图例中的图例标题未正确显示

Question

[我使用JFreeChart API v1.5.0创建了条形图，并在图上添加了带有标题的图例。

我使用了此Bar Chart Demo中的示例，并在示例中添加了以下图例代码。

//Legend default properties
protected static final boolean LEGEND_ON = true;
private static final RectangleEdge LEGEND_POSITION = RectangleEdge.RIGHT;
private static final String LEGEND_TITLE_TEXT = "Legend";
private static final Font LEGEND_TITLE_FORMAT = new Font(Font.SANS_SERIF, Font.PLAIN, 12);
private static final Color LEGEND_TITLE_COLOR = Color.BLACK;
private static final double LEGEND_MAX_WIDTH = 0.0;
private static final Color LEGEND_BG_COLOR = Color.WHITE;
private static final Color LEGEND_BORDER_COLOR = Color.WHITE;
private static final Font LEGEND_TEXT_FORMAT = new Font(Font.SANS_SERIF, Font.PLAIN, 12);
private static final Color LEGEND_TEXT_COLOR = Color.BLACK;

LegendTitle legend = chart.getLegend();
legend.setPosition(LEGEND_POSITION);
legend.setWidth(LEGEND_MAX_WIDTH);
legend.setBackgroundPaint(LEGEND_BG_COLOR);
legend.setFrame(new BlockBorder(1, 1, 1, 1, LEGEND_BORDER_COLOR));
legend.setItemFont(LEGEND_TEXT_FORMAT);
legend.setItemPaint(LEGEND_TEXT_COLOR);

if (LEGEND_TITLE_TEXT != null) {
    TextTitle legendTitle = new TextTitle();
    legendTitle.setText(LEGEND_TITLE_TEXT);
    legendTitle.setPosition(LEGEND_POSITION);
    legendTitle.setPaint(LEGEND_TITLE_COLOR);
    legendTitle.setFont(LEGEND_TITLE_FORMAT);
    legendTitle.setHorizontalAlignment(HorizontalAlignment.CENTER);
    legendTitle.setVerticalAlignment(VerticalAlignment.CENTER);
    chart.addSubtitle(1, legendTitle);
}

当我运行示例以及上面的图例代码时，得到以下输出。

我确实注意到图例标题显示不正确，因为它在右侧的图例容器中垂直放置，而不是水平放置（如下图所示，为“预期输出”。我确实尝试了一些步骤，例如使用TextUtils.drawRotatedString（）和TextUtils.drawAlignedString（），但无法固定图例标题位置及其对齐方式。

如何将图例标题放置在图例容器的顶部并使其水平对齐？

我正在寻找图例标题的类似输出，如下所示，它是使用不同的图表框架生成的。

我想对齐并定位我的图例标题，如上面的输出所示。

Answer 1

基于此link中提供的示例，我修改了代码以使用BlockContainer添加自定义图例，以获取所需的输出，如上面问题中的图像1所示。

更新的代码：

//Legend default properties
pro tected static final boolean LEGEND_ON = true;
private static final RectangleEdge LEGEND_POSITION = RectangleEdge.RIGHT;
private static final String LEGEND_TITLE_TEXT = "Legend";
private static final Font LEGEND_TITLE_FORMAT = new Font(Font.SANS_SERIF, Font.PLAIN, 12);
private static final Color LEGEND_TITLE_COLOR = Color.BLACK;
private static final double LEGEND_MAX_WIDTH = 0.0;
private static final Color LEGEND_BG_COLOR = Color.WHITE;
private static final Color LEGEND_BORDER_COLOR = Color.WHITE;
private static final Font LEGEND_TEXT_FORMAT = new Font(Font.SANS_SERIF, Font.PLAIN, 12);
private static final Color LEGEND_TEXT_COLOR = Color.BLACK;

LegendTitle legend = chart.getLegend();
legend.setPosition(LEGEND_POSITION);
legend.setWidth(LEGEND_MAX_WIDTH);
legend.setBackgroundPaint(LEGEND_BG_COLOR);
legend.setFrame(new BlockBorder(1, 1, 1, 1, LEGEND_BORDER_COLOR));
legend.setItemFont(LEGEND_TEXT_FORMAT);
legend.setItemPaint(LEGEND_TEXT_COLOR);

if (LEGEND_TITLE_TEXT != null) {
    TextTitle legendTitle = new TextTitle();
    legendTitle.setText(LEGEND_TITLE_TEXT);
    legendTitle.setPosition(LEGEND_POSITION);
    legendTitle.setPaint(LEGEND_TITLE_COLOR);
    legendTitle.setFont(LEGEND_TITLE_FORMAT);
    legendTitle.setHorizontalAlignment(HorizontalAlignment.CENTER);
    legendTitle.setVerticalAlignment(VerticalAlignment.CENTER);

    BlockContainer legendCont = new BlockContainer(new ColumnArrangement());
    legendCont.add(legendTitle, RectangleEdge.TOP);
    BlockContainer items = legend.getItemContainer();
    legendCont.add(items);      
    legend.setWrapper(legendCont);
    //Remove existing legend to avoid duplicate legend display.
    chart.removeLegend();
    //show legend container with title and items
    chart.addSubtitle(legend);
}

执行上述代码后，得到以下输出。