Develop Reference

Why is the text not showing up on screen?

I'm trying to create a countdown where the text displays, "GAME STARTS IN: " and using a for loop and Thread.Sleep a variable counts down from three. I started by using the designer to create the "game starts in:" part, but after the variable wouldn't show up I moved it to code. Now nothing shows up. This is what I have now in my timer method:
if (!countedDown)
DoCountdown();
Countdown.Hide();
And then in a DoCountdown method:
this.Countdown.BackColor = System.Drawing.Color.Transparent;
this.Countdown.ForeColor = System.Drawing.Color.White;
this.Countdown.Location = new System.Drawing.Point(360, 17);
this.Countdown.Name = "Countdown";
this.Countdown.Font = new System.Drawing.Font("Segoe UI", 12F,
System.Drawing.FontStyle.Regular,
System.Drawing.GraphicsUnit.Point);
this.Countdown.Size = new System.Drawing.Size(185, 24);
this.Countdown.TabIndex = 6;
countedDown = true;
for (int i = 3; i > 0; i--)
{
Countdown.Text = "GAME STARTS IN: " + i;
System.Threading.Thread.Sleep(1000);
}
I put a breakpoint at System.Threading.Thread.Sleep(100) and everything seemed normal. Countdown.Text was equal to "GAME STARTS IN: 3". After trying to integrate the solutions the text doesn't show up. Here is some more context in my code:
This is from my start screen form
private void QuitGame(object sender, EventArgs e)
{
Application.Exit();
}
private void StartMultiplayerGame(object sender, EventArgs e)
{
GameScreen startGame = new GameScreen();
startGame.Show();
Hide();
}

Try something like below. A button is used to start the timer and set the initial values.
int count = 3;
private void button2_Click(object sender, EventArgs e) {
timer1.Interval = 1000;
count = 3;
label1.Text = "GAME STARTS IN: " + count;
timer1.Start();
}
private void timer1_Tick(object sender, EventArgs e) {
count--;
if (count != 0) {
label1.Text = "GAME STARTS IN: " + count;
}
else {
timer1.Stop();
label1.Text = "GAME STARTED";
MessageBox.Show(" -> GO");
}
}
Edit per OP comments.
Try the code like this in the start screen form...
private void StartMultiplayerGame(object sender, EventArgs e) {
count = 3;
label1.Text = "GAME STARTS IN: " + count;
timer1.Start();
}
Then change the timer code to...
private void timer1_Tick(object sender, EventArgs e) {
count--;
if (count != 0) {
label1.Text = "GAME STARTS IN: " + count;;
}
else {
timer1.Stop();
label1.Text = "Game Started";
GameScreen startGame = new GameScreen();
startGame.Show();
this.Hide();
}
}

loop blocking the main thread to refresh UI so the required scenario can be archived by moving the loop to a separate method
void doCountDown()
{
for (int i = 10; i > 0; i--)
{
setCountDownText( "GAME STARTS IN: " + i);
System.Threading.Thread.Sleep(1000);
}
}
creating anew thread that start this method
new System.Threading.Thread(new System.Threading.ThreadStart(doCountDown)).Start();
and because of the need to update UI in another thread and to make it safe separate the setText in a separate method that update based on checking required to invoke property this will make it work in all cases
void setCountDownText(string txtValue)
{
if (Countdown.InvokeRequired)
{
Action safeWrite = delegate { setCountDownText(txtValue); };
Countdown.Invoke(safeWrite);
}
else
Countdown.Text = txtValue;
}

The "modern" way to do this is using async/await.
For example, launching the DoCountdown() from a button handler could look like this:
async void testBtn_Click(object sender, EventArgs e)
{
await DoCountdown();
}
async Task DoCountdown()
{
// <Initialisation of Countdown elided for brevity>
for (int i = 3; i > 0; i--)
{
Countdown.Text = "GAME STARTS IN: " + i;
await Task.Delay(1000);
}
}
However, whatever calls DoCountdown() will need to be declared as async, and so on up the call tree.
Note that the only acceptable place to have async void rather than async Task as a return type for an async method is where the method is an event handler such as the button handler in the example above.

Timer firing every second and updating GUI (C# Windows Forms)

I have a Windows Forms application where I need to have a timer working for 90 seconds and every second should be shown after it elapses, kind of like a stopwatch 1..2..3 etc, after 90 seconds is up, it should throw an exception that something is wrong.
I have the following code, but the RunEvent never fires.
private void ScanpXRF()
{
bool demo = false;
System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
try
{
for (int timerCounter = 0; timerCounter < 90; timerCounter++)
{
timer.Interval = 1000;
timer.Tick += new EventHandler(RunEvent);
timer.Start();
if(timerCounter == 89) {
throw new Exception();
}
}
}
catch (Exception e)
{
timer.Dispose();
MessageBox.Show("There is a problem!");
}
}
private void RunEvent(object sender, System.EventArgs e)
{
//boxStatus.AppendText("RunEvent() called at " + DateTime.Now.ToLongTimeString() + "\n");
MessageBox.Show("timer fired!");
}
Is there anything I am doing wrong here or are there other suggestions for other ways to achieve the same result?

A timer needs to be declared at the form level, or else it may not be disposed of when the form closes:
System.Windows.Forms.Timer timer;
int counter = 0;
Your starting code should just start the timer:
private void ScanpXRF()
{
counter = 0;
timer = new System.Windows.Forms.Timer();
timer.Interval = 1000;
timer.Tick += RunEvent;
timer.Start();
}
The RunEvent is your Tick event being called every second, so your logic needs to go in there:
private void RunEvent(object sender, EventArgs e)
{
counter++;
if (counter >= 90) {
timer.Stop();
// do something...
}
}

made it work
private void ScanpXRF()
{
_pXRFTimerCounter = 0;
pXRFTimer.Enabled = true;
pXRFTimer.Interval = 1000;
pXRFTimer.Elapsed += new ElapsedEventHandler(pXRFTimer_Tick);
pXRFTimer.Start();
}
private static void pXRFTimer_Tick(Object sender, EventArgs e)
{
_pXRFTimerCounter++;
if (_pXRFTimerCounter >= 90)
{
pXRFTimer.Stop();
// do something...
}
else
{
MessageBox.Show(_pXRFTimerCounter.ToString() + " seconds passed");
}
}
I made the timer
System.Timers

How do you select next combo box selection automatically in x second?

Using C#, windows form.
I am trying to make the program automatically select next item on combo box every x seconds and once it reaches the last one, it goes back to the first one on list. i got pretty much everything minus auto combo box selection part. :(
help please.
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
//pictureBox1.Image = Image.FromFile(#"Z:\DSCF1661.jpg");
DirectoryInfo test = new DirectoryInfo(#"C:\temp");//Assuming Test is your Folder
FileInfo[] Files = test.GetFiles("*.pdf"); //Getting Text files
comboBox1.DataSource = Files;
comboBox1.DisplayMember = "Name";
timerset();
}
public void axSetting()
{
axAcroPDF1.setShowToolbar(false);
axAcroPDF1.setView("FitH");
axAcroPDF1.setPageMode("none");
axAcroPDF1.setLayoutMode("SinglePage");
axAcroPDF1.Show();
}
private void comboBox1_SelectedIndexChanged_1(object sender, EventArgs e)
{
axAcroPDF1.LoadFile(#"C:\temp\" + comboBox1.Text);
axAcroPDF1.src = #"C:\temp\" + comboBox1.Text;
axSetting();
}
//private System.Windows.Forms.Timer timer1;
public void comboBoxSelect()
{
if (comboBox1.SelectedIndex < comboBox1.Count) // this part... :(
{
comboBox1.SelectedIndex += 1;
}
else
{
comboBox1.SelectedIndex = 0;
}
}
public void timerset()
{
timer1 = new System.Windows.Forms.Timer();
timer1.Tick += new EventHandler(timer1_Tick);
timer1.Interval = 5000; // in miliseconds
timer1.Start();
}
private void timer1_Tick(object sender, EventArgs e)
{
comboBoxSelect();
}

This should work:
if(combobox.SelectedIndex < (combobox.Items.Count -1))
{
combobox.SelectedIndex += 1;
}
else
{
combobox.SelectedIndex = 0;
}

c# real time update a chart

Here I have a chart (graph1) that normally should add a random point every 1second. but it doesn't... I tried to find out what the problem is but here I don't have anymore ideas...
The timer is started, label1 change every seconds but the chart doesn't change... with button one when I click it adds a new point.
what did I miss? please help... thanks a lot.
namespace Test_Chart1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
graph1.ChartAreas[0].AxisX.ScrollBar.Enabled = true;
graph1.ChartAreas[0].AxisX.IsLabelAutoFit = true;
graph1.ChartAreas[0].AxisX.ScaleView.Size = 40;
System.Timers.Timer _Timer1s = new System.Timers.Timer(1000); //object
_Timer1s.Elapsed += _Timer1sElapsed; //event in object
_Timer1s.Start(); //start counting
}
private void _Timer1sElapsed(object sender, EventArgs e)//Timer each 100ms
{
if (label1.BackColor == Color.Red)
{
label1.BackColor = Color.Blue;
PutValueInGraph1();
}
else label1.BackColor = Color.Red;
}
private void button1_Click(object sender, EventArgs e)
{
PutValueInGraph1();
}
private void PutValueInGraph1()
{
graph1.ChartAreas[0].AxisX.ScrollBar.Enabled = true;
graph1.ChartAreas[0].AxisX.IsLabelAutoFit = true;
graph1.ChartAreas[0].AxisX.ScaleView.Size = 100;
Random Rand_Value = new Random();
int ValueToAdd = Rand_Value.Next(1, 100);
listBox1.Items.Add(ValueToAdd.ToString());
graph1.Series["Data1"].Points.AddY(ValueToAdd);
if (graph1.ChartAreas[0].AxisX.Maximum-10 > graph1.ChartAreas[0].AxisX.ScaleView.Size)
{
graph1.ChartAreas[0].AxisX.ScaleView.Scroll(graph1.ChartAreas[0].AxisX.Maximum);
graph1.Series["Data1"].Points.RemoveAt(0);
}
}
}
}
ok here is the new one:
public partial class Form1 : Form
{
static System.Windows.Forms.Timer myTimer = new System.Windows.Forms.Timer();
public Form1()
{
InitializeComponent();
myTimer.Tick += new EventHandler(TimerEventProcessor);
myTimer.Interval = 1;
}
private void TimerEventProcessor(Object myObject, EventArgs myEventArgs)
{
Random Rand_Value = new Random();
int ValueToAdd = Rand_Value.Next(1, 100);
listBox1.Items.Add(ValueToAdd.ToString());
graph1.Series["Data1"].Points.AddY(ValueToAdd);
if (graph1.ChartAreas[0].AxisX.Maximum - 10 > graph1.ChartAreas[0].AxisX.ScaleView.Size)
{
graph1.ChartAreas[0].AxisX.ScaleView.Scroll(graph1.ChartAreas[0].AxisX.Maximum);
graph1.Series["Data1"].Points.RemoveAt(0);
}
}
private void btn_Start_Click_1(object sender, EventArgs e)
{
graph1.ChartAreas[0].AxisX.ScrollBar.Enabled = true;
graph1.ChartAreas[0].AxisX.IsLabelAutoFit = true;
graph1.ChartAreas[0].AxisX.ScaleView.Size = 100;
myTimer.Start();
BlinkLed.BackColor = Color.YellowGreen;
}
private void btn_Stop_Click(object sender, EventArgs e)
{
myTimer.Stop();
BlinkLed.BackColor = Color.AliceBlue;
}
}
Do you think it's better?
What about the changing thread?
If I had a button:
private void PutValueInGraph1()
{
Random Rand_Value = new Random();
int ValueToAdd = Rand_Value.Next(1, 100);
listBox1.Items.Add(ValueToAdd.ToString());
graph1.Series["Data1"].Points.AddY(ValueToAdd);
if (graph1.ChartAreas[0].AxisX.Maximum-10 > graph1.ChartAreas[0].AxisX.ScaleView.Size)
{
graph1.ChartAreas[0].AxisX.ScaleView.Scroll(graph1.ChartAreas[0].AxisX.Maximum);
graph1.Series["Data1"].Points.RemoveAt(0);
}
}
private void button1_Click(object sender, EventArgs e)
{//try to raise exception
PutValueInGraph1();
}
and I change the event like this:
private void TimerEventProcessor(Object myObject, EventArgs myEventArgs)
{//try to raise exception
PutValueInGraph1();
}
The data input accelerate when I'm started the timer and I click all the time on the button1.
Why is there no exception as tom_imk said??
because we can access the same function at the same time....?
Thanks for your answers.

I tried below sample code and it is working fine for me.
public Form7()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
chart1.ChartAreas[0].AxisX.Maximum = 100;
chart1.ChartAreas[0].AxisX.Minimum = 0;
chart1.ChartAreas[0].AxisX.Interval = 1;
timer1.Start();
}
private void timer1_Tick(object sender, EventArgs e)
{
Random Rand_Value = new Random();
int ValueToAdd = Rand_Value.Next(1, 100);
chart1.Series[0].Points.AddY(ValueToAdd);
}

I'm surprised you didn't get an exception. You are manipulating UI elements outside the UI thread, something you musn't do, ever.
Refer to the answer in this question:
How to update the GUI from another thread in C#?
EDIT:
To make clear why the timerelapsed method does not run on the UI thread: It's simply the wrong class that is used here. So the easy solution would be to not created a System.Timers.Timer in the Form-constructor but to drop a timer on the form in the form designer and use that instead. The solution by sowjanya attaluri should be marked as the correct answer.

Text animation in Windows Forms

I was wondering if there was a way of adding a sort of animation to text displayed on a form.
What I had in mind when I thought of this was kind of similar to what you can do with text in PowerPoint (i.e. a typewriter-like animation where the text is typed one at a time, have the whole textbox appear with a certain effect etc), I'm just looking to find out what you can do using Windows Forms.
Currently I'm using a textbox to display information on my form application, though in hindsight I realise labels would have worked just as well.
EDIT: Turns out I was using labels after all, I just gave it a name with 'textbox' inside for lack of a better description.

public partial class Form1 : Form
{
int _charIndex = 0;
string _text = "Hello World!!";
public Form1()
{
InitializeComponent();
}
private void button_TypewriteText_Click(object sender, EventArgs e)
{
_charIndex = 0;
label1.Text = string.Empty;
Thread t = new Thread(new ThreadStart(this.TypewriteText));
t.Start();
}
private void TypewriteText()
{
while (_charIndex < _text.Length)
{
Thread.Sleep(500);
label1.Invoke(new Action(() =>
{
label1.Text += _text[_charIndex];
}));
_charIndex++;
}
}
}

Now, I personally wouldn't do this because gratuitous animations tend to annoy users. I'd only use animation sparingly - when it really makes sense.
That said, you can certainly do something like:
string stuff = "This is some text that looks like it is being typed.";
int pos = 0;
Timer t;
public Form1()
{
InitializeComponent();
t = new Timer();
t.Interval = 500;
t.Tick += new EventHandler(t_Tick);
}
void t_Tick(object sender, EventArgs e)
{
if (pos < stuff.Length)
{
textBox1.AppendText(stuff.Substring(pos, 1));
++pos;
}
else
{
t.Stop();
}
}
private void button1_Click(object sender, EventArgs e)
{
pos = 0;
textBox1.Clear();
t.Start();
}
or something like that. It'll tick off ever half second and add another character to the multi-line text box. Just an example of what someone could do.