diff options
Diffstat (limited to 'include/freetype/internal/ftcalc.h')
| -rw-r--r-- | include/freetype/internal/ftcalc.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/freetype/internal/ftcalc.h b/include/freetype/internal/ftcalc.h index a04a3cb80..38c6f7741 100644 --- a/include/freetype/internal/ftcalc.h +++ b/include/freetype/internal/ftcalc.h @@ -293,6 +293,21 @@ FT_BEGIN_HEADER /* + * Check a matrix. If the transformation would lead to extreme shear or + * extreme scaling, for example, return 0. If everything is OK, return 1. + * + * Based on geometric considerations we use the following inequality to + * identify a degenerate matrix. + * + * 50 * abs(xx*yy - xy*yx) < xx^2 + xy^2 + yx^2 + yy^2 + * + * Value 50 is heuristic. + */ + FT_BASE( FT_Bool ) + FT_Matrix_Check( const FT_Matrix* matrix ); + + + /* * A variant of FT_Vector_Transform. See comments for * FT_Matrix_Multiply_Scaled. */ |