使用 C++ 在演示文稿中管理图表数据标签

图表中的数据标签显示有关图表数据系列或单个数据点的详细信息。它们使读者能够快速识别数据系列，并让图表更易于理解。

在图表数据标签中设置数据精度

此 C++ 代码演示如何在图表数据标签中设置数据精度：

	// 文档目录的路径
	const String outPath = u"../out/SettingPrecisionOfDataLabel_out.pptx";

	// 实例化表示 PPTX 文件的 Presentation 类
	SharedPtr<Presentation> pres = MakeObject<Presentation>();

	// 获取第一张幻灯片
	SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);

	// 添加带有默认数据的图表
	SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::Line, 0, 0, 500, 500);

	// 设置系列数字格式
	chart->set_HasDataTable( true);
	chart->get_ChartData()->get_Series()->idx_get(0)->set_NumberFormatOfValues (u"#,##0.00");

	// 将演示文稿文件写入磁盘
	pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);

显示百分比为标签

Aspose.Slides for C++ 允许在显示的图表上设置百分比标签。此 C++ 代码演示该操作：

	// 文档目录的路径
	const String outPath = u"../out/DisplayPercentageAsLabels_out.pptx";

	// 创建 Presentation 类的实例
	System::SharedPtr<Presentation> presentation = System::MakeObject<Presentation>();

	System::SharedPtr<ISlide> slide = presentation->get_Slides()->idx_get(0);
	System::SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::StackedColumn, 20, 20, 400, 400);
	System::SharedPtr<IChartSeries> series = chart->get_ChartData()->get_Series()->idx_get(0);
	System::SharedPtr<IChartCategory> cat;
	System::ArrayPtr<double> total_for_Cat = System::MakeObject<System::Array<double>>(chart->get_ChartData()->get_Categories()->get_Count(), 0);
	for (int32_t k = 0; k < chart->get_ChartData()->get_Categories()->get_Count(); k++)
	{
		cat = chart->get_ChartData()->get_Categories()->idx_get(k);

		for (int32_t i = 0; i < chart->get_ChartData()->get_Series()->get_Count(); i++)
		{
			total_for_Cat[k] = total_for_Cat[k] + System::Convert::ToDouble(chart->get_ChartData()->get_Series()->idx_get(i)->get_DataPoints()->idx_get(k)->get_Value()->get_Data());
		}
	}

	double dataPontPercent = 0.f;

	for (int32_t x = 0; x < chart->get_ChartData()->get_Series()->get_Count(); x++)
	{
		series = chart->get_ChartData()->get_Series()->idx_get(x);
		series->get_Labels()->get_DefaultDataLabelFormat()->set_ShowLegendKey(false);

		for (int32_t j = 0; j < series->get_DataPoints()->get_Count(); j++)
		{
			System::SharedPtr<IDataLabel> lbl = series->get_DataPoints()->idx_get(j)->get_Label();
			dataPontPercent = (System::Convert::ToDouble(series->get_DataPoints()->idx_get(j)->get_Value()->get_Data()) / total_for_Cat[j]) * 100;

			System::SharedPtr<IPortion> port = System::MakeObject<Portion>();
			port->set_Text(System::String::Format(u"{0:F2} %", dataPontPercent));
			port->get_PortionFormat()->set_FontHeight(8.f);
			lbl->get_TextFrameForOverriding()->set_Text(u"");
			System::SharedPtr<IParagraph> para = lbl->get_TextFrameForOverriding()->get_Paragraphs()->idx_get(0);
			para->get_Portions()->Add(port);

			lbl->get_DataLabelFormat()->set_ShowSeriesName(false);
			lbl->get_DataLabelFormat()->set_ShowPercentage(false);
			lbl->get_DataLabelFormat()->set_ShowLegendKey(false);
			lbl->get_DataLabelFormat()->set_ShowCategoryName(false);
			lbl->get_DataLabelFormat()->set_ShowBubbleSize(false);

		}

	}

	// 保存包含图表的演示文稿
	presentation->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);

在图表数据标签中设置百分号

此 C++ 代码演示如何为图表数据标签设置百分号：

	// 文档目录的路径。
	const String outPath = u"../out/DataLabelsPercentageSign_out.pptx";

	// 创建 Presentation 类的实例
	SharedPtr<Presentation> pres = MakeObject<Presentation>();

	// 通过索引获取幻灯片的引用
	SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);

	// 在幻灯片上创建 PercentsStackedColumn 图表
	SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::PercentsStackedColumn, 0, 0, 500, 500);

	// 将 NumberFormatLinkedToSource 设置为 false
	chart->get_Axes()->get_VerticalAxis()->set_IsNumberFormatLinkedToSource ( false);
	chart->get_Axes()->get_VerticalAxis()->set_NumberFormat(u"0.00%");


	// 设置图表数据表的索引
	int defaultWorksheetIndex = 0;

	// 获取图表数据工作表
	SharedPtr<IChartDataWorkbook> fact = chart->get_ChartData()->get_ChartDataWorkbook();


	// 删除默认生成的系列 
	chart->get_ChartData()->get_Series()->Clear();
	

	// 添加新系列
	chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 2, ObjectExt::Box<System::String>(u"Series 2")), chart->get_Type());


	// 获取第一条图表系列
	SharedPtr<IChartSeries> series=chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 1, ObjectExt::Box<System::String>(u"Red")), chart->get_Type());
	// 填充系列数据
	series->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 1, 1, ObjectExt::Box<double>(0.50)));
	series->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 2, 1, ObjectExt::Box<double>(0.50)));
	series->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 3, 1, ObjectExt::Box<double>(0.80)));
	series->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 4, 1, ObjectExt::Box<double>(0.65)));

	// 设置系列的填充颜色
	series->get_Format()->get_Fill()->set_FillType(FillType::Solid);
	series->get_Format()->get_Fill()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_Red());

	// 设置 LabelFormat 属性
	series->get_Labels()->get_DefaultDataLabelFormat()->set_ShowValue(true);
	series->get_Labels()->get_DefaultDataLabelFormat()->set_IsNumberFormatLinkedToSource ( false);
	series->get_Labels()->get_DefaultDataLabelFormat()->set_NumberFormat (u"0.0%");
	series->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->set_FontHeight ( 10);
	series->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->get_FillFormat()->set_FillType(FillType::Solid);
	series->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->get_FillFormat()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_White());
	series->get_Labels()->get_DefaultDataLabelFormat()->set_ShowValue(true);

	// 获取第二条图表系列
	SharedPtr<IChartSeries> series2 = chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 2, ObjectExt::Box<System::String>(u"Blues")), chart->get_Type());
	// 填充系列数据
	series2->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 1, 2, ObjectExt::Box<double>(0.70)));
	series2->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 2, 2, ObjectExt::Box<double>(0.50)));
	series2->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 3, 2, ObjectExt::Box<double>(0.20)));
	series2->get_DataPoints()->AddDataPointForBarSeries(fact->GetCell(defaultWorksheetIndex, 4, 2, ObjectExt::Box<double>(0.35)));

	// 设置系列的填充颜色
	series2->get_Format()->get_Fill()->set_FillType(FillType::Solid);
	series2->get_Format()->get_Fill()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_Blue());

	// 设置 LabelFormat 属性
	series2->get_Labels()->get_DefaultDataLabelFormat()->set_ShowValue(true);
	series2->get_Labels()->get_DefaultDataLabelFormat()->set_IsNumberFormatLinkedToSource(false);
	series2->get_Labels()->get_DefaultDataLabelFormat()->set_NumberFormat(u"0.0%");
	series2->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->set_FontHeight(10);
	series2->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->get_FillFormat()->set_FillType(FillType::Solid);
	series2->get_Labels()->get_DefaultDataLabelFormat()->get_TextFormat()->get_PortionFormat()->get_FillFormat()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_White());
	series2->get_Labels()->get_DefaultDataLabelFormat()->set_ShowValue(true);

	// 将演示文稿文件写入磁盘
	pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);

设置标签与坐标轴的距离

此 C++ 代码演示在从坐标轴绘制的图表中如何设置标签与分类坐标轴的距离：

	// 文档目录的路径
	const String outPath = u"../out/CategoryAxisLabelDistance_out.pptx";

	// 创建 Presentation 类的实例
	SharedPtr<Presentation> pres = MakeObject<Presentation>();

	// 获取幻灯片的引用
	SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);

	// 在幻灯片上创建图表
	SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::ClusteredColumn, 0, 0, 500, 500);


	// 获取图表系列集合
	SharedPtr<IChartSeriesCollection> seriesCollection = chart->get_ChartData()->get_Series();

	// 设置标签与坐标轴的距离
	chart->get_Axes()->get_HorizontalAxis()->set_LabelOffset ( 500);

	// 将演示文稿文件写入磁盘
	pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);

调整标签位置

当创建不依赖任何坐标轴的图表（例如饼图）时，图表的数据标签可能会靠得太近边缘。此时，需要调整数据标签的位置，以便清晰显示引导线。

此 C++ 代码演示如何在饼图上调整标签位置：

System::SharedPtr<Presentation> pres = System::MakeObject<Presentation>();

System::SharedPtr<IChart> chart = pres->get_Slide(0)->get_Shapes()->AddChart(ChartType::Pie, 50.0f, 50.0f, 200.0f, 200.0f);

System::SharedPtr<IChartSeriesCollection> series = chart->get_ChartData()->get_Series();
System::SharedPtr<IDataLabel> label = series->idx_get(0)->get_Label(0);
System::SharedPtr<IDataLabelFormat> dataLabelFormat = label->get_DataLabelFormat();

dataLabelFormat->set_ShowValue(true);
dataLabelFormat->set_Position(LegendDataLabelPosition::OutsideEnd);
label->set_X(0.71f);
label->set_Y(0.04f);

pres->Save(u"pres.pptx", SaveFormat::Pptx);

FAQ

如何防止在密集图表上数据标签重叠？
结合自动标签布局、引导线和减小字体大小；必要时隐藏某些字段（例如类别）或仅对极值/关键点显示标签。

如何仅为零、负数或空值禁用标签？
在启用标签之前过滤数据点，并根据定义的规则关闭对值为 0、负数或缺失的显示。

如何确保导出为 PDF/图像时标签样式保持一致？
显式设置字体（族、大小），并确保渲染端已安装相应字体，以避免回退。