[fpc-pascal] fpcanvas and Interpolation filters

Michael Van Canneyt michael at freepascal.org
Thu Jun 28 13:54:48 CEST 2007

On Thu, 28 Jun 2007, Graeme Geldenhuys wrote:

> Hi,
> Looking at the 'fpcanvas' unit in FCL it seems we only have the
> Mitchel Interpolation implemented.  Is this a correct assumption?

No. There is a second unit which implements other interpolations:
extinterpolation. It registers the following interpolations:

  TBlackmanInterpolation = class (TFPBaseInterpolation)
  TBlackmanSincInterpolation = class (TFPBaseInterpolation)
  TBlackmanBesselInterpolation = class (TFPBaseInterpolation)
  TGaussianInterpolation = class (TFPBaseInterpolation)
  TBoxInterpolation = class (TFPBaseInterpolation)
  THermiteInterpolation = class (TFPBaseInterpolation)
  TLanczosInterpolation = class (TFPBaseInterpolation)
  TQuadraticInterpolation = class (TFPBaseInterpolation)
  TCubicInterpolation = class (TFPBaseInterpolation)
  TCatromInterpolation = class (TFPBaseInterpolation)
  TBilineairInterpolation = class (TFPBaseInterpolation)
  THanningInterpolation = class (TFPBaseInterpolation)
  THammingInterpolation = class (TFPBaseInterpolation)

> What about a few other types?
> 'Box' aka "Nearest Neighbour"
> 'Triangle' aka "Linear" or "Bilinear"
> 'Hermite'
> 'Bell'
> 'B-Spline'
> 'Lanczos3'
> I have some pascal implementations for the others and if they are not
> part of FCL already, I can always create a patch to add them.  Would
> this be a worthy effort?

Make sure they don't overlap with the currently existing ones. Box and
Lanczos seem to be there already.

You can implement them in the same unit btw.



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