Task Percent Complete shows the completion status of the task. To specify the completion status of a task in the GanttView, you can use the PercentComplete property of the Task class.

A 100 percent complete task is represented differently in the GanttView control. The following image shows the task indicator which appears next to the tasks which are 100% complete:

In code, the value of PercentComplete property should be between 0 and 1. For example, if you want to set PercentComplete property for a task to 30% then, write the following code:

//Set task percent complete in GanttView control
Task1.PercentComplete = 0.30;