The content of each drawing is divided in layers. The layers of a drawing are contained in a NLayerCollection instance, accessible from the Layers property. Of all layers in a drawing only one can be active at a time. The active layer is obtained from the ActiveLayer property and is specified by the ActiveLayerUniqueId property. By default each drawing is created with only one layer, which is at the same time the active layer.

The following code adds a new layer to a drawing document and makes it the currently active one:

// create a new layer and make it the active one
NLayer layer = new NLayer();
drawing.Layers.AddChild(layer);
drawing.Layers.ActiveLayerUniqueId = layer.UniqueId;

' create a new layer and make it the active one
Dim layer As New NLayer
drawing.Layers.AddChild(layer)
drawing.Layers.ActiveLayerUniqueId = layer.UniqueId

Typically you will add shapes to the active layer. For example:

// add a rectangle shape to the active layer
drawing.ActiveLayer.AddChild(new NRectangleShape(0, 0, 100, 100);

' add a rectangle shape to the active layer
drawing.ActiveLayer.AddChild(New NRectangleShape(0, 0, 100, 100))

Guidelines are infinite lines, which help you better align and reposition the content of a drawing. Currently there are two types of guidelines - horizontal and vertical - represented by the NHorizontalGuideline and NVerticalGuideline classes respectively. They both derive from the base NGuideline abstract class. The guidelines of a drawing are contained in an instance of the NGuidelineCollection class, an instance of which can be obtained from the Guidelines property.

The following code adds a horizontal and a vertical guideline to a drawing document:

// create a horizontal guideline with Y coordinate 20 (in scene units)
NHorizontalGuideline hguide =  new NHorizontalGuideline(20);
drawing.Guidelines.AddChild(hguide);
// create a vertical guideline with X coordinate 30 (in scene units)
NVerticalGuideline vguide =  new NVerticalGuideline(20);
drawing.Guidelines.AddChild(vguide);

' create a horizontal guideline with Y coordinate 20 (in scene units)
Dim hguide As New NHorizontalGuideline(30)
drawing.Guidelines.AddChild(hguide)
' create a vertical guideline with X coordinate 30 (in scene units)
Dim vguide As New NVerticalGuideline(30)
drawing.Guidelines.AddChild(vguide)

The content of a drawing is measured in logical measurement units. The logical measurement unit is controlled by the MeasurementUnit property. The measurement unit in which the content is painted is called world measurement unit. In case there is no drawing scale the world measurement unit is equal to the logical measurement unit. This is the most common case.

Some applications however require to display either too small or too large scenes, which are impossible to visualize without a drawing scale. You must have a large monitor to display a room of 3x3 meters and there is no monitor, which can display something measured in kilometers. In these cases you must use a drawing scale.

Drawing scale is a user defined ratio between the logical measurement unit and the world measurement unit. For example 1 meter = 1 mm is a commonly used Metric drawing scale. The ratio can however not be 1:1 - you can for example specify: 1 meter = 2 mm.

Drawing scale helps you work with the document content as if it is measured with the real world measurement unit that you want to use. For example: a room can be defined as a rectangle with width 3 and height 3 meters in logical measurement units. If the 1 meter = 2 mm drawing scale is applied, on the screen it will be represented by a rectangle with width 6 mm and height 6 mm. In case there is no drawing scale the world measurement unit is equal to the logical measurement unit.

The following code example applies a drawing scale in which 1 meter = 1 mm:

drawing.MeasurementUnit = NMetricUnit.Meter;
drawing.DrawingScaleMode = DrawingScaleMode.CustomScale;
drawing.CustomWorldMeasurementUnit = NMetricUnit.Millimeter;
drawing.CustomScale = 1;

drawing.MeasurementUnit = NMetricUnit.Meter
drawing.DrawingScaleMode = DrawingScaleMode.CustomScale
drawing.CustomWorldMeasurementUnit = NMetricUnit.Millimeter
drawing.CustomScale = 1

Drawings have bounds, which are accessible from the Bounds property. The bounds of the drawing are measured in the logical measurement unit. The drawing bounds can be calculated in several modes:

• CustomNonConstrained - user defined bounds are used. The descendant nodes can be placed outside the drawing bounds.
• CustomConstrained - user defined bounds are used. The descendant nodes cannot be placed outside the drawing bounds.
• AutoSizeToContent - the drawing bounds are automatically sized to the content bounds.
• AutoInflateToContent - the document bounds are automatically inflated to contain the content bounds.

The current bounds mode is controlled by the AutoBoundsMode property.

In case the mode is set to AutoInflateToContent or AutoSizeToContent, the drawing will take into account the AutoBoundsPadding property (controls the padding applied to the computed bounds) and the AutoBoundsMinSize property (controls the minimal size of automatic bounds).

In case the mode is set to CustomNonConstrained or CustomConstrained you can manually resize the drawing by invoking the SizeToContent or InflateToContent methods.

The Z-order of the shadows displayed by the elements in a drawing is controlled by the ShadowsZOrder property (accepts values from the ShadowsZOrder enumeration). Currently you can specify one of the following values:

• BehindDocument - shadows are displayed behind the all document elements-
• BehindLayer - shadows are displayed behind all elements in one layer
• BehindAggregate - shadows are displayed behind all elements in one aggregate
• BehindElement - shadows are displayed behind the element to which they belong

Drawings have the following set of additional attributes:

• Style - holds the document style. If shapes or layers do not have some local style they inherit it from the style of the document. Accessible from the Style property.
• Connection Container - holds the connections between the document elements. Accessible from the ConnectionContainer property.
• Routing Manager - manages the routing of routes. Accessible from the RoutingManager property. See Routable Connectors and Routing for more information.
• Bridge Manager - manages the creation of bridged paths. Accessible from the BridgeManager property. See Bridgeable Shapes and Bridges for more information.
• Hit Test Settings - defines various hit test settings. Accessible from the HitTestSettings property.
• Graphics Settings - controls the graphics settings with which the drawing must be rendered. Accessible from the GraphicsSettings property.
• Settings - contains miscellaneous settings related to layout, printing, image export etc. Accessible from the Settings property.

By default drawings add an instance of the NDrawingDataObjectAdaptor class to their DataObjectAdaptors collection. This type of adaptor can adapt data objects of the following formats:

• Text - converts any text as a NTextShape instance wrapped in a NDrawingDataObject instance. This helps you paste and drop text in the drawings.
• Library data object - converts any NLibraryDataObject instance to NDrawingDataObject instance. This helps you paste and drop masters in the drawing.
• Drawing data object - Adapts the specified drawing data object as a drawing data object, ready to be inserted in a drawing document. This helps you paste and drop drawing clippings extracted from other drawings.