画线：

要点：

请原谅我糟糕的 mspaint 技能。

但我希望你明白我的意思。你取顶部中心、中间右侧、底部中心和中间左侧点并在这些点之间画线（我认为使用 generalPath）