Java Swing中的图形绘制仅绘制点 [英] Graph plotting in Java Swing only draws points

问题描述

我目前正在研究一个程序，其中某些数值变量会随着时间而变化，并在每次迭代中显示其值。这很好，但现在我想绘制一张图表，展示它们随着时间的演变。
所以，我看了一个在Swing中绘制图表的代码示例。我的最终代码如下所示：

  public class Populus3 extends JPanel 
 {
 public static void main String [] args）抛出IOException {
 
 final Populus3 pop = new Populus3（）; 
 
 JFrame f = new JFrame（）; //我要绘制图形
 f.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 f.add（new GraphingData（））; 
 f.setSize（400,400）; 
 f.setLocation（200,200）; 
 f.setVisible（true）; 
 
 
 frame = new JFrame（Animation Frame）; //我正在为程序的另一个元素运行动画
 frame.add（pop，BorderLayout.CENTER）; 
 frame.setSize（graphSize，graphSize）; 
 frame.setVisible（true）; 
 frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 
 //插入各种东西
 
 
 
 $ b $ public void paint（Graphics g）
 {
 super.paint（g）; 
 paintCell（g，1）; 
 Toolkit.getDefaultToolkit（）。sync（）; //需要linux用户正确绘制和动画图像
 g.dispose（）; 
} 
 
 
 public void actionPerformed（ActionEvent e）{
 repaint（）; 
 
 
 
 $ b @Override 
 protected void paintComponent（Graphics g）
 {
 super.paintComponent（g）; 
 for（int i = 0; i< particleType.length; i ++）
 paintCell（g，i）; //为动画面板绘制一个小圆圈的方法
} 
 
 
 
 public static class GraphingData extends JPanel {
 int [] data = {
 21，14，18，03，86，88，74，87，54，77，
 61,55,48,60,49,36,38,27,20,18 
}; 
 final int PAD = 20; 
 
保护void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 Graphics2D g2 =（Graphics2D）g; 
 g2.setRenderingHint（RenderingHints.KEY_ANTIALIASING，
 RenderingHints.VALUE_ANTIALIAS_ON）; 
 int w = getWidth（）; 
 int h = getHeight（）; 
 //绘制坐标。 
 g2.draw（新的Line2D.Double（PAD，PAD，PAD，h-PAD））; 
 
 //绘制abcissa。 
 g2.draw（新Line2D.Double（PAD，h-PAD，w-PAD，h-PAD））; 
 double xInc =（double）（w  -  2 * PAD）/（data.length-1）; 
 double scale =（double）（h  -  2 * PAD）/ getMax（）; 
 //标记数据点。 
 g2.setPaint（Color.red）; 
 for（int i = 0; i< data.length; i ++）{
 double x = PAD + i * xInc; 
 double y = h  -  PAD  -  scale * data [i]; 
 g2.fill（new Ellipse2D.Double（x-2，y-2，4，4））; 
 
 
 
 private int getMax（）{
 int max = -Integer.MAX_VALUE; （int i = 0; i  if（data [i]> max）
 max = data [i]; 
} 
 return max; 
} 
} 
} 
  

现在，动画面板的作品正好。另一方面，图形面板......当我运行该程序时，它显示了一串红点，没有线连接它们。我做错了什么？

解决方案

除了@ Hovercraft的有用建议外，还考虑其他方法：

• 在 GeneralPath 中累积可根据需要呈现的点，。

• 查看 JFreeChart 。
  

I'm currently working on a program where certain numerical variables, which evolve over time, have their value displayed on each iteration. That works well enough, but now I want to plot a graph that shows their evolution over time. So, I looked into an example of code for plotting graphs in Swing. My final code looks like this:

public class Populus3 extends JPanel
{
    public static void main(String[] args) throws IOException {

        final Populus3 pop = new Populus3();

        JFrame f = new JFrame(); //where I want to plot the graph
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new GraphingData());
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);


        frame = new JFrame("Animation Frame"); //where I'm running animation for another element of the program
        frame.add(pop, BorderLayout.CENTER);
        frame.setSize(graphSize, graphSize);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //insert all sort of things

    }


    public void paint(Graphics g) 
    {
        super.paint(g);
        paintCell(g, 1);
        Toolkit.getDefaultToolkit().sync(); // necessary for linux users to draw  and animate image correctly
        g.dispose();
    }


      public void actionPerformed(ActionEvent e) {
        repaint();
    }



    @Override
    protected void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        for(int i = 0; i < particleType.length; i++)
            paintCell(g, i);  //a method that draws a small circle for the animation panel
    }



    public static class GraphingData extends JPanel {
        int[] data = {
            21, 14, 18, 03, 86, 88, 74, 87, 54, 77,
            61, 55, 48, 60, 49, 36, 38, 27, 20, 18
        };
        final int PAD = 20;

        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2 = (Graphics2D)g;
            g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                                RenderingHints.VALUE_ANTIALIAS_ON);
            int w = getWidth();
            int h = getHeight();
            // Draw ordinate.
            g2.draw(new Line2D.Double(PAD, PAD, PAD, h-PAD));

            // Draw abcissa.
            g2.draw(new Line2D.Double(PAD, h-PAD, w-PAD, h-PAD));
            double xInc = (double)(w - 2*PAD)/(data.length-1);
            double scale = (double)(h - 2*PAD)/getMax();
            // Mark data points.
            g2.setPaint(Color.red);
            for(int i = 0; i < data.length; i++) {
                double x = PAD + i*xInc;
                double y = h - PAD - scale*data[i];
                g2.fill(new Ellipse2D.Double(x-2, y-2, 4, 4));
            }
        }

        private int getMax() {
            int max = -Integer.MAX_VALUE;
            for(int i = 0; i < data.length; i++) {
                if(data[i] > max)
                    max = data[i];
            }
            return max;
        }
    }
}

Now, the animation panel works just fine. The graph panel, on the other hand...when I run the program, it displays a bunch of red dots, without lines to connect them. What am I doing wrong?

解决方案

In addition to @Hovercraft's helpful suggestions, also consider these other approaches:

• Accumulate the points in a GeneralPath that may be rendered as required, for example.

• Connect the points using repeated calls to drawLine() using a suitable coordinate system, outlined here.

• Look at JFreeChart.

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