Manage Chart Data Labels in Presentations Using C++
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Introduction
Data labels on a chart show details about the chart data series or individual data points. They allow readers to quickly identify data series and they also make charts easier to understand.
Set Data Precision in Chart Data Labels
This C++ code shows you how to set the data precision in a chart data label:
#include <DOM/Chart/ChartType.h>
#include <DOM/Chart/IChartData.h>
#include <DOM/Chart/IChartSeries.h>
#include <DOM/Chart/IChartSeriesCollection.h>
#include <DOM/IChart.h>
#include <DOM/IShapeCollection.h>
#include <DOM/ISlide.h>
#include <DOM/ISlideCollection.h>
#include <DOM/Presentation.h>
#include <Export/SaveFormat.h>
#include <system/string.h>
using namespace Aspose::Slides;
using namespace Aspose::Slides::Charts;
using namespace Aspose::Slides::Export;
using namespace System;
// The path to the documents directory
const String outPath = u"../out/SettingPrecisionOfDataLabel_out.pptx";
// Instantiates a Presentation class that represents a PPTX file
SharedPtr<Presentation> pres = MakeObject<Presentation>();
// Gets the first slide
SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);
// Adds chart with default data
SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::Line, 0, 0, 500, 500);
// Sets series number format
chart->set_HasDataTable( true);
chart->get_ChartData()->get_Series()->idx_get(0)->set_NumberFormatOfValues (u"#,##0.00");
// Writes the presentation file to disk
pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);
Display Percentages as Labels
Aspose.Slides for C++ allows you to set percentage labels on displayed charts. This C++ code demonstrates the operation:
#include <DOM/Chart/ChartType.h>
#include <DOM/Chart/IChartCategory.h>
#include <DOM/Chart/IChartCategoryCollection.h>
#include <DOM/Chart/IChartData.h>
#include <DOM/Chart/IChartDataPoint.h>
#include <DOM/Chart/IChartDataPointCollection.h>
#include <DOM/Chart/IChartSeries.h>
#include <DOM/Chart/IChartSeriesCollection.h>
#include <DOM/Chart/IDataLabel.h>
#include <DOM/Chart/IDataLabelCollection.h>
#include <DOM/Chart/IDataLabelFormat.h>
#include <DOM/Chart/IDoubleChartValue.h>
#include <DOM/IChart.h>
#include <DOM/IParagraph.h>
#include <DOM/IParagraphCollection.h>
#include <DOM/IPortion.h>
#include <DOM/IPortionCollection.h>
#include <DOM/IPortionFormat.h>
#include <DOM/IShapeCollection.h>
#include <DOM/ISlide.h>
#include <DOM/ISlideCollection.h>
#include <DOM/ITextFrame.h>
#include <DOM/Portion.h>
#include <DOM/Presentation.h>
#include <Export/SaveFormat.h>
#include <system/string.h>
using namespace Aspose::Slides;
using namespace Aspose::Slides::Charts;
using namespace Aspose::Slides::Export;
using namespace System;
// The path to the documents directory
const String outPath = u"../out/DisplayPercentageAsLabels_out.pptx";
// Creates an instance of the Presentation class
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);
}
}
// Saves the presentation containing the chart
presentation->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);
Set the Percentage Sign with Chart Data Labels
This C++ code shows you to set the percentage sign for a chart data label:
#include <DOM/Chart/ChartType.h>
#include <DOM/Chart/IAxesManager.h>
#include <DOM/Chart/IAxis.h>
#include <DOM/Chart/IChartData.h>
#include <DOM/Chart/IChartDataPointCollection.h>
#include <DOM/Chart/IChartDataWorkbook.h>
#include <DOM/Chart/IChartPortionFormat.h>
#include <DOM/Chart/IChartSeries.h>
#include <DOM/Chart/IChartSeriesCollection.h>
#include <DOM/Chart/IChartTextFormat.h>
#include <DOM/Chart/IDataLabelCollection.h>
#include <DOM/Chart/IDataLabelFormat.h>
#include <DOM/Chart/IFormat.h>
#include <DOM/FillType.h>
#include <DOM/IChart.h>
#include <DOM/IColorFormat.h>
#include <DOM/IFillFormat.h>
#include <DOM/IShapeCollection.h>
#include <DOM/ISlide.h>
#include <DOM/ISlideCollection.h>
#include <DOM/Presentation.h>
#include <Export/SaveFormat.h>
#include <drawing/color.h>
#include <system/object_ext.h>
#include <system/string.h>
using namespace Aspose::Slides;
using namespace Aspose::Slides::Charts;
using namespace System;
// The path to the documents directory.
const String outPath = u"../out/DataLabelsPercentageSign_out.pptx";
// Creates an instance of the Presentation class
SharedPtr<Presentation> pres = MakeObject<Presentation>();
// Gets a slide's reference through its index
SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);
// Creates the PercentsStackedColumn chart on a slide
SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::PercentsStackedColumn, 0.0f, 0.0f, 500.0f, 500.0f);
// Sets the NumberFormatLinkedToSource to false
chart->get_Axes()->get_VerticalAxis()->set_IsNumberFormatLinkedToSource(false);
chart->get_Axes()->get_VerticalAxis()->set_NumberFormat(u"0.00%");
// Sets the index of chart data sheet
int defaultWorksheetIndex = 0;
// Gets the chart data worksheet
SharedPtr<IChartDataWorkbook> fact = chart->get_ChartData()->get_ChartDataWorkbook();
// Deletes default generated series
chart->get_ChartData()->get_Series()->Clear();
// Adds a new series
chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 2, ObjectExt::Box<System::String>(u"Series 2")), chart->get_Type());
// Takes the first chart series
SharedPtr<IChartSeries> series = chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 1, ObjectExt::Box<System::String>(u"Red")), chart->get_Type());
// Populates the series data
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)));
// Sets fill color for series
series->get_Format()->get_Fill()->set_FillType(FillType::Solid);
series->get_Format()->get_Fill()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_Red());
// Sets LabelFormat properties
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);
// Takes the second chart series
SharedPtr<IChartSeries> series2 = chart->get_ChartData()->get_Series()->Add(fact->GetCell(defaultWorksheetIndex, 0, 2, ObjectExt::Box<System::String>(u"Blues")), chart->get_Type());
// Populates series data
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)));
// Sets fill color for series
series2->get_Format()->get_Fill()->set_FillType(FillType::Solid);
series2->get_Format()->get_Fill()->get_SolidFillColor()->set_Color(System::Drawing::Color::get_Blue());
// Sets LabelFormat properties
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);
// Writes the presentation file to disk
pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);
Set Label Distance from Axis
This C++ code shows you how to set the label distance from a category axis when you are dealing with a chart plotted from axes:
#include <DOM/Chart/ChartType.h>
#include <DOM/Chart/IAxesManager.h>
#include <DOM/Chart/IAxis.h>
#include <DOM/Chart/IChartData.h>
#include <DOM/Chart/IChartSeriesCollection.h>
#include <DOM/IChart.h>
#include <DOM/IShapeCollection.h>
#include <DOM/ISlide.h>
#include <DOM/ISlideCollection.h>
#include <DOM/Presentation.h>
#include <Export/SaveFormat.h>
#include <system/string.h>
using namespace Aspose::Slides;
using namespace Aspose::Slides::Charts;
using namespace Aspose::Slides::Export;
using namespace System;
// The path to the documents directory
const String outPath = u"../out/CategoryAxisLabelDistance_out.pptx";
// Creates an instance of the Presentation class
SharedPtr<Presentation> pres = MakeObject<Presentation>();
// Gets a slide's reference
SharedPtr<ISlide> slide = pres->get_Slides()->idx_get(0);
// Creates a chart on the slide
SharedPtr<IChart> chart = slide->get_Shapes()->AddChart(Aspose::Slides::Charts::ChartType::ClusteredColumn, 0, 0, 500, 500);
// Gets the chart series collection
SharedPtr<IChartSeriesCollection> seriesCollection = chart->get_ChartData()->get_Series();
// Sets the label distance from an axis
chart->get_Axes()->get_HorizontalAxis()->set_LabelOffset ( 500);
// Writes the presentation file to disk
pres->Save(outPath, Aspose::Slides::Export::SaveFormat::Pptx);
Adjust Label Location
When you create a chart that does not rely on any axis such as a pie chart, the chart’s data labels may end up being too close to its edge. In such a case, you have to adjust the location of the data label so that the leader lines get displayed clearly.
This C++ code shows you how to adjust the label location on a pie chart:
#include <DOM/Chart/ChartType.h>
#include <DOM/Chart/IChartData.h>
#include <DOM/Chart/IChartSeries.h>
#include <DOM/Chart/IChartSeriesCollection.h>
#include <DOM/Chart/IDataLabel.h>
#include <DOM/Chart/IDataLabelFormat.h>
#include <DOM/Chart/LegendDataLabelPosition.h>
#include <DOM/IChart.h>
#include <DOM/IShapeCollection.h>
#include <DOM/ISlide.h>
#include <DOM/Presentation.h>
#include <Export/SaveFormat.h>
#include <system/smart_ptr.h>
using namespace Aspose::Slides;
using namespace Aspose::Slides::Charts;
using namespace Aspose::Slides::Export;
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
How can I prevent data labels from overlapping on dense charts?
Combine automatic label placement, leader lines, and reduced font size; if necessary, hide some fields (for example, the category) or show labels only for extreme/key points.
How can I disable labels only for zero, negative, or empty values?
Filter data points before enabling labels and turn off display for values of 0, negative values, or missing values according to a defined rule.
How can I ensure a consistent label style when exporting to PDF/images?
Explicitly set fonts (family, size) and verify that the font is available on the rendering side to avoid fallback.