GeometryHandler Class

GeometryHandler is a class that is used for extracting geometry from a DWG file. It consists of a series of methods that are called for each shape type in the as well as for changes in color and line style.

Nearly all of the OnBegin... methods return an enumerated value. This is to indicate to Distill whether or not the user GeometryHandler wants the geometry to be reduced further or not. The GeometryHandler base class implements all OnBegin... methods for shapes such that they return DwgReduction.Reduce. The GeometryHandler base class therefore causes a model to be fully reduced to primitives. Client code should subclass GeomtryHandler and override the methods they wish to intercept.

For example, an application that wishes to extract text from a DWG file would only need to override OnBeginText.

OnBeginPage should return true if the client wishes to process the page.

OnBeginDocument does not have a return value.

OnPolygon and OnPolyline represent primitives for which there is no further reduction.

All the OnBeginShape and OnEndShape methods take a shape ID parameter. This is unique ID that is assigned to every shape. This is to make it easier to identify when all reduction is done for a particular shape.

Many of the routines take arrays of double precision floating point numbers. These represent 3D coordinates of the shapes in the order X, Y, Z. The length of each array will always be a multiple of 3. At present, the Z coordinate is ignored since the shapes are projected onto a 2D sheet.

Inheritance Hierarchy

SystemObject
Atalasoft.Imaging.Codec.CadCamGeometryHandler

Namespace: Atalasoft.Imaging.Codec.CadCam
Assembly: Atalasoft.dotImage.Dwg (in Atalasoft.dotImage.Dwg.dll) Version: 11.4.0.9.0.377 (.NET 4.5.2, x86)

Syntax

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public class GeometryHandler

Public Class GeometryHandler

The GeometryHandler type exposes the following members.

Constructors

	Name	Description
	GeometryHandler	Initializes a new instance of the GeometryHandler class

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Methods

	Name	Description
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	OnBeginCircle	This method is called when a circle has been encountered.
	OnBeginCircularArc3Point	Describes a circular using three points.
	OnBeginCircularArcCenterRadius	Describes a circular arc via a circle's center, radius and sweep angle.
	OnBeginDocument	Constructs a new default GeometryHandler.
	OnBeginEllipticalArc	Describes an elliptical arc
	OnBeginPage	Called when page processing starts.
	OnBeginPolygon	Describes a closed polygon
	OnBeginRay	Describes an infinite mathematical ray.
	OnBeginSimplePolyline	Describes an open polygon to be drawn.
	OnBeginText	Describes text presented on the page
	OnBeginXLine	Describes a mathematical infinite line
	OnEndCircle	Describes completion of a circle
	OnEndCircularArc3Point	Describes completion of a circular arc
	OnEndCircularArcCenterRadius	Describes completion of a circular arc
	OnEndDocument	Describes completion of the document
	OnEndEllipticalArc	Describes completion of an elliptical arc
	OnEndPage	Describes completion of a page
	OnEndPolygon	Describes completion of a polygon
	OnEndRay
	OnEndSimplePolyline	Describes completion of a simple polyline
	OnEndText	Describes completion of text
	OnEndXLine	Describes completion of a line
	OnPolygon	Describes a request to render a primitive closed polygon
	OnPolyline	Describes a request to render a primitive open polygon
	OnSetColor	Represents a request to change the color of subsequent objects
	OnSetFillMode	Represents a request to set the fill mode of subsequent filled shapes
	OnSetLineWidth	Represents a request to set the line characteristics of subsequent shapes
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Examples

Extracting Fonts (C#)

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public class FontExtractorHandler : GeometryHandler {
    private List<Font> _fonts = new List<Font>();
    public override DwgReduction OnBeginText(int shapeId, double[] position,
        double[] direction, double[] up, string text, bool raw,
        DwgTextStyle textStyle, double[] extrusion)
    {
        if (textStyle.Font != null) {
            _fonts.Add(textStyle.Font);
        }
        return DwgReduction.DontReduce;
    }
    public List<Font> Fonts { get { return _fonts; } }
}

Reference

Atalasoft.Imaging.Codec.CadCam Namespace