Brtdku

I have an ACR122U NFC reader where I read MiFare UltraLight NFC tags. I downloaded a framework for my reader. However when the event handler is called, the update of the GUI is very slow.

I have not much experience in threaded programming and event handling. Maybe the solution for my question is very easy.

However it only updates 'label by label' in the UpdateInterface()-method and one all by once. I can see each label disappearing. So the updating of the UI is very slow.

I guess this has something to do with the (hardware-)events called by the reader-classes in background.

The program is generally working only it is very slow.

private void StartMonitor()

{

        //Function called when starting the Windows Forms Application

        IMonitorFactory monitorfactory = MonitorFactory.Instance;

        monitor = monitorfactory.Create(SCardScope.System);

        monitor.Start(ReaderNames[0]);

        monitor.StatusChanged += Monitor_StatusChanged;

}



private void Monitor_StatusChanged(object sender, StatusChangeEventArgs e)

{

        strPassportNo = "";

        strPassportNo = lPassportNumberNo.Text;



        if (e.NewState.ToString().ToLower().Contains("empty".ToLower()) == true)

        {

            //Interface should be deleted all by once now as no NFC tag is on the reader.

            UpdateInterface();

        }

}



private void UpdateInterface()

{

        if (InvokeRequired)

        {

            this.BeginInvoke(new Action(() =>

            {

                lPassportNumberNo.Text = "";

                lPassengerName.Text = "";

                lPax.Text = "";

                lTableNo.Text = "";

                lRoomNo.Text = "";

                pbTables.Hide();

                pbPasspic.Hide();

                this.BackgroundImage = BackgroundWelcome;

            }));

        }

        else

        {

            lPassportNumberNo.Text = "";

            lPassengerName.Text = "";

            lPax.Text = "";

            lTableNo.Text = "";

            lRoomNo.Text = "";

            pbTables.Hide();

            pbPasspic.Hide();

            this.BackgroundImage = BackgroundWelcome;

        }

}

The expected output should be that the performance of the UI is a lot faster than it is actually. Or at least the labels with data in it should appear and disappear at once.

Not sure what is this actually: this.BackgroundImage = BackgroundWelcome; but is it really necessary to assign such static data every time?

Also i dont think that frequency of your update event is too high - information on the screen should be human-readable so it's definitely only one update of all data required after the entire tag is readed. If there are many read events for every single tag - then store all of them into temporary list and update the form at the read end (entire tag).
When i say "tag" i mean the entire mifare card content.

The UI-Update was in my case to just clear the labels (see UpdateInterface()). However I found the "error". It was the ".jpg" file als BackgroundImage I loaded on every refresh. Although it was "just" 1280x1024, it was too much for the frontend to update.

When I cleared the Images, the refresh was immediately.

My solution now is:

this.BackgroundImage = ((System.Drawing.Image(resources.GetObject("$this.BackgroundImage")));

this.BackgroundImageLayout = System.Windows.Forms.ImageLayout.Zoom;

this.SetStyle(System.Windows.Forms.ControlStyles.OptimizedDoubleBuffer | System.Windows.Forms.ControlStyles.AllPaintingInWmPaint, true);

in the Form1.Designer.cs

and Suspending and Resuming the Layout with the following class (which I found somewhere on the Internet)

public static class ControlHelper

{

    #region Redraw Suspend/Resume

    [DllImport("user32.dll", EntryPoint = "SendMessageA", ExactSpelling = true, CharSet = CharSet.Ansi, SetLastError = true)]

    private static extern int SendMessage(IntPtr hwnd, int wMsg, int wParam, int lParam);

    private const int WM_SETREDRAW = 0xB;



    public static void SuspendDrawing(this Control target)

    {

        SendMessage(target.Handle, WM_SETREDRAW, 0, 0);

    }



    public static void ResumeDrawing(this Control target) { ResumeDrawing(target, true); }

    public static void ResumeDrawing(this Control target, bool redraw)

    {

        SendMessage(target.Handle, WM_SETREDRAW, 1, 0);



        if (redraw)

        {

            target.Refresh();

        }

    }

    #endregion

}

Also I changed the ".jpg" files to ".bmp" files. Now the Interface is smooth and fast.

And @Jesting:

Not sure what is this actually: this.BackgroundImage = BackgroundWelcome; but is it really necessary to assign such static data every time?

No, I could have found a better solution. However as the application is very small and I only have four background images, I found it easier to "hard code" it.

Finally, the tag(-reader) was not really the problem.

And for updating the UI, I use this quite easy function:

private void UpdateInterface(PassportDatabaseReader.Passport _passport)

    {

        if (InvokeRequired)

        {

            this.BeginInvoke(new Action<PassportDatabaseReader.Passport>(UpdateInterface), new object { _passport });

            return;

        }

        else

        {

            ControlHelper.SuspendDrawing(this);

            new Thread(() => ChangeBackground(BackgroundPassport)).Start();

            lPassportNumberNo.Text = _passport.PassportNo;

            strPassportNo = _passport.PassportNo;

            lPassengerName.Text = _passport.Name.Replace('$','n');

            lPax.Text = _passport.Pax;

            lTableNo.Text = _passport.TableNo;

            lRoomNo.Text = _passport.RoomNo;

            pbTables.Hide();

            try

            {

                pbPasspic.Load("..\..\Pics\" + _passport.PassportNo + ".png");

                pbPasspic.Show();

                pbTables.ImageLocation = "..\..\Tischordnung_" + _passport.TableNo + ".png";

                pbTables.Show();

            }

            catch (Exception)

            {

                throw;

            }

            ControlHelper.ResumeDrawing(this);

        }

    }

The application is a "wedding passport" reader which shows the name, the guests room number, table number as well as the "passport" picture on screen.