[font] Fix undefined-behavior when scales are negative

Fixes https://github.com/harfbuzz/harfbuzz/issues/3555
This commit is contained in:
Behdad Esfahbod 2022-06-01 07:27:30 -06:00
parent fc4d42ff99
commit cd05d187c8
1 changed files with 4 additions and 2 deletions

View File

@ -631,8 +631,10 @@ struct hb_font_t
void mults_changed ()
{
signed upem = face->get_upem ();
x_mult = ((int64_t) x_scale << 16) / upem;
y_mult = ((int64_t) y_scale << 16) / upem;
bool x_neg = x_scale < 0;
x_mult = (x_neg ? -((int64_t) -x_scale << 16) : ((int64_t) x_scale << 16)) / upem;
bool y_neg = y_scale < 0;
y_mult = (y_neg ? -((int64_t) -y_scale << 16) : ((int64_t) y_scale << 16)) / upem;
slant_xy = y_scale ? slant * x_scale / y_scale : 0.f;
}