Threading instance in WPF (1)

Note: we hope to further understand the working principles of the process by looking at these cases.

1. method 1 describes how to calculate prime numbers in the same window without affecting canvas operations.

Method 1

 1           # Region Long-running calculation in Ui thread 2   3           Public   Delegate   Void  Nextprimedelegate ();  4           Private   Long Num = 3 ;  5           Private   Bool Continuecalculating = False  ;  6           Private   Bool Fnotgateme = False  ;  7   8           Private   Void Btnprimenumber_click ( Object Sender, routedeventargs E)  9   {  10               If  (Continuecalculating)  11   {  12 Continuecalculating = False  ;  13 Btnprimenumber. content = "  Resume  " ;  14   }  15               Else  16   {  17 Continuecalculating = True  ;  18 Btnprimenumber. content = "  Stop  "  ;  19  20                   //  Obtain the system. Windows. Threading. dispatcherobject associated with system. Windows. Threading. Dispatcher  21   22                   //  Public dispatcheroperation begininvoke (dispatcherpriority priority, delegate method );  23                   //  The specified delegate is asynchronously executed on the Thread associated with system. Windows. Threading. Dispatcher Based on the specified priority.  24 Btnprimenumber. Dispatcher. begininvoke (dispatcherpriority. Normal, New Nextprimedelegate (checknextnumber ));  25   26   }  27   }  28   29           Public   Void  Checknextnumber ()  30   {  31               //  Reset flag.  32 Fnotgateme = False  ;  33   34               For ( Long I = 3 ; I <= math. SQRT (Num); I ++ )  35   {  36                   If (Num % I = 0  )  37  {  38                       //  Set not-a-prime flag to true.  39 Fnotgateme = True  ;  40                       Break  ;  41   }  42   }  43   44              //  If a prime number.  45               If (! Fnotaprime)  46   {  47 Tbprime. Text = Num. tostring ();  48   }  49   50 Num + = 2  ; 51   52               If  (Continuecalculating)  53   {  54                   //  3. In the checknextnumber function, because the first parameter  55                   //  Passed into begininvoke is dispatcherpriority. systemidle (process the operation when the system is idle .),  56                   // All of the checknextnumber workitem will not break the UI operation.  57   58   Btnprimenumber. Dispatcher. begininvoke (  59   System. Windows. Threading. dispatcherpriority. systemidle,  60                       New Nextprimedelegate ( This  . Checknextnumber ));  61   }  62  }  63   64           # Endregion 

 

Method 2

 1     # Region Blocking operation in worker thread 2   3           Private   Delegate   Void  Noargdelegate ();  4           Private  Delegate   Void  Oneargdelegate (int32 [] Arg );  5   6           //  1. When the retrieve data from server button is clicked, the click handle retrievedata function is called.  7           Private   Void Btnretrievedata_click ( Object  Sender, routedeventargs E)  8   { 9               This . Btnretrievedata. isenabled = False  ;  10               This . Btnretrievedata. content = "  Contacting Server  "  ;  11   12 Noargdelegate fetcher = New Noargdelegate ( This . Retrievedatafromserver );  13   14               //  2. Then our codes use delegate. begininvoke to start a thread from the thread pool.  15               //  This thread is used to perform the long operation of retrieving data.  16 Fetcher. begininvoke ( Null , Null  );  17   } 18   19           ///   <Summary>  20           ///  Retrieve data in a worker thread (Auxiliary thread ).  21           ///   </Summary>  22           Private   Void  Retrievedatafromserver ()  23   { 24               //  3. We use thread. Sleep (5000) to simulate a 5 seconds delay here.  25               //  Simulate the delay from network access.  26 Thread. Sleep ( 5000  );  27   28               //  4. The codes generate 4 random numbers as data and update them to the UI by calling the dispatcher. begininvoke ().  29  30               //  Generate random data to be displayed.  31 Random Rand = New  Random ();  32 Int32 [] DATA = {  33 Rand. Next ( 1000 ), Rand. Next ( 1000  ),  34 Rand. Next (1000 ), Rand. Next ( 1000  )  35   };  36   37               //  Schedule the UPDATE function in the UI thread.  38               This  . Dispatcher. begininvoke (system. Windows. Threading. dispatcherpriority. Normal,  39                   New Oneargdelegate (updateuserinterface), data );  40                 41   }  42   43           ///   <Summary>  44           ///  Update the UI about the new data. The function runs in the UI thread.  45           ///   </Summary>  46           ///  <Param name = "data"> </param>  47           Private   Void  Updateuserinterface (int32 [] data)  48   {  49               This . Btnretrievedata. isenabled = True  ;  50               This . Btnretrievedata. content = "  Retrieve data from server "  ;  51               This . Tbdata1.text = data [ 0  ]. Tostring ();  52               This . Tbdata2.text = data [ 1  ]. Tostring ();  53               This . Tbdata3.text = data [ 2  ]. Tostring ();  54               This . Tbdata4.text = data [ 3  ]. Tostring ();  55   }  56   57           # Endregion