Activity Dependencies

Activities within a project could have dependencies on other activities. The dependent activity's start time is then constrained by the predecessor activity's times. The GanttControl supports these 4 different types of dependency constraints:

There can also be a "lag" specified between the 2 times above.

A FinishToStart dependency between these 2 activities with a lag of 4 hours

is represented as follows:

{TaskName="Task 1", TaskID="5" ....}

{TaskName="Task 2", TaskID="6", PredecessorIndices="5+4"}

The PredecessorIndices property indicates a dependency with activity ID "5" and a lag of "4 hours". "5-4" would correspond to a negative lag of "-4 hours".  The lag number by default is considered a hours. If you want this to be something else then set the LagStringUnitsInHours property appropriately (24, if you want it to indicate the number of days).

The dependency type is indicated with a corresponding suffix ("FS", "SF", "SS" or "FF") as follows:

{TaskName="Task 2", TaskID="6", PredecessorIndices="5SF"}

The above example indicates a StartToFinish dependency. Specifying the "FS" (Finish To Start) suffix is optional since that's the default.

Multiple predecessors

If an activity is constrained by more than 1 predecessor activity, then the dependency is represented as follows:

PredecessorIndices="4, 2, 9+3"

Simply separate the different predecessor activity IDs by commas.

Editing the Dependencies

End-users can simply drag and drop a connection line from one activity to another in the gantt chart to setup a dependency connection between the two. This results in the default FinishToStart type of dependency. If you need to change the dependency type to something else and/or specify a lag between the from and to activity times, edit the field's value in the corresponding gantt table field.

When the end-user connects 2 tasks to create a new dependency, the DependencyLineAdded event will be raised, where you can get hold of the from and to activity as follows:

        void ganttControl_DependencyLineAdded(object sender, DependencyLineEventArgs e)

        {

            e.DependencyLine.Loaded += delegate(object s, RoutedEventArgs args)

            {

                GanttDependencyView depLineView = ((GanttDependencyLine)s).DataContext as GanttDependencyView;

                IActivity fromActivity = depLineView.Dependency.FromActivity;

                IActivity toActivity = depLineView.Dependency.ToActivity;

            };

        }

Deleting a Dependency

Easily delete the dependency programmatically as follows:

            this.ganttControl.Model.Dependencies.Remove(dependency);

Validating the predecessor-dependency setting

During runtime the gantt control validates all predecessor settings before applying it. For example, a parent cannot be a predecessor to it's child. The gantt prevents applying such dependecy settings. If you want to programatically validate a dependency setting before applying it, use this API:

// The arguments are IActivity instances

this.ganttControl.Model.CanAddNewDependency(fromActivity, toActivity);

Preventing Dependency Constraints Conditionally

You can choose to prevent getting the dependency constraints applied on some activities, conditionally as follows, by listening to the ShouldEnforceDependencyConstraintsOnActivity event.

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