/// <summary>
/// Version of load images using WhenAll. Not a good idea,
/// since we can show something only when we have all results
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button_Click(object sender, EventArgs e)
{
var t1 = AsyncTaskModel.DownloadImageFromUrlAsync(url1.Text);
var t2 = AsyncTaskModel.DownloadImageFromUrlAsync(url2.Text);
var t3 = AsyncTaskModel.DownloadImageFromUrlAsync(url3.Text);
Task.WhenAll(t1, t2, t3).
ContinueWith(t => {
if (t.Status == TaskStatus.Faulted)
{
ShowErrors(t.Exception);
}
else
{
pictureBox1.Image = t.Result[0];
pictureBox2.Image = t.Result[1];
pictureBox3.Image = t.Result[2];
}
}); //, TaskScheduler.FromCurrentSynchronizationContext());
}
/// <summary>
/// A version of handler made async to avoid explicit continuations
/// that use the launch downloads in sequence. Not good!
/// Note that the ConfigureAwait call results in an error since the
/// continuation will not run on the UI thread!
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private async void button3_Click(object sender, EventArgs e)
{
string[] sites =
{
url1.Text, url2.Text, url3.Text
};
Debug.WriteLine("Start in UI thread {0}",
Thread.CurrentThread.ManagedThreadId);
PictureBox[] viewers = { pictureBox1, pictureBox2, pictureBox3 };
int index = 0;
foreach (string url in sites)
{
Image img =
await AsyncTaskModel.DownloadImageFromUrlAsync(url);
Debug.WriteLine("Continuation on thread {0}",
Thread.CurrentThread.ManagedThreadId);
viewers[index].Image = img;
index++;
status.Text = "Done with Success";
}
}
