Special functions of trends

The following points won't be practiced in the application. We mention the possibilities of using the above described objects for information purposes only.
PmTrend – ReadOnly:

We come back to the PmTrend object in the application editor. Any PmTrend object can read and evaluate the data either from databases created by the PROMOTIC system or from databases created by any other system, by the 3rd party in the mode "read only". This possibility can be configured by setting the option PmTrend > Trend > Read only (new records cannot be written).

Viewing as function f(x):

The TrendsView ActiveX object can be used even as a common stand-alone viewer of 2-dimensional function f(x) (i.e. there needn't be presented only the process of the time on the x-axis).

This view type is set by the TrendsView.TimeType property, then all methods of the tvPoints object take real values instead of time parameters and they return real values instead of time values, for example the tvPoints.AddPoints method in the vTimes parameter takes the real value array instead of the time array.

See also: Example of displaying mathematical functions by a trends viewer.

Editing trend points by mouse events:

By the TrendsView ActiveX object it is possible, by clicking the mouse, to define a trend process (i.e. add new points or delete existing ones) or a graph of 2-dimensional function f(x) (according to setting the TrendsView.TimeType property), namely by definition in the script of the TrendsView.onMouseArea event. By the methods tvPoints.AddPoints, tvPoints.RemovePoints it is possible to place a new point on the position where the mouse was clicked, or to remove the point(s)from it, see the example in the onMouseArea event.

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