Tags

A tag is an annotation used to identify drawing elements. The API exposes the IndependentTag and RoomTag classes to cover most tags used in the Revit application. For more details about RoomTag, see Rooms in the Revit Architecture section.

Note: The IndependentTag class represents the tag element in Revit and other specific tags such as keynote, beam system tag, electronic circuit symbol (Revit MEP), and so on. In Revit internal code, the specific tags have corresponding classes derived from IndependentTag. As a result, specific features are not exposed by the API and cannot be created using the NewTag() method. They can be distinguished by the following categories:

Table 37: Tag Name and Category

Tag Name	BuiltInCategory
Keynote Tag	OST_KeynoteTags
Beam System Tag	OST_BeamSystemTags
Electronic Circuit Tag	OST_ElectricalCircuitTags
Span Direction Tag	OST_SpanDirectionSymbol
Path Reinforcement Span Tag	OST_PathReinSpanSymbol
Rebar System Span Tag	OST_IOSRebarSystemSpanSymbolCtrl

In this section, the main focus is on the tag type represented in the following picture.

Figure 73: IndependentTag

Every category in the family library has a pre-made tag. Some tags are automatically loaded with the default Revit application template, while others are loaded manually. The IndependentTag objects return different categories based on the host element if it is created using the By Category option. For example, the Wall and Floor IndependentTag are respectively OST_WallTags and OST_FloorTags.

If the tag is created using the Multi-Category or Material style, their categories are respectively OST_MultiCategoryTags and OST_MaterialTags.

Note: Note that NewTag() only works in the 2D view or in a locked 3D view, otherwise an exception is thrown. The following code is an example of IndependentTag creation. Run it when the level view is the active view.

Note: You can't change the text displayed in the IndependentTag directly. You need to change the parameter that is used to populate tag text in the Family Type for the Element that's being tagged. In the example below, that parameter is "Type Mark", although this setting can be changed in the Family Editor in the Revit UI.

Code Region 16-5: Creating an IndependentTag

private IndependentTag CreateIndependentTag(Autodesk.Revit.DB.Document document, Wall wall)
{
    // make sure active view is not a 3D view
    Autodesk.Revit.DB.View view = document.ActiveView;
            
    // define tag mode and tag orientation for new tag
    TagMode tagMode = TagMode.TM_ADDBY_CATEGORY;
    TagOrientation tagorn = TagOrientation.Horizontal;

    // Add the tag to the middle of the wall
    LocationCurve wallLoc = wall.Location as LocationCurve;
    XYZ wallStart = wallLoc.Curve.GetEndPoint(0);
    XYZ wallEnd = wallLoc.Curve.GetEndPoint(1);
    XYZ wallMid = wallLoc.Curve.Evaluate(0.5, true);

    IndependentTag newTag = document.Create.NewTag(view, wall, true, tagMode, tagorn, wallMid);
    if (null == newTag)
    {
        throw new Exception("Create IndependentTag Failed.");
    }

    // newTag.TagText is read-only, so we change the Type Mark type parameter to
    // set the tag text.  The label parameter for the tag family determines
    // what type parameter is used for the tag text.

    WallType type = wall.WallType;

    Parameter foundParameter = type.get_Parameter("Type Mark");
    bool result = foundParameter.Set("Hello");

    // set leader mode free
    // otherwise leader end point move with elbow point

    newTag.LeaderEndCondition = LeaderEndCondition.Free;
    XYZ elbowPnt = wallMid + new XYZ(5.0, 5.0, 0.0);
    newTag.LeaderElbow = elbowPnt;
    XYZ headerPnt = wallMid + new XYZ(10.0, 10.0, 0.0);
    newTag.TagHeadPosition = headerPnt;

    return newTag;
}

Figure 74: Create IndependentTag using sample code