Working with Custom Bar Styles

Overview

In Microsoft Project, the Gantt chart view allows users to define custom bar styles to improve visualization or emphasize specific types of tasks. This includes changing the appearance of bars (start, middle, end), adding custom colors, adjusting shapes, and configuring text labels around task bars.

Aspose.Tasks for .NET supports this level of customization via the GanttBarStyle class. With it, developers can programmatically control how each task (or group of tasks) is displayed in the rendered Gantt chart image, making reporting and visual analysis more meaningful.

Defining a Custom Bar Style

To define a new style for a specific task or set of tasks, you must:

1. Create a new instance of GanttBarStyle.
2. Set properties like ShowForTaskUid, MiddleShape, StartShape, EndShape, FillColor, and others.
3. Add the style to the ImageSaveOptions.BarStyles collection before rendering.

Tip: The ShowForTaskUid property specifies which task UID this style applies to. You can also apply a style globally by omitting it.

Example: Apply Custom Style to a Specific Task

static void ImplementCustomBarStyle()
{
    Project project = new Project("New Project.mpp");
    project.RootTask.Children.Add("Task");

    GanttChartView view = project.DefaultView as GanttChartView;
    GanttBarStyle custom = GetCustomBarStyle();

    // Add the custom bar style to the custom bar collection of the project view
    view.CustomBarStyles.Add(custom);

    MPPSaveOptions options = new MPPSaveOptions();
    options.WriteViewData = true;

    project.Save("ImplementCustomBarStyle_out.mpp", options);
}

static GanttBarStyle GetCustomBarStyle()
{
    GanttBarStyle style = new GanttBarStyle();
    style.ShowFor = "1";
    style.MiddleShape = GanttBarMiddleShape.RectangleBottom;
    style.MiddleFillPattern = GanttBarFillPattern.MediumFill;
    style.MiddleShapeColor = Color.Blue;

    style.StartShape = GanttBarEndShape.ArrowDown;
    style.StartShapeColor = Color.Red;

    style.EndShape = GanttBarEndShape.ArrowUp;
    style.EndShapeColor = Color.Yellow;

    style.LeftField = Field.TaskResourceNames;
    style.RightField = Field.TaskName;
    style.TopField = Field.TaskStart;
    style.BottomField = Field.TaskFinish;
    style.InsideField = Field.TaskDuration;

    return style;
}

Reading Existing Custom Bar Styles

Aspose.Tasks also allows reading the GanttBarStyle objects from existing MPP files. This can be useful if you need to analyze or replicate the styling applied in Microsoft Project.

Example: Read All Custom Styles from a Project

Project project = new Project("New Project.mpp");

GanttChartView view = project.DefaultView as GanttChartView;
Console.WriteLine("Custom bar styles count: {0}", view.CustomBarStyles.Count);

GanttBarStyle style1 = view.CustomBarStyles[0];

Console.WriteLine("Style1.LeftField is TaskDurationText : {0}", style1.LeftField.Equals(Field.TaskDurationText));
Console.WriteLine("Style1.RightField is TaskResourceNames : {0}", style1.RightField.Equals(Field.TaskResourceNames));
Console.WriteLine("Style1.TopField is TaskACWP: {0}", style1.TopField.Equals(Field.TaskACWP));
Console.WriteLine("Style1.BottomField is Undefined : {0}", style1.BottomField.Equals(Field.Undefined));
Console.WriteLine("Style1.InsideField is Undefined : {0}", style1.InsideField.Equals(Field.Undefined));

GanttBarStyle style2 = view.CustomBarStyles[1];
Console.WriteLine("Style2.LeftField is TaskActualWork : {0}", style2.LeftField.Equals(Field.TaskActualWork));
Console.WriteLine("Style2.RightField is TaskActualCost : {0}", style2.RightField.Equals(Field.TaskActualCost));
Console.WriteLine("Style2.TopField is Undefined : {0}", style2.TopField.Equals(Field.Undefined));
Console.WriteLine("Style2.BottomField is Undefined : {0}", style2.BottomField.Equals(Field.Undefined));
Console.WriteLine("Style2.InsideField is Undefined : {0}", style2.InsideField.Equals(Field.Undefined));

GanttBarStyle style3 = view.CustomBarStyles[2];
Console.WriteLine("Style3.LeftField is TaskPercentComplete : {0}", style3.LeftField.Equals(Field.TaskPercentComplete));
Console.WriteLine("Style3.RightField is TaskPercentWorkComplete : {0}", style3.RightField.Equals(Field.TaskPercentWorkComplete));
Console.WriteLine("Style3.TopField is Field.TaskActive : {0}", style3.TopField.Equals(Field.TaskActive));
Console.WriteLine("Style3.BottomField is TaskActualCost : {0}", style3.BottomField.Equals(Field.TaskActualCost));
Console.WriteLine("Style3.InsideField is Field.TaskActualDuration : {0}", style3.InsideField.Equals(Field.TaskActualDuration));

Console.WriteLine("Style3.StartShape is HouseDown : {0}", style3.StartShape.Equals(GanttBarEndShape.HouseDown));
Console.WriteLine("Style3.StartShapeType is Framed : {0}", style3.StartShapeType.Equals(GanttBarType.Framed));
Console.WriteLine("Style3.StartShapeColor is Red : {0}", style3.StartShapeColor.Equals(Color.FromArgb(Color.Red.ToArgb())));

Console.WriteLine("Style3.EndShape is CircleDiamond : {0}", style3.EndShape.Equals(GanttBarEndShape.CircleDiamond));
Console.WriteLine("Style3.EndShapeType is Solid : {0}",  style3.EndShapeType.Equals(GanttBarType.Solid) );
Console.WriteLine("Style3.EndShapeColor is Yellow : {0}",  style3.EndShapeColor.Equals(Color.FromArgb(Color.Yellow.ToArgb())));

Console.WriteLine("Style3.MiddleShape is RectangleTop : {0}", style3.MiddleShape.Equals(GanttBarMiddleShape.RectangleTop));
Console.WriteLine("Style3.MiddleFillPattern is SolidFill : {0}", style3.MiddleFillPattern.Equals(GanttBarFillPattern.SolidFill));
Console.WriteLine("Style3.EndShapeColor is Red : {0}", style3.MiddleShapeColor.Equals(Color.FromArgb(Color.Red.ToArgb())));

Common Use Cases

Custom bar styles are commonly used to:

• Visually distinguish milestones, critical tasks, or summary tasks.
• Apply color-coding for different teams or departments.
• Label tasks dynamically based on custom fields (Text1, ResourceNames, etc.).
• Highlight delayed tasks with unique colors or shapes.

Summary

Aspose.Tasks for .NET provides full control over how tasks are visualized in Gantt charts via the GanttBarStyle class. Whether you’re creating a new report or replicating Microsoft Project output, the API allows for precise control of shapes, colors, text labels, and styling logic.