How to display the current state of the sub-thread
A small program just completed is to analyze a data file using a vertical arrangement of 24-pin printhead, analyze some parameters such as the number of times of each needle, and life analysis to the mechanical development department.
Since the data file may be large, the analysis time will be longer, so it is possible to display the analysis schedule, otherwise it will make the program to die.
Therefore, the analysis work is placed in the sub-thread, and the main thread update state is notified by generating "state change event" and "analysis end event". The thread is defined as follows:
/ / ==================================
// mythread.pas
/ / =================================== //
TSTATUSCHANGEDEVENT = Procedure (Percent: integer) of object; // Status change event
TfinishedEvent = procedure of object; // Analysis end event
Tmythread = Class (TTHREAD)
Private
Fonstatuschanged: TSTATUSCHANGEDEVENT;
Fonfinished: tfinished: tfinished;
protected
Procedure execute; override;
public
Property OnStatuschanged: TSTATUSCHANGEDEVENT Read FonstatusChanged Write FonstatusChanged;
Property onfinished: Tfinished Write Fonfinished;
END;
Procedure Tmythread.execute;
VAR
PERCENT: INTEGER;
Begin
...
IF (Percent has changed) And Assigned (Fonstatuschanged) THEN
FonstatusChanged (Percent);
...
// Analysis end
IF Assigned (Fonfinished) THEN
Fonfinished; // Notify the main thread at the end of the analysis
END;
The status display is implemented by a form, which has a progress bar, a state Label, a cancel button, and a timer. Define as follows (no progress bar, Label, button code)
// =====================================
// tfrmstatus.pas
/ / ============================================= // TFRMSTATUS = Class (TFORM) // Display Progress form
Timer1: TTIMER;
Procedure formcreate (Sender: TOBJECT);
Private
Procedure setpercent (Value: integer);
Procedure setterminate (Value: Boolean);
Public
Property Percent: Integer Read Fpercent Write SetPerCent;
Property Terminate: Boolean Read Fterminate Write Setterminate;
END;
Procedure TfrmStatus. Formcreate (Sender: TOBJECT);
Begin
Fterminate: = false;
Timer1.enable: = FALSE;
END;
Procedure TfrmStatus. setpercent (value: integer); // Setting percentage progress
Begin
/ / Set the control status to indicate the current percentage progress
END;
Procedure tfrmStatus.setterminate (Value: Boolean;) // Set the end status
Begin
IF fterminate <> value kil
Begin
Fterminate: = value;
Timer1.interval: = 2;
Timer1.enable: = TRUE;
END;
END;
Procedure TfrmStatus.timer1Timer (Sender: TOBJECT); / / Response Timer, Close Window, Return to MROK
Begin
CLOSE;
ModalResult: = mrok;
END;
// >>>>>>>>>>>>>>>>>>>>>>>>>>>
The main form is responsible for creating an analysis thread and status display form, and responding to "Status change event" generated by the analysis thread and "Analysis Events".
// main form
TfrmMain: = Class (TFORM)
Private
FFRMSTATUS: TFRMSTATUS;
Procedure DostatusChange (Percent: Integer); / / Response Analysis Progress Change Event
Procedure dofinished; // Response analysis end event
public
PROCEDURE DO;
END;
// operation analysis
Procedure tfrmmain.do;
VAR
Mythread: Tmythread;
FRMSTATUS: TFRMSTATUS;
Begin
Try
Mythread: = Tmythread.create (TRUE);
Mythread.onstatuschange: = dostatuschange;
Mythread.onfinished: = DOFINISHED;
Try
FRMSTATUS: = TfrmStatus.create (nil);
FfrmStatus: = frmstatus; mythread.resume; // Start thread
IF frMstatus.showmodal = mrok dam
Showanalyseresult; // Display analysis results
Finally
FFRMSTATUS: = NIL;
FRMSTATUS.FREE;
END;
Finally
Mythread.freeonterminate: = true;
Mythread.terminate;
END;
END;
/ / Response status change event, display progress
Procedure tfrmmain.dostatuschange (percent: integer)
Begin
IF FFRMSTATUS <> NIL THEN
FFRMSTATUS.PERCENT: = percent;
END;
