2. Dependencies between tasks

Links between tasks - Ancestors and Descendants

• See documentation for Defining dependencies.

• Defining dependencies

  • Dependencies are defined in column set by

    GanttAncestors

    and / or

    GanttDescendants

    attributes.
    If defined both columns, the dependency can be entered in any 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.
    
  • The GanttDescendants and GanttAncestors are defined per Gantt cell and one value contains all dependencies of all tasks in the Gantt cell.
    The individual dependencies are separated by RangeSeparator (<Lang><Format RangeSeparator=';'/></Lang>), by defaults by semicolon ';'.
    Every task can have more dependencies.
  • The one

    dependency definition

    has this format " from,to@idtype+/-lag!float#color ", for example 3ss+3!1. Only the id is mandatory.
    • The from and to identify main bar plan or run box id. They can be omitted if the bar is default GanttTask, except for Run box.
    • The id is row id the dependency points to (for GanttDescendants) or the row id the dependency coming from (for GanttAncestors).
      The id is the only required part of the depedency definition.
    • 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 (ancestor->descendant).
    • 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 be always written with the sign + or -. The lag value is in GanttDataUnits.
      The lag can be also in percentage of duration (in workdays) of the source (ancestor) task (with % suffix).
    • 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 value is in GanttDataUnits.
      The float can be also in percentage of duration (in workdays) of the source (ancestor) task (with % suffix).
      Missing float value is set according to GanttIncorrectDependencies setting, for '1' is unlimited and for '2' is 0.
    • The color specifies color and style of the depencency line and arrow.
      There are predefined 10 colors in 4 shape sets, together 40 different lines and arrows.
  • Dependencies can be connected only to Gantt tasks, defined by

    GanttTask

    .
    It is Main by default for the first main bar plan and can be also Main1, Main2, Main3, ... for different main bar plans, All for all main bar plans, Run for the whole run and Box for individual run boxes.
  • The dependencies are attached always to the whole main bar (to the first and to the last part). But different main bar plans can have different dependencies in the same row.
    The dependencies can be attached to the whole run bar (if GanttTask contains "Run", see tutorial 06-Run_bar_as_task) or to every run box separately (if GanttTask contains "Box", see tutorial 07-Run_box_as_task).
    

• Creating and editing dependencies

  • Dependencies are fully editable by default. It is possible to restrict editing dependencies by removing dependency flag from

    GanttEdit

    .
    To not edit dependency type remove dependencytypes flag from GanttEdit. All new dependencies will get FS type in this case.
    To not edit dependency lag remove dependencylags flag from GanttEdit.
    
  • By default the dependencies can be created only between the same GanttTask type (the same Main bar plan and between run bars).
    By GanttDragDependenciesBetween is possible to permit dependencies between different main bar plans or between run bar and main bar.
    
  • By default there can be only one dependency between two bars.
    By GanttDragDependenciesMore is possible to permit more dependencies between two bars, with different or even the same type.
    
  • It is possible to permit or restrict circular dependencies by GanttCheckDependencies attribute.

• Dependency colors and shapes

  • By default the correct (normal) dependencies are shown blue, the incorrect dependencies in red and disabled dependencies in gray.
    
  • If dependency has not assigned color or when one bar edge has more connected dependencies, the dependency color can be assigned automatically according to GanttAssignDependencies and GanttDependencyColor values.
    
  • 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 or by float part in individual dependency definition.
    The color for incorrect dependency is set by GanttMarkIncorrectDependencies and GanttColorIncorrectDependencies attributes.
    The incorrect dependencies can be automatically corrected by moving tasks, see tutorial 03-Scheduling_tasks.
    
  • The

    disabled dependency

    is connected to disabled task.
    The color for disabled dependency is set by GanttMarkDisabledDependencies and GanttColorDisabledDependencies attributes.
    
  • It is possible to hide arrow or stub dependency icons by GanttDependencyArrows attribute.
• The dependencies can be controlled by API methods GetDependencies, AddDependencies and DeleteDependencies and event OnGetDependency.
• The two vertical red lines are automatically calculated base and finish dates for the whole chart. See tutorial 01-Constraints - Project constraints.