Manage Callouts in Presentation Charts with Python

Overview

This article explains how to work with callouts for chart data labels in Aspose.Slides. It shows how to use the show_label_as_data_callout property to display labels as callouts, how to configure callout-related label settings for a doughnut chart, and notes that callouts and their appearance are preserved when presentations are exported to PDF, HTML5, SVG, and raster image formats.

Using Callouts

New property show_label_as_data_callout has been added to DataLabelFormat class, which determines either specified chart’s data label will be displayed as data callout or as data label. In the example given below, we have set the Callouts.

import aspose.slides as slides

with slides.Presentation() as presentation:
    chart = presentation.slides[0].shapes.add_chart(slides.charts.ChartType.PIE, 50, 50, 500, 400)
    chart.chart_data.series[0].labels.default_data_label_format.show_value = True
    chart.chart_data.series[0].labels.default_data_label_format.show_label_as_data_callout = True
    chart.chart_data.series[0].labels[2].data_label_format.show_label_as_data_callout = False
    presentation.save("DisplayChartLabels_out.pptx", slides.export.SaveFormat.PPTX)

Set Callout for Doughnut Chart

Aspose.Slides for Python via .NET provides support for setting series data label callout shape for a Doughnut chart. Below sample example is given. 

import aspose.slides.charts as charts
import aspose.slides as slides
import aspose.pydrawing as draw

with slides.Presentation() as pres:
    slide = pres.slides[0]
    chart = slide.shapes.add_chart(charts.ChartType.DOUGHNUT, 10, 10, 500, 500, False)
    workBook = chart.chart_data.chart_data_workbook
    chart.chart_data.series.clear()
    chart.chart_data.categories.clear()
    chart.has_legend = False
    seriesIndex = 0
    while seriesIndex < 15:
        series = chart.chart_data.series.add(workBook.get_cell(0, 0, seriesIndex + 1, "SERIES " + str(seriesIndex)), chart.type)
        series.explosion = 0
        series.parent_series_group.doughnut_hole_size = 20
        series.parent_series_group.first_slice_angle = 351
        seriesIndex += 1
    categoryIndex = 0
    while categoryIndex < 15:
        chart.chart_data.categories.add(workBook.get_cell(0, categoryIndex + 1, 0, "CATEGORY " + str(categoryIndex)))
        i = 0
        while i < len(chart.chart_data.series):
            iCS = chart.chart_data.series[i]
            dataPoint = iCS.data_points.add_data_point_for_doughnut_series(workBook.get_cell(0, categoryIndex + 1, i + 1, 1))
            dataPoint.format.fill.fill_type = slides.FillType.SOLID
            dataPoint.format.line.fill_format.fill_type = slides.FillType.SOLID
            dataPoint.format.line.fill_format.solid_fill_color.color = draw.Color.white
            dataPoint.format.line.width = 1
            dataPoint.format.line.style = slides.LineStyle.SINGLE
            dataPoint.format.line.dash_style = slides.LineDashStyle.SOLID
            if i == len(chart.chart_data.series) - 1:
                lbl = dataPoint.label
                lbl.text_format.text_block_format.autofit_type = slides.TextAutofitType.SHAPE
                lbl.data_label_format.text_format.portion_format.font_bold = 1
                lbl.data_label_format.text_format.portion_format.latin_font = slides.FontData("DINPro-Bold")
                lbl.data_label_format.text_format.portion_format.font_height = 12
                lbl.data_label_format.text_format.portion_format.fill_format.fill_type = slides.FillType.SOLID
                lbl.data_label_format.text_format.portion_format.fill_format.solid_fill_color.color = draw.Color.light_gray
                lbl.data_label_format.format.line.fill_format.solid_fill_color.color = draw.Color.white
                lbl.data_label_format.show_value = False
                lbl.data_label_format.show_category_name = True
                lbl.data_label_format.show_series_name = False
                lbl.data_label_format.show_leader_lines = True
                lbl.data_label_format.show_label_as_data_callout = False
                chart.validate_chart_layout()
                lbl.as_i_layoutable.x += 0.5
                lbl.as_i_layoutable.y += 0.5
            i += 1
        categoryIndex +=1 
    pres.save("chart.pptx", slides.export.SaveFormat.PPTX)

FAQ

Are callouts preserved when converting a presentation to PDF, HTML5, SVG, or images?

Yes. Callouts are part of the chart rendering, so when you export to PDF, HTML5, SVG, or raster images, they are preserved together with the slide’s formatting.

Do custom fonts work in callouts, and can their appearance be preserved on export?

Yes. Aspose.Slides supports embedding fonts into the presentation and controls font embedding during exports such as PDF, ensuring the callouts look the same across different systems.