用Java绘制一个漂亮的圆圈
我正在使用Java Graphics而且我一直在变得“丑陋”。
这是我的Java程序所做的 
这是在Matlab中做的同样的事情 
我认为Java显然不像Matlab那样“好看”，特别是在圆的边缘。 请注意，这与分辨率无关……这些图像的大小几乎相同。 另请注意，我已经设置了渲染提示。
这是一个独立的主要function，你可以运行来测试它。
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); } } } 编辑：请参阅Code Guy的答案以获得解决方案。 这标记是正确的，因为Joey Rohan最初想出来了！
当我尝试同样的事情时，我得到了顺利的优势：
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")); } }
更新：
搜索了很多：
代码没有错，但是，
好吧，不幸的是Java 2D（或者至少Sun目前的实现）不支持“软剪辑”。
但也有一个技巧的剪辑：按照这个链接 ，你可以实现你所要求的。
（另外，我有一个光滑的边缘，因为我不会使用剪辑的东西，在我上面的图像）
这是答案。 我改编了这个网站的大部分代码。 看一看：
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); }
更新
好。 然后，我们的想法是不使用剪裁，而是通过减去彼此的区域来制作剪裁的形状。
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); } } }
旧代码
部分问题是渲染操作通常不适用于Clip ，尽管它们在绘制时将应用于Shape 。 我通常通过（最后）绘制Shape本身来解决这个问题。 例如
这里使用1.5像素的BasicStroke作为红色圆圈 - 平滑Clip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); } } }
我使用drawPolygon方法通过在建议半径的圆周上生成大多数点的数组来绘制圆。 码：
import java.awt.*; import java.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); } }
您可以启用消除锯齿：
Graphics2D g2 = (Graphics2D) g; Map hints = new HashMap(); hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2.setRenderingHints(hints);
我还建议你绘制到paintComponent方法得到的Graphics对象，而不是创建一个中间的BufferedImage 。