prs/prs.mobile.new/PRS.Mobile/Components/DocumentList/DocumentViewer.xaml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using InABox.Core;
using InABox.Mobile;
using Syncfusion.SfPdfViewer.XForms;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
using XF.Material.Forms.UI.Dialogs;

namespace PRS.Mobile
{

    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class DocumentViewer
    {

        public static async Task<DocumentViewer> Load(Guid id)
        {
            DocumentModel docmodel = new DocumentModel(App.Data,
                () => new Filter<Document>(x => x.ID).IsEqualTo(id)) { FileName = $"{id}.document" };
                    
            using (await MaterialDialog.Instance.LoadingDialogAsync("Loading Document"))
                docmodel.Refresh(true);

            if (docmodel.Any())
            {
                var editor = new DocumentViewer();
                editor.Load(docmodel.First().FileName, docmodel.First().Data);
                return editor;
            }
            else
                await MaterialDialog.Instance.AlertAsync("Cannot Load Document!");
            return null;
        }
        
        public void Load(String filename, byte[] data)
        {
            _filename.Text = filename;
            _filename.IsVisible = ShowFileName && !String.IsNullOrWhiteSpace(filename);
            if (data?.Any() == true)
            {
                if (filename.ToUpper().EndsWith(".PDF"))
                    LoadPDF(data);
                else
                    LoadImage(data);
                _noimage.IsVisible = false;
            }
            else
            {
                _noimage.IsVisible = true;
                _pdf.IsVisible = false;
                _image.IsVisible = false;
            }

        }

        private bool _showfilename = false;
        public bool ShowFileName
        {
            get => _showfilename;
            set
            {
                _showfilename = value;
                _filename.IsVisible = value && !String.IsNullOrWhiteSpace(_filename.Text);
            }
        }
        
        public DocumentViewer()
        {
            InitializeComponent();
            BindingContext = this;
            if (Device.RuntimePlatform.Equals(Device.Android))
            {
                var service = DependencyService.Get<ICustomPdfRendererService>();
                var renderer = service?.AlternatePdfRenderer;
                _pdf.CustomPdfRenderer = renderer;
            }
        }

        private byte[]? _data;
        public event EventHandler DocumentLoaded;
        
        private void LoadPDF(byte[] data)
        {
            _data = data;
            _image.IsVisible = false;
            MemoryStream memoryStream = new MemoryStream(data);
            _pdf.LoadDocument(memoryStream);
            _pdf.IsVisible = true;
            DocumentLoaded?.Invoke(this, EventArgs.Empty);
        }
        
        private void LoadImage(byte[] data)
        {
            _data = data;
            _pdf.IsVisible = false;
            _image.Source = ImageSource.FromStream(() => new MemoryStream(data));
            _image.IsVisible = true;
            DocumentLoaded?.Invoke(this, EventArgs.Empty);
        }

        public byte[] GetThumbnail()
        {
            if (_data?.Any() != true)
                return new byte[] { };

            if (_image.IsVisible)
            {
                return MobileUtils.ImageTools.CreateThumbnail(_data, 256, 256);
            }
            else if (_pdf.IsVisible)
            {
                var stream = _pdf.ExportAsImage(0) as MemoryStream;
                if (stream?.Length > 0)
                {
                    var imgdata = stream.ToArray();
                    return MobileUtils.ImageTools.CreateThumbnail(imgdata, 256, 256);
                }
            }
            return new byte[] { };
        }

    }
}