inabox/InABox.Avalonia.Platform.Desktop/Desktop.PdfRenderer.cs

using InABox.Core;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.PdfToImageConverter;

namespace InABox.Avalonia.Platform.Desktop;

public class Desktop_PdfRenderer : IPdfRenderer
{
    public byte[]? PdfToImage(byte[]? pdf, int page, int dpi)
    {
        if (pdf?.Any() != true)
            return null;

        using var inData = new MemoryStream(pdf);
        using var converter = new PdfToImageConverter(inData);
        var output = converter.Convert(page, true, false) as MemoryStream;
        return output.ToArray();

    }

    public Task<byte[]?> PdfToImageAsync(byte[]? pdf, int page, int dpi)
        => Task.Run(() => PdfToImage(pdf, page, dpi));

    public byte[][]? PdfToImages(byte[]? pdf, int dpi)
    {
        if (pdf is null || pdf.Length == 0)
            return null;

        using var inData = new MemoryStream(pdf);
        using var converter = new PdfToImageConverter(inData);
        return Enumerable.Range(0, converter.PageCount).Select(i =>
        {
            var output = converter.Convert(i, true, false) as MemoryStream;
            return output.ToArray();
        }).ToArray();
    }

    public Task<byte[][]?> PdfToImagesAsync(byte[]? pdf, int dpi)
        => Task.Run(() => PdfToImages(pdf, dpi));

    public int? PdfPageCount(byte[]? pdf)
    {
        if (pdf is null || pdf.Length == 0)
            return null;

        using var inData = new MemoryStream(pdf);
        using var converter = new PdfToImageConverter(inData);
        return converter.PageCount;
    }

    public Task<int?> PdfPageCountAsync(byte[]? pdf)
        => Task.Run(() => PdfPageCount(pdf));

    public byte[]? ImageToPdf(byte[]? image)
    { 
        if (image?.Any() != true)
            return null;

        using var imgStream = new MemoryStream(image);
        
        var bmp = new PdfBitmap(imgStream);
        
        var doc = new PdfDocument();
        
        var section = doc.Sections.Add();
        section.PageSettings.Margins.All = 0;
        section.PageSettings.Width = bmp.Width;
        section.PageSettings.Height = bmp.Height;
        
        var page = section.Pages.Add();
        page.Graphics.DrawImage(bmp, 0, 0, page.Size.Width, page.Size.Height);

        using var docStream = new MemoryStream();
        
        doc.Save(docStream);
        return docStream.GetBuffer();
    }

    public Task<byte[]?> ImageToPdfAsync(byte[]? image)
        => Task.Run(() => ImageToPdf(image));

    public Logger? Logger { get; set; }
}