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[sdf] Fixed corner checks and improved performance. 

* src/sdf/ftsdf.c (sdf_generate_bounding_box): Always check for
  corner if two distance (for different curves) are very close.

* src/sdf/ftsdf.c (sdf_conic_to): Added check to figure out if
  the conic can be treated as a line (which happens if the control
  point coincide with any end-point).

  Also, replace tabs `\t` with spaces.
This commit is contained in:
Anuj Verma 2021-10-16 10:02:30 +05:30
parent 3d3be1dfd1
commit 31c0a833d6
1 changed files with 40 additions and 23 deletions
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63
src/sdf/ftsdf.c
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@ -738,6 +738,18 @@
contour = shape->contours;
/* If the control point coincide with any of the end point */
/* then it's a line and should be treated as one to avoid */
/* unnecessary complexity later in the algorithm. */
if ( ( contour->last_pos.x == control_1->x &&
contour->last_pos.y == control_1->y ) ||
( control_1->x == to->x &&
control_1->y == to->y ) )
{
sdf_line_to( to, user );
goto Exit;
}
FT_CALL( sdf_edge_new( memory, &edge ) );
edge->edge_type = SDF_EDGE_CONIC;
@ -1160,9 +1172,9 @@
/* we check the deviation of the bezier and stop if it is */
/* lower than a pre-defined `threhold` value. */
if ( FT_ABS( 2 * cpos[0].x - 3 * cpos[1].x + cpos[3].x ) < threshold &&
FT_ABS( 2 * cpos[0].y - 3 * cpos[1].y + cpos[3].y ) < threshold &&
FT_ABS( 2 * cpos[0].y - 3 * cpos[1].y + cpos[3].y ) < threshold &&
FT_ABS( cpos[0].x - 3 * cpos[2].x + 2 * cpos[3].x ) < threshold &&
FT_ABS( cpos[0].y - 3 * cpos[2].y + 2 * cpos[3].y ) < threshold )
FT_ABS( cpos[0].y - 3 * cpos[2].y + 2 * cpos[3].y ) < threshold )
{
split_cubic( cpos );
goto Append;
@ -1264,29 +1276,29 @@
/* Subdivide the curve and add it to the list. */
{
FT_26D6_Vec ctrls[3];
FT_26D6 dx, dy;
FT_UInt num_splits;
FT_26D6 dx, dy;
FT_UInt num_splits;
ctrls[0] = edge->start_pos;
ctrls[1] = edge->control_a;
ctrls[2] = edge->end_pos;
dx = FT_ABS( ctrls[2].x + ctrls[0].x - 2 * ctrls[1].x );
dy = FT_ABS( ctrls[2].y + ctrls[0].y - 2 * ctrls[1].y );
dx = FT_ABS( ctrls[2].x + ctrls[0].x - 2 * ctrls[1].x );
dy = FT_ABS( ctrls[2].y + ctrls[0].y - 2 * ctrls[1].y );
if ( dx < dy )
dx = dy;
dx = dy;
/* Here we calculate the number of necessary bisections. Each */
/* bisection reduces the deviation by exactly 4-fold, hence */
/* we bisect the bezier until the deviation becomes less than */
/* 1/8th of a pixel. For more details check `ftgrays.c`. */
num_splits = 1;
while ( dx > ONE_PIXEL / 8 )
{
dx >>= 2;
num_splits <<= 1;
}
/* Here we calculate the number of necessary bisections. Each */
/* bisection reduces the deviation by exactly 4-fold, hence */
/* we bisect the bezier until the deviation becomes less than */
/* 1/8th of a pixel. For more details check `ftgrays.c`. */
num_splits = 1;
while ( dx > ONE_PIXEL / 8 )
{
dx >>= 2;
num_splits <<= 1;
}
error = split_sdf_conic( memory, ctrls, num_splits, &new_edges );
}
@ -3316,6 +3328,7 @@
FT_26D6_Vec grid_point = zero_vector;
SDF_Signed_Distance dist = max_sdf;
FT_UInt index = 0;
FT_16D16 diff = 0;
if ( x < 0 || x >= width )
@ -3343,7 +3356,7 @@
if ( dist.distance > sp_sq )
continue;
/* square_root the values and fit in a 6.10 fixed-point */
/* square_root the values if required */
if ( USE_SQUARED_DISTANCES )
dist.distance = square_root( dist.distance );
@ -3355,11 +3368,15 @@
/* check whether the pixel is set or not */
if ( dists[index].sign == 0 )
dists[index] = dist;
else if ( dists[index].distance > dist.distance )
dists[index] = dist;
else if ( FT_ABS( dists[index].distance - dist.distance )
< CORNER_CHECK_EPSILON )
dists[index] = resolve_corner( dists[index], dist );
else
{
diff = FT_ABS( dists[index].distance - dist.distance );
if ( diff <= CORNER_CHECK_EPSILON )
dists[index] = resolve_corner( dists[index], dist );
else if ( dists[index].distance > dist.distance )
dists[index] = dist;
}
}
}