///<summary>Non-blocking call. Every type of progress window should eventually call this method which does the hard stuff for the calling method.
///Spawns a separate thread that will instantiate a FormProgressBase within the new thread's context by invoking the func passed in.
///The FormProgressBase that funcGetNewProgress returns should be a form that is instatiated within the func (in order to avoid cross-threading).
///The global static FormProgressCurS will get set to the newly instantiated progress so that the entire application knows progress is showing.
///Finally returning a close action for the calling method to invoke whenever long computations are finished.
///Two critical portions of the closing method are 1 - it closes progress gracefully and 2 - FormProgressCurS gets set to null.</summary>
public static Action ShowProgressBase(Func <FormProgressBase> funcGetNewProgress, string threadName = "Thread_ODProgress_ShowProgressBase")
{
if (ODEnvironment.IsWindows7(false) || ODInitialize.IsRunningInUnitTest)
{
return(new Action(() => {
//Do nothing.
}));
}
FormProgressBase FormPB = null;
ManualResetEvent manualReset = new ManualResetEvent(false);
ODThread odThread = new ODThread(o => {
//It is very important that this particular thread instantiates the form and not the calling method.
//This is what allows the progress window to show and be interacted with without joining or invoking back to the parent thread.
FormPB = funcGetNewProgress();
AddActiveProgressWindow(FormPB); //Let the entire application know that a progress window is showing.
FormPB.Shown += (obj, eArg) => manualReset.Set();
FormPB.FormClosed += (obj, eArg) => RemoveActiveProgressWindow(FormPB);
FormPB.ShowDialog(); //We cannot utilize the "owner" overload because that would cause a cross threaded exception.
});
odThread.SetApartmentState(ApartmentState.STA); //This is required for ReportComplex due to the history UI elements.
odThread.AddExceptionHandler(e => e.DoNothing()); //The progress window had an exception... Not worth crashing the program over this.
odThread.Name = threadName;
odThread.Start();
//Force the calling thread to wait for the progress window to actually show to the user before continuing.
manualReset.WaitOne();
return(() => {
FormPB.ForceClose = true;
odThread.Join(Timeout.Infinite);
});
}
private static void RemoveActiveProgressWindow(FormProgressBase formPB)
{
_lockProgressCur.EnterWriteLock();
try {
_listActiveProgressForms.Remove(formPB);
}
finally {
_lockProgressCur.ExitWriteLock();
}
}
///<summary>Invokes one of the funcs passed in based on if there are any active progress windows showing and has focus.
///Will invoke funcShowProgress if a progress window is active. Otherwise; invokes funcShow.
///Recursively calls itself as needed if the active progress window was in the middle of closing when this method was invoked.</summary>
///<param name="funcShowOverProgress">The func that should execute if a progress window is currently showing to the user.</param>
///<param name="funcShow">The func that should execute if no progress window is currently showing to the user.</param>
///<returns>The dialog result from the func that ended up getting invoked.</returns>
private static System.Windows.Forms.DialogResult ShowHelper(Func <FormProgressBase, System.Windows.Forms.DialogResult> funcShowOverProgress,
Func <System.Windows.Forms.DialogResult> funcShow)
{
//Unit tests are not designed to display message boxes.
//Throw an exception instead of displaying the message so that unit tests cannot get locked up.
if (ODInitialize.IsRunningInUnitTest)
{
throw new ApplicationException("Message boxes are not allowed for unit tests.");
}
//Get the active form for the current application. This property will return null if another application has focus (not our application).
//This is rare enough that it is acceptable to default the parent of the message box to the progress window (if one is present).
//This may cause the MessageBox to show up behind a form that HAD focus with a progress window behind it (e.g. Registration Key Edit window).
Form FormActive = Form.ActiveForm;
//Get the "active" progress window if one is present. Utilize a shallow copy so race conditions don't affect us inadvertently.
FormProgressBase FormPB = ODProgress.FormProgressActive;
//So that the logic is easier to follow, check for the two scenarios that can cause an immediate kick out.
if (FormPB == null || //The easiest scenario is when there is no active progress window.
(FormActive != null && FormActive != FormPB)) //There is a progress window but there is another form owned by the application that has focus.
{
//There is no progress window showing or there is one showing but we know that a different window of our application has focus.
return(funcShow()); //Show the message box like normal and don't override its Parent property with the progress window.
}
//There is a progress window present and it could be the active form for the application or another application has focus and we don't know.
//It is rare enough for applications to leave progress windows open while showing dialogs or new forms to the user.
//Default to forcing the active progress window to be the parent form of the new message box because that scenario is so rare.
System.Windows.Forms.DialogResult dialogResult = System.Windows.Forms.DialogResult.Abort;
try {
FormPB.InvokeIfRequired(() => dialogResult = funcShowOverProgress(FormPB));
}
catch (ObjectDisposedException ode) {
//Explicitly catch object disposed exceptions due to rare race conditions.
//The active progress window that was just showing could have been placed on the "invoke stack" for close and disposal prior to our invoke.
//The active progress window would successfully close and dispose first and then FormPB would be a reference to a disposed window
//which would cause .InvokeIfRequired() to throw an ObjectDisposedException.
//No error should be thrown in this scenario and instead we should retry this method because the active progress window could be different.
//E.g. there will be a different active progress window if multiple progress windows were showing at the same time
//OR we we eventually get back to the main thread which will not require invoking over to a progress window at all.
ode.DoNothing();
dialogResult = ShowHelper(funcShowOverProgress, funcShow); //Recursive call on purpose.
}
return(dialogResult);
}
