TdxGanttControlTaskDragAndDropEvent Type

Performs a set of actions during task row rearrangement in the Chart View‘s task sheet.

Declaration

TdxGanttControlTaskDragAndDropEvent = procedure(Sender: TObject; ATask: TdxGanttControlTask; ANewID: Integer; var AAccept: Boolean) of object;

Parameters

Name	Type	Description
Sender	TObject	The Chart View that raised the event.
ATask	TdxGanttControlTask	A task that a user drags.
ANewID	Integer	A new ID of the task.
AAccept	Boolean	If True, a user can drop the dragged sheet row that corresponds to a task. If False, the operation is declined.

Remarks

You can open the Features Demo and modify its code. The code snippet below shows how to handle the OnTaskDragDrop event to allow users to rearrange tasks in their summary task:

Delphi

procedure TFeaturesDemoMainForm.GanttControlViewChartOptionsSheetTaskDragAndDrop(
  Sender: TObject; ATask: TdxGanttControlTask; ANewID: Integer; var AAccept: Boolean);
  function GetSummaryID(ATaskID: Integer): Integer;
  var
    I: Integer;
    AChild: TdxGanttControlTask;
  begin
    Result := 0;
    ATaskID := Min(ATaskID, GanttControl.DataModel.Tasks.Count - 1);
    AChild := GanttControl.DataModel.Tasks[ATaskID];
    if AChild.OutlineLevel = 0 then
      Exit;
    for I := AChild.ID - 1 downto 0 do
      if (GanttControl.DataModel.Tasks[I].Summary) and (GanttControl.DataModel.Tasks[I].OutlineLevel = AChild.OutlineLevel - 1) then
        Exit(I);
  end;
begin
  inherited;
  AAccept := GetSummaryID(ATask.ID) = GetSummaryID(ANewID);
end;

C++

void __fastcall TFeaturesDemoMainForm::GanttControlViewChartOptionsSheetTaskDragAndDrop(TObject *Sender,
          TdxGanttControlTask *ATask, int ANewID, bool &AAccept)
{
  AAccept = GetSummaryID(ATask->ID) == GetSummaryID(ANewID);
}
//---------------------------------------------------------------------------
int TFeaturesDemoMainForm::GetSummaryID(int ATaskID)
{
  ATaskID = Min(ATaskID, GanttControl->DataModel->Tasks->Count - 1);
  TdxGanttControlTasks *ATasks = GanttControl->DataModel->Tasks;
  TdxGanttControlTask *AChild = ATasks->Items[ATaskID];;
  if (AChild->OutlineLevel == 0)
    return 0;
  for (int I = AChild->ID - 1; I >= 0; I--)
    if (ATasks->Items[I]->Summary && (ATasks->Items[I]->OutlineLevel == AChild->OutlineLevel - 1))
      return I;
  return 0;
}