Question

I am trying to populate a text box with some data, namely the names of several instruments a line at a time.

I have a class that will generate and return a list of instruments, I then iterate through the list and append a new line to the text box after each iteration.

Starting the Thread:

private void buttonListInstruments_Click(object sender, EventArgs e)
        {
            if (ins == null)
            {
                ins = new Thread(GetListOfInstruments);
                ins.Start();
            }
            else if (ins != null)
            {
                textBoxLog.AppendText("Instruments still updating..");
            }

        }

Delegate to update textbox:

public delegate void UpdateLogWithInstrumentsCallback(List<Instrument> instruments);

private void UpdateInstruments(List<Instrument> instruments)
        {
            textBoxLog.AppendText("Listing available Instruments...\n");

            foreach (var value in instruments)
            {
                textBoxLog.AppendText(value.ToString() + "\n");
            }
            textBoxLog.AppendText("End of list. \n");

            ins = null;
        }

Invoking the control:

private void GetListOfInstruments()
        {
            textBoxLog.Invoke(new UpdateLogWithInstrumentsCallback(this.UpdateInstruments),
                new object[] { midiInstance.GetInstruments() });
        }

Note: GetInstruments() returns a List of type Instrument.

I am implementing therads to try to keep the GUI functional whilst the text box updates.
For some reason the other UI controls on the WinForm such as a seperate combo box remain inactive when pressed until the text box has finished updating.

Am I using threads correctly?

Thanks.

Answer 1

You haven’t accomplished anything, the UpdateInstruments() method still runs on the UI thread, just like it did before. Not so sure why you see such a long delay, that must be a large number of instruments. You can possibly make it is less slow by first appending all of them into a StringBuilder, then append its ToString() value to the TextBox. That cuts out the fairly expensive Windows call.