How To Create Aspose.Tasks Project Calculation Modes

When working with projects, different scenarios may require different approaches to recalculating schedules, costs, or resources. Aspose.Tasks for .NET provides flexible calculation modes, so you can decide whether project properties should be updated automatically, manually, or not recalculated at all. This ensures you have full control over performance, accuracy, and the behavior of your project files.

Project Calculation Modes

Aspose.Tasks for .NET API provides three project calculation modes which define how values of dependent properties are calculated when the value of a property is set.
Choosing the right mode allows you to balance between efficiency and precision depending on your use case.

These calculation modes are:

• None – Sets only necessary properties and does not perform any calculations. Useful when you want to adjust values quickly without recalculating the entire project.
• Manual – Sets dependent object properties without triggering full recalculation of other project data. This mode is helpful when partial updates are needed.
• Automatic – Recalculates dates, work and cost properties immediately after changes. Recommended when accuracy and consistency are critical.

The examples below demonstrate how each mode can be applied in code.

Project Calculation Mode - None

In this mode, the project skips recalculation. It is efficient when performing batch updates or when you only need to change raw values without dependencies being adjusted.

// Create empty project and set calculation mode to None
Project project = new Project();
project.CalculationMode = CalculationMode.None;

// Add a new task
Task task = project.RootTask.Children.Add("Task");

// Note that even ids were not calculated
Console.WriteLine("Task.Id Equals 0 : {0} ",  task.Get(Tsk.Id).Equals(0));
Console.WriteLine("Task.OutlineLevel Equals 0 : {0} ", task.Get(Tsk.OutlineLevel).Equals(0));
Console.WriteLine("Task Start Equals DateTime.MinValue : {0} ", task.Get(Tsk.Start).Equals(DateTime.MinValue));
Console.WriteLine("Task Finish Equals DateTime.MinValue : {0} ", task.Get(Tsk.Finish).Equals(DateTime.MinValue));
Console.WriteLine("Task Duration Equals 0 mins : {0} ", task.Get(Tsk.Duration).ToString().Equals("0 mins"));

// Set duration property
task.Set(Tsk.Duration, project.GetDuration(2, TimeUnitType.Day));
Console.WriteLine("Task Duration Equals 2 days : {0} ", task.Get(Tsk.Duration).ToString().Equals("2 days"));
Console.WriteLine("Task Start Equals DateTime.MinValue  : {0} ", task.Get(Tsk.Start).Equals(DateTime.MinValue));
Console.WriteLine("Task Finish Equals DateTime.MinValue  : {0} ", task.Get(Tsk.Finish).Equals(DateTime.MinValue));

Project Calculation Mode - Manual

Manual mode updates dependent object properties but avoids triggering global recalculations.
This strikes a balance between performance and keeping related values aligned.

// Create empty project and set calculation mode to Manual
Project project = new Project();
project.CalculationMode = CalculationMode.Manual;

// Set project start date and add new tasks
project.Set(Prj.StartDate, new DateTime(2015, 4, 15));
Task task1 = project.RootTask.Children.Add("Task 1");
Task task2 = project.RootTask.Children.Add("Task 2");

// The necessary properties are set in manual mode
Console.WriteLine("Task1.Id Equals 1 : {0} ", task1.Get(Tsk.Id).Equals(1));
Console.WriteLine("Task1 OutlineLevel Equals 1 : {0} ", task1.Get(Tsk.OutlineLevel).Equals(1));
Console.WriteLine("Task1 Start Equals 15/04/2015 08:00 AM : {0} ", task1.Get(Tsk.Start).Equals(new DateTime(2015, 4, 15, 8, 0, 0)));
Console.WriteLine("Task1 Finish Equals 15/04/2015 05:00 PM : {0} ", task1.Get(Tsk.Finish).Equals(new DateTime(2015, 4, 15, 17, 0, 0)));
Console.WriteLine("Task1 Duration Equals 1 day : {0} ", task1.Get(Tsk.Duration).ToString().Equals("1 day"));
Console.WriteLine("Task2 Start Equals 15/04/2015 08:00 AM : {0} ", task2.Get(Tsk.Start).Equals(new DateTime(2015, 4, 15, 8, 0, 0)));
Console.WriteLine("Task2 Finish Equals 15/04/2015 05:00 PM : {0} ", task2.Get(Tsk.Finish).Equals(new DateTime(2015, 4, 15, 17, 0, 0)));
Console.WriteLine("Task2 Duration Equals 1 day : {0} ", task2.Get(Tsk.Duration).ToString().Equals("1 day"));

// When we link two tasks together their dates are not recalculated in manual mode
TaskLink link = project.TaskLinks.Add(task1, task2, TaskLinkType.FinishToStart);

// Task 2 Start has not been changed
Console.WriteLine("Task1 Start Equals Task2 Start : {0} ", task1.Get(Tsk.Start).Equals(task2.Get(Tsk.Start)));
Console.WriteLine("Task1 Finish Equals Task2 Finish : {0} ", task1.Get(Tsk.Finish).Equals(task2.Get(Tsk.Finish)));

Project Calculation Mode - Automatic

Automatic mode ensures that all dates, costs, and work values stay consistent as soon as any related property changes.
It provides maximum accuracy and is closest to how Microsoft Project handles recalculations by default.

// Create empty project and set calculation mode to Automatic
Project project = new Project();
project.CalculationMode = CalculationMode.Automatic;

// Set project start date and add new tasks
project.Set(Prj.StartDate, new DateTime(2015, 4, 15));
Task task1 = project.RootTask.Children.Add("Task 1");
Task task2 = project.RootTask.Children.Add("Task 2");

// Link tasks
TaskLink link = project.TaskLinks.Add(task1, task2, TaskLinkType.FinishToStart);

// Verify dates have been recalculated
Console.WriteLine("Task1 Start + 1 Equals Task2 Start : {0} ", task1.Get(Tsk.Start).AddDays(1).Equals(task2.Get(Tsk.Start)));
Console.WriteLine("Task1 Finish + 1 Equals Task2 Finish : {0} ", task1.Get(Tsk.Finish).AddDays(1).Equals(task2.Get(Tsk.Finish)));
Console.WriteLine("RootTask Finish Equals Task2 Finish : {0} ", task2.Get(Tsk.Finish).Equals(project.RootTask.Get(Tsk.Finish)));
Console.WriteLine("Project Finish Date Equals Task2 Finish : {0} ", task2.Get(Tsk.Finish).Equals(project.Get(Prj.FinishDate))); 

By offering three calculation modes — None, Manual, and Automatic — Aspose.Tasks for .NET gives developers the flexibility to choose how project data should be processed.
Whether you prioritize performance, control, or accuracy, the right calculation mode allows you to handle project updates in the most efficient way for your scenario.