I'm developing a WPF desktop application in c# 4.0 which has to handle a lot of long-running operations (loading data from the DB, calculating simulations, optimizing routes, etc.).
When these long-running operations run in the background I want to show a Please-Wait dialog. When the Please-Wait dialog is shown the application should be locked, but to just disable the application window isn't a good idea because all the DataGrids would lose their status (SelectedItem).
What I have so far works but there are some problems:
A new WaitXUI is created using the Create-factory method. The Create method expects caption text and a refernce to the host control that should be locked. The Create method sets the StartupLocation of the window, the caption text and the host to lock:
WaitXUI wait = WaitXUI.Create("Simulation running...", this);
wait.ShowDialog(new Action(() =>
{
// long running operation
}));
With the overloaded ShowDialog method the WaitXUI can then be displayed. The ShowDialog overload does expect an Action which wraps the long running operation.
In the ShowDialog overload I just start the Action in its own thread and then disable the host control (set Opacity to 0.5 and set IsEnabled to false) and call ShowDialog of the base class.
public bool? ShowDialog(Action action)
{
bool? result = true;
// start a new thread to start the submitted action
Thread t = new Thread(new ThreadStart(delegate()
{
// start the submitted action
try
{
Dispatcher.UnhandledException += Dispatcher_UnhandledException;
Dispatcher.Invoke(DispatcherPriority.Normal, action);
}
catch (Exception ex)
{
throw ex;
}
finally
{
// close the window
Dispatcher.UnhandledException -= Dispatcher_UnhandledException;
this.DoClose();
}
}));
t.Start();
if (t.ThreadState != ThreadState.Stopped)
{
result = this.ShowDialog();
}
return result;
}
private new bool? ShowDialog()
{
DisableHost();
this.Topmost = true;
return base.ShowDialog();
}
private void DisableHost()
{
if (host != null)
{
host.Dispatcher.Invoke(new Action(delegate()
{
this.Width = host.Width - 20;
host.Cursor = Cursors.Wait;
host.IsEnabled = false;
host.Opacity = 0.5;
}));
}
}
Here are the problems with this:
Disabling the host control results in lost of status information (SelectedItems...)
The WaitXUI sometimes is shown for only some milliseconds when the thread ends a few ms after the WaitXUI is shown
Sometimes the dialog doesn't appear at all although the thread is still running
These are the main problems which come to my mind at the moment. How can this concept be improved, or what other methods can be employed to address this problem?
Thanks in advance!
A little lateral thinking always helps when developing WPF applications. You can fulfil your requirements easily with just a Grid, a Rectangle, a bool property (which you could already have) and a BooleanToVisibilityConverter and you won't have to disable any controls.
The idea is simple. Add a white Rectangle in front of your view content with its Opacity property set between 0.5 and around 0.75. Data bind its Visibility property to the bool property in your view model or code behind and plug in the BooleanToVisibilityConverter:
<Grid>
<Grid>
<!--Put your main content here-->
</Grid>
<Rectangle Fill="White" Opacity="0.7" Visibility="{Binding IsWaiting,
Converter={StaticResource BooleanToVisibilityConverter}}" />
<!--You could add a 'Please Wait' TextBlock here-->
</Grid>
Now when you want to disable the controls, you just set the bool property to true and the Rectangle will make the UI appear faded:
IsWaiting = true;
Don't really need to create own implementation, I think it's redundant.
take a look into already created component, like BusyIndicator, for similar needs. which is vital and effective. .
more info from codeplex
Related
We have built a huge winforms project, already in progress for multiple years.
Sometimes, our users get an exception which looks like this one.
The resolution of this problem seems to be:
don't acces UI components from a background thread
.
But since our project is a very big project with a lot of different threads, we don't succeed in finding all these.
Is there a way to check (with some tool or debugging option) which components are called from a background thread?
To clarify:
I created a sample winforms project with a single Form, containing two Button
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
button1.Text = "Clicked!";
}
private void button2_Click(object sender, EventArgs e)
{
Task.Run(() =>
{
button2.BackColor = Color.Red; //this does not throw an exception
//button2.Text = "Clicked"; //this throws an exception when uncommented
});
}
}
The background color of button2 is set to red when the button is clicked. This happens in a background thread (which is considered bad behavior). However, it doesn't (immediately) throw an exception. I would like a way to detect this as 'bad behavior'. Preferably by scanning my code, but if it's only possible by debugging, (so pausing as soon as a UI component is accessed from a background thread) it's also fine.
I've got 2 recommendations to use together, the first is a Visual Studio Plugin called DebugSingleThread.
You can freeze all the threads and work on one at a time (obviously the non-main-UI threads) and see each threads access to controls. Tedious I know but not so bad with the second method.
The second method is to get the steps in order to reproduce the problem. If you know the steps to reproduce it, it will be easier to see whats causing it. To do this I made this User Action Log project on Github.
It will record every action a user makes, you can read about it here on SO: User Activity Logging, Telemetry (and Variables in Global Exception Handlers).
I'd recommend you also log the Thread ID, then when you have been able to reproduce the problem, go to the end of the log and work out the exact steps. Its not as painful as it seems and its great for getting application telemetry.
You might be able to customise this project, eg trap a DataSource_Completed event or add a dummy DataSource property that sets the real Grids DataSource property and raises an INotifyPropertyChanged event - and if its a non-main thread ID then Debugger.Break();.
My gut feeling is you're changing a control's (eg a grid) data source in a background thread (for that non-freeze feel) and thats causing a problem with synchronisation. This is what happened to the other DevExpress customer who experienced this. Its discussed here in a different thread to the one you referenced.
Is your app set to ignore cross threading intentionally?
Cross-thread operations should be blowing up all the time in winforms. It checks for them like crazy in just about every method. for a starting point check out https://referencesource.microsoft.com/#System.Windows.Forms/winforms/Managed/System/WinForms/Control.cs.
Somewhere in your app, somebody might have put this line of code:
Control.CheckForIllegalCrossThreadCalls = False;
Comment that out and run the app, then follow the exceptions.
(Usually you can fix the problem by wrapping the update in an invoke, e.g., in a worker thread if you see textbox1.text=SomeString; change it to `textbox.invoke(()=>{textbox1.text=SomeString;});.
You may also have to add checking for InvokeRequired, use BeginInvoke to avoid deadlocks, and return values from invoke, those are all separate topics.
this is assuming even a moderate refactor is out of the question which for even a medium sized enterprise app is almost always the case.
Note: it's not possible to guarantee successful discovery of this case thru static analysis (that is, without running the app). unless you can solve the halting problem ... https://cs.stackexchange.com/questions/63403/is-the-halting-problem-decidable-for-pure-programs-on-an-ideal-computer etc...
I did this to search for that specific situation but of course, need to adjust it to your needs, but the purpose of this is to give you at least a possibility.
I called this method SearchForThreads but since it's just an example, you can call it whatever you want.
The main idea here is perhaps adding this Method call to a base class and call it on the constructor, makes it somewhat more flexible.
Then use reflection to invoke this method on all classes deriving from this base, and throw an exception or something if it finds this situation in any class.
There's one pre req, that is the usage of Framework 4.5.
This version of the framework added the CompilerServices attribute that gives us details about the Method's caller.
The documentation for this is here
With it we can open up the source file and dig into it.
What i did was just search for the situation you specified in your question, using rudimentary text search.
But it can give you an insight about how to do this on your solution, since i know very little about your solution, i can only work with the code you put on your post.
public static void SearchForThreads(
[System.Runtime.CompilerServices.CallerMemberName] string memberName = "",
[System.Runtime.CompilerServices.CallerFilePath] string sourceFilePath = "",
[System.Runtime.CompilerServices.CallerLineNumber] int sourceLineNumber = 0)
{
var startKey = "this.Controls.Add(";
var endKey = ")";
List<string> components = new List<string>();
var designerPath = sourceFilePath.Replace(".cs", ".Designer.cs");
if (File.Exists(designerPath))
{
var designerText = File.ReadAllText(designerPath);
var initSearchPos = designerText.IndexOf(startKey) + startKey.Length;
do
{
var endSearchPos = designerText.IndexOf(endKey, initSearchPos);
var componentName = designerText.Substring(initSearchPos, (endSearchPos - initSearchPos));
componentName = componentName.Replace("this.", "");
if (!components.Contains(componentName))
components.Add(componentName);
} while ((initSearchPos = designerText.IndexOf(startKey, initSearchPos) + startKey.Length) > startKey.Length);
}
if (components.Any())
{
var classText = File.ReadAllText(sourceFilePath);
var ThreadPos = classText.IndexOf("Task.Run");
if (ThreadPos > -1)
{
do
{
var endThreadPos = classText.IndexOf("}", ThreadPos);
if (endThreadPos > -1)
{
foreach (var component in components)
{
var search = classText.IndexOf(component, ThreadPos);
if (search > -1 && search < endThreadPos)
{
Console.WriteLine($"Found a call to UI thread component at pos: {search}");
}
}
}
}
while ((ThreadPos = classText.IndexOf("Task.Run", ++ThreadPos)) < classText.Length && ThreadPos > 0);
}
}
}
I hope it helps you out.
You can get the Line number if you split the text so you can output it, but i didn't want to go through the trouble, since i don't know what would work for you.
string[] lines = classText.Replace("\r","").Split('\n');
Try that:
public static void Main(string[] args)
{
// Add the event handler for handling UI thread exceptions to the event.
Application.ThreadException += new ThreadExceptionEventHandler(exception handler);
// Set the unhandled exception mode to force all Windows Forms errors to go through the handler.
Application.SetUnhandledExceptionMode(UnhandledExceptionMode.CatchException);
// Add the event handler for handling non-UI thread exceptions to the event.
AppDomain.CurrentDomain.UnhandledException += // add the handler here
// Runs the application.
Application.Run(new ......);
}
Then you can log the message and the call stack and that should give you enough information to fix the issue.
I recommend you update your GUI to handle this situation automatically for your convenience. You instead use a set of inherited controls.
The general principle here is to override the property Set methods in a way to make them Thread Safe. So, in each overridden property, instead of a straight update of the base control, there's a check to see if an invoke is required (meaning we're on a separate thread the the GUI). Then, the Invoke call updates the property on the GUI thread, instead of the secondary thread.
So, if the inherited controls are used, the form code that is trying to update GUI elements from a secondary thread can be left as is.
Here is the textbox and button ones. You would add more of them as needed and add other properties as needed. Rather than putting code on individual forms.
You don't need to go into the designer, you can instead do a find/replace on the designer files only. For example, in ALL designer.cs files, you would replace System.Windows.Forms.TextBox with ThreadSafeControls.TextBoxBackgroundThread and System.Windows.Forms.Button with ThreadSafeControls.ButtonBackgroundThread.
Other controls can be created with the same principle, based on which control types & properties are being updated from the background thread.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace ThreadSafeControls
{
class TextBoxBackgroundThread : System.Windows.Forms.TextBox
{
public override string Text
{
get
{
return base.Text;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.Text = value; });
else
base.Text = value;
}
}
public override System.Drawing.Color ForeColor
{
get
{
return base.ForeColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.ForeColor = value; });
else
base.ForeColor = value;
}
}
public override System.Drawing.Color BackColor
{
get
{
return base.BackColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.BackColor = value; });
else
base.BackColor = value;
}
}
}
class ButtonBackgroundThread : System.Windows.Forms.Button
{
public override string Text
{
get
{
return base.Text;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.Text = value; });
else
base.Text = value;
}
}
public override System.Drawing.Color ForeColor
{
get
{
return base.ForeColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.ForeColor = value; });
else
base.ForeColor = value;
}
}
public override System.Drawing.Color BackColor
{
get
{
return base.BackColor;
}
set
{
if (this.InvokeRequired)
this.Invoke((MethodInvoker)delegate { base.BackColor = value; });
else
base.BackColor = value;
}
}
}
}
PROBLEM
I am using a secondary view to run my media files, but When I close my secondary view with close button on it ( while media is still playing ) the secondary view/window closes but the media somehow keeps playing because I can hear the sound and source of sound seems to be the primary view ( main app window ). how can I completely terminate the secondary window when I close it?
TRIED
I followed windows samples multiple views and was able to complete all steps, I copied the ViewLifetimeControl.cs file from the sample and used it in my project. the code runs fine until it reaches Windows.Current.Close() in released event of the secondary view.
Then it gives an exception when it tries "Window.Current.Close()" with in the released event. according to documentation exception occurs due to any on going changes ( which might be because of media file playing ), but I need to force close the window even when media file is playing how can I do that? btw here is the exception :
Message = "COM object that has been separated from its underlying RCW cannot be used."
Code to Create and Show secondary view
internal static async Task CompactOpen(string Title, string caption)
{
ViewLifetimeControl viewControl = null;
await CoreApplication.CreateNewView().Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
viewControl = ViewLifetimeControl.CreateForCurrentView();
viewControl.Title = Title;
viewControl.StartViewInUse();
var frame = new Frame();
frame.MinHeight = 200;
frame.MinWidth = 200;
frame.Navigate(typeof(CompactNowPlayingPage), new object[] { viewControl,caption});
Window.Current.Content = frame;
Window.Current.Activate();
ApplicationView.GetForCurrentView().Title = viewControl.Title;
});
((App)App.Current).SecondaryViews.Add(viewControl);
var selectedView = viewControl;
var sizePreference = new SizePreferenceString() { Title = "SizePreference", Preference = ViewSizePreference.Default };
var anchorSizePreference = new SizePreferenceString() { Title = "AnchorSizePreference", Preference = ViewSizePreference.Default };
if (selectedView != null && sizePreference != null && anchorSizePreference != null)
{
try
{
selectedView.StartViewInUse();
var viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(
selectedView.Id,
sizePreference.Preference,
ApplicationView.GetForCurrentView().Id,
anchorSizePreference.Preference);
if (!viewShown)
{
// The window wasn't actually shown, so release the reference to it
// This may trigger the window to be destroyed
}
// Signal that switching has completed and let the view close
selectedView.StopViewInUse();
}
catch (InvalidOperationException)
{
// The view could be in the process of closing, and
// this thread just hasn't updated. As part of being closed,
// this thread will be informed to clean up its list of
// views (see SecondaryViewPage.xaml.cs)
}
}
}
Released Event
private async void ViewLifetimeControl_Released(Object sender, EventArgs e)
{
((ViewLifetimeControl)sender).Released -= ViewLifetimeControl_Released;
// The ViewLifetimeControl object is bound to UI elements on the main thread
// So, the object must be removed from that thread
await mainDispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
((App)App.Current).SecondaryViews.Remove(thisViewControl);
});
// The released event is fired on the thread of the window
// it pertains to.
//
// It's important to make sure no work is scheduled on this thread
// after it starts to close (no data binding changes, no changes to
// XAML, creating new objects in destructors, etc.) since
// that will throw exceptions
Window.Current.Close(); //this is where that exception occurs
}
Note : both of above methods and even all the related variables, all of them I have followed the guidelines within the uwp sample for multiple views.
Thanks in advance, any help would be really appreciated, I only want to force close the secondary view ( If that's possible )
Is this in the editor or the app? If it's in your debug or build of the app, the secondary view is most likely still open but hidden. You may be using a custom close button which doesn't perform its job well enough. Instead of putting down SecondaryViews.Remove you should do what you had originally written and try StopViewInUse. It may not work, I'm not used to this kind of thing.
so after more than a week of trying to solve it on my own I officially give up and turn to your help. Basically, it should not be so complicated so I have no idea why it does not work. I have a WPF app which contains a Main Window called surprise surpise...: Main_Window.
That window contain a user control called 'pageTransitionControl' that change its content according to what the client want to see. the 'pageTransitionControl' is there to support multiple animations and so on... Anyway, among all of the user controls, i have a preety havy uc called ucBanks. before it shows, the ucBanks load a lot of data, manipulating it and display it on a very beautiful and smart charts. the problem is it takes some time to load it, approximately 6-7 seconds so i need the UI to show 'Loading' animation during that time (another user control called 'ucSpinner').
I'm Trying to load the ucBanks on a different thread to avoid freezing the application and it works great: the ucSpinner is showed immidiatlly and the ucBanks is loading on the background but when i change the content of the 'pageTransitionControl' i get this error:
"The calling thread cannot access this object because a different thread owns it".
I think i tried basically everything but i must missing somthing or doing somthing wrong.
This is where it all start, the btn_click event that load ucBanks:
ShowSpinner();
Thread.Sleep(100);
Thread newThread = new Thread(new ThreadStart(LoadUc));
newThread.SetApartmentState(ApartmentState.STA);
newThread.IsBackground = true;
newThread.Start();
This is the ShowSpinner method:
private void ShowSpinner()
{
ucSpinner.Opacity = 1;
}
and this is the LoadUc method:
private void LoadUc()
{
ucOsh ucOshx = new ucOsh();
Utils.LoadUc(ucOshx, null, PageTransitions.PageTransitionType.GrowAndFade, true, this, null, true);
}
With the LoadUc i called static class called 'Utils' holding the 'LoadUc' method:
public static void LoadUc(System.Windows.Controls.UserControl ucParent, System.Windows.Controls.UserControl ucChild, PageTransitions.PageTransitionType tranType, bool removeChildrens = true, System.Windows.Window w = null, List<Plist.Plist> lst = null, bool hideMenu = false)
{
MainWindow win = null;
if (w != null) { win = (MainWindow)w; }
else { win = (MainWindow)System.Windows.Window.GetWindow(ucChild); }
win.Dispatcher.Invoke(
System.Windows.Threading.DispatcherPriority.ContextIdle, (System.Action)delegate
{
win.pageTransitionControl.TransitionType = tranType;
win.pageTransitionControl.PARAMS = lst;
win.pageTransitionControl.Tag = ucParent.ToString();
win.pageTransitionControl.pages.Push(ucParent);
win.pageTransitionControl.Content = ucParent; ----------->>>>This is where i get the error!!!
});
}
I understand that the main window is locked inside another thread but i cant see any other option to load it without freezing the entire app.
Does anyone have a suloution to my problem? SA :-) ?
What I have tried:
i tried working with background-worker, i chaned all of the settings of the dispatcher, loaded the user control inside and outside the threads...
Following method is from mainwindow, which calls the method Show() in the sub window. I used Dispatcher.Invoke thread to update the labels in the sub window untill the device search is done, which is working good upto target framework 3.5 and not working in 4.5 framework
private void OnShowBTWindow(bool isSrchDev)
{
BTMeasure winBTMeasure = new BTMeasure();
winBTMeasure.Owner = this;
if (!isSrchDev)
{
winBTMeasure.ShowDialog();
}
else {
**winBTMeasure.Show(this);**
if (AvailableDevices != null)
{
winBTMeasure = null;
winBTMeasure = new BTMeasure();
winBTMeasure.Owner = this;
winBTMeasure.ShowDeviceListWindow(this);
}
}
}
Following method is from sub window, which updates the text block in sub window until the device search is completed the window will be appearing which may take 2 seconds to find the devices. Once the DeviceSearch() is true, the sub window will be closed. This code is working good upto target framework 3.5 but not working in the target framework 4.5
public void Show(Window owner)
{
try
{
this.Owner = owner;
this.Dispatcher.Invoke((Action)(() =>
{
txtHeader.Visibility = System.Windows.Visibility.Hidden;
txtbody.Text = "Searching for the device..!!";
btnCancel.Visibility = System.Windows.Visibility.Hidden;
btnSearchCont.Visibility = System.Windows.Visibility.Hidden;
this.Show();
}));
if (DeviceSearch())
{
this.Close();
}
}
}
Please help provide input in fixing this issue.
You should be more specific about what "this issue" is.
That said, I see you are calling "this.Close()" outside of the anonymous method invoked by Dispatcher.Invoke(). Like other GUI object members, that has to be executed on the dispatcher thread as well.
For that matter, I'm not entirely sure it's safe to set the Owner property outside the dispatcher thread. In general, you really should work hard to avoid any access of a thread-affinitied object outside that object's owning thread.
I have a Winforms Application with a TabStrip Control. During runtime, UserControls are to be loaded into different tabs dynamically.
I want to present a "User Control xyz is loading" message to the user (setting an existing label to visible and changing its text) before the UserControl is loaded and until the loading is completely finished.
My approaches so far:
Trying to load the User Control in a BackgroundWorker thread. This fails, because I have to access Gui-Controls during the load of the UserControl
Trying to show the message in a BackgroundWorker thread. This obviously fails because the BackgroundWorker thread is not the UI thread ;-)
Show the Message, call DoEvents(), load the UserControl. This leads to different behaviour (flickering, ...) everytime I load a UserControl, and I can not control when and how to set it to invisible again.
To sum it up, I have two questions:
How to ensure the message is visible directly, before loading the User control
How to ensure the message is set to invisible again, just in the moment the UserControl is completely loaded (including all DataBindings, grid formattings, etc.)
what we use is similar to this:
create a new form that has whatever you want to show the user,
implement a static method where you can call this form to be created inside itself, to prevent memory leaks
create a new thread within this form so that form is running in a seperated thread and stays responsive; we use an ajax control that shows a progress bar filling up.
within the method you use to start the thread set its properties to topmost true to ensure it stays on top.
for instance do this in your main form:
loadingForm.ShowLoadingScreen("usercontrollname");
//do something
loadingform.CloseLoadingScreen();
in the loading form class;
public LoadingScreen()
{
InitializeComponent();
}
public static void ShowLoadingScreen(string usercontrollname)
{
// do something with the usercontroll name if desired
if (_LoadingScreenThread == null)
{
_LoadingScreenThread = new Thread(new ThreadStart(DoShowLoadingScreen));
_LoadingScreenThread.IsBackground = true;
_LoadingScreenThread.Start();
}
}
public static void CloseLoadingScreen()
{
if (_ls.InvokeRequired)
{
_ls.Invoke(new MethodInvoker(CloseLoadingScreen));
}
else
{
Application.ExitThread();
_ls.Dispose();
_LoadingScreenThread = null;
}
}
private static void DoShowLoadingScreen()
{
_ls = new LoadingScreen();
_ls.FormBorderStyle = FormBorderStyle.None;
_ls.MinimizeBox = false;
_ls.ControlBox = false;
_ls.MaximizeBox = false;
_ls.TopMost = true;
_ls.StartPosition = FormStartPosition.CenterScreen;
Application.Run(_ls);
}
Try again your second approach:
Trying to show the message in a BackgroundWorker thread. This obviously fails because the BackgroundWorker thread is not the UI thread ;-)
But this time, use the following code in your background thread in order to update your label:
label.Invoke((MethodInvoker) delegate {
label.Text = "User Control xyz is loading";
label.Visible = true;
});
// Load your user control
// ...
label.Invoke((MethodInvoker) delegate {
label.Visible = false;
});
Invoke allows you to update your UI in another thread.
Working from #wterbeek's example, I modified the class for my own purposes:
center it over the loading form
modification of its opacity
sizing it to the parent size
show it as a dialog and block all user interaction
I was required to show a throbber
I received a null error on line:
if (_ls.InvokeRequired)
so I added a _shown condition (if the action completes so fast that the _LoadingScreenThread thread is not even run) to check if the form exists or not.
Also, if the _LoadingScreenThread is not started, Application.Exit will close the main thread.
I thought to post it for it may help someone else. Comments in the code will explain more.
public partial class LoadingScreen : Form {
private static Thread _LoadingScreenThread;
private static LoadingScreen _ls;
//condition required to check if the form has been loaded
private static bool _shown = false;
private static Form _parent;
public LoadingScreen() {
InitializeComponent();
}
//added the parent to the initializer
//CHECKS FOR NULL HAVE NOT BEEN IMPLEMENTED
public static void ShowLoadingScreen(string usercontrollname, Form parent) {
// do something with the usercontroll name if desired
_parent = parent;
if (_LoadingScreenThread == null) {
_LoadingScreenThread = new Thread(new ThreadStart(DoShowLoadingScreen));
_LoadingScreenThread.SetApartmentState(ApartmentState.STA);
_LoadingScreenThread.IsBackground = true;
_LoadingScreenThread.Start();
}
}
public static void CloseLoadingScreen() {
//if the operation is too short, the _ls is not correctly initialized and it throws
//a null error
if (_ls!=null && _ls.InvokeRequired) {
_ls.Invoke(new MethodInvoker(CloseLoadingScreen));
} else {
if (_shown)
{
//if the operation is too short and the thread is not started
//this would close the main thread
_shown = false;
Application.ExitThread();
}
if (_LoadingScreenThread != null)
_LoadingScreenThread.Interrupt();
//this check prevents the appearance of the loader
//or its closing/disposing if shown
//have not found the answer
//if (_ls !=null)
//{
_ls.Close();
_ls.Dispose();
//}
_LoadingScreenThread = null;
}
}
private static void DoShowLoadingScreen() {
_ls = new LoadingScreen();
_ls.FormBorderStyle = FormBorderStyle.None;
_ls.MinimizeBox = false;
_ls.ControlBox = false;
_ls.MaximizeBox = false;
_ls.TopMost = true;
//get the parent size
_ls.Size = _parent.Size;
//get the location of the parent in order to show the form over the
//target form
_ls.Location = _parent.Location;
//in order to use the size and the location specified above
//we need to set the start position to "Manual"
_ls.StartPosition =FormStartPosition.Manual;
//set the opacity
_ls.Opacity = 0.5;
_shown = true;
//Replaced Application.Run with ShowDialog to show as dialog
//Application.Run(_ls);
_ls.ShowDialog();
}
}