Menu
▾
▴
[JVCL-Checkins] CVS: dev/help JvScheduledEvents.dtx,NONE,1.1
|
From: Marcel B. <jed...@us...> - 2002-11-09 21:58:11
|
Update of /cvsroot/jvcl/dev/help
In directory usw-pr-cvs1:/tmp/cvs-serv6102/dev/help
Added Files:
JvScheduledEvents.dtx
Log Message:
Documented JvScheduledEvents.pas
--- NEW FILE: JvScheduledEvents.dtx ---
@@JvScheduledEvents.pas
<GROUP JVCL.FileRef>
Summary
Provides code and a component to schedule execution of events.
<INCLUDE JVCL.UnitText.dtx>
Author
Marcel Bestebroer
----------------------------------------------------------------------------------------------------
@@TJvScheduledEvents
##JVCL:Component
<GROUP JVCL.System.AlarmsAndTimers.Alarms>
<TITLEIMG TJvCustomScheduledEvents>
Summary
Allows you to schedule execution of events using a recurring schedule.
Description
TJvScheduledEvents allows you to schedule execution of events based on a recurring schedule, much
like the recurring appointments/tasks in Microsoft® Outlook® or the replication/job scheduler in
Microsoft® SQL Server.
The component uses the JclSchedule unit and it's interface to generate the execution times. For
more information on scheduling posibilities, check out the help for JclSchedule.
Components usage:
* Drop a TJvScheduledEvents component on a form or a datamodule
* Optionally specify if schedule states should be
<LINK TJvCustomScheduledEvents.AutoSave, automatically saved/restored> when the application is
terminated/started.
* Optionally specify the <LINK TJvCustomScheduledEvents.AutoSave, registry key> to store/retrieve
the schedule states.
* Add some events (at design time using the component popup menu or the
<LINK TJvCustomScheduledEvents.Events, events property>, specifying the
<LINK TJvEventCollectionItem.Schedule, schedule> and the
<LINK TJvEventCollectionItem.OnExecute, handler>; at run time by using
<LINK TJvEventCollection.Add, Events.Add>).
* Optionally assign handlers to to fire <LINK TJvCustomScheduledEvents.OnStartEvent, before>
and/or <LINK TJvCustomScheduledEvents.OnEndEvent, after> an event is/has fired.
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents
Summary
Base class for the TJvScheduleEvents component.
Description
TJvCustomScheduledEvents is the base class for the TJvScheduledEvents component. It provides the
base functionalitiy but does not publish anything.
You should not create an instance of this class. Use one of the descendants instead.
See Also
TJvScheduledEvents
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.AutoSave
Summary
Specifies if the component should save the event states when it is destroyed.
Description
AutoSave determines if the component stores all event states and last execution times in the
registry when the component is destroyed (usually when the application terminates).
When set to True, all event states and last execution times are saved to the location specified
by the SaveTo property when the component is destroyed and are read back in from that location
when the component is created.
When set to False, no information is saved.
See Also
SaveTo
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.OnEndEvent
Summary
Event called when a scheduled events has been completed.
Description
Write an OnEndEvent handler to take special action when a scheduled event has just been executed.
See Also
OnStartEvent
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.OnStartEvent
Summary
Event called when a scheduled event is about to be executed.
Description
Write an OnStartEvent handler to take special action when a scheduled event is about to be
executed.
See Also
OnEndEvent
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.SaveTo
Summary
Specifies the location where event states are stored to or retrieved from.
Description
SaveTo specifies where event states and last execution time should be saved to or retrieved from
when AutoSave is True. SaveTo should point to a registry location.
The string should be in the format <<B><I>HKEY_specifier</I>\</B>><B><I>path</I></B> where
<I>HKEY_Specifier</I> specifies which root key to use and <I>path</I> specifies the path in that
root key.
<I>HKEY_Specifier</I> can be one of the following values:
<TABLE>
Value Alternate
===== =========
HKEY_CLASSES_ROOT HKCR
HKEY_CURRENT_USER HKCU
HKEY_LOCAL_MACHINE HKLM
HKEY_USERS HKU
HKEY_PERFORMANCE_DATA HKPD
HKEY_CURRENT_CONFIG HKCC
HKEY_DYN_DATA HKDD
</TABLE>
If you ommit the <I>HKEY_Specifier</I> when setting SaveTo <B>HKEY_CURRENT_USER</B> is assumed.
See Also
AutoSave
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.Handle
Summary
Window handle used by background thread to signal the execution of an event.
Description
Handle is the window handle to receives messages from the background thread to signal when an
event should be executed.
----------------------------------------------------------------------------------------------------
@@TJvCustomScheduledEvents.Events
Summary
Holds a collection of events and their schedules.
Description
Events is a collection of events and their schedules.
At run time you can iterate over the items to retrieve information on each of the event or add new
events on the fly.
At design time you can use the editor to add events and set the schedule for each of them.
----------------------------------------------------------------------------------------------------
@@TJvEventCollection
Summary
Maintains a list of scheduled events.
Description
TJvEventCollection maintains a list of scheduled events as used by TJvCustomScheduledEvents
descendants.
The collection will be populated with TJvEventCollectionItem objects.
See Also
TJvCustomScheduledEvents, TJvCustomScheduledEvents.Events, TJvEventCollectionItem
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem
Summary
Represents a single scheduled event.
Description
TJvEventCollectionItem represents a single scheduled event. It allows you to specify:
* if <LINK TJvEventCollectionItem.CountMissedEvents, missed events> since the last save or the
start of the schedule should be counted.
* the <LINK TJvEventCollectionItem.Name, name> to represent the event with.
* the <LINK TJvEventCollectionItem.Schedule, (recurring) schedule> for the event.
* the <LINK TJvEventCollectionItem.OnExecute, handler> for the event.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.CountMissedEvents
Summary
Specifies if events missed since the start of the schedule or since the last saved state should be
counted.
Description
CountMissedEvents determines if events that should have occured since the start of the schedule or
since the last saved state should be counted. This could potentionally influence the ending of the
schedule if it's end type is set to a specific day count and/or trigger count.
If set to True events that should have occured are counted when determining the end of the
schedule.
If set to False events that should have occured are not counted when determining the end of the
schedule.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.Initialized
Summary
Determines if the scheduled event is initialized and is awaiting execution.
Description
Intialized determines if the scheduled event is properly initialized and ready to be triggered.
If Initialized is True, the scheduled event is ready to be triggered.
If Initialized is False, the scheduled event has not been properly initialized or it has ended.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.Name
Summary
Represents the name of the scheduled event.
Description
Name represents the name of the scheduled event. It's main purpose is to identify different events
at design time, but could be used also at run time to identify the various events.
At design time when a new event is added it's given a unique name <within the component> based on
the format <B>Event<I>n</I></B> when <I>n</I> is the lowest number (larger than 0) that makes the
name unique.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.NextFire
Summary
Determines the date and time at which the event is fired again.
Description
NextFire determines the timestamp at which the event will be fired again. If there are no more
events, NextFire will hold NullStamp.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.Schedule
Summary
Specifies the dates and times at which the event should fire.
Description
Schedule specifies at which dates and times the event should fire. Schedule uses the IJclSchedule
interface as defined in the JclSchedule unit (JEDI Code Library) to represent a recurring schedule
for the event. For full information on recurring schedules you should read the help for
IJclSchedule.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.LoadState
Summary
Initializes the schedule to a specific state.
Description
LoadState initializes the schedule state to the one specified by the input parameters.
LoadState and SaveState are used by descendant components of TJvCustomScheduledEvent when its
<LINK TJvCustomScheduledEvent.AutoSave, AutoSave> property is set to True.
Parameters
TriggerStamp - Timestamp of next event.
DayCount - Number of days events have been triggered <B>after</B> the event specified by
TriggerStamp is executed.
TriggerCount - Number of events that have been triggered <B>after</B> the event specified by
TriggerStamp is executed.
See Also
SaveState
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.OnExecute
Summary
Event to call at the preset dates and times.
Description
Write an OnExecute event handler to execute at the intervals specified by the Schedule property.
The event will be executed in the context of the main VCL thread.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.SaveState
Summary
Retrieves the current state of the schedule.
Description
SaveState retrieves the current state of the schedule and stores it in the parameters.
LoadState and SaveState are used by descendant components of TJvCustomScheduledEvent when its
<LINK TJvCustomScheduledEvent.AutoSave, AutoSave> property is set to True.
Parameters
TriggerStamp - Timestamp of next event.
DayCount - Number of days events have been triggered <B>after</B> the event specified by
TriggerStamp is executed.
TriggerCount - Number of events that have been triggered <B>after</B> the event specified by
TriggerStamp is executed.
See Also
LoadState
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.Start
Summary
Initializes the scheduled event.
Description
Start will initialize the scheduled event to its initial values.
----------------------------------------------------------------------------------------------------
@@TJvEventCollectionItem.Stop
Summary
Ends the scheduled event.
Description
Stop will end the schedule of the scheduled event.
----------------------------------------------------------------------------------------------------
|