c# - Async/await deadlock while downloading images -

i'm developing windows phone 8.1 app. have screen list of news' titles thumbnails.

first i'm making asynchronous http request news collection in json (satisfying notifytaskcompletion pattern)

newscategories = new notifytaskcompletion<observablecollection<newscategory>>(_newsservice.getnewscategoriesasync()); 

newscategory:

public class newscategory : observableobject {     ...     public string title { get;  set; }     public observablecollection<news> items { get;  set; } } 

news:

public class news : observableobject {     ...     public string title { get; set; }     public string imagepath { get; set; } } 

so far works perfectly, imagepath property, download , display given image. i've found solution asynchronously here: wp 8.1 binding image http request - when xaml gets image path, calls converter class (binarytoimagesourceconverter), using notifytaskcompletion pattern.

the problem occurs in following method:

private async task<bitmapimage> getimage(string path) {     httpclient webclient = new httpclient();     var responsestream = await webclient.getstreamasync(path);     var memorystream = new memorystream();     await responsestream.copytoasync(memorystream);     memorystream.position = 0;     var bitmap = new bitmapimage();     await bitmap.setsourceasync(memorystream.asrandomaccessstream());     return bitmap; } 

when first await called, debugger never reach next line , method never returns. string path variable has proper content.

so far have tried use configureawait(false), doesn't work in case.

i have found out in topic: deadlock while using async await , that:

when you're using configureawait(false), tell program dont mind context. can solve deadlocking problems, isn't right solution. right solution never wait tasks in blocking way, , being asynchronous way.

i don't know have stuff in blocking way. can reason deadlock?

and if it's wrong approach, know pattern more appropriate downloading thumbnails collection of items?

thank help.

---

update: how getimage invoked: it's in topic: wp 8.1 binding image http request

public class webpathtoimage : ivalueconverter {     public object convert(object value, type targettype, object parameter, string language)     {         if (value == null) return null;         return new notifytaskcompletion<bitmapimage>(getimage((string)value));     }      public object convertback(object value, type targettype, object parameter, string language)     { throw new notimplementedexception(); }      private async task<bitmapimage> getimage(string path)     {         using (var webclient = new httpclient())         {             webclient.defaultrequestheaders.add("user-agent", "bot");             var responsestream =  await webclient.getstreamasync(path).configureawait(false);             var memorystream = new memorystream();             await responsestream.copytoasync(memorystream);             memorystream.position = 0;             var bitmap = new bitmapimage();             await bitmap.setsourceasync(memorystream.asrandomaccessstream());             return bitmap;           }     } } 

and in xaml:

<image  datacontext="{binding imagepath, converter={staticresource webpathtoimage}}" source="{binding result}"  stretch="uniformtofill"  height="79" width="79"/> 

first, if on windows phone 8.1 recommended use httpclient namespace windows.web.http , not system.net.http. reasons explained on this link.

my answer uses new windows.web.http.httpclient getimage method can this:

        private async task<bitmapimage> getimage(string path)         {             using (var webclient = new windows.web.http.httpclient())             {                 webclient.defaultrequestheaders.add("user-agent", "bot");                 var responsestream = await webclient.getbufferasync(new uri(path));                 var memorystream = new memorystream(responsestream.toarray());                 memorystream.position = 0;                 var bitmap = new bitmapimage();                 await bitmap.setsourceasync(memorystream.asrandomaccessstream());                 return bitmap;             }         } 

i have tested method on sample url , displayed correctly in image control.

second, why don't let image control handle downloading bitmapimage without converter, xaml looks this:

<image     source="{binding imagepath}"      stretch="uniformtofill"      height="79"      width="79" /> 

this way imagepath can path resource internet , local resource.