Re: [Devel] Matrix (not the movie) ...

[Scott Long]

On Thu, 11 Dec 2003 20:33:58 +0100
 "David Schweiger" <address@hidden> wrote:
> Newbie question:
> I have a matrix [m0 m1 m2 m3] which transforms the "width" and 
> "height" of a font, result is "transformed_width" and 
> "transformed_height".
> Does Freetype provide any function which takes "transformed_width", 
> "transformed_height" and the matrix as input and returns the 
> untransformed "width" and "height"?

Strictly, the matrix doesn't transform a particular dimension such as 
width or height. You can transform a vector (0, h) where h is the 
height of the glyph. The result is not necessarily going to be of the 
form (0, h'), because of possible rotation. But if your question is 
simply how to reverse this operation, then you can use:

FT_Matrix_Invert(FT_Matrix* matrix);

Which will invert the matrix in-place. You can then apply the matrix 
to the output vectors to recover the input vectors.

Scott Long
SwiftView, Inc. http://www.swiftview.com