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  • returning correct multiTouch id

    - by Max
    I've spent countless hours on reading tutorials and looking at every question related to multiTouch from here and Stackoverflow. But I just cannot figure out how to do this correctly. I use a loop to get my pointerId, I dont see alot of people doing this but its the only way I've managed to get it somewhat working. I have two joysticks on my screen, one for moving and one for controlling my sprites rotation and the angle he shoots, like in Monster Shooter. Both these work fine. My problem is that when I Move my sprite at the same time as Im shooting, my touchingPoint for my movement is set to the touchingPoint of my shooting, since the x and y is higher on the touchingPoint of my shooting (moving-stick on left side of screen, shooting-stick on right side), my sprite speeds up, this creates an unwanted change in speed for my sprite. I will post my entire onTouch method here with some variable-changes to make it more understandable. Since I do not know where Im going wrong. public void update(MotionEvent event) { if (event == null && lastEvent == null) { return; } else if (event == null && lastEvent != null) { event = lastEvent; } else { lastEvent = event; } int pointerCount = event.getPointerCount(); for (int i = 0; i < pointerCount; i++) { int x = (int) event.getX(i); int y = (int) event.getY(i); int id = event.getPointerId(i); int action = event.getActionMasked(); int actionIndex = event.getActionIndex(); String actionString; switch (action) { case MotionEvent.ACTION_DOWN: actionString = "DOWN"; break; case MotionEvent.ACTION_UP: shooting=false; // when shooting is true, it shoots dragging=false; // when dragging is true, it moves actionString = "UP"; break; case MotionEvent.ACTION_POINTER_DOWN: actionString = "PNTR DOWN"; break; case MotionEvent.ACTION_POINTER_UP: shooting=false; dragging=false; actionString = "PNTR UP"; break; case MotionEvent.ACTION_CANCEL: shooting=false; dragging=false; actionString = "CANCEL"; break; case MotionEvent.ACTION_MOVE: try{ if((int) event.getX(id) > 0 && (int) event.getX(id) < touchingBox && (int) event.getY(id) > touchingBox && (int) event.getY(id) < view.getHeight()){ movingPoint.x = (int) event.getX(id); movingPoint.y = (int) event.getY(id); dragging = true; } else if((int) event.getX(id) > touchingBox && (int) event.getX(id) < view.getWidth() && (int) event.getY(id) > touchingBox && (int) event.getY(id) < view.getHeight()){ shootingPoint.x = (int) event.getX(id); shootingPoint.y = (int) event.getY(id); shooting=true; }else{ shooting=false; dragging=false; } }catch(Exception e){ } actionString = "MOVE"; break; default: actionString = ""; } Wouldnt post this much code if I wasnt at an absolute loss of what I'm doing wrong. I simply can not get a good understanding of how multiTouching works. basicly movingPoint changes for both my first and second finger. I bind it to a box, but aslong as I hold one finger within this box, it changes its value based on where my second finger touches. It moves in the right direction and nothing gives an error, the problem is the speed-change, its almost like it adds up the two touchingPoints.

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  • Perl Threads with binmode

    - by jAndy
    Hi Folks, this call my $th = threads->create(\&print, "Hello thread World!\n"); $th->join(); works fine. But as soon as I add binmode(STDOUT, ":encoding(ISO-8859-1)"); to my script file, I get an error like "segmentation fault", "access denied". What is wrong to define an encoding type when trying to call a perl thread? Kind Regards --Andy

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  • How can i get a list of currently running threads in objective-C(iphone)

    - by krasnyk
    Is there a way to get the list of currently running threads in objective-C? I'm mostly interested in getting the NSThreads objects, cause i want to replace the assertion handler for each running thread? If such thing is not possible, maybe i could set my own selector to be invoked after any thread is spawn(so that i could do the assertion handler replacement over there)?

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  • Java Swing GUI exception - Exception in thread "AWT-EventQueue-0" java.util.NoSuchElementException:

    - by rgksugan
    I get this exception when i run my application. I dont have any idea what is going wrong here. Can someone help please. Exception in thread "AWT-EventQueue-0" java.util.NoSuchElementException: Vector Enumeration at java.util.Vector$1.nextElement(Vector.java:305) at javax.swing.plaf.basic.BasicTableHeaderUI.getPreferredSize(BasicTableHeaderUI.java:778) at javax.swing.JComponent.getPreferredSize(JComponent.java:1634) at javax.swing.ViewportLayout.preferredLayoutSize(ViewportLayout.java:78) at java.awt.Container.preferredSize(Container.java:1599) at java.awt.Container.getPreferredSize(Container.java:1584) at javax.swing.JComponent.getPreferredSize(JComponent.java:1636) at javax.swing.ScrollPaneLayout.layoutContainer(ScrollPaneLayout.java:702) at java.awt.Container.layout(Container.java:1421) at java.awt.Container.doLayout(Container.java:1410) at java.awt.Container.validateTree(Container.java:1507) at java.awt.Container.validate(Container.java:1480) at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:669) at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:124) at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) at java.awt.EventQueue.dispatchEvent(EventQueue.java:597) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

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  • DataGridView bound to a Dictionary and updated with a thread

    - by Manjoor
    I have a Dictionary binded to DataGridView by using following sample code. http://stackoverflow.com/questions/854953/datagridview-bound-to-a-dictionary Please see the above question first The diffrence is that i am updating dictionary from a thread. (Event handler of another class). My Event handler is as below static void f_PriceChanged(Objet f, eventData e) { if (prices.ContainsKey(e.ItemText)) prices[e.ItemText] = e.price; else prices.Add(e.ItemText, e.price); } Not to mention the prices is declared as class level. I have modified the button code from original post as Button btn = new Button(); btn.Dock = DockStyle.Bottom; btn.Click += delegate { bl.Reset(); }; form.Controls.Add(btn); Internally the Dictionary is updated as expected but grid does not update. Clicking on button generate exception Collection was modified; enumeration operation may not execute What to do?

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  • Android: Quitting the Looper?

    - by stormin986
    I have a thread I use to periodically update the data in my Activity. I create the thread and start a looper for using a handler with postDelay(). In onDestroy() for my activity, I call removeCallbacks() on my handler. Should I then call handler.getLooper().quit()? Or not worry about it and let the OS deal with it? Or would it just run forever then, consuming CPU cycles?

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  • Updating UISearchDisplayController with Core Data results using GCD

    - by Brian Halpin
    I'm having trouble displaying the results from Core Data in my UISearchDisplayController when I implement GCD. Without it, it works, but obviously blocks the UI. In my SearchTableViewController I have the following two methods: - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { // Tell the table data source to reload when text changes [self filterContentForSearchText:searchString]; // Return YES to cause the search result table view to be reloaded. return YES; } // Update the filtered array based on the search text -(void)filterContentForSearchText:(NSString*)searchText { // Remove all objects from the filtered search array [self.filteredLocationsArray removeAllObjects]; NSPredicate *predicate = [CoreDataMaster predicateForLocationUsingSearchText:@"Limerick"]; CoreDataMaster *coreDataMaster = [[CoreDataMaster alloc] init]; // Filter the array using NSPredicate self.filteredLocationsArray = [NSMutableArray arrayWithArray: [coreDataMaster fetchResultsFromCoreDataEntity:@"City" UsingPredicate:predicate]]; } You can probably guess that my problem is with returning the array from [coreDataMaster fetchResultsFromCoreDataEntity]. Below is the method: - (NSArray *)fetchResultsFromCoreDataEntity:(NSString *)entity UsingPredicate:(NSPredicate *)predicate { NSMutableArray *fetchedResults = [[NSMutableArray alloc] init]; dispatch_queue_t coreDataQueue = dispatch_queue_create("com.coredata.queue", DISPATCH_QUEUE_SERIAL); dispatch_async(coreDataQueue, ^{ NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entity inManagedObjectContext:self.managedObjectContext]; NSSortDescriptor *nameSort = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObjects:nameSort, nil]; [fetchRequest setEntity:entityDescription]; [fetchRequest setSortDescriptors:sortDescriptors]; // Check if predicate is set if (predicate) { [fetchRequest setPredicate:predicate]; } NSError *error = nil; NSArray *fetchedManagedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error]; for (City *city in fetchedManagedObjects) { [fetchedResults addObject:city]; } NSDictionary *userInfo = [NSDictionary dictionaryWithObject:[NSArray arrayWithArray:fetchedResults] forKey:@"results"]; [[NSNotificationCenter defaultCenter] postNotificationName:@"fetchResultsComplete" object:nil userInfo:userInfo]; }); return [NSArray arrayWithArray:fetchedResults]; } So the thread hasn't finished executing by the time it returns the results to self.filteredLocationsArray. I've tried added a NSNotification which passes the NSDictionary to this method: - (void)updateSearchResults:(NSNotification *)notification { NSDictionary *userInfo = notification.userInfo; NSArray *array = [userInfo objectForKey:@"results"]; self.filteredLocationsArray = [NSMutableArray arrayWithArray:array]; [self.tableView reloadData]; } I've also tried refreshing the searchViewController like [self.searchDisplayController.searchResultsTableView reloadData]; but to no avail. I'd really appreciate it if someone could point me in the right direction and show me where I might be going wrong. Thanks

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  • C++ using this pointer in constructors

    - by gilbertc
    In c++, during a class constructor, I started a new thread with 'this' pointer as a parameter which will be used in the thread extensively (say, calling member functions). Is that a bad thing to do? Why and what are the consequences? Thanks, Gil.

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  • Server Side code Pushing Data to client Browser while current thread is busy Comet (programming)

    - by h_power11
    Hello Friends, I am writing one simple web page with bunch of textboxes and a button control. Now when user finished editing the values on this text boxes user has to click the button and this button invoke heavily process intensive algorithm on server side code based on the data received from client (Textboxes) And it could some time takes up to 30 to 45 minutes to complete the whole operation so the current thread is still inside the button click event handler function. That background task only provides one event, and the web page subscribes to it to get some text data after each stage of processing I was wandering if there is any way I can keep user up-to-date with what is the current progress on that background task. I have div element to print the current status information So I am looking for some sort of reverse mechanism then "get" and "post". I have read some articles on the Comet (programming) but I can't find any easy or definitive answer Thanks in advance

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  • Android: Stopping method to be called twice if already running.

    - by user285831
    I'm trying to prevent my application to call the same method twice in the event of a double-click, or if the user presses different buttons quickly, almost at the same time. I have clickable Views, acting as buttons, that call the same method but passing different parameters. This is the call: startTheSearch(context, getState(), what, where); Inside this method I'm creating a new Thread, because it queries a web server for the result: new Thread(new Runnable() { public void run() { progDiag = ProgressDialog.show(ctx, null, "Searching", true); getServerXML(context, what, where, searchIsCustom, mOffset); handler.sendEmptyMessage(0); } }).start(); The problem is that upon two quick clicks, the method is fired twice, two threads are created, and consequently two new activities are created. That makes my app crash. When the methods are done, and we have the result from the server, we call the handler: private Handler handler = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); try { Intent i = new Intent(Golf.this, Result.class); Bundle b = new Bundle(); b.putString("what", mWhat); b.putString("where", mWhere); b.putInt("offset", mOffset); b.putBoolean("searchIsCustom", searchIsCustom); i.putExtras(b); startActivityForResult(i, Activity.RESULT_OK); progDiag.dismiss(); } catch (Exception e) { Alerts.generalDialogAlert("Error", "settings", ctx); } } }; I tried to have a global boolean variable called "blocked" initially set to false, creating a condition like: if(!blocked){ blocked = true; new Thread(new Runnable() { public void run() { But this only seems to work on slower phones like the G1, I tried on Nexus and before it set blocked = true, the second request has was granted. So is there any way I can block the method being called if it's already running, or if the thread has started so it wont create a new one? Please, I really need to fix this. I've been developing on Android for almost 2 months now, but I'm yet to tackle that bug. Thanks in advance.

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  • New to MVVM - Best practices for seperating Data processing thread and UI Thread?

    - by OffApps Cory
    Good day. I have started messing around with the MVVP pattern, and I am having some problems with UI responsiveness versus data processing. I have a program that tracks packages. Shipment and package entities are persisted in SQL database, and are displayed in a WPF view. Upon initial retrieval of the records, there is a noticeable pause before displaying the new shipments view, and I have not even implemented the code that counts shipments that are overdue/active yet (which will necessitate a tracking check via web service, and a lot of time). I have built this with the Ocean framework, and all appears to be doing well, except when I first started my foray into multi-threading. It broke, and it appeared to break something in Ocean... Here is what I did: Private QueryThread As New System.Threading.Thread(AddressOf GetShipments) Public Sub New() ' Insert code required on object creation below this point. Me.New(ViewManagerService.CreateInstance, ViewModelUIService.CreateInstance) 'Perform initial query of shipments 'QueryThread.Start() GetShipments() Console.WriteLine(Me.Shipments.Count) End Sub Public Sub New(ByVal objIViewManagerService As IViewManagerService, ByVal objIViewModelUIService As IViewModelUIService) MyBase.New(objIViewModelUIService) End Sub Public Sub GetShipments() Dim InitialResults = From shipment In db.Shipment.Include("Packages") _ Select shipment Me.Shipments = New ShipmentsCollection(InitialResults, db) End Sub So I declared a new Thread, assigned it the GetShipments method and instanced it in the default constructor. Ocean freaks out at this, so there must be a better way of doing it. I have not had the chance to figure out the usage of the SQL ORM thing in Ocean so I am using Entity Framework (perhaps one of these days i will look at NHibernate or something too). Any information would be greatly appreciated. I have looked at a number of articles and they all have examples of simple uses. Some have mentioned the Dispatcher, but none really go very far into how it is used. Anyone know any good tutorials? Cory

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  • Thread resource sharing

    - by David
    I'm struggling with multi-threaded programming... I have an application that talks to an external device via a CAN to USB module. I've got the application talking on the CAN bus just fine, but there is a requirement for the application to transmit a "heartbeat" message every second. This sounds like a perfect time to use threads, so I created a thread that wakes up every second and sends the heartbeat. The problem I'm having is sharing the CAN bus interface. The heartbeat must only be sent when the bus is idle. How do I share the resource? Here is pseudo code showing what I have so far: TMainThread { Init: CanBusApi =new TCanBusApi; MutexMain =CreateMutex( "CanBusApiMutexName" ); HeartbeatThread =new THeartbeatThread( CanBusApi ); Execution: WaitForSingleObject( MutexMain ); CanBusApi->DoSomething(); ReleaseMutex( MutexMain ); } THeartbeatThread( CanBusApi ) { Init: MutexHeart =CreateMutex( "CanBusApiMutexName" ); Execution: Sleep( 1000 ); WaitForSingleObject( MutexHeart ); CanBusApi->DoHeartBeat(); ReleaseMutex( MutexHeart ); } The problem I'm seeing is that when DoHeartBeat is called, it causes the main thread to block while waiting for MutexMain as expected, but DoHeartBeat also stops. DoHeartBeat doesn't complete until after WaitForSingleObject(MutexMain) times out in failure. Does DoHeartBeat execute in the context of the MainThread or HeartBeatThread? It seems to be executing in MainThread. What am I doing wrong? Is there a better way? Thanks, David

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  • Pylons error "No object (name: request) has been registered for this thread" with debug = false

    - by Evgeny
    I'm unable to access the request object in my Pylons 0.9.7 controller when I set debug = false in the .ini file. I have the following code: def run_something(self): print('!!! request = %r' % request) print('!!! request.params = %r' % request.params) yield 'Stuff' With debugging enabled this works fine and prints out: !!! request = <Request at 0x9571190 POST http://my_url> !!! request.params = UnicodeMultiDict([... lots of stuff ...]) If I set debug = false I get the following: !!! request = <paste.registry.StackedObjectProxy object at 0x4093790> Error - <type 'exceptions.TypeError'>: No object (name: request) has been registered for this thread The stack trace confirms that the error is on the print('!!! request.params = %r' % request.params) line. I'm running it using the Paste server and these two lines are the very first lines in my controller method. This only occurs if I have yield statements in the method (even though the statements aren't reached). I'm guessing Pylons sees that it's a generator method and runs it on some other thread. My questions are: How do I make it work with debug = false ? Why does it work with debug = true ? Obviously this is quite a dangerous bug, since I normally develop with debug = true, so it can go unnoticed during development.

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  • multi thread apps crashes in release mode

    - by etzarfat
    Hello, I'm using Visual Studio 2008 (programming in c). I've a weird problem I worte a program that has 2 threads that runs simultaneously, a recording thread (using audio card to record into memory) and a translation thread (using a speech engine to recognize the words). when I run my program in debug mode (aka setting a breakpoint in the code) it runs great, however when I run in debug mode or release mode (outside the visual studio enviroment) it crashes and give me the following exception: "Unhandled exception at 0x7c911129 in LowLevel.exe: 0xC0000005: Access violation reading location 0x014c7245." My stack looks: LowLevel.exe!__set_flsgetvalue() Line 256 + 0xc bytes C LowLevel.exe!_isleadbyte_l(int c=4359676, localeinfo_struct * plocinfo=0x00000001) Line 57 C++ 014b00d8() LowLevel.exe!PlayDateOfExam(int option=1) Line 2240 + 0x7 bytes C++ LowLevel.exe!NSCThread(void * arg=0x00000000) Line 1585 + 0xb bytes C++ kernel32.dll!7c80b729() winmm.dll!76b5b294() I uses the following file in my project "nsc.lib" and WinMM.lib" I'm not really familiar with threads I used a sample (which works great) and built on it. I saw a similiar question year on the forum but I didn't really understand the answers since I'm not familiar with with threads. Can someone help me? Thanks

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  • Entity Framework lazy loading doesn't work from other thread

    - by Thomas Levesque
    Hi, I just found out that lazy loading in Entity Framework only works from the thread that created the ObjectContext. To illustrate the problem, I did a simple test, with a simple model containing just 2 entities : Person and Address. Here's the code : private static void TestSingleThread() { using (var context = new TestDBContext()) { foreach (var p in context.Person) { Console.WriteLine("{0} lives in {1}.", p.Name, p.Address.City); } } } private static void TestMultiThread() { using (var context = new TestDBContext()) { foreach (var p in context.Person) { Person p2 = p; // to avoid capturing the loop variable ThreadPool.QueueUserWorkItem( arg => { Console.WriteLine("{0} lives in {1}.", p2.Name, p2.Address.City); }); } } } The TestSingleThread method works fine, the Address property is lazily loaded. But in TestMultiThread, I get a NullReferenceException on p2.Address.City, because p2.Address is null. It that a bug ? Is this the way it's supposed to work ? If so, is there any documentation mentioning it ? I couldn't find anything on the subject on MSDN or Google... And more importantly, is there a workaround ? (other than explicitly calling LoadProperty from the worker thread...) Any help would be very appreciated PS: I'm using VS2010, so it's EF 4.0. I don't know if it was the same in the previous version of EF...

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  • iPhone SDK background thread image loading problem

    - by retailevolved
    I have created a grid view that displays six "cells" of content. In each cell, an image is loaded from the web. There are a multiple pages of this grid (the user moves through them by swiping up / down to see the next set of cells). Each cell has its own view controller. When these view controllers load, they use an ImageLoader class that I made to load and display an image. These view controllers implement an ImageLoaderDelegate that has a single method that gets called when the image is finished loading. ImageLoader does its work on a background thread and then simply notifies its delegate when it is done loading, passing the image to the delegate method. Trouble is that if the user moves on to the next page of grid content before the image has finished loading (releasing the GridCellViewControllers that use the ImageLoaders), the app crashes. I suspect that this is because along the line, an asynchronous method finishes and attempts to notify its delegate but can't because it's been released. Here's some code to give a better picture: GridCellViewController.m: - (void)viewDidLoad { [super viewDidLoad]; // ImageLoader _loader = [[ProductImageLoader alloc] init]; _loader.delegate = self; if(_boundObject) [_loader loadImageForProduct:_boundObject]; } //ImageLoaderDelegate method - (void) imageDidFinishLoading: (UIImage *)image { [_imgController setImage:image]; } ProductImageLoader.m - (void) loadImageForProduct: (Product *) product { // Get image on another thread [NSThread detachNewThreadSelector:@selector(getImageForProductInBackground:) toTarget:self withObject:product]; } - (void) getImageForProductInBackground: (Product *) product { NSAutoreleasePool *tempPool = [[NSAutoreleasePool alloc] init]; HttpRequestLoader *tempLoader = [[HttpRequestLoader alloc] init]; NSURL *tempUrl = [product getImageUrl]; NSData *imageData = tempUrl ? [tempLoader loadSynchronousDataFromAddress:[tempUrl absoluteString]] : nil; UIImage *image = [[UIImage alloc] initWithData:imageData]; [tempPool release]; if(delegate) [delegate imageDidFinishLoading:image]; } The app crashes with EXC_BAD_ACCESS. Disclaimer: The code has been slightly modified to focus on the issue at hand.

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  • Thread implemented as a Singleton

    - by rocknroll
    Hi all, I have a commercial application made with C,C++/Qt on Linux platform. The app collects data from different sensors and displays them on GUI. Each of the protocol for interfacing with sensors is implemented using singleton pattern and threads from Qt QThreads class. All the protocols except one work fine. Each protocol's run function for thread has following structure: void <ProtocolClassName>::run() { while(!mStop) //check whether screen is closed or not { mutex.lock() while(!waitcondition.wait(&mutex,5)) { if(mStop) return; } //Code for receiving and processing incoming data mutex.unlock(); } //end while } Hierarchy of GUI. 1.Login screen. 2. Screen of action. When a user logs in from login screen, we enter the action screen where all data is displayed and all the thread's for different sensors start. They wait on mStop variable in idle time and when data arrives they jump to receiving and processing data. Incoming data for the problem protocol is 117 bytes. In the main GUI threads there are timers which when timeout, grab the running instance of protocol using <ProtocolName>::instance() function Check the update variable of singleton class if its true and display the data. When the data display is done they reset the update variable in singleton class to false. The problematic protocol has the update time of 1 sec, which is also the frame rate of protocol. When I comment out the display function it runs fine. But when display is activated the application hangs consistently after 6-7 hours. I have asked this question on many forums but haven't received any worthwhile suggestions. I Hope that here I will get some help. Also, I have read a lot of literature on Singleton, multithreading, and found that people always discourage the use of singletons especially in C++. But in my application I can think of no other design for implementation. Thanks in advance A Hapless programmer

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  • Using Qt signals/slots instead of a worker thread

    - by Rob
    I am using Qt and wish to write a class that will perform some network-type operations, similar to FTP/HTTP. The class needs to connect to lots of machines, one after the other but I need the applications UI to stay (relatively) responsive during this process, so the user can cancel the operation, exit the application, etc. My first thought was to use a separate thread for network stuff but the built-in Qt FTP/HTTP (and other) classes apparently avoid using threads and instead rely on signals and slots. So, I'd like to do something similar and was hoping I could do something like this: class Foo : public QObject { Q_OBJECT public: void start(); signals: void next(); private slots: void nextJob(); }; void Foo::start() { ... connect(this, SIGNAL(next()), this, SLOT(nextJob())); emit next(); } void Foo::nextJob() { // Process next 'chunk' if (workLeftToDo) { emit next(); } } void Bar::StartOperation() { Foo* foo = new Foo; foo->start(); } However, this doesn't work and UI freezes until all operations have completed. I was hoping that emitting signals wouldn't actually call the slots immediately but would somehow be queued up by Qt, allowing the main UI to still operate. So what do I need to do in order to make this work? How does Qt achieve this with the multitude of built-in classes that appear to perform lengthy tasks on a single thread?

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  • How do I find out what process Id and thread id / name has a file open

    - by peter
    Hi All, I am using C# in an application and am having some problems with a file becoming locked. The piece of code does this, while (true) { Read a packet from a socket (with data in it to add to the file) Open a file Writes data to it Close a file } But in the process the file becomes locked. I don't really understand how, we are are definately catching and reporting exceptions so I don't see how the file doesn't get closed every time. My best guess is that something else is opening the file, but I want to prove it. Can someone please provide a piece of code to check whether the file is open and if so report what processid and threadid has the file open. For example if I had this code, StreamWriter streamWriter1 = new StreamWriter(@"c:\logs\test.txt"); streamWriter1.WriteLine("Test"); // code to check for locks?? StreamWriter streamWriter2 = new StreamWriter(@"c:\logs\test.txt"); streamWriter1.Close(); streamWriter2.Close(); That will throw an exception because the file is locked when we try and open it the second time. So where the comment is what could I put in there to report that the current app (process Id) and the current thread (thread Id) have the file locked? Thanks.

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  • Calling QAxWidget method outside of the GUI thread

    - by user304361
    I'm beginning to wonder if this is impossible, but I thought I'd ask in case there's a clever way to get around the problems I'm having. I have a Qt application that uses an ActiveX control. The control is held by a QAxWidget, and the QAxWidget itself is contained within another QWidget (I needed to add additional signals/slots to the widget, and I couldn't just subclass QAxWidget because the class doesn't permit that). When I need to interact with the ActiveX control, I call a method of the QWidget, which in turn calls the dynamicCall method of the QAxWidget in order to invoke the appropriate method of the ActiveX control. All of that is working fine. However, one method of the ActiveX control takes several seconds to return. When I call this method, my entire GUI locks up for a few seconds until the method returns. This is undesirable. I'd like the ActiveX control to go off and do its processing by itself and come back to me when it's done without locking up the Qt GUI. I've tried a few things without success: Creating a new QThread and calling QAxWidget::dynamicCall from the new thread Connecting a signal to the appropriate slot method of the QAxWidget and calling the method using signals/slots instead of using dynamicCall Calling QAxWidget::dynamicCall using QtConcurrent::run Nothing seems to affect the behavior. No matter how or where I use dynamicCall (or trigger the appropriate slot of the QAxWidget), the GUI locks until the ActiveX control completes its operation. Is there any way to detach this ActiveX processing from the Qt GUI thread so that the GUI doesn't lock up while the ActiveX control is running a method? Is there something clever I can do with QAxBase or QAxObject to get my desired results?

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