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Correct implementation of UTP

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* src/sfnt.c (sfnt_interpret_utp): Derive which flags to reset
from the freedom vector.
This commit is contained in:
Po Lu 2023-12-11 11:28:34 +08:00
parent 64cdcf7f51
commit 1ec8e76bcf
1 changed files with 27 additions and 1 deletions
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28
src/sfnt.c
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@ -7450,6 +7450,8 @@ static void
sfnt_interpret_utp (struct sfnt_interpreter *interpreter,
uint32_t p)
{
unsigned char mask;
if (!interpreter->state.zp0)
{
if (p >= interpreter->twilight_zone_size)
@ -7463,7 +7465,31 @@ sfnt_interpret_utp (struct sfnt_interpreter *interpreter,
|| p >= interpreter->glyph_zone->num_points)
TRAP ("UTP[] p lies outside glyph zone");
interpreter->glyph_zone->flags[p] &= ~SFNT_POINT_TOUCHED_X;
/* The flags unset by UTP are subject to which axes in the freedom
vector are significant, as stated in the TrueType reference
manual by this needless mouthful:
A point may be touched in the x-direction, the y-direction, or
in both the x and y-directions. The position of the freedom
vector determines whether the point is untouched in the
x-direction, the y-direction, or both. If the vector is set to
the x-axis, the point will be untouched in the x-direction. If
the vector is set to the y-axis, the point will be untouched in
the y-direction. Otherwise the point will be untouched in both
directions.
A points that is marked as untouched will be moved by an IUP[]
instruction even if the point was previously touched. */
mask = 0xff;
if (interpreter->state.freedom_vector.x)
mask &= ~SFNT_POINT_TOUCHED_X;
if (interpreter->state.freedom_vector.y)
mask &= ~SFNT_POINT_TOUCHED_Y;
interpreter->glyph_zone->flags[p] &= mask;
}
/* Save the specified unit VECTOR into INTERPRETER's graphics state as