JFreeChart chart.getWidth() 在尝试 left-align 字幕居中时不起作用

Question

我正在尝试 left-align 一个 JFreeChart 副标题居中的标题，这样主标题在 ChartFrame 中居中，但副标题与 ChartFrame 的左边距对齐标题。我能想到的唯一方法是将标题和副标题设置为 HorizontalAlignment.LEFT。然后我让程序手动设置标题的左填充，使其居中，然后设置字幕填充以匹配标题的填充，从而将它们排列成相同的 left-margin 计算为将标题对齐到框架的中心，如下所示：

// Make the chart
JFreeChart chart = ChartFactory.createTimeSeriesChart(title, "Time (Hour)", "Vehicles Parked", dataset, true, true, false);

ChartFrame frame = new ChartFrame("Chart", chart);
frame.pack();
frame.setVisible(true);

chart.getTitle().setHorizontalAlignment(HorizontalAlignment.LEFT);
chart.getTitle().setPadding(0, (frame.getWidth()/2)-(chart.getTitle().getWidth()/2), 0, 0);

TextTitle subtitle1 = new TextTitle(
        "This is a test subtitle in which I would like\nthe subtitle to be lined up to the title", // text
        chart.getTitle().getFont().deriveFont(chart.getTitle().getFont().getSize() * 0.6f), // font (shrunk title)
        chart.getTitle().getPaint(), // paint
        RectangleEdge.TOP, // position
        HorizontalAlignment.LEFT, //chart2.getTitle().DEFAULT_HORIZONTAL_ALIGNMENT, // horizontal alignment
        VerticalAlignment.BOTTOM, // vertical alignment
        chart.getTitle().getPadding() // padding
);
chart.addSubtitle(subtitle1);

在尝试这样做时，chart.getTitle().getWidth() 方法每次都是 returning 0.0，我不明白为什么。我试过将 chart.getTitle() 转换为 AbstractBlock 但这没有区别。我相信这与 JavaDoc for the getWidth() method in the AbstractBlock class 中的事实有关，它提到如果它事先知道宽度，它将 return 宽度，显然它不知道。

我想知道如何使图表标题正确 return 其宽度，无论是否使用 getWidth() 函数。我还想知道是否有更好的方法将图表的元素彼此对齐，而不是 ChartFrame 的两侧而不是调整它们的填充。

交叉发布 here.

Answer 1

如回答here。

我必须做的是将字幕与标题的左边距对齐，但要使整个内容与框架的中心对齐，就是将两个元素都放入 BlockContainer 和 ColumnArrangement，然后从 BlockContainer 创建一个 CompositeTitle，并相应地对齐 CompositeTitle。

JFreeChart chart = ChartFactory.createXYLineChart(
        "Has to have a wider title than subtitle", // chart title
        "X", // x axis label
        "Y", // y axis label
        dataset, // data
        PlotOrientation.VERTICAL,
        true, // include legend
        true, // tooltips
        false // urls
);

String subtitleText = "This is a test subtitle\nIt is also a test of whether or not newlines work";

TextTitle subtitle = new TextTitle(
        subtitleText, // text
        chart.getTitle().getFont().deriveFont(chart.getTitle().getFont().getSize() * 0.6f), // font (shrunk title)
        chart.getTitle().getPaint(), // paint
        RectangleEdge.TOP, // position
        HorizontalAlignment.LEFT, //chart2.getTitle().DEFAULT_HORIZONTAL_ALIGNMENT, // horizontal alignment
        VerticalAlignment.BOTTOM, // vertical alignment
        chart.getTitle().getPadding() // padding
);

BlockContainer blockContainer = new BlockContainer(new ColumnArrangement(HorizontalAlignment.LEFT, VerticalAlignment.TOP, 0, 0));
blockContainer.add(chart.getTitle());
blockContainer.add(subtitle);
CompositeTitle compositeTitle = new CompositeTitle(blockContainer);
compositeTitle.setPosition(RectangleEdge.TOP);
compositeTitle.setVerticalAlignment(VerticalAlignment.CENTER);
chart.getTitle().setVisible(false);
chart.addSubtitle(compositeTitle);

ChartFrame frame = new ChartFrame("Frame", chart);
frame.pack();
frame.setVisible(true);

JFreeChart chart.getWidth() 在尝试 left-align 字幕居中时不起作用

JFreeChart chart.getWidth() not working when trying to left-align subtitle to centered title

java

charts

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jfreechart