vtkCaptionActor2D

Section: Visualization Toolkit Hybrid Classes

Usage

vtkCaptionActor2D is a hybrid 2D/3D actor that is used to associate text with a point (the AttachmentPoint) in the scene. The caption can be drawn with a rectangular border and a leader connecting the caption to the attachment point. Optionally, the leader can be glyphed at its endpoint to create arrow heads or other indicators. To use the caption actor, you normally specify the Position and Position2 coordinates (these are inherited from the vtkActor2D superclass). (Note that Position2 can be set using vtkActor2D's SetWidth() and SetHeight() methods.) Position and Position2 define the size of the caption, and a third point, the AttachmentPoint, defines a point that the caption is associated with. You must also define the caption text, whether you want a border around the caption, and whether you want a leader from the caption to the attachment point. The font attributes of the text can be set through the vtkTextProperty associated to this actor. You also indicate whether you want the leader to be 2D or 3D. (2D leaders are always drawn over the underlying geometry. 3D leaders may be occluded by the geometry.) The leader may also be terminated by an optional glyph (e.g., arrow).

The trickiest part about using this class is setting Position, Position2, and AttachmentPoint correctly. These instance variables are vtkCoordinates, and can be set up in various ways. In default usage, the AttachmentPoint is defined in the world coordinate system, Position is the lower-left corner of the caption and relative to AttachmentPoint (defined in display coordaintes, i.e., pixels), and Position2 is relative to Position and is the upper-right corner (also in display coordinates). However, the user has full control over the coordinates, and can do things like place the caption in a fixed position in the renderer, with the leader moving with the AttachmentPoint.

To create an instance of class vtkCaptionActor2D, simply invoke its constructor as follows

  obj = vtkCaptionActor2D

Methods

The class vtkCaptionActor2D has several methods that can be used. They are listed below. Note that the documentation is translated automatically from the VTK sources, and may not be completely intelligible. When in doubt, consult the VTK website. In the methods listed below, obj is an instance of the vtkCaptionActor2D class.