Java 2D - 散点图 - 点未渲染

Question

我一直在学习 2D/Swing 教程并制作了一个循环运行 20 次的图表，并向图表添加了 20 个不同的点。我的问题是只出现一个点，而且它总是在 x 轴上。

从看到我的控制台日志消息开始，循环运行 20 次。循环本身位于代码的底部。

我对 Java 还是很陌生，所以任何建议或指示都会很棒。

package scattergraph;

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.Stroke;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

/**
 *
 * @author scott
 */
public class ScatterGraph extends JPanel {

    private List<Double> scores;
    private int padding = 20;
    private int labelPadding = 12;
    private int numberYDivisions = 6;
    private int pointWidth = 10;
    private Color gridColor = new Color(200, 200, 200, 200);
    private Color pointColor = new Color(255, 0, 255);
    private Color lineColor = new Color(255, 255, 253);
    private static final Stroke GRAPH_STROKE = new BasicStroke(2f);

    public ScatterGraph(List<Double> scores){
        this.scores = scores;
    }

    @Override
    protected void paintComponent(Graphics g){
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;

        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        double xScale = ((double) getWidth() - (3 * padding) - labelPadding) / (scores.size() - 1);
        double yScale = ((double) getHeight() - (2 * padding) - labelPadding) / (getMaxScore() - getMinScore());


    List<Point> graphPoints = new ArrayList<>();
    for(int i = 0; i < scores.size(); i++){

        int x1 = (int)(i * xScale + padding + labelPadding);
        int y1 = (int)((getMaxScore() - scores.get(i) * yScale) + padding);

        graphPoints.add(new Point(x1, y1));
    }

    g2.setColor(Color.WHITE);
    g2.fillRect(padding + labelPadding, padding, getWidth() - (2*padding) - labelPadding, getHeight() - 2 * padding - labelPadding);
    g2.setColor(Color.BLUE);

    for(int i = 0; i < numberYDivisions + 1; i++){
        int x0 = padding + labelPadding;
        int x1 = pointWidth + padding + labelPadding;
        int y0 = getHeight() - ((i * (getHeight() - padding * 2 - labelPadding)) / numberYDivisions + padding + labelPadding);

        int y1 = y0;
        if(scores.size() > 0){
            g2.setColor(gridColor);
            g2.drawLine(padding + labelPadding + 1 + pointWidth, y0, getWidth() - padding, y1);
            g2.setColor(Color.BLACK);
            String yLabel = ((int) ((getMinScore() + (getMaxScore() - getMinScore()) * ((i * 8.0) / numberYDivisions)) * 100))/ 100.0 + "";

            FontMetrics metrics = g2.getFontMetrics();
            int labelWidth = metrics.stringWidth(yLabel);
            g2.drawString(yLabel, x0 - labelWidth - 6, y0 + (metrics.getHeight() / 2) - 3);

        }
            g2.drawLine(x0, y0, x1, y1);

    }

    for (int i = 0; i < scores.size(); i++){

        if (scores.size() > 1) {

            int x0 = i * (getWidth() - padding * 2 - labelPadding) / (scores.size() - 1) + padding + labelPadding;
            int x1 = x0;
            int y0 = getHeight() - padding - labelPadding;
            int y1 = y0 - pointWidth;
            if ((i % ((int) ((scores.size() / 8.0)) + 3)) == 0) {

                g2.setColor(gridColor);
                g2.drawLine(x0, getHeight() - padding - labelPadding - 1 - pointWidth, x1, padding);
                g2.setColor((Color.BLACK));
                String xLabel = i + "";
                FontMetrics metrics = g2.getFontMetrics();
                int labelWidth = metrics.stringWidth(xLabel);
                g2.drawString(xLabel, x0 - labelWidth / 2, y0 + metrics.getHeight() + 3);

            }

            g2.drawLine(x0, y0, x1, y1);



        }

    }

    g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, padding + labelPadding, padding);
    g2.drawLine(padding + labelPadding, getHeight() - padding - labelPadding, getWidth() - padding, getHeight() - padding - labelPadding);

    Stroke oldStroke = g2.getStroke();
    g2.setColor(lineColor);
    g2.setStroke(GRAPH_STROKE);

    for (int i = 0; i < graphPoints.size() - 1; i++){
        int x1 = graphPoints.get(i).x;
        int y1 = graphPoints.get(i).y;
        int x2 = graphPoints.get(i + 1).x;
        int y2 = graphPoints.get(i + 1).y;
        g2.drawLine(x1, y1, x2, y2);

    }

    g2.setStroke(oldStroke);
    g2.setColor(pointColor);
    for (int i = 0; i < graphPoints.size(); i++){

           int x = graphPoints.get(i).x - pointWidth / 2;
           int y = graphPoints.get(i).y - pointWidth / 2;
           int ovalW = pointWidth;
           int ovalH = pointWidth;
           g2.fillOval(x, y, ovalW, ovalH);

    }


    }
    private double getMinScore(){
        double minScore = Double.MAX_VALUE;
        for(Double score: scores){
            minScore = Math.min(minScore, score);
        }
        return minScore;
    }


    private double getMaxScore(){
            double maxScore = Double.MIN_VALUE;
        for(Double score: scores){
            maxScore = Math.min(maxScore, score);
        }
        return maxScore;
    }


    public void setScores(List<Double> scores) {

          this.scores = scores;
          invalidate();
          this.repaint();

    }

        public List<Double> getScores() {
        return scores;
    }

    private static void createAndShowGui(){

        List<Double> scores = new ArrayList();
        Random random = new Random();

        int maxDataPoints = 20;
        int maxScore = 8;

        for(int i = 0 ; i < maxDataPoints; i++){

            scores.add((double)random.nextDouble() * maxScore);
            System.out.println("Score added");
        }


        ScatterGraph mainPanel = new ScatterGraph(scores);
        mainPanel.setPreferredSize(new Dimension(700,600));

        JFrame frame = new JFrame("My Scatter Graph");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }


    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable(){

            public void run(){
                createAndShowGui();
            }    

        });
    }

}

Answer 1

我发现了两点。

y 的负值。

你有一些奇怪的 y 值。

您必须更改先进行乘法运算的后续语句

int y1 = (int) ((getMaxScore() - scores.get(i) * yScale) + padding);

到

int y1 = (int) (((getMaxScore() - scores.get(i)) * yScale) + padding);

最高分

必须更改 getMaxScore 方法

maxScore = Math.min(maxScore, score);

到

maxScore = Math.max(maxScore, score);

如果我理解正确的话，这是一个输出图像。

希望对您有所帮助

Java 2D - 散点图 - 点未渲染

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