Infragistics ultragrid with datatable binding - multithreading

I have a ultragrid which is bound to a datatable, i update datatable in a thread (not a gui thread). My question is that while updating datatable do I need to delegate it on gui thread (so that update on grid happens in gui thread) or I can simply update datatable in any thread and infragistics grid takes care of updating itself in correct thread?
I couldn't find answer to simple question in infragistics online help or docs.
thanks

You need to update the data source on the UI thread. There are some similar discussions on the Infragistics forums, for example: one, two, three.

best way i found to do this was to use a synchronizationContext object to post the .add call to the GUI thread.
in my situation i have classes with a property of type synchronizationContext that i set to SynchronizationContext.Current when the class is initialized. then i can call something like:
SyncContext.Post(Sub()
_displaySource.Rows.Add(r)
End Sub, Nothing)
when the class is running on a different thread and it works fine. without this you will get the annoying red X occasionally

Related

UWP bitmapimage on background thread

I have a simple question.
In my UWP app I am using multiple threads and while on a background thread when i try to create a simple BitmapImage by using code: var image=new BitmapImage();. It throws an exception
The application called an interface that was marshalled for a different thread.
this exception occurs on the very line where I try to create the image. I simply want to create this image, deal with its properties and then store it in my datalist.
Note: datalist is a simple public static property which is accesible throughout the app. thankyou
I can't see the full context from the question, so I am not sure why this exception is bubbling up, but one sure way to fix it is using CoreDispatcher.RunAsync().
The documentation says:
If you are on a worker thread and want to schedule work on the UI thread, use CoreDispatcher::RunAsync.
If you are using MVVMLight, you can also make use of it's DispatcherHelper class' CheckBeginInvokeOnUI method. It's a bit better, since it first checks which thread it is called on and if it's the UI thread, it executes the action immediately and passes it to the UI thread only if needed.

Is it possible to Derive class from CWinThread Class in dialog based application

I am working with Dialog based application.
My Question is that, I want to show Waiting dialog, until some database operation carried out.
i Used Derived class from CWinThread, but problem is that, when this thread close, the background (Main application dialog) remains at deactivated means( it hide behind another window).
i am thinking that, this is happening because of WaitDialog used CWinThread class.
The problem is not unique to a dialog based application. Creating windows of any kind in more than one thread is difficult and not recommended. In your case it sounds like your wait dialog is modal, while its parent dialog is in another thread. That is even worse and can lead to deadlocks between threads.
The reliable solution is to put the wait dialog (and all other GUI) in the main thread, and the lengthy database processing in a secondary thread.
Another alternative would be to use a Modeless Dialogbox which can also optionally show the status and call the DestroyWindow function when the database operation is completed -- you may need to disable some operations of the main window while the Modeless Dialogbox is visible, though.
From the comments on my previous answer, it looks like that alternative is not viable in this situation.
Maybe a better way would be to create a normal modal "wait" dialog box, start the background thread in the dialog's InitDialog, periodically check the status of the thread using a timer and end the dialog when the thread completes?

Manage multiple embedded javafx JFXPanel into swing tabbedpane

I'm using swing to display multiple javafx Tableview, each embeded (thanks to JFXPanel) in a swing TabbedPane
I use the well know pattern described in the oracle doc, in scala way :
implicit def fun2Run[T](x: ⇒ T) = new Runnable {
def run = x
}
def myTabbedScene():Scene = {
val root = new StackPane
root.getChildren.add(new Label("Hello world!"))
new Scene(root, 300, 300)
}
def initFxPanel(fxPanel: JFXPanel, s: ⇒ Scene) = {
fxPanel.setScene(s)
}
def initSwingGui(panel: PluginPanel) = {
val fxPanel = new JFXPanel()
// code to add panel to JPanel
panel.peer.add(fxPanel)
Platform runLater initFxPanel(fxPanel,myTabbedScene())
}
val jfxSwingPanel = new PluginPanel("wrap 2") {
var jtemp = new JPanel()
contents += jtemp
}
SwingUtilities invokeLater initSwingGui(jfxSwingPanel)
This code is executed each time the user open a new swing tab (only scene method differs) but i'm not sure this is the best way to manage thread in this case :-/
When i close or open a tab, i have some incoherent state in my application and error during display.
An example of my use case, and somes questions linked :
I open a first tab J1, a runlater is invoked, my scene display without problem in the tab.
I open a second tab J2, a new runlater is invoked on javafx Thread,
I switch to tab J1, how display in my tab is refresh ? An implicit runnable action is launched to main thread to make this possible ? How javafx recognized the good tab to refresh ? If i have a button which launch some action, i launch a runlater() action on the javafx main thread which dispatch ?
Update:
I find a code source which can help reader on this point, you can revalidate() or/and repaint() your swing panel (here _contentpane) which contain your jfxPanel
SwingUtilities.invokeLater(new Runnable() {
public void run() {
_contentPane.add(_jfxPanel);
_contentPane.revalidate();
_contentPane.repaint(); }});
I close the first tab J1, javafx automaticly close/garbage the javafx resource associated?
I have multiples other general questions :
How javafx application main thread manage this multiple runlater() call
when they arrive from different jfxpanel in swing ?
How can i close properly the resources (without close main javafx thread with exit() Platform method) associated to my jfxpanel when user close a tab ? If i destroy the JFXPanel,javafx resources used to display are liberated ?
Using task to manage my thread can be an answer to my problem ?
My question are probably naive, but i start in gui building, and i have problem to understand how javafx manage scene on different embedded panel.
How javafx application thread manage this multiple runlater() call when they arrive from different jfxpanel in swing ?
From the Platform.runLater javadoc:
Run the specified Runnable on the JavaFX Application Thread at some
unspecified time in the future. This method, which may be called from
any thread, will post the Runnable to an event queue and then return
immediately to the caller. The Runnables are executed in the order
they are posted. A runnable passed into the runLater method will be
executed before any Runnable passed into a subsequent call to
runLater.
Further:
How can i close properly the thread (without close main javafx thread) which execute my jfxpanel when user close a tab?
It's unclear which thread you are referring to. In general, when integrating JavaFX and Swing there are only two threads to be concerned with - the Swing dispatch thread and the JavaFX application thread - both of which should be managed by the respective underlying frameworks and you don't need to explicitly close. You don't need any other threads unless you are trying to do something which should not execute on either of those threads (such as a highly CPU intensive task or a remote I/O) - which from your sample code would not be appear to be the case.
Using task to manage my thread can be an answer to my problem ?
Unless you have a specific need for such a thing, such a solution would likely further complicate your situation than improve it.
I close the first tab J1, javafx automaticly close/garbage the javafx resource associated?
If you don't keep a reference to any of the resources in the related jfxpanel, then the Java Virtual Machine can garbage collect the jfxpanel and and resources associated with it - this is just standard Java garbage collection technology, nothing special here.
I switch to tab J1, how display in my tab is refresh ? An implicit runnable action is launched to main thread to make this possible ?
Sounds like a bad idea (the main thread in Java terms is the thread used to launch the Java's main function and is not involved in GUI programming at all). You probably want to submit your runnable refresh request via Platform.runLater() so that it will be executed on the JavaFX application thread.
How javafx recognized the good tab to refresh ?
You have a JavaFX JFXPanel in each swing tab and each swing tab knows which JFXPanel it has, so when you invoke Platform.runLater to refresh the specific panel, pass a (final) reference to the JFXPanel to be used. Here is some psuedo-code in no language whatsoever to illustrate the concept:
on swing tab change event
final JFXPanel curPanel = tab.getJFXPanel()
Platform.runLater() {
// update curPanel here...
}
If i have a button which launch some action, i launch a runlater() action on the javafx main thread which dispatch ?
In essence I think you are correct here, I'll just rewrite your question to clarify some of the terminology - let's say it's a swing button and on performing an action on the swing button, you make a call to Platform.runLater, then the code in the runLater call will be eventually be executed on the JavaFX application thread.
Other questions I cannot answer as I am not fluent enough in Scala to provide a reasonable answer.
Honestly, if you are just starting GUI building, then my unsolicited advice would be to use Java rather than Scala and stick with either Swing or JavaFX, but not mix it all together until you are really comfortable with the GUI building process - otherwise there are just way too many traps and pitfalls you may encounter during the integration that few will be able to assist you with.

MFC/3rd party multithreading hang

I'm currently working on a program using MFC. The current third party function starts a thread after an action has been completed using MFC (ie. Checking a checkbox, which starts a MFC thread I believe).
The problem occurs when I check the checkbox, at which point the entire program hangs. I read a few interesting discussions on CProgramming and msdn, it seems that the problem occurs because the new third party thread is calling WaitToSomething() when MFC is updating a control.
Something interesting to note:
When I debug the program, the program hangs (aka. repeatedly calls WaitToRead() ) after I check the checkbox and a new thread is trying to start
When I run the program without debugger, the program is fine UNTIL I switch to another window (ie. Internet browser, Notepad, etc)
My hypothesis:
check to make sure that MFC has finished updating the control before starting a new thread
If anyone has any suggestions or solutions, please leave a comment. Thanks.
Edit:
MFC is not thread-safe at object level (only at class level), so problem occurs when two threads work on the same CButton object.
Q: How do I make it thread safe?
A colleague helped me figure out what the problem was.
The reason why it was hanging is because that the control containing the checkbox is a child dialog, and when it finished updating the message never got passed up to its parent (so when 3rd party thread calls WaitFor(), the MFC thread never completes because a parent dialog thinks its child is still updating the controls).
Fix:
Under 'Properties' in the child dialog's control, set the 'Control' flag to true (and if it has children, set the 'Control Parent' flag to true as well).
Hope this helps.

How to avoid use of timer when using TThread to communicate with UI thread

I have a TThread which receives and sends to a device on a COM port. After I read the data, I want to activate the GUI (not in the same thread) using Synchronize(function name). However, when I call the GUI's form function to perform a button click, I get an access violation. I checked to see if the form's value is null and it is not, since this would be an obvious reason for access violation. Right now, I am setting global flags and using a timer that continuously checks to see if a certain condition is met and if so, then I fire off the button click event in that form. That seems to be the only way to avoid getting the access violation.
I really don't like timers so is there a way to avoid having to use a timer on the form?
You can post a message to the window in question. The timer works in a similar manner. It just fires off a windows message inside the form. You obviously have a handle to the window.
CWnd::PostMessage(...) Don't use send message, it gets processed inline and could cause your thread to stop working.
Typically when you have a worker thread that attempts to access Guithread, they conflict. It's been a while since I've used MFC and threading but that's what I remember. I believe it's documented to work that way.
I found the problem. I thought I was checking if my Form was null, but I was not. I fixed it making sure the form I was referencing is not null.
Edit: Turns out that one of the forms that is called when I call Fbutton1Click() is Modal so it blocks my thread. I ended having to go back to a timer to call the button click instead.. oh well.

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