webclient Asyncdownloadfile...

[cugone]

...works fine for my purposes for checking for a new file version, but it still locks up the UI when it is connecting to the server. Once it connects, the UI unlocks but I'd like to eliminate the brief 3 second lag it causes.

[Nate Bross]

Can you post the code that you are using?

[cugone]

The user clicks on a menuitem then this code executes:

 

   ''' <summary>
   ''' Gets the update information.
   ''' </summary>
   ''' <remarks></remarks>
   Friend Sub GetUpdate()

       If My.Computer.FileSystem.FileExists(MainForm.Path & "newVersion.txt") Then
           My.Computer.FileSystem.DeleteFile(MainForm.Path & "newVersion.txt")
       End If

       Dim baseUri As New Uri("http://www.blisspointranch.com/")
       Dim basePath As New Uri(baseUri, "programs/charactersheet/")
       Dim filePath As New Uri(basePath, "version.txt")

       'Disable menu item.
       MainForm.menuitemUpdate.Text = "Checking for Updates..."
       MainForm.menuitemUpdate.Enabled = False

       'Try to download file. If can't: Display returned server error, re-enable menus, exit subroutine.
       Try
           MainForm.webclient.DownloadFileAsync(filePath, MainForm.Path & "newVersion.txt")
       Catch ex As UriFormatException
           MessageBox.Show("Could not check for new version, server reported an error: " & vbCrLf & _
                                      ex.Message & vbCrLf & _
                                      "If this problem persists contact the program vender for support.", _
                                      My.Application.Info.Title, _
                                      MessageBoxButtons.OK, _
                                      MessageBoxIcon.Error)
       Catch ex As WebException
           MessageBox.Show("Could not check for new version, server reported an error: " & vbCrLf & _
                                     ex.Message & vbCrLf & _
                                     "If this problem persists contact the program vender for support.", _
                                      My.Application.Info.Title, _
                                      MessageBoxButtons.OK, _
                                      MessageBoxIcon.Error)
       Catch ex As InvalidOperationException
           MessageBox.Show("Could not check for new version, server reported an error: " & vbCrLf & _
                                     ex.Message & vbCrLf & _
                                    "If this problem persists contact the program vender for support.", _
                                    My.Application.Info.Title, _
                                    MessageBoxButtons.OK, _
                                    MessageBoxIcon.Error)
       Finally
           MainForm.menuitemUpdate.Text = "Check for Updates..."
           MainForm.menuitemUpdate.Enabled = True
       End Try

   End Sub

[Nate Bross]

You may try something ~ like this: [you'll need to use threads]

 

using System.Threading;
// add top
public delegate void CheckForUpdateCallback();
private Thread updateChecker;

// menu_click
updateChecker = new System.Threading.Thread(GetUpdate);
updateChecker.Start();

// add to end of GetUpdate
this.Invoke(new CheckForUpdateCallback(Finished), new object[] {  });

// create new method for "finished"
private void Finished()
{
MessageBox.Show("Finished - " + DateTime.Now.ToString());
}

 

 

This should cause the entire operation to run Asnyc from the UI.