inabox/InABox.Avalonia.Platform.iOS/PDFRenderer.iOS.cs

using InABox.Core; 

namespace InABox.Avalonia.Platform.iOS;

public class iOS_PdfRenderer : IPdfRenderer
{

    public Logger? Logger { get; set; }

    private byte[] PdfDocToImage(CGPDFDocument document, int pageIndex, int dpi)
    {
        float scale = 2F;

        using var page = document.GetPage(pageIndex + 1); // Pages are 1-indexed
        var pageRect = page.GetBoxRect(CGPDFBox.Media);
        var scaledSize = new CGSize(pageRect.Width * scale, pageRect.Height * scale);

        // Step 2: Render the page to an image
        UIGraphics.BeginImageContextWithOptions(scaledSize, false, 1.0f);
        using (var context = UIGraphics.GetCurrentContext())
        {
            context.SaveState();
            context.TranslateCTM(0, scaledSize.Height);
            context.ScaleCTM(scale, -scale); // Flip and scale
            context.DrawPDFPage(page);
            context.RestoreState();
        }

        using var image = UIGraphics.GetImageFromCurrentImageContext();
        UIGraphics.EndImageContext();

        // Step 3: Convert UIImage to PNG byte array
        using var pngData = image.AsPNG();
        return pngData.ToArray();
    }

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

        // Step 1: Load the PDF document from byte array
        using var data = NSData.FromArray(pdf);
        using var provider = new CGDataProvider(data);
        using var pdfDoc = new CGPDFDocument(provider);

        // Validate page index
        int pageCount = (int)pdfDoc.Pages;
        if (pageIndex < 0 || pageIndex >= pageCount)
            throw new ArgumentOutOfRangeException(nameof(pageIndex), "Invalid PDF page index.");

        return PdfDocToImage(pdfDoc, pageIndex, dpi);
    }

    public byte[][]? PdfToImages(byte[]? pdf, int dpi)
    {
        if (pdf is null || pdf.Length == 0)
            return null;
        float scale = 2F;

        // Step 1: Load the PDF document from byte array
        using var data = NSData.FromArray(pdf);
        using var provider = new CGDataProvider(data);
        using var pdfDoc = new CGPDFDocument(provider);

        // Validate page index
        int pageCount = (int)pdfDoc.Pages;

        return Enumerable.Range(0, pageCount).Select(pageIndex =>
        {
            return PdfDocToImage(pdfDoc, pageIndex, dpi);
        }).ToArray();
    }

    public int? PdfPageCount(byte[]? pdf)
    {
        if (pdf is null || pdf.Length == 0)
            return null;
        // Step 1: Load the PDF document from byte array
        using var data = NSData.FromArray(pdf);
        using var provider = new CGDataProvider(data);
        using var pdfDoc = new CGPDFDocument(provider);
        return (int)pdfDoc.Pages;
    }

    public Task<byte[]?> PdfToImageAsync(byte[]? pdf, int page, int dpi)
    {
        var tcs = new TaskCompletionSource<byte[]?>();

        UIApplication.SharedApplication.BeginInvokeOnMainThread(() =>
        {
            try
            {
                var result = PdfToImage(pdf, page, dpi);
                tcs.SetResult(result);
            }
            catch (Exception ex)
            {
                tcs.SetException(ex);
            }
        });

        return tcs.Task;
    }

    public Task<byte[][]?> PdfToImagesAsync(byte[]? pdf, int dpi)
    {
        var tcs = new TaskCompletionSource<byte[][]?>();

        UIApplication.SharedApplication.BeginInvokeOnMainThread(() =>
        {
            try
            {
                var result = PdfToImages(pdf, dpi);
                tcs.SetResult(result);
            }
            catch (Exception ex)
            {
                tcs.SetException(ex);
            }
        });

        return tcs.Task;
    }

    public Task<int?> PdfPageCountAsync(byte[]? pdf)
    {
        var tcs = new TaskCompletionSource<int?>();

        UIApplication.SharedApplication.BeginInvokeOnMainThread(() =>
        {
            try
            {
                var result = PdfPageCount(pdf);
                tcs.SetResult(result);
            }
            catch (Exception ex)
            {
                tcs.SetException(ex);
            }
        });

        return tcs.Task;
    }

    public byte[]? ImageToPdf(byte[]? image)
    {
        return null;
    }

    public Task<byte[]?> ImageToPdfAsync(byte[]? image)
    {
        var tcs = new TaskCompletionSource<byte[]?>();

        UIApplication.SharedApplication.BeginInvokeOnMainThread(() =>
        {
            try
            {
                var result = ImageToPdf(image);
                tcs.SetResult(result);
            }
            catch (Exception ex)
            {
                tcs.SetException(ex);
            }
        });

        return tcs.Task;
    }


}