All region methods accept a null reference (Nothing in Visual Basic). In that case, no transformation occurs. The scalar fields default to 1, the offsets default to 0, and the view perspective defaults to the image view perspective.

Several of the LEADTOOLS methods for creating and working with an image region use coordinates from an external representation of the region, such as a shape drawn in a device context. To compensate for possible differences in view perspective, scaling, and display offsets, these LEADTOOLS methods require that you provide translation information in an RasterRegionXForm object.

In most cases, the external representation of an image region is scaled and positioned relative to the display coordinates of a LEADTOOLS painting method. Therefore, the following table describes the fields to set in the RasterRegionXForm object, based on the parameters of the display methods.

When assigning an external representation to an image, every point (Xa, Ya) in the an external representation is transformed (by RasterRegionXForm) to point (Xc, Yc) in the image region as follows:

1. Add offsets:
     Xb = Xa + XForm.XOffset
     Yb = Ya + XForm.YOffset

2. Multiply by scalars:
     Xc = (Xb * XForm.XScalarNumerator) / XForm.XScalarDenominator
     Yc = (Yb * XForm.YScalarNumerator) / XForm.YScalarDenominator

3. Compensate for view perspective (updating Xc and Yc in place):
     PointToImage(XForm.ViewPerspective, Xc, Yc)

When retrieving an external representation from an image, every point (Xa, Ya) in the image region is transformed (by RasterRegionXForm) to point (Xc, Yc) in the external region as follows:

1. Compensate for view perspective (updating Xa and Ya in place):
     PointFromImage(XForm.ViewPerspective, Xa, Ya)

2. Mulitply by scalars:
     Xb = (Xa * XForm.XScalarNumerator) / XForm.XScalarDenominator
     Yb = (Ya * XForm.YScalarNumerator) / XForm.YScalarDenominator

3. Add offsets:
     Xc = Xb + XForm.XOffset
     Yc = Yb + XForm.YOffset

For more information, refer to Translating Coordinates for a Region..

System.Object
   Leadtools.RasterRegionXForm

Target Platforms: Microsoft .NET Framework 3.0, Windows XP, Windows Server 2003 family, Windows Server 2008 family

Reference