Nevron .NET Vision Documentation
Layers

Layers are the primary diagram element containers, which can be used to logically group related elements. Typically layers contain only shapes, but can also contain other types of diagram elements (including other layers). The content of each drawing is organized in layers. Each layer is represented by an instance of the NLayer class.
Active layer

Of all layers currently existing in a drawing only one can be active at a time. The currently active layer can be obtained from the ActiveLayer property of the NDrawingDocument class. For example:

C#
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// obtain the document active layer
NLayer activeLayer = document.ActiveLayer;
Visual Basic
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' obtain the document active layer
Dim activeLayer As NLayer = document.ActiveLayer

Drawings can have multiple layers, which are accessible from the Layers property. The active layer for a drawing is specified by the ActiveLayerUniqueId property of the NDrawingDocument class. The following code adds a new layer to a drawing document and makes it the currently active one:

C#
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// create a new layer and make it the active one
NLayer layer = new NLayer();
drawingDocument.Layers.AddChild(layer);
drawingDocument.Layers.ActiveLayerUniqueId = layer.UniqueId;
Visual Basic
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' create a new layer and make it the active one
Dim layer As New NLayer
drawingDocument.Layers.AddChild(layer)
drawingDocument.Layers.ActiveLayerUniqueId = layer.UniqueId
Drawing views by default modify the content of the currently active layer. This helps you focus on the concrete active layer content.
Layer features

Layers implement the following features:

  • Painting - layers implement the INPaintable interface. The implementation delegates the painting to the layer children. The layer visibility is controlled from its Visible property.
    C#
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    // hide the active layer
    drawingDocument.ActiveLayer.Visible = false;
    
    Visual Basic
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    ' hide the active layer
    drawingDocument.ActiveLayer.Visible = False
    
  • Shadows - object shadows can be cast on a per layer basis. For example:
    C#
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    // cast object shadows behind all nodes in this layer
    drawingDocument.ShadowsZOrder = ShadowsZOrder.BehindLayer;
    
    Visual Basic
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    ' cast object shadows behind all nodes in this layer
    drawingDocument.ShadowsZOrder = ShadowsZOrder.BehindLayer
    
  • Hit Tests  - you can hit test only the elements, which reside in a particular layer, hence NLayer implements the INHitTest interface.
Related Examples
Windows Forms: Document Object Model - Layers folder 
See Also

 

 


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