java – JFreeChart自定义x轴标签

我有多个系列的数据.

>系列年份：2013,2014,2015等
>数据是给定年份内的日期值.
>因为数据需要按年份分类,我在x轴上使用“一年中的某一天”值,范围在1到366之间.因此给定年份的值如下所示：(1,80),(30,100) ),(60,71)…..(255,130)

示例图：

我的问题是X轴包含“一年中的某一天”值,但我必须在那里放置月份名称.不幸的是,使用简单的DateAxis不是一个选项,因为X值是日期数字(不是日期),而AFAIK没有可以将“335”转换为“12月”的日期格式. DateAxis的另一个问题是它表示时间点,它为任何时间点提供单独的X轴标签.但我需要及时写出确切时间点的标签.即：仅在几个月的开始.我真正想要的是这样的：

例如.而不是在一个月的开头/结尾放置“滴答声”,我想显示区域.更难的是月份有不同的长度.由于二月有闰年29天,我想我将不得不使用固定点(一年中的数值).

我是否必须为此编写自定义轴渲染器？怎么样？我的问题有更简单的解决方案吗？

解决方法:

import java.awt.Graphics2D;
import java.awt.font.LineMetrics;
import java.awt.geom.Rectangle2D;
import java.util.List;
import java.awt.Color;

import org.jfree.chart.axis.AxisState;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.ValueTick;
import org.jfree.text.TextUtilities;
import org.jfree.ui.RectangleEdge;
import org.jfree.ui.TextAnchor;



public class DayOfYearAxis extends NumberAxis {
    /* Day of the year values for month end days. */
    public static final Integer[] MONTH_LENGTHS = {
            31,29,31,30,31,30,31,31,30,31,30,31
    };
    public static final String[] MONTH_NAMES = {
        "Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"
};

    protected AxisState  drawTickMarksAndLabels(Graphics2D g2,double cursor,Rectangle2D plotArea,Rectangle2D dataArea,RectangleEdge edge) {
        AxisState state = new AxisState(cursor);

        g2.setFont(getTickLabelFont());

        double ol = getTickMarkOutsideLength();
        double il = getTickMarkInsideLength();
        int y = (int)(Math.round(cursor-ol));
        LineMetrics lineMetrics = g2.getFont().getLineMetrics("Ápr", g2.getFontRenderContext());        
        int h = (int) (lineMetrics.getHeight() + 6);

        List<ValueTick> ticks = refreshTicks(g2, state, dataArea, edge);
        state.setTicks(ticks);

        /* Last x point */
        ValueTick tick = ticks.get(ticks.size()-1);     
        float[] prevAnchorPoint = calculateAnchorPoint(tick, cursor,dataArea, edge);
        double xmax = prevAnchorPoint[0];
        double max_day = tick.getValue();

        /* First x point */
        tick = ticks.get(0);
        prevAnchorPoint = calculateAnchorPoint(tick, cursor,dataArea, edge);
        double xmin = Math.round(prevAnchorPoint[0]);
        double min_day = tick.getValue();       
        double days_visible = max_day - min_day + 1;
        /* 0.1 day horizontal gap. */
        double gap = 0.1*(xmax-xmin)/days_visible;

        System.out.println("min_day "+min_day+" max_day"+max_day);

        g2.setFont(getTickLabelFont());
        g2.setColor(Color.BLACK);
        int start_day = 0;
        for (int month=0;month<12;month++) {
            int end_day = start_day + MONTH_LENGTHS[month] - 1;
            System.out.println("start-end "+start_day+" "+end_day);
            if ( (start_day>=min_day) && (start_day<=max_day) && (end_day>=min_day) && (end_day<=max_day) ) {
                double factor_x1 = (start_day - min_day) / days_visible;
                double x1 = xmin + (xmax-xmin)* factor_x1;
                double factor_x2 = (end_day - min_day) / days_visible;
                double x2 = xmin + (xmax-xmin)* factor_x2;
                System.out.println("month="+month+", start_day="+start_day+" end_day="+end_day+" x1="+x1+" x2="+x2);
                g2.setColor(Color.LIGHT_GRAY);
                g2.fill3DRect((int)(x1+gap),y,(int)(x2-x1-2*gap),h,true);
                g2.setColor(Color.BLACK);
                TextUtilities.drawAlignedString(MONTH_NAMES[month], g2, (float)((x1+x2)/2), (float)(y+ol), TextAnchor.TOP_CENTER);
            }           
            start_day += MONTH_LENGTHS[month];
        }
        return state;
    }

}

用法：

    JFreeChart chart = ChartFactory.createXYLineChart(...);
    DayOfYearAxis doyAxis = new DayOfYearAxis();
    /* optional
    doyAxis.setAutoRange(false);
    doyAxis.setRange(new Range(min_yday, max_yday));
    */
    chart.getXYPlot().setDomainAxis(doyAxis);        

输出示例(匈牙利月份名称)：

标签：java,jfreechart,axis-labels
来源： https://codeday.me/bug/20190628/1317886.html