Timer (Function)

ONLINE HELP
WINDEV, WEBDEV AND WINDEV MOBILE

Version:

Home | Sign in | English

This content has been translated automatically. Click here to view the French version.

Help / WLanguage / WLanguage functions / Standard functions / Windows functions / Windows Event functions

Differences between the Timer and TimerSys functions
Locking or non-locking operations
Execution time of procedure
Process for calling the timer
Process for calling the timer
Timer and sibling windows
Timer and Thread
Timer and Windows service

WINDEV

WEBDEV

WINDEV Mobile

Others

See also

Timer (Function)

In french: Timer

Periodically and automatically calls a WLanguage procedure. Called in the procedure, Timer is used to identify the timer that started the procedure.

The sequence of periodic calls to a procedure is called timer. This periodic call will be stopped by EndTimer.

Tip: In most cases, use the TimerSys function .

Example

// Procédure permettant l'affichage régulier de l'heure dans SAI_HEURE1
PROCEDURE Affiche_Heure()
SAI_HEURE1 = TimeSys()

// Traitement à l'ouverture de la fenêtre / de la page
// Affiche_Heure sera automatiquement appelée chaque seconde
IF Timer("Affiche_Heure", 100, 1) = 0 THEN
	Error("Création du timer impossible")
END

Syntax

Starting a procedure periodically Hide the details

<Result> = Timer(<Procedure name> , <Period>)

<Result>: Integer

Number of the opened timer (<Number> if this parameter is specified),
0 if the timer was not opened.

<Procedure name>: Character string

Name of WLanguage procedure that will be started periodically.
Note: If this parameter corresponds to the name of an internal procedure, the name of the internal procedure must not be enclosed in quotation marks..

<Period>: Integer or Duration

Time (in hundredths of a second) between two calls to the procedure by timer. The period precision depends on the pending system status.
This parameter can correspond to:
an integer corresponding to the number of hundredths of a second,
a Duration variable,
the duration in a readable format (e.g., '1s' or '10cs').

Remarks

Differences between the Timer and TimerSys functions

Timer allows you to use a timer managed by WINDEV. In this case, the frequency of the call is calculated from the moment when the call to the timer was performed.
TimerSys allows you to use a timer managed by the system. In this case, the frequency of the call is calculated from the end of the procedure execution.

Tip: In most cases, use TimerSys.
Indeed, Timer consumes more resources than TimerSys and it operates only when WINDEV windows are displayed (the timer stops when a message box is displayed).

Locking or non-locking operations

A timer is not locked when opening menus, when opening a window, when opening the windows associated with Warning, Confirm, Error, Info, OKCancel and YesNo.
A timer is locked when the windows are moved or resized.

Execution time of procedure

If the time it takes to process the procedure called by timer is greater than the time requested between each call to the procedure, calls to the timer won't pile up: only one call will be waiting.

Process for calling the timer

Code of the project:
- If Timer is called in a project code, the timer is associated with the project. The timer is interrupted by EndTimer and when the execution of the application is over. The procedure called by the timer must be:
  - a global procedure of the project:
    Timer("<procédure globale>", 1000)
    No parameter can be passed to the procedure called (use global variables).
  - a static method of a class:
    Timer("<classe>::<méthode statique>", 1000)
- If Timer is used in the opening process of project and if no window is opened, the timer will be valid for the entire project. It is in a pending status and it will be automatically triggered as soon as a window is opened or during the calls to Multitask.
Code of a window, control or local procedure:
If Timer is called in the code of a window, one of its controls or local procedures, the timer is associated with the window. The timer is interrupted by EndTimer and when closing the window. The procedure called by the timer must be:
- a local procedure of the window:
  Timer("<procédure locale>", 1000)
  No parameter can be passed to the procedure called (use global variables).
- a global procedure of the project:
  Timer("<procédure globale>", 1000)
  No parameter can be passed to the procedure called (use global variables).
- a static method of a class:
  Timer("<classe>::<méthode statique>", 1000)
Code of a static method of a class:
If Timer is called in a static method of a class, the timer is associated with the class. The timer is interrupted by EndTimer and when the execution of the application is over. The procedure called by the timer must be:
- a static method of the class:
  Timer("::<méthode statique>", 1000)
- a static method of another class:
  Timer("<classe>::<méthode statique>", 1000)
- a global procedure of the project:
  Timer("<procédure globale>", 1000)
Code of an object method:
If Timer is called in a method of an object, the timer is associated with the object. The timer is interrupted by EndTimer or when freeing the object. The procedure called by the timer must be:
- a non-static method of the object:
  Timer("<:méthode>", 1000)
- a static method of the object class:
  Timer("::<méthode statique>", 1000)
- a static method of another class:
  Timer("<classe>::<méthode>", 1000)
- a global procedure of the project:
  Timer("<procédure globale>", 1000)

Process for calling the timer

If Timer is called in the code of a page, one of its controls or browser local procedures, the timer is associated with the page. The timer is interrupted by:

EndTimer,
the page validation,
the replacement of the page by another page in the browser.

The procedure called by the timer must be a local browser procedure on the page: Timer("", 1000)

Timer and sibling windows

When the same window that manages a timer is opened several times (sibling windows in MDI mode), Timer must be used with no timer number. Therefore, a timer number will be automatically assigned to each window.

Timer and Thread

A procedure started by Timer or TimerSys from a secondary thread (ThreadExecute) will not be called. In fact, a secondary thread has no interface (i.e. no open window): this secondary thread does not receive messages from the system (the "message loop") like the application's main thread.

Timer and Windows service

To use Timer from a Windows service, this function must be called from a window opened by the service code.

Caution: This solution is not recommended. To repeat a process from a service, we advise you to call this process from the code of the service (the code of the service being run in loop).

Related Examples:

Unit examples (WINDEV): The alarms

[ + ] Implementing an alarm to display an alert message in the title bar of the active window (regardless of the application).
The following topics are presented:
1/ The system functions (retrieving the handle of a window)
2/ Triggering a process according to a given frequency (timers)

Training (WINDEV): WD Screen Saver

[ + ] This example illustrates the creation of a screen saver with the WLanguage functions.
The following topics are presented in this example:
1/ the periodic call to a procedure ("timers")
2/ the management of Windows events
3/ the system functions (call to Windows APIs)
To use the screen saver:
- Rename the executable (.EXE) to.SCR
- Copy the file to the directory of Windows (Ex: C:\WINDOWS)
- Open the window for the display properties of the desktop
- Choose the "Screen Saver" tab
- Select the screen saver generated by WINDEV

Training (WINDEV): WD Who is locking

[ + ] This example explains how to notify to the users of a HFSQL database in network "who" is locking an inaccessible record.

The following topics are presented in this example:
1/ management of concurrent accesses
2/ automatic refresh by timer
3/ management of a "system" file to store information about the locks.

Summary of the example supplied with WINDEV:
This example, powered by WINDEV, includes 2 projects:
- WD Who is locking: test application that manages a "client" file in network
- WD Supervisor of locks: management tool used to view the existing locks and to force the unlocking if necessary.
An edit form may have been left opened by a user for quite a long time ; this may interfere with the other users.
The 'Free' button sends a message to the relevant user and asks him to free the record.
The 'Unlock!' button is used to force the unlocking of the record.
Caution: This operation will send a message forcing the closing of the application that performed the lock.

Unit examples (WINDEV Mobile): Managing the timers

[ + ] Implementing a timer:
- start a timer
- run a code whenever the timer is called
- stop a timer

Unit examples (WINDEV Mobile): The Chrono functions

[ + ] Using the WLanguage "Chrono" functions.
These functions are used to calculate the time passed between the start (ChronoStart) and the end (ChronoEnd).

Unit examples (WEBDEV): Managing the timers

[ + ] This example explains how to implement a timer and it allows you to:
- Start a timer
- Run a code whenever the timer is called
- Stop a timer

Component: wd300vm.dll