FreeBASIC MutexLock

' 'Threadcreate' は、別々の実行スレッドで、ユーザー定義 Sub を1回起動します
'    (これはメインコードの残りの部分と同時に実行されます).
' スレッドから定期的に表示したい場合は、
'    スレッドの中に、[Do...Loop]ブロックと、表示期間を調整する 'Sleep x, 1' を 入れる必要があります
'    そして、ループを終了し、スレッドを終了するフラグも
'
' Warning:
' - Each thread has not its own memory of cursor position, so for that and other reasons, it is mandatory
'      to apply an exclusion between displaying from the main code (main thread) and displaying from the user thread,
'      by using a 'Mutex' ([Mutexlock...Mutexunlock] block).
'   At beginning of each display block both into main thread and user thread,
'      the initial cursor position must also be re-initialized.
' - The input keywords (like keyboard, mouse) cannot be safely run when the screen is locked,
'      therefore a such keyword must be outside of any [Screenlock...Screenunlock] block (outside this block in its own thread,
'      and protected of block of another thread by a 'Mutex').
'
' See below a rustic program, but showing all these constraints:


Dim Shared As Any Ptr sync   '' pointer to Mutex
Dim Shared As Byte quit = 0  '' flag to end user thread
Dim As Any Ptr handle        '' pointer to thread handle

Sub ProcedureThread (ByVal param As Any Ptr)  '' param not used in thread body
    Do
        MutexLock(sync)       '' Mutex for exclusion of displaying
            ScreenLock        '' keyword after Mutexlock
                Locate 1, 70  '' re-initialize cursor position
                Print Date
                Locate , 71
                Print Time;
            ScreenUnlock      '' keyword before Mutexunlock
        MutexUnlock(sync)     '' end exclusion
        Sleep 100, 1          '' ajust display period
    Loop Until quit <> 0      '' test for exit thread
End Sub


Screen 12
Locate 1, 62
Print "Date:"
Locate , 62
Print "Time:";
Locate 15, 20
Print "Mouse (position):"
Locate , 20
Print "Mouse (buttons) :";
Locate 30, 2
Print "<any_key> or <click on window close button>: exit";

sync = MutexCreate                          '' create Mutex (before Threadcreate)
handle = ThreadCreate(@ProcedureThread, 0)  '' launch thread

Dim As String s
Do
    MutexLock(sync)                     '' Mutex for exclusion of displaying
        Dim As Long x, y, b
        GetMouse x, y , , b             '' keyword outside [Screenlock...Screenunlock] and protected by Mutex
        ScreenLock                      '' keyword after Mutexlock
            Locate 15, 37               '' re-initialize cursor position
            Print Using "######"; x; y
            Locate , 43
            Print Using "##"; b;
        ScreenUnlock                    '' Keyword before Mutexunlock
        s = Inkey                       '' keyword outside [Screenlock...Screenunlock] and protected by Mutex
    MutexUnlock(sync)                   '' end exclusion
    Sleep 10, 1                         '' ajust display period
Loop Until s <> ""
 
quit = Not quit     '' order thread end
ThreadWait(handle)  '' wait for thread end
MutexDestroy(sync)  '' free Mutex