TreeGrid Gantt Chart Tutorial
3. Dependencies between tasks
Links between tasks - Ancestors and Descendants
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Dependencies are defined in column set by
GanttAncestors
or GanttDescendants
.
If defined both columns, the dependency can be entered only in one and is mirrored to the other column.
The GanttAncestors (in some other programs called predecessors) are the previous tasks and the GanttDescendants (successors) are the next tasks.
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Every task can have more dependencies defined in ancestors or descendants, separated by RangeSeparator, by defaults by semicolon ';'.
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The one dependency definition has this format "idtype+/-lag!float", for example 3ss+3!1. Only the id is mandatory.
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The id is row id the dependency points to (for GanttDescendants) or the row id the dependency coming from (for GanttAncestors).
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The type can be fs (finish->start),ff (finish->finish),ss (start->start) and sf (start->finish).
The default is fs that is used if the type is omited.
The type controls which edge of the tasks will be referenced.
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The lag is reserved time between dependency start and its end, the lag is used to check if the dependency is correct or not and when correcting dependencies.
The lag can be positive or negative, it must always written with the sign + or -. The lag value is in GanttDataUnits.
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The float value is maximal permitted time between dependency start+lag and its end, the float is used to check if the dependency is correct or not and when correcting dependencies.
The float is value in GanttDataUnits.
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For which bar type will be dependencies connect is set by
GanttObject
.
It is Main by default for the main bar and can be also Flow and Run to connect dependencies for these bar types.
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The correct dependencies are shown blue, the incorrect dependencies in red.
The incorrect dependency has its end before its start. It is possible also to mark as incorrect dependency the one that has not exactly its start equal to its end.
Or mark all dependencies always correct.
It is controlled by GanttIncorrectDependencies attribute.
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The two vertical red lines are automatically calculated base and finish dates for the whole chart. See next example Gantt Constraints.