Java Swing 折线图

Question

我正在尝试根据数组中保存的数据绘制折线图。我设法绘制了 X 和 Y 轴。但是，当我将带有数据的线绘制到图表上时，它不会与 X 和 Y 轴值对齐。我不确定如何解决这个问题。我已经展示了下面的代码：

public void drawLineG(Graphics g, int yCoords[]) {
    String maxY = Integer.toString(getMax(yCoords));
    String minY = Integer.toString(getMin(yCoords));
    String maxX = Double.toString((xInterval * yCoords.length) - xInterval);
    String minX = Double.toString(xStart);

    g.setColor(Color.BLUE);
    int height = (getHeight() / 2);
    int x = 200; // start x point

    // previous coord positions.
    int prevX = x;
    int prevY = yCoords[0];

    g.setColor(Color.BLACK);
    g.drawLine(prevX, getHeight() / 2, 500, getHeight() / 2);
    g.drawLine(prevX, 200, 200, getHeight() / 2);

    g.setColor(Color.BLUE);
    g.drawString(minY, 190, (getHeight() / 2));
    g.drawString(maxY, 180, (getHeight() / 2) - 255);
    g.drawString(yLabel, 140, (getHeight() / 2) - 100);
    g.drawString(minX, 192, (getHeight() / 2) + 20);
    g.drawString(maxX, 500, (getHeight() / 2) + 20);
    g.drawString(xLabel, 350, (getHeight() / 2) + 50);
    for (int y : yCoords) {
        g.setColor(Color.RED);
        g.drawLine(prevX, height - prevY, x, height - y);
        prevX = x;
        prevY = y;

        // add an increment to the X pos.
        x = x + 50;
    }
}

我一直在测试的数据数组包含以下值：0, 3, 4, 7, 5, 10, 3

但是，当它绘制在图表上时，它与 x 和 y 轴上的值不一致。

当前：https://i.stack.imgur.com/Ju8BQ.jpg 我想要达到的目标：https://i.stack.imgur.com/n9Aio.jpg

有什么帮助吗？
谢谢

Answer 1

您的问题是您的比例，您正在尝试按照给定的方式绘制 yCoords（3, 10 等），但它们应该是：30, 100 以适应窗口的比例（Window =你的程序窗口）。

例如在我下面的代码中，每个“正方形”或每个“单位”都是 30 x 30 像素，所以我必须将 yCoord = 3 转换为等效的 3 * 30 = 90 但因为轴低于起始在400，我必须减去它，这样我才能从轴或窗口底部获得坐标到真正的yCoord，即400 - 90 = 310，现在这是我必须绘制的真正要点。

但是绘画应该在paintComponent方法中完成。

在我的示例中，我没有为 0, 10, 0.0, 90.0 绘制字符串，但如果您愿意，可以稍后再绘制

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class GraphSample {
    private JFrame frame;

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

    private void createAndShowGui() {
        frame = new JFrame(getClass().getSimpleName());

        GraphDrawer drawer = new GraphDrawer(new int[] {0, 3, 4, 7, 5, 10, 3});

        frame.add(drawer);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    @SuppressWarnings("serial")
    class GraphDrawer extends JPanel {
        private int[] yCoords;
        private int startX = 100;
        private int startY = 100;
        private int endX = 400;
        private int endY = 400;
        private int unitX = (endX - startX) / 10;
        private int unitY = (endY - startY) / 10;
        private int prevX = startX;
        private int prevY = endY;

        public GraphDrawer(int[] yCoords) {
            this.yCoords = yCoords;
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g;

            //We draw in the following 2 loops the grid so it's visible what I explained before about each "unit"
            g2d.setColor(Color.BLUE);
            for (int i = startX; i <= endX; i += unitX) {
                g2d.drawLine(i, startY, i, endY);
            }

            for (int i = startY; i <= endY; i += unitY) {
                g2d.drawLine(startX, i, endX, i);
            }

            //We draw the axis here instead of before because otherwise they would become blue colored.
            g2d.setColor(Color.BLACK);
            g2d.drawLine(startX, startY, startX, endY);
            g2d.drawLine(startX, endY, endX, endY);

            //We draw each of our coords in red color
            g2d.setColor(Color.RED);
            for (int y : yCoords) {
                g2d.drawLine(prevX, prevY, prevX += unitX, prevY = endY - (y * unitY));
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(endX + 100, endY + 100);
        }
    }
}

我希望很清楚错误是什么。

这是一个 10 x 10 网格的输出样例