diff options
| author | Keith Packard <keithp@keithp.com> | 2009-02-03 20:12:42 -0800 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2009-02-03 20:20:57 -0800 |
| commit | 62fc98cb88e4e8b636f343453fc1168a87c58972 (patch) | |
| tree | baa8dd1a1cf45ca1c2576844452b1b97d9df823d /randr | |
| parent | 7a3ddef3bc27982f3558183c74fc8e365cf2e7fd (diff) | |
Handle matrix computation overflow in RRTransformCompute
If the computation of the composite fixed-point transform for RandR
overflows at any point, take the resulting floating point transform and
scale that back to fit in a fixed point matrix. This ensures that a matrix
will always be available, although perhaps at reduced precision. Someday we
should add floating point matrices to Render.
Signed-off-by: Keith Packard <keithp@keithp.com>
Diffstat (limited to 'randr')
| -rw-r--r-- | randr/rrtransform.c | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/randr/rrtransform.c b/randr/rrtransform.c index a901df4ac..cc18a0662 100644 --- a/randr/rrtransform.c +++ b/randr/rrtransform.c @@ -120,6 +120,22 @@ RRTransformCopy (RRTransformPtr dst, RRTransformPtr src) #define F(x) IntToxFixed(x) +static void +RRTransformRescale(struct pixman_f_transform *f_transform, double limit) +{ + double max = 0, v, scale; + int i, j; + + for (j = 0; j < 3; j++) + for (i = 0; i < 3; i++) + if ((v = abs (f_transform->m[j][i])) > max) + max = v; + scale = limit / max; + for (j = 0; j < 3; j++) + for (i = 0; i < 3; i++) + f_transform->m[j][i] *= scale; +} + /* * Compute the complete transformation matrix including * client-specified transform, rotation/reflection values and the crtc @@ -141,6 +157,7 @@ RRTransformCompute (int x, { PictTransform t_transform, inverse; struct pixman_f_transform tf_transform, tf_inverse; + Bool overflow = FALSE; if (!transform) transform = &t_transform; if (!f_transform) f_transform = &tf_transform; @@ -234,7 +251,8 @@ RRTransformCompute (int x, #ifdef RANDR_12_INTERFACE if (rr_transform) { - pixman_transform_multiply (transform, transform, &rr_transform->transform); + if (!pixman_transform_multiply (transform, transform, &rr_transform->transform)) + overflow = TRUE; pixman_f_transform_multiply (f_transform, f_transform, &rr_transform->f_transform); pixman_f_transform_multiply (f_inverse, &rr_transform->f_inverse, f_inverse); } @@ -242,19 +260,26 @@ RRTransformCompute (int x, /* * Compute the class of the resulting transform */ - if (pixman_transform_is_identity (transform)) + if (!overflow && pixman_transform_is_identity (transform)) { pixman_transform_init_translate (transform, F ( x), F ( y)); - pixman_f_transform_init_translate (f_transform, F( x), F( y)); - pixman_f_transform_init_translate (f_inverse, F(-x), F(-y)); + pixman_f_transform_init_translate (f_transform, x, y); + pixman_f_transform_init_translate (f_inverse, -x, -y); return FALSE; } else { - pixman_transform_translate (&inverse, transform, x, y); - pixman_f_transform_translate (f_inverse, f_transform, x, y); + pixman_f_transform_translate (f_inverse, f_transform, -x, -y); + if (!pixman_transform_translate (&inverse, transform, F(-x), F(-y))) + overflow = TRUE; + if (overflow) + { + struct pixman_f_transform f_scaled; + f_scaled = *f_transform; + RRTransformRescale(&f_scaled, 16384.0); + pixman_transform_from_pixman_f_transform(transform, &f_scaled); + } return TRUE; } } - |