如何从 Xamarin 表单中的 URI 异步加载图像

Question

Here is my current code for loading the Image:

System.Uri uri;
System.Uri.TryCreate (imageURI, UriKind.Absolute, out uri);
_companyImage.Source = ImageSource.FromUri (uri);

The problem is that the whole program has to wait for this task to complete, I would like to load the image asynchronously but I can't work out how to create an image source asynchronously.

Answer 1

Grab the data asynchronously and assign it to your Source once it is done.

System.Uri uri;
System.Uri.TryCreate(imageURI, UriKind.Absolute, out uri);
Task<ImageSource> result = Task<ImageSource>.Factory.StartNew(() => ImageSource.FromUri(uri));
_companyImage.Source = await result;

Answer 2

You can simply set the Image.Source property to a URI and let Xamarin.Forms do the work for you (per "Working with Images" in Xamarin.Forms docs ).

Example

var someImage = new Image() {
    Aspect = Aspect.AspectFit,
    Source = ImageSource.FromUri(new Uri("http://xamarin.com/content/images/pages/branding/assets/xamagon.png")),
};

Answer 3

Set your url to Source proprty or bind from viewmodel

https://developer.xamarin.com/guides/xamarin-forms/user-interface/images/

<Image Source="yoururl"  Aspect="AspectFill" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"/>

Answer 4

In the special case that you're trying to use a ContentUri on Android (eg content://com.android.contacts/contacts/18/photo ), this is the required incantation:

var uri = Android.Net.Uri.Parse(str);
_companyImage.Source = ImageSource.FromStream(() => Android.App.Application.Context.ContentResolver.OpenInputStream(uri));