Open local PDF file from embedded resources on iOS and Android about pdfjs

[jfversluis]

Make sure the build action is set to AndroidAsset

Then, you will have to modify the code a bit. I have done this in the pdfjsPage.xaml.cs:

if (Device.RuntimePlatform == Device.Android)
{
    //var dependency = DependencyService.Get<ILocalFileProvider>();

    //if (dependency == null)
    //{
    //    DisplayAlert("Error loading PDF", "Computer says no", "OK");

    //    return;
    //}

   // var fileName = Guid.NewGuid().ToString();
    //// Download PDF locally for viewing
    //using (var httpClient = new HttpClient())
    //{
    //    var pdfStream = Task.Run(() => httpClient.GetStreamAsync(url)).Result;

    //    localPath =
    //        Task.Run(() => dependency.SaveFileToDisk(pdfStream, $"{fileName}.pdf")).Result;
    //}

    localPath = "file:///android_asset/pdffile.pdf";

    //if (string.IsNullOrWhiteSpace(localPath))
    //{
    //   DisplayAlert("Error loading PDF", "Computer says no", "OK");

    //    return;
    //}
}

Note the commented out piece and how I set the localPath variable to a local file that is in the assets folder directly.

[jfversluis]

You will probably have to add it to the resources there, but you will need to extend the https://github.com/jfversluis/pdfjs/blob/master/iOS/PlatformSpecifics/LocalFileProvider.cs class to give you the right local file path.

Add the file to your iOS project and set the build action to EmbeddedResource

Then expand the IFileProvider like this

using System.IO;
using System.Threading.Tasks;

namespace pdfjs.Interfaces
{
    public interface ILocalFileProvider
    {
        Task<string> SaveFileToDisk(Stream stream, string fileName);

        string GetLocalFilePath();
    }
}

And implement it on iOS (LocalFileProvider.cs), like this:

public string GetLocalFilePath()
{
    return NSBundle.MainBundle.PathForResource("pdffile", "pdf");
}

Of course, you might want to implement some stuff to not hardcode the filename and extension here, but I trust you can do that yourself ;)

Now just assign this as the URL in pdfjsPage.xaml.cs:

PdfView.Source = dependency.GetLocalFilePath();

If you optimize some stuff then you will be able to use the same code for Android and iOS

[jfversluis]

Leaving this open so people might benefit from it in the future :)

[jfversluis]

Hi Bernard,

Thank you for reading my blog! I'd love to help out, but I'm not sure what you mean by "read local files only" can you please elaborate a bit more?

[bernardojb]

Ty for the attention Gerald!!
So, i'm making a school project and i want my app to load only local file PDF's.
I'm not being successful on finding what i need to change. I tried to add my file into assets folder and than calling it replacing the URL you've used. (sorry for the bad explanation, but um new on programing)

[jfversluis]

Do you get any errors? Or what is happening?

[bernardojb]

Not getting any errors! I just don't know what i need to do to make the code recognize where is my local pdf file, and than rendering it, instead of rendering the url you provided on the MainPage (app.xaml.cs)

[jfversluis]

Did you see the addition I just made on the blog post? Under Update Jan 2019?

You might need a custom renderer now

[bernardojb]

Yes!! I'm using the updated version you've posted here. My issue is just finding on your code, or where i need to add on your code, a function that renders a pdf from my APP storage (offline), and not a url link. I'm trying to make a simple pdf reader for me, and i want the app to access the pdf's from the app itself and not the internet, but i don't know how. I tried adding my file into Droid assets directory but i'm not doing it right

[jfversluis]

Do you have the code somewhere I can have a look at it?

[bernardojb]

https://uploaddeimagens.com.br/imagens/meajuda-png I'm still testing using only your code

[bernardojb]

It worked perfectly on Android Gerald!!! Ty so much for your help, it was way easier than i thought!! If i wan't to do the same thing with IoS, i just need to create a device.runtime for ios ?

[bernardojb]

Hey Gerald, once again, thank you so much for your time!!
I have 2 questions, the first one is about NSBundle.

1. Do i need to add "using Foundation;" to have access to this function?
2. When assigning the URL in pdfjsPage.xaml.cs, do i have to create a new "...(Device.RuntimePlatform == Device.iOS)" or i can add it on the else:

// if (Device.RuntimePlatform == Device.Android)
// PdfView.Source = $"file:///android_asset/pdfjs/web/viewer.html?file=
// {WebUtility.UrlEncode(localPath)}";
else
PdfView.Source = dependency.GetLocalFilePath();"

Because when i do that (example above), i get an error on "dependency".

[jfversluis]

The "solution" I gave was based on the questions you were asking. It's not a full solution, but it shouldn't be too hard to put it all together yourself.

Since you will not be retrieving the file from the local app in both cases, you might be able to remove the check for a certain platform altogether. It could be as simple as implementing the GetLocalFilePath method also for Android and simply returning the static string "file:///android_asset/pdffile.pdf".

The code to set the source for the PDF would then simply be:

var dependency = DependencyService.Get<ILocalFileProvider>();
PdfView.Source = dependency.GetLocalFilePath();

Of course, if it should be a bit more dynamic, probably in the filename area, you might want to implement some more logic for it.

For your question about using Foundation;; I'm guessing NSBundle resides in that namespace, so yeah you should include it or simply type return Foundation.NSBundle.MainBundle.PathForResource("pdffile", "pdf");

[carlosagudop]

Hi, and thank you for your work. I have a lot of questions about how to read local files, although i have read the entire issue.

The first question is about the "url" the parameter of the "pdfjsPage.xaml.cs", that url from a local file will be only the name of the file and the extension or i have to give the entire route? and in that case how i know the entire route?

My second question is about what i have to do inside that "if" "(Device.RuntimePlatform == Device.Android)" in "pdfjsPage.xaml.cs" if i give it the localpath, the url what is for? and this code

 if (Device.RuntimePlatform == Device.Android)
                PdfView.Source = $"file:///android_asset/pdfjs/web/viewer.html?file={WebUtility.UrlEncode(localPath)}";
            else
                PdfView.Source = url;

is even necesary?

Im sorry for my english i tried to explain myself the best as possible. I am and student and its my first aproximattion at c# and xamarin, so im very lost. 😅

Thank you so much!!

[jfversluis]

Hey @carlosagudop thanks for your message.

• The url comes from here and is an online URL, because the file is downloaded first for iOS: https://github.com/jfversluis/pdfjs/blob/master/pdfjs/App.xaml.cs#L11

• SO as I mentioned on iOS I download the PDF file first to a local path and then show it. For Android you can take the online url directly and show that. That is why that difference is there. Maybe things have changed and this isn’t necessary anymore, but at the time it was.

I hope that helps you a bit further!

[carlosagudop]

Ty for your answer!!

So, if i have the pdf already dowloaded in the assets folder in android, the url parameter is no longer neccesary, isn´t it? Im just trying to show in the webvier the local pdf,

[jfversluis]

Correct. If you have the file locally already, just figure out the path where it is stored and supply that to the PDF viewer

[carlosagudop]

And how i know the path of the pdf file? the file is inside the assets folder in android.

Thank you very much for your time!

[jfversluis]

If it’s just a static file sitting there then it will probably be something like "file:///android_asset/pdffile.pdf" else, you probably want to have a look at this concept: https://github.com/jfversluis/pdfjs/blob/master/Droid/PlatformSpecifics/LocalFileProvider.cs

[carlosagudop]

Where do i use the LocalFileProvider? This is my constructor of the content page

public LocalWB(String url)
        {
            InitializeComponent();
            PdfView.Source = url;
       
        }

and this is the event of a button where i open the contentpage
var localroute = "file:///android_asset/sample.pdf"; Application.Current.MainPage.Navigation.PushModalAsync(new LocalWB(localroute));

But i only get a blankpage 😫

[jfversluis]

Can you share the code somewhere?

[MickLesk]

Hey @jfversluis,

im using pdf.js with Xamarin Forms, the PDF work correctly, but i dont have "touch-events" for example, pinch to zoom, or double tap. Do you have any idea?

[jfversluis]

Could you please open a separate issue and post some relevant code? Also is it iOS or Android? Both?