[Closed] Dotnet: Updating a UI control from a different thread

from what I can tell, managed services doesn’t exist for max 2009

On the positive side, I solved my problem by creating a static c# class and routing my function through that.

Nice im happy that u solved your problem, it would be great if you can post example im interested how you did it with maxscript.

It wasn’t exactly with maxscript. As I said, I created the delegate in a c# class, and called it from maxscript using dotnetclass. The method invokes a datagridview progressbar column to change its value:

public class ProgressUpdater
	{
		public delegate void UpdateProgressDelegate(DataGridView ctr, int index, int amount);
		
		public static void UpdateProgressBar(DataGridView ctr, int index, int amount)
		{
			UpdateProgressDelegate del = new UpdateProgressDelegate(UpdateSync);
			IAsyncResult result = del.BeginInvoke(ctr, index, amount, CallBackVoid, null);
		}
		
		public static void UpdateSync(DataGridView ctr, int index, int amount)
		{
			ctr.Rows[index].Cells["Progress"].Value = amount;
		}
		
		public static void CallBackVoid(IAsyncResult result)
		{
			//garbage
		}		
	}

You’ll notice I’m not using the .invokerequired test because I know for sure all the calls will be from a thread other than the UI thread.

Looks nice… good luck with your project.

Thanks for your help

I would pass in your case DataGridViewCell. The cell object can tell you the parent DataGridView, row, and column. You can sort rows (by progress for example) and it doesn’t need to update the progress pointer. Also you don’t need to hardcode Column’s name. Using the same class you can update any cell because value is a property of any datagridview cell types.

Other thing I want to understand is how the webClient object was run in other than UI thread. Probably I’m missing something. You can use UploadDataAsync, DownloadDataAsync, … other Async methods; and DownloadProgressChanged and UploadProgressChanged events to update the UI. It’s a theory, and it might not work in practice for any reason, but I don’t see the problem.

Alright, so I stripped the project down to a sample which uploads 5 junk files to an ftp address you will need to provide as I don’t know any public ones I can upload to.
Replace the 3 first lines of the struct to do this.

The annoying part is that somehow in this particular sample, everything works fine and there is no cross thread errors whatsoever even without using the c# delegate :banghead: :banghead: :banghead:

I hate it when that happens.

Uncompress everything to the same folder and run the ms.

There are two lines in the uploadprogresschanged event, one to update with the delegate and one for direct update.

Overriding the class sounds a bit more elegant, but could you please explain why using the userstate for this purpose is not correct?

The reason I am not using the TotalBytesToSend property is that some FTPs including the one I am using do not return the correct value in this field, they always return 0 (something to do with passive transfers or something like that, I don’t remember). So I must know in advance the size of the file.
For downloads, I first query the size of the file on the ftp and the insert that into the userstate.

I agree it’s not safe to use row indices in general practice but because I know no sorting or deletion will take place it is safe in my case.

edit: Just out of curiosity, If I were saving the cell/row in the user state instead of just the index, would I be suffering a memory/performance hit in any way? Or does it not matter because they are reference values?

I realized the reason I might have been having problems in my project but not in this sample is because in my project I first compress the files before uploading them using an external process.
The process Exited event is what triggers the start of the upload. I’ll try to check it out.