Multi-thread programming (17)-waitabletimer for multi-thread synchronization (waiting for timer objects) [continued 3]

According to the main function of waitabletimer, it is a bit inappropriate to discuss it in the thread synchronization topic. It is about to end.

 
// Check the APC callback function Format again: Procedure timerapcproc (lpargtocompletionroutine: pointer; dwtimerlowvalue, dwtimerhighvalue: DWORD); stdcall;

  
 

The last two parameters of timerapcproc are actually passing a value. They must be combined into a tfiletime type for use.
This time is the time when the APC function is called. Let's take a look at the above example with a slight modification:

Code File:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) button1: tbutton; button2: tbutton; procedure button1click (Sender: tobject); Procedure button2click (Sender: tobject); Procedure formdestroy (Sender: tobject); end; var form1: tform1; implementation {$ R *. DFM} var htimer: thandle; {APC function} procedure merge (vertex: pointer; dwtimerlowvalue: DWORD; dwtimerhighvalue: DWORD); stdcall; var utcfiletime, localfiletime: tfiletime; systemtime: tsystemtime; datetime: tdatetime; begin {combine dwtimerlowvalue with dwtimerhighvalue into a time in tfiletime format} utcfiletime. dwlowdatetime: = dwtimerlowvalue; utcfiletime. dwhighdatetime: = dwtimerhighvalue; filetimetolocalfiletime (utcfiletime, localfiletime); {from world standard timing to local time} filetimetosystemtime (localfiletime, systemtime); {to System Format time} datetime: = systemtimetodatetime (systemtime); {convert to tdatetime} form1.text: = datetimetostr (datetime); sleepex (infinite, true); end; {thread entry function} function mythreadfun (P: pointer): integer; stdcall; var duetime: int64; begin duetime: = 0; If setwaitabletimer (htimer, duetime, 1000, @ timerapcproc, nil, false) then begin sleepex (infinite, true); end; Result: = 0; end; Procedure tform1.button1click (Sender: tobject); var ID: DWORD; begin if htimer = 0 then htimer: = createwaitabletimer (nil, true, nil); createthread (nil, 0, @ mythreadfun, nil, 0, ID); end; Procedure tform1.button2click (Sender: tobject); begin cancelwaitabletimer (htimer); end; procedure tform1.formdestroy (Sender: tobject); begin closehandle (htimer); end.
 
   
 

Form file:

 
Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 86 clientwidth = 256 color = clbtnface font. charset = default_charset font. color = clwindowtext font. height =-11 font. name = 'tahoma 'font. style = [] oldcreateorder = false pixelsperinch = 96 textheight = 13 object button1: tbutton left = 23 Top = 32 width = 97 Height = 25 caption = #21551 #21160 #23450 #26102 #22120 taborder = 0 onclick = button1click end object button2: tbutton left = 134 Top = 32 width = 97 Height = 25 caption = #21462 #28040 #23450 #26102 #22120 taborder = 1 onclick = button2click endend

  
 

The pointer parameter next to the callback function in setwaitabletimer will be passed to the first parameter of the APC function;
As a pointer, it can carry any data. Here, it carries a coordinate point (the place where the mouse clicks the form), for example:

Code file:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) Procedure formdestroy (Sender: tobject ); procedure formmousedown (Sender: tobject; button: tmousebutton; shift: tshiftstate; X, Y: integer); end; var form1: tform1; implementation {$ R *. DFM} var htimer: thandle; Pt: tpoint; {APC function} procedure merge (vertex: pointer; dwtimerlowvalue: DWORD; dwtimerhighvalue: DWORD); stdcall; var utcfiletime, localfiletime: tfiletime; systemtime: tsystemtime; datetime: tdatetime; pt2: tpoint; begin utcfiletime. dwlowdatetime: = dwtimerlowvalue; utcfiletime. dwhighdatetime: = dwtimerhighvalue; filetimetolocalfiletime (utcfiletime, localfiletime); filetimetosystemtime (localfiletime, systemtime); datetime: = systemtimetodatetime (systemtime); pt2: = Ppoint; {accept pointer parameter} form1.canvas. lock; form1.canvas. textout (pt2.x, pt2.y, datetimetostr (datetime); form1.canvas. unlock; sleepex (infinite, true); end; {thread entry function} function mythreadfun (P: pointer): integer; stdcall; var duetime: int64; begin duetime: = 0; {parameter @ PT here is the pointer to the coordinate structure when the mouse clicks the form, it will be passed to the first parameter of the APC function} If setwaitabletimer (htimer, duetime, 1000, @ timerapcproc, @ PT, false) then begin sleepex (infinite, true); end; Result: = 0; end; {create a waitabletimer object and thread} procedure tform1.formmousedown (Sender: tobject; button: tmousebutton; shift: tshiftstate; X, Y: integer); var ID: DWORD; begin PT: = point (x, y ); {coordinate point assignment here} If htimer = 0 then htimer: = createwaitabletimer (nil, true, nil); createthread (nil, 0, @ mythreadfun, nil, 0, ID); end; Procedure tform1.formdestroy (Sender: tobject); begin closehandle (htimer); end.
 
   
 

Form file:

 
Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 135 clientwidth = 195 color = clbtnface font. charset = default_charset font. color = clwindowtext font. height =-11 font. name = 'tahoma 'font. style = [] oldcreateorder = false onmousedown = formmousedown pixelsperinch = 96 textheight = 13end