public static void GethttpImage1(string urlImage, Action<BitmapImage> action) \n{\n var request = (HttpWebRequest)WebRequest.Create(urlImage);\n request.BeginGetResponse(result =>\n {\n using (var sr = request.EndGetResponse(result))\n {\n Deployment.Current.Dispatcher.BeginInvoke(() =>\n {\n var image = new BitmapImage();\n image.SetSource(sr.GetResponseStream());\n if (action != null)\n action(image);\n sr.Close();\n });\n }\n }\n}\n<\/pre>\nurlImage is a string representation of the url of the image\u00a0: example\u00a0: http:\/\/dev.bratched.fr\/download\/testimage1.png<\/a><\/p>\nThis method uses the WebRequest class and reads the response as a Stream using request.EndGetResponse.<\/p>\n
The<\/p>\n
Deployment.Current.Dispatcher.BeginInvoke(() =>\n<\/pre>\ncall is very important as it allows us to use the BitmapImage on the main UI thread even when the callback is invoked on a background thread.<\/p>\n
The method will invoke the action and pass the retrieved image to this action as parameter.<\/p>\n
It can be invoked like this in order to set a property of type BitmapImage:<\/p>\n
HttpImageService.GethttpImage1(\"http:\/\/dev.bratched.fr\/download\/testimage1.png\", b =>\n {\n Image = b;\n });<\/pre>\nImplementation with async\/await:<\/h1>\n
The “Microsoft Async” allows to use the async\/await pattern in the standard Windows Phone methods.<\/p>\n
![\"NuGetPackagesAsync\"](\"http:\/\/dev.bratched.fr\/fr\/wp-content\/uploads\/sites\/2\/2014\/06\/NuGetPackagesAsync.jpg\")
<\/a><\/p>\nThis package adds some extension methods to the standard WebRequest class returning Task<BitmapImage><\/p>\n
using (WebResponse response = await request.GetResponseAsync())<\/pre>\n <\/p>\n
Replaces the following elements:<\/p>\n
request.BeginGetResponse(result =>\n {\n using (var sr = request.EndGetResponse(result))\n {<\/pre>\nThe function returns directly a Task<BitmapImage> instead of passing an action as parameter<\/p>\n
public static async Task<BitmapImage> GethttpImage2(string urlImage)\n{\n try\n {\n var request = (HttpWebRequest)WebRequest.Create(urlImage);\n using (WebResponse response = await request.GetResponseAsync())\n {\n BitmapImage image = null;\n DispatcherSynchronizationContext dsc = new DispatcherSynchronizationContext(Deployment.Current.Dispatcher);\n await Task.Factory.StartNew(() =>\n {\n dsc.Send(_ =>\n {\n image = new BitmapImage();\n image.SetSource(response.GetResponseStream());\n }, null);\n });\n return image;\n }\n }\n catch (Exception)\n {\n return null;\n }\n}\n<\/pre>\nRemark\u00a0:<\/p>\n
DispatcherSynchronizationContext dsc = new DispatcherSynchronizationContext(Deployment.Current.Dispatcher);\n await Task.Factory.StartNew(() =>\n {\n dsc.Send(_ =>\n {\n<\/pre>\nreplaces<\/p>\n
Deployment.Current.Dispatcher.BeginInvoke(() =><\/pre>\nHere we still need to marshal the call on the main Thread to allow using the returned BitmapImage and bind it on the UI.<\/p>\n
The async\/await pattern illustrated here allows better management of the threads as it relies on the TPL. Vous pouvez la remplacer sans soucis par l\u2019ancien code.<\/p>\n
Here’s how you could call the function: (Image is a property of type BitmapImage)<\/p>\n
Image = await HttpImageService.GethttpImage2(\"http:\/\/dev.bratched.fr\/download\/testimage1.png\");\n<\/pre>\nHttpClient<\/h1>\n
The “Microsoft\u00a0HTTP Client Libraries” NuGet needs to be installed in order to be able to use the HttpClient class. The advantage of this class is that it allows to use the same syntax as we would in a Windows 8 application.<\/p>\n
![\"NuGetPackagesAsync\"](\"http:\/\/dev.bratched.fr\/download\/testimage1.png\")
<\/a><\/p>\n