Annotation view in WPF

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The WpfAnnotationView class is always created on the base of AnnotationData class and defines the annotation's visual appearance and the way the user may interact with annotation.

Link between classes derived from AnnotationData and WpfAnnotationView is registered using the WpfAnnotationViewFactory.RegisterViewForAnnotationData method.

As in the case with classes derived from AnnotationData class, the classes derived from WpfAnnotationView class are divided into 3 types:

views for annotations, which are based on rectangle (base class is WpfRectangleAnnotationView):
- WpfRectangleAnnotationView - defines view for RectangleAnnotationData annotation. This class is the base class for all views of annotations based on rectangle.
- WpfEllipseAnnotationView - defines view for EllipseAnnotationData annotation.
- WpfImageAnnotationView - defines view for EmbeddedImageAnnotationData annotation.
- WpfReferencedImageAnnotationView - defines view for ReferencedImageAnnotationData annotation.
- WpfHighlightAnnotationView - defines view for HighlightAnnotationData annotation.
- WpfTextAnnotationView - defines view for TextAnnotationData annotation.
- WpfLinkAnnotationView - defines view for LinkAnnotationData annotation.
- WpfStampAnnotationView - defines view for StampAnnotationData annotation.
views for annotations, which are based on a set of points (base class is WpfLineAnnotationViewBase):
- WpfLineAnnotationView - defines view for LineAnnotationData annotation.
- WpfLinesAnnotationView - defines view for LinesAnnotationData annotation.
- WpfPolygonAnnotationView - defines view for PolygonAnnotationData annotation.
- WpfRulerAnnotationView - defines view for RulerAnnotationData annotation.
- WpfRulersAnnotationView - defines view for RulersAnnotationData annotation.
- WpfAngleAnnotationView - defines view for AngleAnnotationData annotation.
- WpfLeaderLineAnnotationView - defines view for LeaderLineAnnotationData annotation.
views for composite annotations (base class is WpfCompositeAnnotationView):
- WpfFreeTextAnnotationView - defines view for FreeTextAnnotationData annotation. This view is the combination of WpfTextAnnotationView and WpfLeaderLineAnnotationView.
- WpfGroupAnnotationView - defines view for GroupAnnotationData annotation.

WpfAnnotationView class contains the WpfAnnotationView.Data property, which allows to get reference to a linked instance AnnotationData class. Also WpfAnnotationView class contains a set of properties similar to the properties of AnnotationData class, which allow to relay annotation's properties through WpfAnnotationView.

Here is C#/VB.NET code that shows how to create an instance of view for EllipseAnnotationData annotation:

public static Vintasoft.Imaging.Annotation.Wpf.UI.WpfAnnotationView CreateViewForEllipseAnnotationData(
    Vintasoft.Imaging.Annotation.EllipseAnnotationData ellipseAnnotation)
{
    return new Vintasoft.Imaging.Annotation.Wpf.UI.WpfEllipseAnnotationView(ellipseAnnotation);
}

VB.NET

Public Shared Function CreateViewForEllipseAnnotationData(ellipseAnnotation As Vintasoft.Imaging.Annotation.EllipseAnnotationData) As Vintasoft.Imaging.Annotation.Wpf.UI.WpfAnnotationView
    Return New Vintasoft.Imaging.Annotation.Wpf.UI.WpfEllipseAnnotationView(ellipseAnnotation)
End Function

Annotation bounding rectangles

The visual appearance of annotation has several bounding rectangle types. The following types are used for solving various tasks related to correct drawing and interaction with annotation:

Bounding Box - defines the rectangle aligned by axises, which encloses annotation. That rectangle is defined only by WpfAnnotationView.Location, WpfAnnotationView.Size and WpfAnnotationView.Rotation properties of annotation, and may be used as a basis for Drawing Box calculating. For getting the rectangle is necessary to call WpfAnnotationView.GetBoundingBox method.
Author Bounding Box - defines the rectangle aligned by axises, which by-turn defines the annotation area during annotation transformation, as well as is used for annotation selection in annotation viewer. In most cases Author Bounding Box conforms to Bounding Box area of annotation. For getting the rectangle is necessary to call WpfAnnotationView.GetAuthorBoundingBox method. This method is a virtual one, that's why it's possible to override it in classes derived from WpfAnnotationView class.
Drawing Box - defines the rectangle aligned by axises, which fully encloses the entire visual part of annotation, but nothing more. Drawing Box can be larger than Bounding Box, because of additional visual elements of annotation, like annotation shadow, caption with value of annotation length, smoothinh of interpolated lines, etc.

Render annotations on drawing context

WpfAnnotationView class provides WpfAnnotationView.Render method, which allows to render annotation on specified System.Windows.Media.DrawingContext object.

Here is C#/VB.NET code that shows how to render specified annotation on specified image:

public static void DrawAnnotationOnImage(
    Vintasoft.Imaging.Annotation.Wpf.UI.WpfAnnotationViewCollection annotations,
    Vintasoft.Imaging.VintasoftImage image)
{
    annotations.Draw(image, (Vintasoft.Imaging.VintasoftImage)image.Clone());
}

VB.NET

Public Shared Sub DrawAnnotationOnImage(annotations As Vintasoft.Imaging.Annotation.Wpf.UI.WpfAnnotationViewCollection, image As Vintasoft.Imaging.VintasoftImage)
    annotations.Draw(image, DirectCast(image.Clone(), Vintasoft.Imaging.VintasoftImage))
End Sub

Focus annotation in WPF annotation viewer

Every annotation may receive focus in the image viewer. When an annotation is focused there appears a selection rectangle around it, which can be transformed (scaled, mirrored, rotated) and the annotation will be transformed in proportion to the selection rectangle.

The views for annotations, which are based on a set of points, in addition, may be transformed using points. When annotation is selected - all of its points become selected, the user may change the location of each point using dragging.

Also the views for annotations, which are based on a set of points, support composite selection mode, which allows to transform annotation both using selection rectangle and using points.

The selection/transformation mode of annotation, which are based on a set of points, may be changed using WpfLineAnnotationViewBase.GripMode property.

Build and transform annotation in WPF annotation viewer

WpfAnnotationView.Builder property defines the interactive controller, which is used for annotation building.
WpfAnnotationView.Transformer property defines the interactive controller, which is used for annotation transformation.

Also WpfAnnotationView class has WpfAnnotationView.InteractionController property which defines the currently used interactive controller.
Detailed information about building and transformation of annotation can be found in article: Building and transformation of annotations in WPF.

Monitor the annotation state

WpfAnnotationView class provides events, which allow to monitor the annotation state:

WpfAnnotationView.Rendering - occurs when the annotation is rendering.
WpfAnnotationView.Rendered - occurs when the annotation is rendered.
WpfAnnotationView.MouseDown - occurs when the mouse pointer is over the annotation and the mouse button is pressed.
WpfAnnotationView.MouseUp - occurs when the mouse pointer is over the annotation and the mouse button is released.
WpfAnnotationView.MouseEnter - occurs when the mouse pointer enters the annotation.
WpfAnnotationView.MouseMove - occurs when the mouse pointer rests on the annotation.
WpfAnnotationView.MouseLeave - occurs when the mouse pointer leaves the annotation.
WpfAnnotationView.MouseWheel - occurs when the mouse wheel moves while the annotation has focus.
WpfAnnotationView.Click - occurs when the annotation is clicked.
WpfAnnotationView.DoubleClick - occurs when the annotation is double-clicked.
WpfAnnotationView.StateChanged - occurs when the state of annotation is changed, e.g. arrived PropertyChanged event from Data object.

Annotation collection

The WpfAnnotationViewCollection class is always created on the base of AnnotationDataCollection class and represents a collection of annotation's views, which are linked with annotation data from AnnotationDataCollection.
The WpfAnnotationViewCollection class makes changes synchronously in its collection and in linked AnnotationDataCollection.
The WpfAnnotationViewCollection class provides the ability to add, remove, reorder, resort elements, transform to WpfAnnotationView elements array, access to AnnotationDataCollection. Also WpfAnnotationViewCollection class allows to:

search WpfAnnotationView element linked with specified instance of AnnotationData
render all views from a collection on specified System.Windows.Media.DrawingContext object
render all views from a collection on specified VintasoftImage.

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