对于有使用 jFreeChart for Swing 应用程序经验的任何人：
我无法更改图表的背景。我的最终目标是为我的图表设置一个平滑的渐变背景，但我根本无法更改任何背景。这行代码chart.setBackgroundPaint(Color.BLUE);应该做点什么，对吗？但这并没有改变任何东西。我得到的只是相同的灰色绘图背景和白色图表背景。
我正在为为什么我不能改变颜色而摸不着头脑......非常感谢任何帮助！
这是我的代码（如果您有 jfreechart 库，则可编译和运行）
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.GradientPaint;
import java.awt.Paint;
import java.awt.PaintContext;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import static java.awt.Transparency.OPAQUE;
import java.awt.geom.AffineTransform;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import java.awt.image.ColorModel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.renderer.category.LineAndShapeRenderer;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;
/**
*
* @author Ryan
*/
public class SalesGraph extends JPanel {
/**
* Creates a sample dataset.
*
* @return The dataset.
*/
private static CategoryDataset createDataset() {
DefaultCategoryDataset dataset = new DefaultCategoryDataset();
dataset.addValue(212, "Sales", "Jan");
dataset.addValue(504, "Sales", "Feb");
dataset.addValue(1520, "Sales", "Mar");
dataset.addValue(1842, "Sales", "Apr");
dataset.addValue(2991, "Sales", "May");
dataset.addValue(3500, "Sales", "June");
return dataset;
}
/**
* Creates a sample chart.
*
* @param dataset a dataset.
*
* @return The chart.
*/
private static JFreeChart createChart(CategoryDataset dataset, String subTitle) {
// create the chart...
JFreeChart chart = ChartFactory.createLineChart(
"# of Sales by Month", // chart title
"Month", // domain axis label
"# of Sales", // range axis label
dataset, // data
PlotOrientation.VERTICAL, // orientation
true, // include legend
true, // tooltips
false // urls
);
if(subTitle != null && !subTitle.isEmpty())
chart.addSubtitle(new TextTitle(subTitle));
chart.setBackgroundPaint(Color.BLUE);
// Paint p = new GradientPaint(0, 0, Color.white, 1000, 0, Color.green);
// chart.setBackgroundPaint(p);
CategoryPlot plot = (CategoryPlot) chart.getPlot();
plot.setRangePannable(true);
plot.setRangeGridlinesVisible(true);
plot.setBackgroundAlpha(1);
plot.setBackgroundPaint(Color.BLUE);
// Paint p = new GradientPaint(0, 0, Color.white, 1000, 0, Color.green);
// plot.setBackgroundPaint(p);
NumberAxis rangeAxis = (NumberAxis) plot.getRangeAxis();
rangeAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());
ChartUtilities.applyCurrentTheme(chart);
// customise the renderer...
LineAndShapeRenderer renderer
= (LineAndShapeRenderer) plot.getRenderer();
renderer.setBaseShapesVisible(true);
renderer.setDrawOutlines(true);
// renderer.setUseFillPaint(true);
// renderer.setBaseFillPaint(Color.white);
renderer.setSeriesStroke(0, new BasicStroke(3.0f));
renderer.setSeriesOutlineStroke(0, new BasicStroke(2.0f));
renderer.setSeriesShape(0, new Ellipse2D.Double(0,0,0,0));
renderer.setPaint(Color.RED);
return chart;
}
/**
* Creates a panel for the demo (used by SuperDemo.java).
*
* @return A panel.
*/
public static JPanel createPanel(CategoryDataset dataset, Dimension size) {
JFreeChart chart = createChart(dataset, null);
ChartPanel panel = new ChartPanel(chart);
panel.setMouseWheelEnabled(true);
if(size != null)
panel.setPreferredSize(size);
return panel;
}
public static JPanel createPanel() {
return createPanel(createDataset(), null);
}
/**
* Starting point for the demonstration application.
*
* @param args ignored.
*/
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = createPanel();
frame.add(panel);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
}