I have an old application in Windows Forms, which in many places do some searches on database. Sometimes it takes a lot of time, so I decided to create a loading screen in wpf to show the user that something is loading in separate thread. Basically it's just a full transparent window with loading indicator(a turning circle). Everything works fine on My host computer and on my Virtual Machine, but when I'm trying to deploy it to our demo environments its like - it starts loading the indicator is shown and after few seconds it dissapear and application stops responding like forever. My first thought was that it's the problem with GPU acceleration, that it can't process transparency, but it's being shown for few seconds so it can't be the problem. So most likely I did something bad. Below You can see my code, do You notice something which might be wrong/cause deadlock or something ?
public class LoadingManager
{
public LoadingManager()
{ }
public LoadingManager(string LoadingText)
{
loadingText = LoadingText;
}
private string loadingText = "Please wait ..";
private Thread thread;
private bool ThreadReadyToAbort = false;
private BusyIndicatorView loadingWindow;
public void BeginLoading()
{
this.thread = new Thread(this.RunThread);
this.thread.IsBackground = true;
this.thread.SetApartmentState(ApartmentState.STA);
this.thread.Start();
}
public void EndLoading()
{
if (this.loadingWindow != null)
{
this.loadingWindow.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)(() =>
{ this.loadingWindow.Close(); }));
while (!this.ThreadReadyToAbort) { }; // I also tried to remove this while but it didn't help
}
this.thread.Abort();
}
public void RunThread()
{
this.loadingWindow = new BusyIndicatorView();
loadingWindow.tbLoadingCaption.Text = loadingText;
this.loadingWindow.Closing += new System.ComponentModel.CancelEventHandler(waitingWindow_Closed);
this.loadingWindow.ShowDialog();
}
void waitingWindow_Closed(object sender, System.ComponentModel.CancelEventArgs e)
{
Dispatcher.CurrentDispatcher.InvokeShutdown();
this.ThreadReadyToAbort = true;
}
EDIT.
I noticed that on this machines it usually(sometimes it also fails at first click) works when i click search for the first time. If i click another time it's showing for a second than dissapearing and application stops responding. So it seems like Thread is not beeing shutdown, Dispatcher shutdown failed ? But no exceptions are thrown ...
Your BeginLoading method can be called more than once before it has finished, and so can create more than one wpf window. This messes up all kinds of references. Also do not abort the thread, let it decide for itself. Here are the two changes:
public void BeginLoading()
{
this.thread = new Thread(this.RunThread);
this.thread.IsBackground = true;
this.thread.SetApartmentState(ApartmentState.STA);
this.thread.Start();
while (this.loadingWindow == null) { } // <--- Add this line
}
public void EndLoading()
{
if (this.loadingWindow != null)
{
this.loadingWindow.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)(() =>
{ this.loadingWindow.Close(); }));
while (!this.ThreadReadyToAbort) { };
}
//this.thread.Abort(); // <-- Remove this line
}
Also if this is all just for a busy screen, I would say there has to be a better and safer way than this. For academic purposes this is an interesting problem, but not production code, especially if some junior developer could fiddle with this in the future.
Edit: Still crashing on my machine if I reduce the delay between repeated callds to BeginLoading and EndLoading. It may be related to how the wpf window closes asynchronously. I removed the Closed event handler and just used a boolean flag to indicated that the window 'isLoaded' or not, and I have not seen any problems with this:
public class LoadingManager2
{
public LoadingManager2()
{ }
public LoadingManager2(string LoadingText)
{
loadingText = LoadingText;
}
private string loadingText = "Please wait ..";
private Thread thread;
private MyWindow loadingWindow;
private bool isLoaded = false;
public void BeginLoading()
{
this.thread = new Thread(this.RunThread);
this.thread.IsBackground = true;
this.thread.SetApartmentState(ApartmentState.STA);
this.thread.Start();
while (!this.isLoaded) { };
}
public void RunThread()
{
this.loadingWindow = new MyWindow();
this.isLoaded = true;
this.loadingWindow.ShowDialog();
}
public void EndLoading()
{
this.loadingWindow.Dispatcher.BeginInvoke(DispatcherPriority.Normal, (Action)(() =>
{
this.loadingWindow.Close();
this.isLoaded = false;
}));
while (this.isLoaded) { };
}
}
Related
I'd like to keep track of the number of modules that have been loaded over the total so the user can see how much loading is left. So I've decided to load each module individually and then publish an event.
I can see that the Subscriber is getting hit and running through all the correct code, but the UI wont update until all modules have been loaded. So my progress bar just goes from 0 straight to 100.
So to clarify, the problem I have is that the UI appears to be frozen throughout the entire module loading process. Is there any way around this so I can utilize a progress bar?
Bootstrapper
{
protected override void InitializeModules()
{
FillModuleCatalogFromConfig();
// begin the initialization process
eventAggregator = this.Container.Resolve<IEventAggregator>();
eventAggregator.GetEvent<BeginLoadingModulesEvent>().Publish(true);
// load the rest of the modules
InitializeRemainingModules();
eventAggregator.GetEvent<BeginLoadingModulesEvent>().Publish(false);
}
private void InitializeRemainingModules()
{
foreach (var module in ModuleCatalog.Modules)
{
InitializeModule(module);
}
}
private void InitializeModule(ModuleInfo moduleInfo)
{
if (moduleInfo.State == ModuleState.Initialized)
return;
if (moduleInfo.DependsOn.Count > 0)
{
// Load any dependencies first
foreach (var dependenciesModulesName in moduleInfo.DependsOn)
{
// if the dependency isn't loaded then we'll have to load that first
ModuleInfo module = ModuleCatalog.Modules.First(x => x.ModuleName == dependenciesModulesName);
if (module.State != ModuleState.Initialized)
{
// must initialize this module first
InitializeModule(module);
}
}
}
eventAggregator.GetEvent<MyEvent>().Publish(new ProgressChangedEventArgs(CalculateModulesLoadedProgress(), moduleInfo.ModuleName));
moduleManager.LoadModule(moduleInfo.ModuleName);
}
private int CalculateModulesLoadedProgress()
{
decimal progress = Decimal.Divide(ModuleCatalog.Modules.Where(x => x.State == ModuleState.Initialized).Count(), ModuleCatalog.Modules.Count()) * 100;
return (int)(Math.Round(progress));
}
}
ViewModel to the shell that displays the progress bar
public Class ShellViewModel
{
IEventAggregator ea;
ShellViewModel(IEventAggregator ea)
{
this.ea = ea;
this.ea.GetEvent<MyEvent>().Subscribe(this.UpdateProgressBar);
}
public int ProgressValue
{
get { return progressValue; }
set { SetProperty(ref progressValue, value); }
}
private void UpdateProgressBar(ProgressChangedEventArgs args)
{
// this all gets hit and runs fine, but the actual UI bar for progress
// wont get hit until all modules are done loading
this.ProgressValue = args.ProgressPercentage;
}
}
I did end up figuring this out. Or at least getting working the way I wanted it to. I just used the Dispatcher and set it to a background priority.
Instead of
moduleManager.LoadModule(moduleInfo.ModuleName);
I used
Application.Current.Dispatcher.Invoke(() => moduleManager.LoadModule(moduleInfo.ModuleName), DispatcherPriority.Background);
I dont think that I would use EventAggregator for this I think that I would use a regular event with a Progress window to display this something like:
public sealed class ProgressEvent
{
public EventHandler AddModule;
private static ProgressEvent _instance = new ProgressEvent();
public static ProgressEvent GetInstance()
{
return _instance;
}
public void OnAddModule(object sender, EventArgs e)
{
var addModuleDelegate = AddModule as EventHandler;
if(addModuleDelegate != null)
{
addModuleDelegate.Invoke(sender, e);
}
}
}
and inside the module:
public void Initialize()
{
//do work here
ProgressEvent.GetInstance().OnAddModule(this, new EventArgs());
}
register to it like:
public Progressbar()
{
InitializeComponent();
ProgressEvent.GetInstance().AddModule += AddProgress;
}
You defiantly need to load on separate thread.
list Task.Run(()=> load modules);
Working on a C# project which I would like to implement a "waiting" (throbber) indicator in a separate form. After much research and trial and error it appears as the suggested method of doing this is to load a form using a separate thread from the one from the current form/thread.
The reason I went with this method was because initially using the Show() method on the throbber form produced a transparent form. I cannot use ShowDialog because I need to run some code after the throbber is displayed, after which that completes I would like to close the throbber form.
Anyway .. after trying many different methods to load the throbber form in a separate thread I still get an error about trying to access it from a thread which is different from the one it was created in. Here is a skelton version of the project code that should shed some light on my issue:
the example I was working off of for multithreading was this popular link for creating your own spashscreen in a separate thread ... http://www.codeproject.com/Articles/5454/A-Pretty-Good-Splash-Screen-in-C
public class Main
{
public void CheckData()
{
try
{
ProgressBar pb = new ProgressBar();
pb.ShowProgressBar();
//do data checking here
pb.CloseForm()
}
catch(Exception e)
{
}
}
}
public partial class ProgressBar : Form
{
static Thread ms_oThread = null;
public bool shouldStop = false;
static ProgressBar ms_ProgBar = null;
public ProgressBar()
{
InitializeComponent();
//DoWork();
}
public void ShowForm()
{
ms_ProgBar = new ProgressBar();
Application.Run(ms_ProgBar);
}
public void CloseForm()
{
ms_ProgBar.Close();
}
public void ShowProgressBar()
{
// Make sure it is only launched once.
if (ms_ProgBar != null)
return;
ms_oThread = new Thread(new ThreadStart(ShowForm));
ms_oThread.IsBackground = true;
ms_oThread.SetApartmentState(ApartmentState.STA);
ms_oThread.Start();
while (ms_ProgBar == null || ms_ProgBar.IsHandleCreated == false)
{
System.Threading.Thread.Sleep(1000);
}
}
}
You are creating your ProgressBar twice. Once in your main function, and once in your new thread. You are also calling your CloseWindow method from your main function (and on the window that is never shown), rather than on your new thread window.
You only want to create ProgressBar and show it using your new thread. Make your static ProgressBar field public so you can call close on it directly from Main, but make sure to use Invoke to do it since it's not on that Window's GUI thread.
Also, ShowProgressBar should be static.
Here's a rewrite attempt:
public class Main
{
public void CheckData()
{
try
{
ProgressBar.ShowProgressBar();
//do data checking here
ProgressBar.CloseForm();
}
catch(Exception e)
{
}
}
}
public partial class ProgressBar : Form
{
static ProgressBar _progressBarInstance;
public ProgressBar()
{
InitializeComponent();
//DoWork();
}
static void ShowForm()
{
_progressBarInstance = new ProgressBar();
Application.Run(ms_ProgressBar);
}
public static void CloseForm()
{
_progressBarInstance.Invoke(new Action(_progressBarInstance.Close));
_progressBarInstance= null;
}
public static void ShowProgressBar()
{
// Make sure it is only launched once.
if (_progressBarInstance != null)
return;
var ms_oThread = new Thread(new ThreadStart(ShowForm));
ms_oThread.IsBackground = true;
ms_oThread.SetApartmentState(ApartmentState.STA);
ms_oThread.Start();
}
}
The problem is that i have some kind of splash screen which shows loading animation.
I have special manager that show and hide it.
class Manager
{
private Form CurForm;
Thread curt;
private Manager()
{
curt= new Thread(start);
curt.ApartmentState = ApartmentState.STA;
curt.IsBackground = true;
curt.Start();
}
void start()
{
CurForm = new Animation();
Application.Run(CurForm);
}
public static readonly Manager Active = new Manager();
public static void Show()
{
if (Active.CurForm != null)
{
Active.CurForm.Invoke(new Action(() => { Active.CurForm.Show(); }));
}
}
public static void Hide()
{
if (Active.CurForm != null)
{
Active.CurForm.Invoke(new Action(() => { Active.CurForm.Hide(); }));
}
}
}
I open some modal form (ShowDialog). This modal form doesn't show in taskbar.
I easily can minimise it and after clicking on main form on task bar it show that modal form on top.
But when I show this loading animation while it's loading all necessary data.
some kind like that (of course it is just a sample to test it work, and in real app it tooks much time to load all data and form with lots of controls)
public modal()
{
Manager.Show();
InitializeComponent();
Thread.Sleep(5000);
Manager.Hide();
}
And when i'm trying to minimise and restore it like i said above it doesn't restore my modal form and just show my main not available form. And more than that it works in some cases but in some not.
Does anybody know why it is happens or how to fix it?
it is strange but when i modify like this, everything seems to work normal.
I just kill separate ui thread.
public class MyApplicationContext:ApplicationContext
{
public Form CurForm;
ManualResetEvent ready = new ManualResetEvent(false);
public MyApplicationContext()
{
CurForm=new Animation();
CurForm.Show();
}
}
class Manager
{
private MyApplicationContext CurContext;
Thread curt;
void start()
{
try
{
CurContext = new MyApplicationContext();
Application.Run(CurContext);
}
catch
{
CurContext.CurForm.Close();
}
}
private void Init()
{
curt = new Thread(start);
curt.SetApartmentState(ApartmentState.STA);
curt.IsBackground = true;
curt.Start();
}
public static Manager Active
{
get
{
if (active == null)
{
active = new Manager();
}
return active;
}
}
private static Manager active;
public static void Show()
{
Active.Init();
}
public static void Hide()
{
Active.curt.Abort();
}
OK guys, I have this Class that shows a "Loading..." Splash Screen. It works great when I call it on Initialize() but not on Form_Load. Instead of showing at the beginning of Form_Load, it shows after all tables are filled and then just hangs there (no lock).
class innerLoad
{
//Delegate for cross thread call to close
private delegate void CloseDelegate();
//The type of form to be displayed as the splash screen.
private static frmLoading splashForm;
static public void ShowSplashScreen()
{
// Make sure it is only launched once.
if (splashForm != null)
return;
Thread thread = new Thread(new ThreadStart(innerLoad.ShowForm));
thread.IsBackground = true;
//Thread.Sleep(100);
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
}
//volatile static public bool isOpen = false;
static private void ShowForm()
{
splashForm = new frmLoading();
splashForm.ShowDialog();
splashForm.Dispose();
}
static public void CloseForm()
{
try
{
if (splashForm == null)
return;
splashForm.Invoke(new CloseDelegate(innerLoad.CloseFormInternal));
}
catch
{
}
}
static private void CloseFormInternal()
{
splashForm.Close();
splashForm = null;
}
}
And here is the Form_Load Code:
private void frmPayGen_Load(object sender, EventArgs e)
{
//th1 = new Thread(LoadingForm);
//th1.Start();
//Thread.Sleep(500);
innerLoad.ShowSplashScreen();
fill();
innerLoad.CloseForm();
//Thread.Sleep(500);
}
I appreciate your help and I love this site... helps me a lot :D
If you set a breakpoint at the start of your Form Load event, and use F11 to step through, you eventually see this exception:
Exceptions in a Form Load event are basically ignored. If an exception is thrown, nothing after the line where the exception was thrown runs, but the Windows Form doesn't crash either. Taking away this line of code should make things work as you wish.
I am trying to create a thread which will continuously check for changes to a value, then visually show that change in a PictureBox located in my GUI.
What I actually wrote is a bit more complicated, so I simplified it while keeping the basic idea, I would be happy to provide clarification if this isn't enough:
public class CheckPictures
{
PictureBox update;
List<String> check;
public CheckPictures(PictureBox anUpdate, List<String> aCheck)
{
update = anUpdate;
check = aCheck;
}
public void start()
{
while(true)
{
if (aCheck[0] == "Me")
{
update.Image = Image.fromFile("");
}
}
}
}
static int Main(string[] args)
{
List<String> picturesList = new List<String>();
CheckPictures thread1 = new CheckPictures(PictureBox1, picturesList);
Thread oThread1 = new Thread(thread1.start));
}
What I want it to do is dynamically change the picture in PictureBox1 if I were to add the string "Me" to pictureList. The above code isn't working like I'd hoped. I had thought that by passing the actual PictureBox and List, any changes to the List elsewhere is the program would be caught by the thread. So my first question is: Is this possible? And if so, what change would I need to make to my code to achieve it?
You might want to use events. You register an eventhandler and when something changes in one thread it calls an event handler in the other to do the work. Busy waiting wastes cpu.
You definetely do not want to do an infinite loop, this will just consume cpu:
while(true)
{
if (aCheck[0] == "Me")
{
update.Image = Image.fromFile("");
}
}
I think you should look into the CountdownLatch class.
public class CountdownLatch
{
private int m_remain;
private EventWaitHandle m_event;
public CountdownLatch(int count)
{
m_remain = count;
m_event = new ManualResetEvent(false);
}
public void Signal()
{
// The last thread to signal also sets the event.
if (Interlocked.Decrement(ref m_remain) == 0)
m_event.Set();
}
public void Wait()
{
m_event.WaitOne();
}
}
The basic idea here is that you need to stop execution on your thread for some time and resume whenever a certain condition has been met (perhaps on another thread).
In other words, you will have a counter, decrement its value on certain condition and whenever it goes to zero you fire your event, execute some code and then start over (stop execution and wait for the counter to go to zero).
In your case you could set the counter to 1 and decrement its value whenever you've set aCheck[0] = "Me"; This way you don't waste CPU.
Pseudo code:
Initialize counter:
CountdownLatch latch = new CountdownLatch(1);
Make thread wait:
public void start()
{
while(true)
{
latch.Wait(); //execution stops
{
//execution resumes once the latch counter is zero.
if (aCheck[0] == "Me") //double check you have what you need
{
update.Image = Image.fromFile("");
latch = new CountdownLatch(1); //reset if you need to do it again
}
}
}
}
Whenever your condition is met (i.e. aCheck[0] = "Me";) signal your latch:
latch.Signal();
this last line will make the thread resume execution. Good stuff.
Create some object, which will raise event, when new picture was added. E.g. class representing pictures collection:
public class PicturesCollection
{
public event EventHandler<PictureAddedEventArgs> PictureAdded;
private List<string> _pictures = new List<string>();
public void Add(string name)
{
_pictures.Add(name);
if (PictureAdded != null)
PictureAdded(this, new PictureAddedEventArgs(name));
}
public IEnumerable<string> Pictures
{
get { return _pictures; }
}
}
If you want to provide some additional data to event, create custom EventArgs:
public class PictureAddedEventArgs : EventArgs
{
public PictureAddedEventArgs(string name)
{
Name = name;
}
public string Name { get; private set; }
}
All you need now - create pictures collection and subscribe to that event:
static int Main(string[] args)
{
PicturesCollection pictures = new PicturesCollection();
pictures.PictureAdded += Pictures_PictureAdded;
}
static void Pictures_PictureAdded(object sender, PictureAddedEventArgs e)
{
if (e.Name == "Me")
PictureBox1.Image = Image.fromFile("");
}
If you add somewhere in your application new picture to collection, it will raise PictureAdded event, which you can handle and update PictureBox. CPU is not wasted in this case.