FindEdges Method

Description

Analyzes the ProfilesAncestor and detects “edges” along selected profiles.

Return Type

A Long value.

The total number of edges on all Selected profiles.

Syntax

object.FindEdges ([Selector], [ClearPlacedEdges])

The FindEdges Method syntax has these parts:

Part	Description
object	An expression evaluating to an object of type McProfileEdges.
Selector	Optional. A Variant value. An empty variant, a single negative value, a single index value, or an array of zero or more index values (negative index values are legal but will be ignored). If the Selector argument is a non-negative scalar index value, then edges for the indicated profile are computed. The value must fall between zero and ProfilesAncestor.CountOfProfiles-1. If the Selector argument is Empty, Error or Null, or any negative scalar value, then edges are found for all ProfilesAncestor.CountOfProfiles profiles. In this case, IsStale is guaranteed to go False. If Selector is an array, then zero or positive values are treated as indices into the ProfilesAncestor profiles, negative values are legal but ignored. In this case, edges will be computed only for the indicated profiles. Edges on all other profiles will be undisturbed. Index values greater or equal to the ProfilesAncestor.CountOfProfiles property are illegal.
ClearPlacedEdges	Optional. A Boolean value. If True (the default), all edges on the selected profiles are removed before new ones are detected and placed. If False, then any existing edges that were added by the AddEdges method (ones with the mcpeeaAddedEdgeFlag set in the EdgeAttributes property) will not be cleared before detecting new edges. Automatically found edges are always cleared before new ones are placed.

Remarks

The FindEdges method invokes the EdgeFindingMethod to find “edges” along selected profiles in the ProfilesAncestor.

Edge finding on each profile is a two phase process: first the profile is analyzed to create a “weighted profile”, and then peak locations above a threshold value are marked as “edges” on that weighted profile. Each element of this process is controlled by McProfileEdges properties. The analysis of the profile to get the weighted profile is controlled by the EdgeFindingMethod, ChannelOfInterest, Weights or Pattern, MatchLength, SizeWeighting and WeightingFlags properties.

The result of the first phase profile analysis is available as the WeightedProfile property. In the second phase, edges are detected on the WeightedProfile based on the ThresholdForEdges, MatchLength, MatchHotspot, MinEdgesPerProfile and MaxEdgesPerProfile properties. Assigning to the WeightedProfile property will invoke this second, edge detection phase directly. This allows custom weighting analyses to be performed (e.g., some analysis of a color profile), while still making use of the McProfileEdges object's tools for finding, maintaining and displaying edges. And of course edges can be added at arbitrary positions along the profiles with the AddEdges method.

FindEdges takes a Selector argument which allows edges to be found on a selected sub-set of the ProfilesAncestor profiles; existing edges on unselected profiles are not disturbed, even if those edges are “stale”. The IsStale property will become False after calling FindEdges only if all “stale” profiles are included in the Selector argument (the default is to find edges on all profiles).

If any edges were added, changed or removed then an McObjMgr McObjStandardNotify.SpecialNotify is fired on the McObject backing this McProfileEdges. The notify code will be SNC_NOTIFY_HO_PROPERTYCHANGED and the notify data will be ID_IMcProfileEdges_EdgeCounts. You can use an instance of McNotifySink WithEvents in VBA to track these notifies.