I have a WinForm called SpalshScreen.cs with a simple label with the Text property is set to "Data Loading...". The label is centered in the Form. I also have a public method called DoClose() method defined.
My MainForm.Form_Load method contains:
Hide();
SplashScreen form = new SplashScreen();
form.Show();
// Simulate Doing Database Table Load(s)
Thread.Sleep(5000);
form.DoClose();
Show();
However when I run, my Splash does appear but, where the Label Text is suppose to be it only shows a Light Colored Box.
If I change form.Show(); to form.ShowDialog(); the text appears correctly but the main loop pauses until I close the Splash Window.
After a bunch of trial and error... The trick is to Not block the UI Thread as #Servy said.
The Form_Load method needed to change to:
Hide();
Splash.Show();
// Everything after this line must be Non UI Thread Blocking
Task task = new Task(LoadDataAsync);
task.Start();
task.Wait();
Splash.DoClose();
Show();
And I created a LoadDataAsync Method to take care of everything else:
private async void LoadDataAsync()
{
await Context.Employees.LoadAsync();
await Context.Customers.LoadAsync();
// The Invoke/Action Wrapper Keeps Modification of UI Elements from
// complaining about what thread they are on.
if (EmployeeDataGridView.InvokeRequired)
{
Action act = () => EmployeeBindingSource.DataSource = Context.Employees.Local.ToBindingList();
EmployeeDataGridView.Invoke(act);
}
if (CustomerComboBox.InvokeRequired)
{
Action act = () =>
{
CustomerBindingSource.DataSource = GetCustomerList();
CustomerComboBox.SelectedIndex = -1;
};
CustomerComboBox.Invoke(act);
}
}
I also set any of the private fields and private methods I was using to static.
Use timer inside your splashscreen form instead of thread.sleep ( for example close splash screen after 5 seconds), and set closed event of it.
var form = new SplashScreen();
form.Closed += (s,e)=>{
Show();
}
form.Show();
Related
I am trying to start a winForm from a thread, but when i do so, the form show but none of the labels are loaded ( the background where they should be is white ) and the form is frozen.
I've tried it with some other winForms that i know that work just fine and it still doesn't seem to work ? Has anyone encountered this problem ?
I know the question is vague but there isn't really any specific code that I could give to help understand the problem.
That is because the Message Loop runs on UI thread only. And when a control or window is created in any other thread, it cannot access that message loop. And thus, cannot process user input.
To solve this, try creating a window from UI thread and create a thread from that window to do whatever you want to do in different thread.
UI thread is supposed to be one.
Then, I suggest you to open your form calling a method of your original form thread, like in the example below:
(To test it just create an empty form called MainForm and paste this code in it)
public delegate void OpenFormDelegate(string txt);
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
var button1 = new Button();
button1.Text = "Run for 5 secs and open new window";
button1.Dock = DockStyle.Top;
this.Controls.Add(button1);
button1.Click += new EventHandler(button1_Click);
}
private void button1_Click(object sender, EventArgs e)
{
Thread t = new Thread(new ThreadStart(Run));
t.Start();
}
public void Run()
{
Thread.Sleep(5000); // sleep for 5 seconds
this.BeginInvoke(new OpenFormDelegate(OpenNewForm), "Hello World !");
}
public void OpenNewForm(string text)
{
Form f = new Form();
f.Text = text;
f.Show();
}
}
It is related to thread access, when the new form is created it will not be able to access the UI thread. Use the main thread to create the form and new thread to process the infomation.
I would like to implement a simple popup window in Windows Forms, which will show a simple timer to the user while some slow-running process is executing. The premise is simple; show to the user that something is indeed going on and the application is not frozen. Note that this slow-running process is not a loop, nor is it something that I can tap into.
What I want is a simple popup window, showing some message along the lines "Elapsed time: x seconds", where x is incremented every second.
The basic concept is the following:
public void test()
{
//Some code which does stuff
//Popup window with counter
//Perform long running process
//Close popup window with counter
//Some other code which does other stuff
}
I tried to do it using various ways, including background workers, threads, and of course timers. But I did not manage to make it work as I wanted. And I would prefer not to post any of my code so as not to "lead" the responses to a specific way of doing this.
So what would be the best way to do this work?
Thanks.
UPDATE:
In reply to some comments, since I cannot paste any code in the replies section, I'm editing my original question to accomodate this. One of the implementations that I tried is to spawn the popup window in a separate thread. Although I got no runtime errors, the popup window did not refresh correctly. It indeed poped-up, but no text would show within it, and the counter would not refresh. Here's the code:
private void test()
{
frmProgressTimer ofrmProgressTimer = new frmProgressTimer(); //Instance of popup Form
System.Threading.Tasks.Task loadTask = new System.Threading.Tasks.Task(() => ProgressTimer(ofrmProgressTimer));
loadTask.Start();
//Perform long running process
System.Threading.Tasks.Task cwt = loadTask.ContinueWith(task => EndProgressTimer(ofrmProgressTimer));
}
private void ProgressTimer(frmProgressTimer ofrmProgressTimer)
{
ofrmProgressTimer.Show();
ofrmProgressTimer.Invoke((Action)(() =>
{
ofrmProgressTimer.startTimer();
}));
}
private void EndProgressTimer(frmProgressTimer ofrmProgressTimer)
{
ofrmProgressTimer.Invoke((Action)(() =>
{
ofrmProgressTimer.stopTimer();
ofrmProgressTimer.Close();
}));
}
And here's my popup form code:
public partial class frmProgressTimer : Form
{
private int counter = 0;
private Timer timer1;
public frmProgressTimer()
{
InitializeComponent();
timer1 = new Timer();
timer1.Interval = 1000;
timer1.Tick += new EventHandler(timer1_Tick);
}
public void startTimer()
{
timer1.Start();
}
public void stopTimer()
{
timer1.Stop();
}
private void timer1_Tick(object sender, EventArgs e)
{
counter += 1;
labelText.Text = counter.ToString();
}
}
This is actually quite easy to do. Create your dialog, define your long running operation to take place in a non-UI thread when it is shown, add a continuation to that operation which closes the dialog when the task finishes, and then show the dialog.
MyDialog dialog = new MyDialog();
dialog.Shown += async (sender, args) =>
{
await Task.Run(() => DoLongRunningWork());
dialog.Close();
};
dialog.ShowDialog();
The code to have the ticking over time should be entirely contained within the dialog, and based on the question it seems you already have that well under control with a simple Timer.
Make a new form, which will pop up, and show a timer. That way it won't be interrupted with all the work on your main form, and the timer will work continuously.
Remember when showing a new from to use newForm.ShowDialog() not newForm.Show(). Your can google the differences
I would simply start your work on a separate thread. Launch a modal form with your timer output. To display the timer use an actual timer instance set to update every second. When the timer event fire update your dialog.
Finally once you're thread completes close the dialog so your main form is active again.
First of all you need to make it not closeable by the user (as if modal dialogs weren't annoying enough) but closeable by your code. You could accomplish this by subscribing to the FormClosing event of the form. Let's say your popup form's name is Form2:
private bool mayClose = false;
public void PerformClose()
{
this.mayClose = true;
this.Close();
}
private void Form2_FormClosing(object sender, FormClosingEventArgs e)
{
if (!this.mayClose)
e.Cancel = true;
}
Create a Timer, provide a Tick event handler, enable it and set its Interval to 500 milliseconds:
Create a label to host your desired text. Let's call it label1.
Within and surrounding your Tick event handler do something like this:
private DateTime appearedAt = DateTime.UtcNow;
private void timer1_Tick(object sender, EventArgs e)
{
int seconds = (int)(DateTime.UtcNow - this.appearedAt).TotalSeconds;
this.label1.Text = string.Format(#"Ellapsed seconds: {0}", seconds);
}
Make sure your long running process is happening on a background thread, not on the GUI thread.
Say your long running process can be thought of as the execution of a method called MyProcess.
If that is the case, then you need to call that method from a secondary thread.
// PLACE 1: GUI thread right here
Thread thread = new Thread(() =>
{
// PLACE 2: this place will be reached by the secondary thread almost instantly
MyProcess();
// PLACE 3: this place will be reached by the secondary thread
// after the long running process has finished
});
thread.Start();
// PLACE 4: this place will be reached by the GUI thread almost instantly
Show the form right before the long running process starts. This can be done in any of the 2 places (marked in the previous section of code) called PLACE1 or PLACE2. If you do it in PLACE2 you will have to marshal a call back to the GUI thread in order to be able to interact with the WinForms framework safely. Why am I bringing this up ? It's because maybe the long running process is not started from within the GUI thread at all and you absolutely need to do this.
Close the form right after the long running process finishes. This can be done only in PLACE3 and you absolutely need to marshal a call.
To wrap the earlier 2 bullets and the answer, you could do this:
private void DoIt()
{
Form2 form2 = new Form2();
Action showIt = () => form2.Show();
Action closeIt = () => form2.PerformClose();
// PLACE 1: GUI thread right here
Thread thread = new Thread(() =>
{
form2.BeginInvoke(showIt);
// PLACE 2: this place will be reached by the secondary thread almost instantly
MyProcess();
form2.BeginInvoke(closeIt);
// PLACE 3: this place will be reached by the secondary thread
// after the long running process has finished
});
thread.Start();
// PLACE 4: this place will be reached by the GUI thread almost instantly
}
Finally I've managed to resolve this in the most simplistic manner. And it works like a charm. Here's how to do it:
//Create an instance of the popup window
frmProgressTimer ofrmProgressTimer = new frmProgressTimer();
Thread thread = new Thread(() =>
{
ofrmProgressTimer.startTimer();
ofrmProgressTimer.ShowDialog();
});
thread.Start();
//Perform long running process
ofrmProgressTimer.Invoke((Action)(() =>
{
ofrmProgressTimer.stopTimer();
ofrmProgressTimer.Close();
}));
You can see the code for the popup window in the original post/question, with the only difference that the tick function changes the label text as:
labelText.Text = string.Format("Elapsed Time: {0} seconds.", counter.ToString());
Thank you to everybody for trying to help me out.
In my wpf application i have made a button click event as seperate thread and run as background process so that the UI is responsive to the user. Code as below,
private void btn_convert_Click(object sender, RoutedEventArgs e)
{
//Makes the conversion process as background task which
//makes the UI responsive to the user.
Thread thread = new Thread(new ThreadStart(WorkerMethod));
thread.SetApartmentState(ApartmentState.MTA);
thread.IsBackground = true;
thread.Start();
}
With in the WorkerMethod I have an option to change the filename which i am providing user a separate window.For this action I am using Dispatcher method as below,
if (MessageBox.Show("Do you want to set filename?",
"Information", MessageBoxButton.YesNo, MessageBoxImage.Asterisk) ==
MessageBoxResult.Yes)
{
Action showOutput = () =>
{
BlueBeamConversion.SetOutput _setOutput =
new BlueBeamConversion.SetOutput();
_setOutput.ShowDialog();
};
Dispatcher.BeginInvoke(showOutput);
if (String.IsNullOrEmpty(MainWindow.destinationFileName))
return;
where destinationFileName will be set in SetOutput window. Now come to my issue, when above code executes SetOutput window shows up and doesn't wait until i set the filename. Before setting the filename it comes to the below code,
if (String.IsNullOrEmpty(MainWindow.destinationFileName))
return;
How can i hold until i click ok button in setoutput window.Any suggessions are most welcome.
I used dispatcher.Invoke instead of BeginInvoke. Now it holds the window and takes new name. But when continues the code in workmethod in a certain line it exits the application itself, please fined the code bekow,
if (MessageBox.Show("Do you want to set filename?", "Information", MessageBoxButton.YesNo, MessageBoxImage.Asterisk) == MessageBoxResult.Yes)
{
Action showOutput = () =>
{ BlueBeamConversion.SetOutput _setOutput = new BlueBeamConversion.SetOutput(); _setOutput.ShowDialog(); };
Dispatcher.Invoke(showOutput);
for (int i = 0; i < _listFiles.Items.Count; i++)--- here it exits
{--------- }
Regards
sangeetha
use ShowDialog() instead of Show() and store the output in the DialogResult
var result = _setOutput.ShowDialog();
You can use Invoke instead of BeginInvoke :
//Dispatcher.BeginInvoke(showOutput);
Dispatcher.Invoke(showOutput);
if you use ShowDialog, you can store the value in a public property of your second window and can access it in a way like this:
Form2 form2 = new Form2();
if (form2.ShowDialog() == DialogResult.OK)
{
if (form2.ReturnData == "myResult")
...
}
while you are using window.show() method in you action you will not receive any result from show method insteed you have to call the show dialog method of window which will inforce the GUI to hold untill the dialog window is closed and after it you will be able to recive the data from you dialog windo.
Action showOutput = () =>
{ BlueBeamConversion.SetOutput _setOutput = new BlueBeamConversion.SetOutput(); _setOutput.ShowDialog(); };
Dispatcher.BeginInvoke(showOutput);
and the other hand you can wait for the thread to be complete first and till you can wait. this approch will also work for you. the dispatcher.Invoke will help you out.or you can try DispatcherOperation here.
try with below changed code.
DispatcherOperation op = Dispatcher.BeginInvoke(showOutput);
op.Wait();
if (String.IsNullOrEmpty(output))
return;
if I call form.show() on a WinForms object from another thread, the form will throw an exception. Is where any way I can add a new, visible form to the main app thread? Otherwise, how can I open the form without stopping my currently executing thread?
Here is my sample code. I am attempting to start a thread and then execute some work within that thread. As the work progresses, I will show the form.
public void Main()
{
new Thread(new ThreadStart(showForm)).Start();
// Rest of main thread goes here...
}
public void showForm()
{
// Do some work here.
myForm form = new myForm();
form.Text = "my text";
form.Show();
// Do some more work here
}
Try using an invoke call:
public static Form globalForm;
void Main()
{
globalForm = new Form();
globalForm.Show();
globalForm.Hide();
// Spawn threads here
}
void ThreadProc()
{
myForm form = new myForm();
globalForm.Invoke((MethodInvoker)delegate() {
form.Text = "my text";
form.Show();
});
}
The "invoke" call tells the form "Please execute this code in your thread rather than mine." You can then make changes to the WinForms UI from within the delegate.
More documentation about Invoke is here: http://msdn.microsoft.com/en-us/library/zyzhdc6b.aspx
EDIT: You will need to use a WinForms object that already exists in order to call invoke. I've shown here how you can create a global object; otherwise, if you have any other windows objects, those will work as well.
You should call Application.Run() after you call form.Show(). For example:
public void showForm()
{
// Do some work here.
myForm form = new myForm();
form.Text = "my text";
form.Show();
Application.Run();
// Do some more work here
}
As for the details behind why, this msdn post may help.
The best way by my experience:
var ac = (ReportPre)Application.OpenForms["ReportPre"];
Thread shower = new Thread(new ThreadStart(() =>
{
if (ac == null)
{
this.Invoke((MethodInvoker)delegate () {
ac = new ReportPre();
ac.Show();
});
}
else
{
this.Invoke((MethodInvoker)delegate
{
pictureBox1.Visible = true;
});
if (ac.InvokeRequired)
{
ac.Invoke(new MethodInvoker(delegate {
ac.Hide();
ac.Show();
}));
}
}
}));
shower.Start();
If your use case is to display a GUI while the Main GUI Thread is busy (like loading bar) you can do the following:
private void MethodWithLoadingBar()
{
Thread t1 = new Thread(ShowLoading);
t1.Start();
// Do the Main GUI Work Here
t1.Abort();
}
private void ShowLoading()
{
Thread.Sleep(1000); //Uncomment this if you want to delay the display
//(So Loading Bar only shows if the Method takes longer than 1 Second)
loadingGUI = new LoadingGUI();
loadingGUI.label1.Text = "Try to Connect...";
loadingGUI.ShowDialog();
}
My LoadingGUI is a simple Form with a public Label and a ProgressBar with Style set to Marquee
After searching the web and not finding a good solution, I came up with my own:
public async Task FunctionWhereIStartForm( Func<Delegate,object>invoke )
{
//this is on another thread
invoke( new MethodInvoker( ( ) =>
{
new formFoo().Show( );
} ) );
}
Then call like this:
await FunctionWhereIStartForm(Invoke);
I am trying to start a winForm from a thread, but when i do so, the form show but none of the labels are loaded ( the background where they should be is white ) and the form is frozen.
I've tried it with some other winForms that i know that work just fine and it still doesn't seem to work ? Has anyone encountered this problem ?
I know the question is vague but there isn't really any specific code that I could give to help understand the problem.
That is because the Message Loop runs on UI thread only. And when a control or window is created in any other thread, it cannot access that message loop. And thus, cannot process user input.
To solve this, try creating a window from UI thread and create a thread from that window to do whatever you want to do in different thread.
UI thread is supposed to be one.
Then, I suggest you to open your form calling a method of your original form thread, like in the example below:
(To test it just create an empty form called MainForm and paste this code in it)
public delegate void OpenFormDelegate(string txt);
public partial class MainForm : Form
{
public MainForm()
{
InitializeComponent();
var button1 = new Button();
button1.Text = "Run for 5 secs and open new window";
button1.Dock = DockStyle.Top;
this.Controls.Add(button1);
button1.Click += new EventHandler(button1_Click);
}
private void button1_Click(object sender, EventArgs e)
{
Thread t = new Thread(new ThreadStart(Run));
t.Start();
}
public void Run()
{
Thread.Sleep(5000); // sleep for 5 seconds
this.BeginInvoke(new OpenFormDelegate(OpenNewForm), "Hello World !");
}
public void OpenNewForm(string text)
{
Form f = new Form();
f.Text = text;
f.Show();
}
}
It is related to thread access, when the new form is created it will not be able to access the UI thread. Use the main thread to create the form and new thread to process the infomation.