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In order to avoid confusion about transformation matrices, we should briefly
discuss the differences between t1lib- and PostScript transformation
matrices. In t1lib-nomenclature a coordinate description is assumed to be
represented by a column vector
. In contrast, PostScript assumes a
coordinate to be represented by a row vector
. This leads to an
exchanged meaning of the second and third matrix element between t1lib and
PostScript. From the mathematical point of view this is caused by matrix
transposition. To make this clear, let me quote the matrix
from the PostScript Language Reference Manual (Adobe, Red Book). If we forget
about translation which in this sense is not implemented by t1lib, we only
have to consider the top left submatrix consisting of
,
,
and
.
The t1lib-equivalent to this matrix would be written as
I.e., the meaning of
and
is exchanged. Notice that font matrices as
found in Type 1 font files have to be interpreted according to the PostScript
notation. But a user should never come close to something other than the
t1lib transformation matrices
Next: Stroking of Character Outlines
Up: Transformation of Fonts
Previous: Transformation at Rastering Time
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2004-10-04