As System.Drawing only supported on Windows in NET6.0, you need to use SkiaSharp instead under NET5.0 or NET6.0 in Linux, or inside docker container. Please follow the next steps to use the NetStandard dlls to get SkiaSharp to your project manually. We will use Spire.Doc as example.

Step 1: Download the latest version of Spire.Doc Pack from this link, unzip it, and you'll get the DLL files for .NET Standarad from the "netstandard2.0" folder or install via NuGet.

PM> Install-Package Spire.Officefor.NETStandard 

If you already have this folder in your disk, go straight to step two.

How to Mannually Add Spire.Doc as Dependency in a .NET Standard Library Project

Step 2: Create a .NET Standard library project in your Visual Studio.

How to Mannually Add Spire.Doc as Dependency in a .NET Standard Library Project

Step 3: Add all DLL files under the "netstandard2.0" folder as dependencies in your project.

Right-click "Dependencies" – select "Add Reference" – click "Browse" – selcet all DLLs under "netstandard2.0" folder – click "Add".

How to Mannually Add Spire.Doc as Dependency in a .NET Standard Library Project

Step 4: Install the other three packages in your project via the NuGet Package Manager. They are SkiaSharp, System.Text.Encoding.CodePages and System.Security.Cryptography.Xml.

Right-click "Dependencies" – select "Manage NuGet Packages" – click "Browse" – type the package name – select the package from the search results – click "Install".

How to Mannually Add Spire.Doc as Dependency in a .NET Standard Library Project

Step 5: Now that you've added all the dependences successfully, you can start to write your own .NET Standard library that is capable of creating and processing Word documents.

using Spire.Doc;
using Spire.Doc.Documents;

namespace SpireDocStandard
{
    public class Class1
    {
        public void CreateWord()
        {
            //Create a document object
            Document doc = new Document();

            //Add a section
            Section section = doc.AddSection();

            //Add a paragrah
            Paragraph paragraph = section.AddParagraph();

            //Append text to the paragraph
            paragraph.AppendText("Hello World");

            //Save to file
            doc.SaveToFile("Output.docx", FileFormat.Docx2013);
        }  
    }
}

This article demonstrates how to add data labels to a chart and set the appearance (border style and fill style) for the data labels in PowerPoint using Spire.Presentation for Java. Note some chart types like Surface3D, Surface3DNoColor, Contour and ContourNoColor do not support data labels.

Below screenshot shows the original chart before adding data labels:

Add Data Labels to Chart in PowerPoint in Java

import com.spire.presentation.FileFormat;
import com.spire.presentation.ISlide;
import com.spire.presentation.Presentation;
import com.spire.presentation.charts.IChart;
import com.spire.presentation.charts.entity.ChartDataLabel;
import com.spire.presentation.charts.entity.ChartSeriesDataFormat;
import com.spire.presentation.drawing.FillFormatType;

import java.awt.*;

public class AddDataLabelsToChart {
    public static void main(String[] args) throws Exception {
        //Load the PowerPoint document
        Presentation ppt = new Presentation();
        ppt.loadFromFile("Chart.pptx");

        //Get the first slide
        ISlide slide = ppt.getSlides().get(0);
        //Get the chart in the slide
        IChart chart = (IChart)slide.getShapes().get(0);

        //Loop through the series in the chart
        for (ChartSeriesDataFormat series:(Iterable<ChartSeriesDataFormat>)chart.getSeries()) {
             ) {
            //Add data labels for the data points in each series
            for(int i = 0; i < 4; i++){
                ChartDataLabel dataLabel = series.getDataLabels().add();
                //Show label value
                dataLabel.setLabelValueVisible(true);
                //Show series name
                dataLabel.setSeriesNameVisible(true);
                //Set border line style
                dataLabel.getLine().setFillType(FillFormatType.SOLID);
                dataLabel.getLine().getSolidFillColor().setColor(Color.RED);
                //Set fill style
                dataLabel.getFill().setFillType(FillFormatType.SOLID);
                dataLabel.getFill().getSolidColor().setColor(Color.YELLOW);
            }
        }

        //Save the resultant document
        ppt.saveToFile("DataLabels.pptx", FileFormat.PPTX_2013);
    }
}

Output:

Add Data Labels to Chart in PowerPoint in Java

Step 1: Download the latest version of Spire.PDF Pack from the link below, unzip it, and you'll get the DLL files for .NET Core in the "netcoreapp2.0" folder. If you already have this folder in your disk, go straight to step two.

How to Mannually Add Spire.PDF as Dependency in a .NET Core Application

Step 2: Create a .NET Core application in your Visual Studio.

How to Mannually Add Spire.PDF as Dependency in a .NET Core Application

Step 3: Add all DLL files under the "netcoreapp2.0" folder as dependencies in your project.

Right-click "Dependencies" – select "Add Reference" – click "Browse" – selcet all DLLs under "netcoreapp2.0" folder – click "Add".

How to Mannually Add Spire.PDF as Dependency in a .NET Core Application

Step 4: Install the other two packages in your project via the NuGet Package Manager. They are System.Drawing.Common and System.Text.Encoding.CodePages.

Right-click "Dependencies" – select "Manage NuGet Packages" – click "Browse" –type the package name – select the package from the search results – click "Install".

Note: If you fail to find these packages in the NuGet Package Manager, check if you have set the "nuget.org" as the "Package source".

How to Mannually Add Spire.PDF as Dependency in a .NET Core Application

Step 5: Now that you’ve added all the dependences successfully, you can start to code. The following code snippet gives you an exmaple of how to create a simple PDF document using Spire.PDF.

using Spire.Pdf;
using Spire.Pdf.Graphics;
using System.Drawing;

namespace SpirePdfCore
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create a PdfDocument object
            PdfDocument doc = new PdfDocument();

            //Add a page
            PdfPageBase page = doc.Pages.Add();

            //Draw text on the page at the specified position
            page.Canvas.DrawString("Hello World",
                                    new PdfFont(PdfFontFamily.Helvetica, 13f),
                                    new PdfSolidBrush(Color.Black),
                                    new PointF(50, 50));

            //Save the document
            doc.SaveToFile("Output.pdf");
        }
    }
}
page 146