For internal use. Creates a GrapeCity.Documents.Drawing.IGcTransparencyGroup compatible with this graphics. This group can be used later for: 1) Compose with graphics using the Composite method 2) Create a transparency mask from this group using the CreateTransparencyMask method Note! If the transparency group supports System.IDisposable interface it will be automatically disposed after usage.

'宣言
 
Public Overrides Function CreateTransparencyGroup( _
   ByVal size As System.Drawing.Rectangle, _
   ByVal isolated As System.Boolean, _
   ByVal knockout As System.Boolean, _
   ByVal pdfSoftMask As System.Boolean _
) As IGcTransparencyGroup

public override IGcTransparencyGroup CreateTransparencyGroup( 
   System.Drawing.Rectangle size,
   System.bool isolated,
   System.bool knockout,
   System.bool pdfSoftMask
)