vtkImageTracerWidget

Section: Visualization Toolkit Widget Classes

Usage

vtkImageTracerWidget is different from other widgets in three distinct ways: 1) any sub-class of vtkProp can be input rather than just vtkProp3D, so that vtkImageActor can be set as the prop and then traced over, 2) the widget fires pick events at the input prop to decide where to move its handles, 3) the widget has 2D glyphs for handles instead of 3D spheres as is done in other sub-classes of vtk3DWidget. This widget is primarily designed for manually tracing over image data. The button actions and key modifiers are as follows for controlling the widget: 1) left button click over the image, hold and drag draws a free hand line. 2) left button click and release erases the widget line, if it exists, and repositions the first handle. 3) middle button click starts a snap drawn line. The line is terminated by clicking the middle button while depressing the ctrl key. 4) when tracing a continuous or snap drawn line, if the last cursor position is within a specified tolerance to the first handle, the widget line will form a closed loop. 5) right button clicking and holding on any handle that is part of a snap drawn line allows handle dragging: existing line segments are updated accordingly. If the path is open and AutoClose is set to On, the path can be closed by repositioning the first and last points over one another. 6) ctrl key + right button down on any handle will erase it: existing snap drawn line segments are updated accordingly. If the line was formed by continous tracing, the line is deleted leaving one handle. 7) shift key + right button down on any snap drawn line segment will insert a handle at the cursor position. The line segment is split accordingly.

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

  obj = vtkImageTracerWidget

Methods

The class vtkImageTracerWidget 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 vtkImageTracerWidget class.