The building of annotation is performed by annotation builder, the transformation of annotation is performed by annotation transformer. The visual tool gets information about builder and transformer from AnnotationView class:

• AnnotationView.Builder - defines the interactive controller, which must be used for building of annotation.
• AnnotationView.Transformer - defines the interactive controller, which must be used for transformation of annotation.
• AnnotationView.InteractionController - defines the current interactive controller.

Build annotation in WinForms annotation viewer

For newly created annotation the value of AnnotationView.InteractionController property is equal to the value of AnnotationView.Builder property, i.e. annotation is ready for building.
The AnnotationVisualTool.AddAndBuildAnnotation method allows to start the annotation building process, i.e. method adds the annotation into the annotation collection of focused image, gets the current interaction controller (builder) using AnnotationView.InteractionController property and starts the building of annotation.
For annotation building can be used the following interaction controllers (builders):

• RectangularAnnotationBuilder - the builder for rectangular-based annotations
• PointBasedAnnotationFreehandBuilder - the builder for point-based annotations, which builds freehand annotation.
• PointBasedAnnotationLineBuilder - the builder for point-based annotations, which builds line annotation.
• PointBasedAnnotationPointBuilder - the builder for point-based annotations, which builds lines annotation.

Transform annotation in WinForms annotation viewer

Transformation of annotation, which is focused in AnnotationViewer, can be started using mouse. For annotation transformation can be used the following interactive controllers:

• RectangularAnnotationTransformer - the transformer of rectangular annotations. Implements relocation, size change, rotation of annotation.
• RectangularTextAnnotationTransformer - the transformer of rectangular annotations implementing IRectangularTextAnnotation interface, which defines rectangular annotation containing Text property of string type. That transformer can be derived from RectangularTextAnnotationTransformer and extends its functionality, providing the window for editing text of annotation.
• PointBasedAnnotationPointTransformer - the transformer for point-based annotations. Implements marking and repositioning of annotation's points.
• PointBasedAnnotationRectangularTransformer - the transformer for point-based annotations. Transforms annotation using its bounding rectangle. Implements relocation, size change, rotation of annotation.

Transform annotation using several controllers

The CompositeInteractionController class allows to combine several interactive controllers.

For example, FreeTextAnnotationView uses composite interaction controller because FreeTextAnnotationView consists from 2 annotations (TextAnnotationView and LeaderLineAnnotationView) and needs to interact with both annotations using different interactive controllers:

• RectangularAnnotationTransformer transforms TextAnnotationView
• PointBasedAnnotationPointTransformer transforms LeaderLineAnnotationView
• RectangularAnnotationTransformer transforms CompositeAnnotationView (the entire annotation)