แปลง PPT เป็น Word ใน C#

using var presentation = new Presentation();
var doc = new Document();
var builder = new DocumentBuilder(doc);
foreach (var slide in presentation.Slides)
{
    // generates and inserts slide image
    using var bitmap = slide.GetThumbnail(1, 1);
    using var stream = new MemoryStream();
    bitmap.Save(stream, ImageFormat.Png);
    stream.Seek(0, SeekOrigin.Begin);
    using var skBitmap = SKBitmap.Decode(stream);
    builder.InsertImage(skBitmap);

    // inserts slide texts
    foreach (var shape in slide.Shapes)
    {
        if (shape is AutoShape autoShape)
        {
            builder.Writeln(autoShape.TextFrame.Text);
        }
    }

    builder.InsertBreak(BreakType.PageBreak);
}
doc.Save("document.docx");