CODEWITHSUNDEEP
wpfbitmapsourcefreezable
ak3nat0n
ak3nat0n

Reputation: 6288

WPF frozen BitmapImage not showing

I am using a viewmodel bound to an image property on the UI and the viewmodel contains an ImageSource property. I set that property using the following function

    private BitmapImage GetImageFromUri(Uri urisource)
    {
        if (urisource == null)
            return null;

        var image = new BitmapImage();
        image.BeginInit();
        image.UriSource = urisource;
        image.EndInit();
        image.Freeze(); //commenting this shows the image if the routine is called from the proper thread.

        return image;
   }

For some odd reason, in the following code, when I call Freeze on my BitmapImage, it does not appear on the main window.I get no exception or crash. Can anybody help me with this? I am setting the image property asynchronously so I need to be able to use the created image, assuming the GetImageFromUri call was made from a thread other than the UI thread.

Upvotes: 0

Views: 3378

Answers (3)

Smagin Alexey
Smagin Alexey

Reputation: 345

IF i use StreamSource, for me is enough:

public static BitmapSource ToBitmap(this MemoryStream stream)
    {
        try
        {
            using (stream)
            {
                stream.Position = 0;
                var image = new BitmapImage();
                image.BeginInit();
                image.CacheOption = BitmapCacheOption.OnLoad;
                image.StreamSource = stream;
                image.EndInit();
                image.Freeze();
                return image;
            }
        }
        catch (Exception)
        {
            return null;
        }
    }

But if i use UriSource i need:

public static async Task<BitmapSource> ToBitmapAsync(this string sourceUri)
    {
        try
        {
            using (var client = new WebClient())
            using (var stream = await client.OpenReadTaskAsync(new Uri(sourceUri)))
            using (var ms = new MemoryStream())
            {
                stream.CopyTo(ms);
                return ms.ToBitmap();
            }
        }
        catch (Exception)
        {
            return null;
        }
    }

BitmapSource has UriSource, but it works after xaml rendered

Upvotes: 0

Rohit Vats
Rohit Vats

Reputation: 81253

Try setting the CacheOption for BitmapImage before freezing it. See if this works -

var image = new BitmapImage();
image.BeginInit();
image.CacheOption = BitmapCacheOption.OnLoad;
image.UriSource = urisource;
image.EndInit();
image.Freeze();

Upvotes: 3

Louis Kottmann
Louis Kottmann

Reputation: 16628

Before you freeze it, you need to fully render it.
You should try to listen to the SourceUpdated event, and only then freeze the image.

On a side note, if you ever want to modify the Image after that, you will have to Clone it.

Upvotes: 1

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