c# - Save BitmapImage to File -

i working on program downloads images url bitmapimageand displays it. next try save bitmapimage harddrive using jpegbitmapencoder. file created actual jpeg image empty or 1 black pixel.

public guid savephoto(string istrimagepath) {     imagepath = istrimagepath;      bitmapimage objimage = new bitmapimage(         new uri(istrimagepath, urikind.relativeorabsolute));     picturedisplayed.source = objimage;     savedcreationobject = objimage;      guid photoid = system.guid.newguid();     string photolocation = photoid.tostring() + ".jpg";  //file name     filestream filestream = new filestream(photolocation, filemode.create);     jpegbitmapencoder encoder = new jpegbitmapencoder();     encoder.frames.add(bitmapframe.create(objimage));     encoder.save(filestream);      return photoid; } 

this function saves , displays photo. photo displayed correctly again when saved empty jpeg or 1 black pixel.

when create bitmapimage uri, time required download image.

if check following property, value true

objimage.isdownloading 

as such, attach listener downloadcompleted event handler , move processing eventhandler.

objimage.downloadcompleted += objimage_downloadcompleted; 

where handler like:

private void objimage_downloadcompleted(object sender, eventargs e) {   jpegbitmapencoder encoder = new jpegbitmapencoder();   guid photoid = system.guid.newguid();   string photolocation = photoid.tostring() + ".jpg";  //file name     encoder.frames.add(bitmapframe.create((bitmapimage)sender));    using (var filestream = new filestream(photolocation, filemode.create))     encoder.save(filestream); }  

you want add eventhandler downloadfailed in order gracefully handle error cases.

edit

added full sample class based on ben's comment:

public partial class mainwindow : window {   public mainwindow()   {     initializecomponent();      savephoto("http://www.google.ca/intl/en_com/images/srpr/logo1w.png");   }    public void savephoto(string istrimagepath)   {     bitmapimage objimage = new bitmapimage(new uri(istrimagepath, urikind.relativeorabsolute));      objimage.downloadcompleted += objimage_downloadcompleted;   }    private void objimage_downloadcompleted(object sender, eventargs e)   {     jpegbitmapencoder encoder = new jpegbitmapencoder();     guid photoid = system.guid.newguid();     string photolocation = photoid.tostring() + ".jpg";  //file name       encoder.frames.add(bitmapframe.create((bitmapimage)sender));      using (var filestream = new filestream(photolocation, filemode.create))       encoder.save(filestream);   }  }