Sequencer Control


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Sequencer Control

This section contains reference material for the Sequencer control and its methods and events, plus the following additional topics:
Sequencer Control VBScript Example
Action Set

The Sequencer control provides timing and sequencing services for action sets, scripts used to control Microsoft® ActiveX™ Controls or scripts on the page. The Sequencer control calls Microsoft JScript™, Microsoft Visual Basic(r) Scripting Edition (VBScript) or other Web scripts.
These procedures are called by the Sequencer control's At Method and can be performed once or they can be looped by the Sequencer control. The Sequencer control calls the named script with the parameter string and the resolved parameter string is executed. Note that this means unresolved parameters don't get executed.
To use the sequencer object, you must first instantiate it on the HTML page, as shown in the following syntax:
Syntax
<OBJECT id=object 
	STYLE=""
	CLASSID=clsid:B0A6BAE2-AAF0-11d0-A152-00A0C908DB96>
</OBJECT>
Parameters

object Name of the Sequencer control, to be used in script.

Sequencer Control Methods

Method Description
At Specifies a new action in the action set.
Pause Stops action set playback at current position. Keeps time pointer and queue.
Play Starts the action set (if stopped). Resumes sequencer playback if sequencer is paused. Ignored if sequencer is playing.
Seek Changes the current playback position of the action set to a new, specified time.
Stop Stops action set playback, resets its playback position to the beginning.

Sequencer Control Events

Event Description

oninit Occurs when sequencer is first completely loaded into memory.

onpause Occurs when action set playback has been paused.

onplay Occurs when the action set has started playback. This event is only called when the action set starts playback from a stopped or paused state, not when a currently playing action set loops back to the beginning to repeat playback.

onseek Occurs after the Seek method call has been completed.

onstop Occurs when the action set playback ends or is stopped.

For optimal performance, use only one sequencer on a page with a single action set that calls a lot of actions. You can run multiple sequencers that each execute fewer action sets simultaneously but will get better performance with a single sequencer executing a larger number of action sets.
As the page is loaded, the sequencers used are loaded into memory. You can use the oninit Event to ensure that the sequencers are fully loaded before starting their playback.
Sequencer Control VBScript Example
This sample demonstrates how to use the Sequencer control in VBScript. It rotates text, and allows the user to stop and restart the rotation by clicking a button.
<HTML>
<HEAD>
<TITLE>Microsoft DirectAnimation Controls - Sequencer</TITLE>

<SCRIPT LANGUAGE=VBSCRIPT>

Sub Window_OnLoad
	call sgMSDHTML.SetIdentity
	Button1.value="Pause"
End Sub

Sub Seq_oninit
	call seq("ActionSet1").At(0.000, "RotateAll",-1, 0.050, 1)
	Call Seq("ActionSet1").Play
End Sub

Sub RotateAll
	Call sgMSDHTML.Rotate(0,9,2)
End Sub

Sub Start
	Select Case Button1.value
	Case "Play"
		Call Seq("ActionSet1").Play
		Button1.value="Pause"
	Case "Pause"
		Call Seq("ActionSet1").Pause
		Button1.value="Play"
	End Select
End Sub

</SCRIPT>
</HEAD>


<BODY BGCOLOR=BLACK>

<OBJECT ID=sgMSDHTML
STYLE="POSITION: ABSOLUTE; HEIGHT:300;WIDTH:450;TOP:100;LEFT:60;VISIBILITY:VISIBLE; ZINDEX:-1" 
CLASSID="CLSID:369303C2-D7AC-11d0-89D5-00A0C90833E6">
<PARAM NAME="Line0001" VALUE="SetLineColor(255,255,255)">
<PARAM NAME="Line0002" VALUE="SetFillColor(0,0,255)">
<PARAM NAME="Line0003" VALUE="SetFillSTYLE(1)">
<PARAM NAME="Line0004" VALUE="SetLineSTYLE(1)">
<PARAM NAME="Line0005" VALUE="SetFont('Verdana',60,650,0,0,0)">
<PARAM NAME="Line0006" VALUE="Text('Microsoft', -120, -100, 0)">
<PARAM NAME="Line0007" VALUE="Text('Dynamic', -120, -50, 0)">
<PARAM NAME="Line0008" VALUE="Text('HTML', -90, 0, 0)">
<PARAM NAME="Line0009" VALUE="Text('Multimedia', -120, 50, 0)">
</OBJECT>

<OBJECT ID="Seq"
	CLASSID="CLSID:B0A6BAE2-AAF0-11d0-A152-00A0C908DB96"
	STYLE="WIDTH:2;HEIGHT:2">
</OBJECT>

<INPUT TYPE=button ID="Button1"
STYLE="POSITION:ABSOLUTE; TOP:10; LEFT:10; z-index:2; VALUE=""; OnClick="Start"> 

</BODY>
</HTML>
Action Set
An action set is a logical grouping of named procedures that are used to control the timing and behavior of objects on the page. Action sets have the following properties:

Name Description
PlayState Retrieves the current playback state of the action set: 0=stopped, 1=playing, 2=paused. Read-only at run time.
Time Retrieves the elapsed time in format seconds/milliseconds (SS.MSS) since the start of action set playback, including iterations. The default setting is zero. Read-only at run time.

PlayState Property
Action Set
Retrieves the state of the sequencer. Read-only at run time.

VBScript Syntax

playstate=object(
  "actionsetname"
  ) .PlayState

JScript Syntax

playstate=object.item(
  "actionsetname"
  ) .Playstate
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.

Return Values

Returns an integer that indicates the sequencer's play state. Possible values are 0 (stopped), 1 (playing) or 2 (paused).
Time Property
Action Set
Represents the amount of time since the start of the sequencer's playback. Read-only at run time.

VBScript Syntax

Time=object(
  "actionsetname"
  ) .Time

JScript Syntax

Time=object.item(
  "actionsetname"
  ) .Time
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.

Return Values

Returns a floating-point value that contains the elapsed sequencer playback time in the format seconds.milliseconds (SS.MSS).
At Method
Sequencer Control
Specifies an action to take place within an action set.

VBScript Syntax

call object(
  "actionsetname"
  ).At(
  time,
  "script",
  [loop,
  interval,
  tiebreak,
  drop threshold]
  )

JScript Syntax

object.item(
  "actionsetname"
  ).At(
  time,
  "script",
  [loop,
  interval,
  tie break,
  drop threshold]
  );
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.
time
Required. Double value in seconds.milliseconds (SS.MSS) format. Sets the start time for the specified action.
script
Required. Text string identifying the named procedure to be called. Can pass parameters as part of the script call, for example, script(param1)
loop
Optional. Integer. Sets the loop count for this action. The default is 1. If set to –1, looping is infinite. Any negative number other than –1 will be treated as 0. Zero loop count value prevents execution. You can use this to programmatically halt action set execution.
interval
Optional. Double value in seconds.milliseconds (SS.MSS) format. Sets the delay between iterations of the specified action. Minimum interval resolution is 20 milliseconds (00.020). The default is 33 milliseconds (00.033), equivalent to 30 frames per second.
tie break
Optional. Integer whose value can be –1, 0, or a positive integer. The default is –1. Sets the priority for the action. In the event that two actions happen at the same time, the action with the lower tie break number will be performed first. Zero is the highest priority action that can be dropped; –1 is the lowest-priority action and will be executed last.
drop threshold
Optional. Double value in seconds.milliseconds (SS.MSS) format. Sets the time by which the action must be performed before it is dropped from the queue. The default value is for the action to never be dropped (–1.000).

Remarks

The drop threshold parameter is useful for optimizing sequencer performance by streamlining the number of actions that the sequencer has to perform at any given moment; for instance, when starting up a complex action set. Thoughtful use of this parameter can keep the sequencer from slowing down or speeding up from backlog of actions to be executed, and keep the timing of actions within reasonable tolerances.
Pause Method
Sequencer Control
Stops the sequencer's playback, but maintains the current playback position.

VBScript syntax
call object(
  "actionsetname"
  ) .Pause

JScript Syntax
object.item(
  "actionsetname"
  ).Pause( )
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.

Play Method
Sequencer Control
Starts the sequencer or resumes it if the sequencer was paused. If the sequencer is playing, the call is ignored.

VBScript Syntax

call object(
  "actionsetname"
  ) .Play

JScript Syntax
object.item(
  "actionsetname"
  ).Play( )
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.

Remarks

The following example starts a sequencer described by the Seq object when the page loads. This sequencer calls the MoveButton action set at time 0, and calls the named procedure MoveButton.
<SCRIPT LANGUAGE=vbscript>

</SCRIPT>
Seek Method
Sequencer Control
Changes the current playback position of the Sequencer control to another specified point in playback.

VBScript Syntax

call object(
  "actionsetname"
  ).Seek(
  time
  )

JScript Syntax

object.item(
  "actionsetname"
  ).Seek(
  time
  )
Parameters

object
Name of sequencer.
actionsetname
Name of the action set.
time
New time for sequencer to continue playback.

Stop Method
Sequencer Control
Stops the sequencer and resets its position to the beginning.

VBScript Syntax

call object(
  "actionsetname"
  ) .Stop

JScript Syntax

object.item(
  "actionsetname"
  ).Stop( )
Parameters

object
Name of the sequencer.
actionsetname
Name of the action set.

Remarks

The following code stops the sequence when the btnEnd button is clicked.
<SCRIPT LANGUAGE=vbscript>

</SCRIPT>
The sequencer automatically stops when the page is unloaded.
oninit Event
Sequencer Control
Called when the sequencer has finished loading into memory and the page is loaded. At this point, the specified script is run. This event is generally used to load the rest of the procedures to be run on the client side.

VBScript Syntax

Sub object_oninit
script
End Sub

JScript Syntax

<script language="javascript" for="object" event="oninit">
<!--
script
//--><script>
Parameters

object
Name of the sequencer to be used in script.
script
Script to be run.

Remarks

The following example shows the oninit event used to play SeqMgr once it has finished loading the other sequencers that it controls. In the example, SeqMgr controls Seq1_Action1.
<SCRIPT LANGUAGE="VBScript">

</SCRIPT>
onpause Event
Sequencer Control
Called when the sequencer playback is paused. At this point, the specified script is run.

VBScript Syntax

Sub object_onpause(
  actionsetname
  )
script
End Sub

JScript Syntax

<script language="javascript" for="object" event="onpause(
  actionsetname
  ) ">
<!--
script
  //--><script>
Parameters

object
Name of the paused sequencer.
actionsetname
Name of the action set that has been paused because the sequencer is paused.

Remarks

In the following example, actionsetname is a variable set to the name of the action set that was last paused. The example tests the actionsetname parameter passed and conditionally executes a script based on which action set has been paused.
Sub Sequencername_onpause(actionsetname)
	If actionsetname="ActionSet1" then
		button1.value="Play"
	Else
		button1.value="Pause"
	Endif
End Sub
onplay Event
Sequencer Control
Occurs when the sequencer starts playback. At this point, the specified script code is run.

VBScript Syntax
Sub SequencerName_onplay(
  actionsetname
  )
script
End Sub

JScript Syntax

<script language="javascript" for="object" event="onplay(
  actionsetname
  ) ">
<!--
script
  //--><script>
Parameters

object
Name of the sequencer played.
actionsetname
Name of the action set played by the sequencer.

Remarks

In the following example, actionsetname is a variable set to the name of the action set that was last played. The example tests the actionsetname parameter passed and conditionally executes a script based on which action set has been played.
Sub Sequencername_onplay(actionsetname)
	If actionsetname="ActionSet1" then
		Call Seq("ActionSet2").stop
	Else
		Call Seq("ActionSet1").stop
	Endif
End Sub
onseek Event
Sequencer Control
Called after the Seek method is invoked against a sequencer has completed changing the playback position. At this point, the specified script code is run.

VBScript Syntax
Sub object_ onseek (
  actionsetname,
  newtime
  )
script
End Sub

JScript Syntax

<script language="javascript" for="object" event="onseek(
  actionsetname,
  newtime
  ) ">
<!--
script
  //--><script>
Parameters

object
Name of the sequencer.
actionsetname
Specific action set from which the Seek method was invoked.
newtime
New playback time to which the sequencer has been moved.

Remarks

You can use this event to determine where the sequencer playback has been moved and to set up conditional actions based on the sequencer's new position. However, you can't have an onseek event call a Seek method that seeks to a position within the same action set from which the onseek event originated.
Sub Sequencername_onseek(actionsetname, time)
	If actionsetname="ActionSet1" then
		If time=10.000 then
			Call Seq("ActionSet2").Play
		Else
			Call Seq("ActionSet1").Play
		EndIf
	EndIf
End Sub
onstop Event
Sequencer Control
Called when the sequencer is stopped. At this point, the specified script code is run.

VBScript Syntax
Sub SequencerName_onstop(
  actionsetname
  )
script
End Sub

JScript Syntax

<script language="javascript" for="object" event="onstop(
  actionsetname
  ) ">
<!--
script
  //--><script>
Parameters

SequencerName
Name of the stopped sequencer.
actionsetname
Name of the action set stopped by the sequencer.

Remarks

In the following example, actionsetname is a variable set to the name of the action set that was last stopped. The example tests the actionsetname parameter and conditionally executes a script based on which action set has been stopped.
Sub Sequencername_onstop(actionsetname)
	If actionsetname="ActionSet1" then
		Call Seq("ActionSet2").play
	Else
		Call Seq("ActionSet1").play
	Endif
End Sub
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.
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Method	Description
At	Specifies a new action in the action set.
Pause	Stops action set playback at current position. Keeps time pointer and queue.
Play	Starts the action set (if stopped). Resumes sequencer playback if sequencer is paused. Ignored if sequencer is playing.
Seek	Changes the current playback position of the action set to a new, specified time.
Stop	Stops action set playback, resets its playback position to the beginning.

Event	Description
oninit	Occurs when sequencer is first completely loaded into memory.
onpause	Occurs when action set playback has been paused.
onplay	Occurs when the action set has started playback. This event is only called when the action set starts playback from a stopped or paused state, not when a currently playing action set loops back to the beginning to repeat playback.
onseek	Occurs after the Seek method call has been completed.
onstop	Occurs when the action set playback ends or is stopped.

Name	Description
PlayState	Retrieves the current playback state of the action set: 0=stopped, 1=playing, 2=paused. Read-only at run time.
Time	Retrieves the elapsed time in format seconds/milliseconds (SS.MSS) since the start of action set playback, including iterations. The default setting is zero. Read-only at run time.