Anyone knows how to create BitmapFrame
asynchronously in WPF?
I want to batch print XAML Image
element whose Source
property is set code behind. Here LogoImageUrl
is the URL of the web image I want to load asynchronously.
LogoImage.Source = BitmapFrame.Create(new Uri(LogoImageUrl));
Can I create an async
method like this:
public async Task<BitmapFrame> GetBitmapFrame(Uri uri)
{
await ... // What to be awaited?
return BitmapFrame.Create(uri);
}
...so I can use that method in a try
block and then print it in finally
block?
You should asynchronously download the web image and create a BitmapFrame from the downloaded buffer:
public async Task<BitmapFrame> GetBitmapFrame(Uri uri)
{
var httpClient = new System.Net.Http.HttpClient();
var buffer = await httpClient.GetByteArrayAsync(uri);
using (var stream = new MemoryStream(buffer))
{
return BitmapFrame.Create(
stream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
}
}
Since the BitmapFrame.Create
call in the above example return a frozen BitmapFrame, you may also create the BitmapFrame asynchronously (although I doubt it's necessary).
public async Task<BitmapFrame> GetBitmapFrame(Uri uri)
{
var httpClient = new System.Net.Http.HttpClient();
var buffer = await httpClient.GetByteArrayAsync(uri);
return await Task.Run(() =>
{
using (var stream = new MemoryStream(buffer))
{
return BitmapFrame.Create(stream, BitmapCreateOptions.None, BitmapCacheOption.OnLoad);
}
});
}
来源:https://stackoverflow.com/questions/42361979/create-bitmapframe-asynchronously-in-an-async-method