Event Handlers

Once you have a function that implements your custom column, you need to know when to update that column. The most common method of doing this is to implement event handlers for particular Process Analyst events. The example below uses the PenCreated event and the HorizontalAxisChanged event. These events will verify that the column values will be updated when pens are added to the display and when the time span changes.

Sub UpdateMyColumn()

	Dim iPaneItem As Integer

	Dim iPane As Integer

	Dim nPanes As Integer

	Dim nSamples As Integer



	Dim penItem As Object

	Dim paneItem As Object



	nSamples = test_CPA.NumberOfSamples

	iPaneItem = 0

	nPanes = test_CPA.Panes.Count

	For iPane = 1 To nPanes

		Dim pane As Object



		Set pane = test_CPA.Panes.Item(iPane)

		If IsNUll(pane) = False Then

			Dim pen As Object

			Dim iPen As Integer

			Dim iPenItem As Integer

			Dim nPens As Integer



			iPaneItem = iPaneItem + 1



			Set paneItem = test_CPA.ObjectView.Items.Item(iPaneItem)



			test_CPA.BlockUpdates

			iPenItem = 0

			nPens = pane.Pens.Count

			For iPen = 1 To nPens	

				Set pen = pane.pens.Item(iPen)



				If IsNUll(pen) = False Then

					Dim dDiff As Double

					Dim sText As string



					Dim dtStart As Date

					Dim dtEnd As Date

					Dim dtStartMs As Integer

					Dim dtEndMs As Integer



					iPenItem = iPenItem + 1



					pen.GetHorizontalAxisTimeSpan dtStart, dtStartMs, dtEnd, dtEndMs,
					False



					dDiff = ((CDbl(dtEnd) - CDbl(dtStart)) / nSamples) * 86400

					If (dDiff >= 0.001) Then

						sText = CStr(Format(dDiff, "#0.000")) + " seconds"

					Else

						sText = "0.001 seconds"

					End If

					Set penItem = paneItem.Items.Item(iPenItem)



					If IsNUll(penItem) = False Then

						penItem.Putfield "DisplayPeriod", sText

					End If

				End If

			Next

			test_CPA.UnblockUpdates

		End If

	Next

End Sub



Sub CPA_E_HorizontalAxisChanged(hPen As Object)

	UpdateMyColumn

End Sub



Sub CPA_E_PenCreated(hPen As Object)

	UpdateMyColumn

End Sub

FUNCTION UpdateMyColumn()

	OBJECT	hPA = ObjectByName("CPA");

	OBJECT	hPanes = _ObjectGetProperty(hPA, "Panes");

	OBJECT	hPane;

	OBJECT	hPens;

	OBJECT	hPen;

	OBJECT	hObjectView = _ObjectGetProperty(hPA, "ObjectView");

	OBJECT	hPaneItems  = _OBJECTGetProperty(hObjectView, "Items");

	OBJECT	hPaneItem;

	OBJECT	hPenItems;

	OBJECT	hPenItem;



	INT nPanes = _ObjectGetProperty(hPanes, "Count");

	INT nPens;

	INT iPen;

	INT iPane = 0;

	INT nSamples = _ObjectGetProperty(hPA, "NumberOfsamples");

	INT iPenItem = 0;

	INT iPaneItem = 0;



	REAL dDiff;

	REAL dtStart;

	REAL dtEnd;

	INT dtStartMs;

	INT dtEndMs;



	STRING	sText;



	FOR iPane = 1 TO nPanes DO

		hPane = _ObjectCallMethod(hPanes, "get_Item", iPane);



		IF ObjectIsValid(hPane) THEN

			hPens = _ObjectGetProperty(hPane, "Pens");

			nPens = _ObjectGetProperty(hPens, "Count");



			iPaneItem = iPaneItem + 1;



			_ObjectCallMethod(hPA, "BlockUpdates");

			hPaneItem = _ObjectCallMethod(hPaneItems, "get_Item", iPaneItem);

			iPenItem = 0;

			FOR iPen = 1 TO nPens DO

				hPen = _ObjectCallMethod(hPens, "get_Item", iPen);



				IF ObjectIsValid(hPen) THEN



					iPenItem = iPenItem + 1;

					_ObjectCallMethod(hPen, "GetHorizontalAxisTimeSpan", dtStart,
					dtStartMs, dtEnd, dtEndMs, 0);



					dDiff = ((dtEnd - dtStart) / nSamples) * 86400;



					IF dDiff > 0.001 THEN

						sText = StrFormat(dDiff, 10, 3, "seconds");

					ELSE

						sText = "0.001 seconds"

					END

					hPenItems = _ObjectGetProperty(hPaneItem, "Items");

					hPenItem = _ObjectCallMethod(hPenItems, "get_Item", iPenItem);



					_ObjectCallMethod(hPenItem, "PutField", "DisplayPeriod", sText);

				END

			END

			_ObjectCallMethod(hPA, "UnblockUpdates");

		END

	END

END



FUNCTION CPA_E_HorizontalAxisChanged(OBJECT hPA, OBJECT hPen)

	UpdateMyColumn();

END



FUNCTION CPA_E_PenCreated(OBJECT hPA, OBJECT hPen)

	UpdateMyColumn();

END