How can I use iText7 .NET to subset only problematic glyphs for minimal PDF size?

You can use iText7’s font subsetting feature to embed only the characters that are used in your document (such as č and ć) rather than the full font. This approach should help keep your file sizes minimal while ensuring that the problematic glyphs are available for rendering on devices that otherwise wouldn’t display them.

Below is an example of how you might do this in iText7:

JAVACopied
import com.itextpdf.io.font.PdfEncodings;
import com.itextpdf.kernel.font.PdfFont;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.layout.Document;
import com.itextpdf.layout.element.Paragraph;

public class SubsetFontExample {
    public static void main(String[] args) throws Exception {
        // Create a PdfWriter instance
        PdfWriter writer = new PdfWriter("subset_example.pdf");
        PdfDocument pdf = new PdfDocument(writer);
        Document document = new Document(pdf);

        // Create a font with subsetting enabled.
        // Make sure the TTF font file supports the characters you need.
        PdfFont font = PdfFontFactory.createFont("path/to/your/font.ttf", PdfEncodings.IDENTITY_H, true);

        // Sample content including problematic characters
        String text = "Example with missing characters: č, ć.";

        // Create the paragraph with the subset font and add it to the document
        Paragraph p = new Paragraph(text).setFont(font);
        document.add(p);

        document.close();
    }
}

Key Points:

• Font Subsetting: When you set the third parameter of createFont to true, iText7 will embed only the glyphs actually used in the document.
• Encoding: Using PdfEncodings.IDENTITY_H ensures that a wide range of Unicode characters is available.
• Font File: Ensure the font you are using contains the glyphs for č, ć, and any other special characters.

By integrating this into your workflow after generating the RDLC report, you should be able to mitigate the issue of missing characters on certain devices while still maintaining file size efficiency.