問題描述
我在繪制謝爾賓斯基三角形(或謝爾賓斯基墊片)的代碼時遇到了一些問題，但我不確定是什么問題.繪制三角形的線，然后繪制所有分形，然后消失.幫忙?
import javax.swing.*;導入 java.awt.*；公共類 SierpinskiGasket 擴展 JFrame {點 x=新點(5,545)，y=新點(300,25)，z=新點(605,545)，當前=x，目標；私人int計數=0；公共SierpinskiGasket(){超級(謝爾賓斯基墊片")；設置大小(610,550)；設置默認關閉操作(JFrame.EXIT_ON_CLOSE)；getContentPane().setBackground(Color.WHITE);setLocationRelativeTo(null);可調整大小(假)；設置可見(真)；}公共無效油漆(圖形g){super.paint(g);如果(計數==0){g.drawLine(x.x,x.y,y.x,y.y);g.drawLine(x.x,x.y,z.x,z.y);g.drawLine(z.x,z.y,y.x,y.y);} 別的 {而(計數<10000){int 選擇=(int)(Math.random()*3);開關(選擇){案例0:目標=x；休息;案例1:目標=y；休息;案例2:目標=z；休息;默認值:System.exit(0)；}當前=中點(當前，目標)；g.drawRect(current.x,current.y,5,5);重繪()；計數++；}}計數++；}公共點中點(點a，點b){返回新點((Math.round(a.x+b.x)/2),(Math.round(a.y+b.y)/2));}公共靜態無效主要(字符串[]參數){新的謝爾賓斯基墊片()；}}- 不要從頂級容器(如
JFrame)擴展，你不會為它添加任何好處. - 避免繪制到頂級容器.而是使用
JPanel之類的東西. - 避免覆蓋
paint，改用paintComponent.有關詳細信息，請參閱I'm having some issues with my code to draw a Sierpinski's Triangle (or Sierpinski's Gasket), but I'm not sure what the problem is. The lines for the triangle are drawn, then all the fractals, then it disappears. Help?
import javax.swing.*; import java.awt.*; public class SierpinskiGasket extends JFrame { Point x=new Point(5,545), y=new Point(300,25), z=new Point(605,545), current=x, target; private int count=0; public SierpinskiGasket () { super("Sierpinski Gasket"); setSize(610,550); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); getContentPane().setBackground(Color.WHITE); setLocationRelativeTo(null); setResizable(false); setVisible(true); } public void paint(Graphics g) { super.paint(g); if(count==0) { g.drawLine(x.x,x.y,y.x,y.y); g.drawLine(x.x,x.y,z.x,z.y); g.drawLine(z.x,z.y,y.x,y.y); } else { while(count<10000) { int choice=(int)(Math.random()*3); switch(choice) { case 0: target=x; break; case 1: target=y; break; case 2: target=z; break; default: System.exit(0); } current=midpoint(current,target); g.drawRect(current.x,current.y,5,5); repaint(); count++; } } count++; } public Point midpoint(Point a, Point b) { return new Point((Math.round(a.x+b.x)/2), (Math.round(a.y+b.y)/2)); } public static void main(String[] args) { new SierpinskiGasket(); } }解決方案- Don't extend from a top level container (like
JFrame), you're not adding anything of benefit to it. - Avoid painting to top level containers. Instead use something like
JPanel. - Avoid overriding
paint, usepaintComponentinstead. See Performing Custom Painting for more details
This is not how paint works (and I'm not going to try to rewrite your code to make it).
Paint is called in response to a number of events when the repaint system decides that part or whole of the UI needs to be updated. Paints are destructive, that is, when paint is called, the
Graphicswill be completely refreshed, requiring you to "rebuild" the output from scratch.Instead.
Write a recursive algorithm that can paint to something like
BufferedImageand draw that within thepaintComponent...Updated
Painting in Swing is controlled by the
RepaintManager, it is it's responsibility to determine what and when to repaint the screen. You seem to be thinking thepaintis something your control, when it's not.You need to either be prepared to completely repaint the UI or have a buffer prepared that you can paint onto the UI, depending on your needs.
import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; 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 SierpinskisGasket { public static void main(String[] args) { new SierpinskisGasket(); } public SierpinskisGasket() { EventQueue.invokeLater(new Runnable() { @Override public void run() { try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { } JFrame frame = new JFrame("Testing"); 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 { public TestPane() { } @Override public Dimension getPreferredSize() { return new Dimension(200, 200); } @Override protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); BaseShape base = new BaseShape(Math.min(getWidth(), getHeight())); Rectangle bounds = base.getBounds(); int x = (getWidth() - bounds.width) / 2; int y = (getHeight() - bounds.height) / 2; base.transform(AffineTransform.getTranslateInstance(x, y)); g2d.fill(base); g2d.dispose(); } } public class BaseShape extends Path2D.Float { public BaseShape(float size) { float subSize = size / 2f; Triangle top = new Triangle(subSize); top.transform(AffineTransform.getTranslateInstance((size - subSize) / 2, 0)); append(top, false); Triangle left = new Triangle(subSize); left.transform(AffineTransform.getTranslateInstance(0, subSize)); append(left, false); Triangle right = new Triangle(subSize); right.transform(AffineTransform.getTranslateInstance(subSize, subSize)); append(right, false); } } public class Triangle extends Path2D.Float { public Triangle(float size) { moveTo(size / 2f, 0); lineTo(size, size); lineTo(0, size); closePath(); } } }You should never be calling anything from
paintthat could alter the state of the UI and trigger anotherrepaint, otherwise you are going to end up in a end cycle of repaints that will eventually consume your CPU.You should also take a look at Painting in AWT and Swing
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