在 JPanel 上绘制条形图并将其添加到 JScrollPane 上适用于 Mac OS 但不适用于 Windows OS？

Question

我的代码的一个特点是它显示一个频率条形图，其中包含给定的数据。在我的 Mac 书中，它工作得很好，但是当我尝试在我的 Razer Blade 灵刃上使用它时，它没有按预期工作。我提供了屏幕截图，这样你就可以看到发生了什么，如果你能给我一些关于这方面的见解。

WindowsOS: https://gyazo.com/5107eed39d548687ad772a60e065055b

MacOS: https://gyazo.com/6d32df9e08b9ce0c089dbe1b4d35af64


import javax.swing.*;
import java.awt.*;
import java.util.HashMap;
import java.util.Map;

public class Main {

    public static void main(String[] args){
        SwingUtilities.invokeLater(BarChartGUI::new);
    }

}

class BarChartGUI extends JFrame{

    public BarChartGUI(){

        Map<String, Integer> frequencyTableData = getFrequencyTableData();
        BarChart barChart = new BarChart(frequencyTableData);
        JScrollPane chartScrollPane = new JScrollPane(barChart);
        chartScrollPane.setPreferredSize(new Dimension(1000, 500));
        add(chartScrollPane);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private Map<String, Integer> getFrequencyTableData(){
        Map<String, Integer> frequencyTableData = new HashMap<>();
        for (int i = 0; i < 2000; i++){
            frequencyTableData.put(String.valueOf(i), i);
        }
        return frequencyTableData;
    }
}

class BarChart extends JPanel {

    // Space to draw Chart Information
    public static final int TOP_BUFFER = 30;
    public static final int AXIS_OFFSET = 20;

    // Hashmap datatype holds the frequency of the String within the columnValues
    private final Map<String, Integer> data;

    // Stores dimension values
    private int chartWidth;
    private int chartHeight;
    private int chartY;

    public BarChart(Map<String, Integer> frequencyTableData){
        super();
        data = frequencyTableData;

        setBackground(Color.white);

    }

    public void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        computeSize();
        drawBars(g2);
    }

    // Retrieves the size of panel
    private void computeSize() {
        // Gets the chart's area size
        chartWidth = this.getWidth() - 2*AXIS_OFFSET;
        chartHeight = this.getHeight() - 2*AXIS_OFFSET - TOP_BUFFER;

        // Get's the chart's coords for the origin
        chartY = this.getHeight() - AXIS_OFFSET;
    }

    // Draws the Bar Chart depending on the values and its frequency stored within data
    public void drawBars(Graphics2D g2) {
        int numberOfBars = data.size();
        double maxHeight = 0;

        // Finds the height of the highest bar
        for (Integer freq : data.values()) {
            if (maxHeight < freq)
                maxHeight = freq;
        }

        // Calculates width of bar
        int barWidth = chartWidth / numberOfBars;
        if ((chartWidth / numberOfBars) < 5){
            barWidth = 5;
        }

        int value;
        int barHeight;
        int xLeftCord;
        int yTopLeftCord;
        int counter = 0;
        g2.setColor(Color.black);

        // Draws the bar for every key in the hashmap
        for (String bar : data.keySet()) {
            value = data.get(bar);

            double barHeightDecimal = (value/maxHeight)* chartHeight;
            barHeight = (int) barHeightDecimal;

            xLeftCord = AXIS_OFFSET + counter * barWidth;
            yTopLeftCord = chartY - barHeight;
            Rectangle rec = new Rectangle(xLeftCord, yTopLeftCord, barWidth, barHeight);

            g2.draw(rec);

            counter++;
        }
    }



}

Answer 1

这个：

public void paintComponent(Graphics g) {
    Graphics2D g2 = (Graphics2D) g;

    computeSize();
    drawBars(g2);
}

缺少对超级方法的调用：

public void paintComponent(Graphics g) {
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;

    computeSize();
    drawBars(g2);
}

没有这个，JPanel 将无法进行内务处理绘画或清除脏像素

在 JPanel 上绘制条形图并将其添加到 JScrollPane 上适用于 Mac OS 但不适用于 Windows OS？

Drawing Bar Chart on JPanel and adding it onto a JScrollPane works on Mac OS but not on Windows OS?

java

graphics

swing