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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2007-07-05 18:52:21 +0100 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2007-07-05 19:15:07 +0100 |
| commit | 35ef8419a981929b65157407485ec001b69b3391 (patch) | |
| tree | f4f0ec173d20f4051dd97e1ee492aa862e1c5aea /src/cairo-matrix.c | |
| parent | 7eaba5d5fbf83f66b39db42a89db3e7a892c2ea0 (diff) | |
| download | cairo-35ef8419a981929b65157407485ec001b69b3391.tar.gz | |
[cairo-matrix] Check determinant for invalid numbers.
By checking matrices for invalid determinants, we can prevent the
setting and application of invalid matrices.
The trick used here is that NaNs, as specified by IEE754, always
return FALSE in comparisons. Since we know that the square of the
determinant must be positive definite, then if the comparison is
FALSE the computation must have resulted in a NaN.
Diffstat (limited to 'src/cairo-matrix.c')
| -rw-r--r-- | src/cairo-matrix.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/src/cairo-matrix.c b/src/cairo-matrix.c index c85b02768..9e51d04c5 100644 --- a/src/cairo-matrix.c +++ b/src/cairo-matrix.c @@ -475,6 +475,10 @@ cairo_matrix_invert (cairo_matrix_t *matrix) if (det == 0) return CAIRO_STATUS_INVALID_MATRIX; + /* this weird construct is for detecting NaNs */ + if (! (det * det > 0.)) + return CAIRO_STATUS_INVALID_MATRIX; + _cairo_matrix_compute_adjoint (matrix); _cairo_matrix_scalar_multiply (matrix, 1 / det); |