在Java中画一个漂亮的圆。

I'm using Java Graphics and I keep getting "ugly" circles.

我使用的是Java图形，而且我一直在使用“丑陋”的圆圈。

Here's what my Java program makes

下面是我的Java程序所做的。

And here's the same thing being made in Matlab

这和在Matlab中做的是一样的。

I think it is clear that the Java one is not as "nice" looking as the Matlab one, particularly on the edges of the circle. Note that this has nothing to do with the resolution...these images are practically the same size. Also note that I am already setting rendering hints.

我认为很明显，Java one并不像Matlab的那样“好看”，尤其是在圆的边缘上。请注意，这与决议没有任何关系……这些图像的大小几乎相同。还要注意，我已经设置了呈现提示。

Here's a stand alone with a Main function you can run to test this out.

这里有一个单独的独立的主函数，你可以运行它来测试它。

package test;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class SimplePaint02 {

    private static final int LINE_THICKNESS = 4;
    private static final int LINE_GAP = 10;
    private Color lineColor = Color.red;

    public static void main(String[] args) {
        new SimplePaint02();
    }

    public SimplePaint02() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

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

    public class TestPane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(100, 100);
        }

        @Override
        public void paintComponent(Graphics g) {

            int radius = 50;
            BufferedImage buffer = new BufferedImage(radius, radius, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2d = buffer.createGraphics();
            g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);

            Ellipse2D circle = new Ellipse2D.Float(0, 0, radius,radius);
            Shape clip = g2d.getClip();
            g2d.setClip(circle);
            AffineTransform at = g2d.getTransform();

            g2d.setTransform(AffineTransform.getRotateInstance(Math.toRadians(45),radius / 2, radius / 2));

            int gap = LINE_GAP;

            g2d.setColor(Color.WHITE);
            g2d.fill(circle);

            g2d.setColor(lineColor);
            //g2d.setStroke(new BasicStroke(LINE_THICKNESS));
            for (int index = 0; index < 10; index++) {
                int x1 = index*gap-(LINE_THICKNESS/2);
                int y1 = 0;
                int x2 = index*gap+(LINE_THICKNESS/2);
                int y2 = radius;
                int width = x2 - x1;
                int height = y2 - y1;

                g2d.fillRect(x1, y1, width, height);
                //g2d.drawLine(index * gap, 0, index * gap, getRadius());
            }

            g2d.setTransform(at);
            g2d.setClip(clip);
            g2d.dispose();
            g.drawImage(buffer, 0, 0, this);
        }

    }

}

5 个解决方案

#1

EDIT: Please see Code Guy's answer below for a solution. This is marked correct because it was Joey Rohan who figured it out initially!

编辑:请参见下面的代码Guy的答案。这是正确的，因为是乔伊·罗汉一开始就知道的!

---

I got smooth edge when i tried out same thing:

当我尝试同样的方法时，我得到了平滑的边缘:

  g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,    RenderingHints.VALUE_ANTIALIAS_ON);

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class DrawSmoothCircle {
    public static void main(String[] argv) throws Exception {
        BufferedImage bufferedImage = new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = bufferedImage.createGraphics();

        g2d.setRenderingHint (RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setPaint(Color.green);
        g2d.fillOval(10, 10, 50, 50);
        g2d.dispose();

        ImageIO.write(bufferedImage, "png", new File("e:\\newimage.png"));
    }
}

UPDATE:

更新:

After searching alot:

后搜索很多:

There is nothing wrong with the code but,

代码没有问题，

Well, unfortunately Java 2D (or at least Sun's current implementation) does not support "soft clipping."

不幸的是，Java 2D(或者至少是Sun的当前实现)不支持“软剪裁”。

But Also got a trick for the clips: Follow This link,you can achieve what you are asking for.

但也有一个小技巧:按照这个链接，你可以实现你想要的。

(Also, i got a smooth edge, cause i din't use clip stuff,in my above image)

(同时，我也得到了平滑的边缘，因为我在上面的图片中没有使用剪辑素材)

#2

Here was the answer. I adapted the majority of the code from this site. Take a look:

这是答案。我修改了这个网站的大部分代码。看一看:

Here's the code:

这是代码:

public void paintComponent(Graphics g) {

        // Create a translucent intermediate image in which we can perform
        // the soft clipping
        GraphicsConfiguration gc = ((Graphics2D) g).getDeviceConfiguration();
        BufferedImage img = gc.createCompatibleImage(getWidth(), getHeight(), Transparency.TRANSLUCENT);
        Graphics2D g2 = img.createGraphics();

        // Clear the image so all pixels have zero alpha
        g2.setComposite(AlphaComposite.Clear);
        g2.fillRect(0, 0, getWidth(), getHeight());

        // Render our clip shape into the image.  Note that we enable
        // antialiasing to achieve the soft clipping effect.  Try
        // commenting out the line that enables antialiasing, and
        // you will see that you end up with the usual hard clipping.
        g2.setComposite(AlphaComposite.Src);
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.WHITE);
        g2.fillOval(0, 0, getRadius(), getRadius());

        // Here's the trick... We use SrcAtop, which effectively uses the
        // alpha value as a coverage value for each pixel stored in the
        // destination.  For the areas outside our clip shape, the destination
        // alpha will be zero, so nothing is rendered in those areas.  For
        // the areas inside our clip shape, the destination alpha will be fully
        // opaque, so the full color is rendered.  At the edges, the original
        // antialiasing is carried over to give us the desired soft clipping
        // effect.
        g2.setComposite(AlphaComposite.SrcAtop);
        g2.setColor(lineColor);
        int gap = LINE_GAP;
        AffineTransform at = g2.getTransform();

        g2.setTransform(AffineTransform.getRotateInstance(Math.toRadians(45),getRadius() / 2, getRadius() / 2));

        for (int index = 0; index < 10; index++) {
            int x1 = index*gap-(LINE_THICKNESS/2);
            int y1 = 0;
            int x2 = index*gap+(LINE_THICKNESS/2);
            int y2 = getRadius();
            int width = x2 - x1;
            int height = y2 - y1;

            g2.fillRect(x1, y1, width, height);
        }

        g2.setTransform(at);
        g2.dispose();

        // Copy our intermediate image to the screen
        g.drawImage(img, 0, 0, null);
    }

#3

Update

OK. Then the idea is to not use clipping at all but instead to make the clipped shape by subtracting areas from each other.

好的。这样做的目的是为了不使用剪切，而是通过减少彼此的区域来实现剪切的形状。

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

public class SimplePaint02 {

    private static final int LINE_THICKNESS = 4;
    private static final int LINE_GAP = 10;
    private Color lineColor = Color.red;

    public static void main(String[] args) {
        new SimplePaint02();
    }

    public SimplePaint02() {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

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

    public class TestPane extends JPanel {

        int radius = 75;

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

        @Override
        public void paintComponent(Graphics g) {


            Ellipse2D circle = new Ellipse2D.Float(0, 0, radius, radius);
            Area lines = new Area();

            int gap = LINE_GAP;

            for (int index = 0; index < 10; index++) {
                int x1 = index * gap - (LINE_THICKNESS / 2);
                int y1 = 0;
                int x2 = index * gap + (LINE_THICKNESS / 2);
                int y2 = radius;
                int width = x2 - x1;
                int height = y2 - y1;

                Shape lineShape = new Rectangle2D.Double(x1, y1, width, height);
                lines.add(new Area(lineShape));

                //g3d.fillRect(x1, y1, width, height);
                //g2d.drawLine(index * gap, 0, index * gap, getRadius());
            }
            //g2d.setClip(circle);

            Area circleNoLines = new Area(circle);
            circleNoLines.subtract(lines);

            Area linesCutToCircle = new Area(circle);
            linesCutToCircle.subtract(circleNoLines);

            //g2d.setTransform(at);
            BufferedImage buffer = new BufferedImage(radius * 2, radius * 2, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2d = buffer.createGraphics();

            RenderingHints rh = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g2d.setTransform(AffineTransform.getRotateInstance(Math.toRadians(45), radius / 2, radius / 2));
            g2d.setRenderingHints(rh);
            g2d.setColor(Color.ORANGE);
            g2d.fill(linesCutToCircle);
            g2d.setColor(Color.RED);
            g2d.fill(circleNoLines);

            g2d.dispose();
            g.drawImage(buffer, 0, 0, this);
        }
    }
}

Old code

Part of the problem is that the rendering operations typically do not apply to a Clip, though they will apply to the Shape when it is drawn. I generally solve that by (last) painting the Shape itself. E.G.

部分问题是，呈现操作通常不应用于剪辑，尽管它们将在绘制时应用于形状。我通常是通过(最后)画出形状本身来解决这个问题。如

A 1.5 pixel BasicStroke is used here for the red circle - smoothing the rough edges produced by the Clip.

在这里使用1.5像素的BasicStroke用于红圆——平滑剪辑所产生的粗糙边缘。

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class SimplePaint02 {

    private static final int LINE_THICKNESS = 4;
    private static final int LINE_GAP = 10;
    private Color lineColor = Color.red;

    public static void main(String[] args) {
        new SimplePaint02();
    }

    public SimplePaint02() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (Exception ex) {
                }

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

    public class TestPane extends JPanel {

        int radius = 75;

        @Override
        public Dimension getPreferredSize() {
            return new Dimension((int)(1.1*radius), (int)(1.1*radius));
        }

        @Override
        public void paintComponent(Graphics g) {

            BufferedImage buffer = new BufferedImage(radius*2, radius*2, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2d = buffer.createGraphics();

            RenderingHints rh = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            rh.put(RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE);
            rh.put(RenderingHints.KEY_COLOR_RENDERING,RenderingHints.VALUE_COLOR_RENDER_QUALITY);
            g2d.setRenderingHints(rh);

            Ellipse2D circle = new Ellipse2D.Float(0, 0, radius,radius);
            Shape clip = g2d.getClip();
            g2d.setClip(circle);
            AffineTransform at = g2d.getTransform();

            g2d.setTransform(AffineTransform.getRotateInstance(Math.toRadians(45),radius / 2, radius / 2));

            int gap = LINE_GAP;

            g2d.setColor(Color.WHITE);
            g2d.fill(circle);

            g2d.setColor(lineColor);
            //g2d.setStroke(new BasicStroke(LINE_THICKNESS));
            for (int index = 0; index < 10; index++) {
                int x1 = index*gap-(LINE_THICKNESS/2);
                int y1 = 0;
                int x2 = index*gap+(LINE_THICKNESS/2);
                int y2 = radius;
                int width = x2 - x1;
                int height = y2 - y1;

                g2d.fillRect(x1, y1, width, height);
                //g2d.drawLine(index * gap, 0, index * gap, getRadius());
            }

            g2d.setTransform(at);
            g2d.setClip(clip);
            g2d.setClip(null);
            g2d.setStroke(new BasicStroke(1.5f));
            g2d.draw(circle);
            g2d.dispose();
            g.drawImage(buffer, 0, 0, this);
        }
    }
}

#4

I used drawPolygon method to draw circle by generating array of most of the points on circumference of circle with proposed radius. Code:

我使用了drawPolygon方法来绘制圆的大部分点的圆，并给出了半径。代码:

           import java.awt.*;
           import java.applet.*;

            /*<applet code="OnlyCircle" width=500 height=500>
                 </applet>*/

          public class OnlyCircle extends Applet{

            public void paint(Graphics g){


              int r=200;//radius
              int x1=250;//center x coordinate
              int y1=250;//center y coordinate
              double x2,y2;
              double a=0;
              double pi=3.14159;
              int count=0; 
              int i=0;
              int f=0;
              int[] x22=new int[628319];
              int[] y22=new int[628319];

             while(a<=2*pi&&i<628319&&f<628319)
                  {
                   double k=Math.cos(a);
                   double l=Math.sin(a);
                     x2=x1+r*k;
                     y2=y1+r*l;
                  x22[i]=(int)x2;
                  y22[f]=(int)y2;
                   i++;
                   f++;
                   a+=0.00001;
                  }
               int length=x22.length;
               g.drawPolygon(x22,y22,length);
                 }
               }

#5

You can enable anti-aliasing:

您可以启用反锯齿:

Graphics2D g2 = (Graphics2D) g;
Map<RenderingHints.Key, Object> hints = new HashMap<RenderingHints.Key, Object>();
hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); 
g2.setRenderingHints(hints);

I also suggest you draw to the Graphics object you get from the paintComponent method rather than creating an intermediate BufferedImage.

我还建议您从paintComponent方法中得到的图形对象，而不是创建一个中间的BufferedImage。