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[sdf] The module can now generate SDF for outline with only lines.

This commit is contained in:
Anuj Verma 2020-06-29 11:49:47 +05:30 committed by anujverma
parent 063b65d583
commit 03e6debb80
3 changed files with 93 additions and 21 deletions
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18
[GSoC]ChangeLog
View File

@ -1,3 +1,21 @@
2020-06-27 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf] The module can now generate signed distance
fields for outline with only lines.
* src/sdf/ftsdf.c (get_min_distance_line): Calculation
mistake.
* src/sdf/ftsdf.c (square_root): Added function to calculate
square root of a 16.16 fixed point integer.
* src/sdf/ftsdf.c (sdf_generate): Assign values to the output
bitmap, currently the output is 6.10 fixed point which can
contain values from [-32, 32]. Also fixed a bug which was
causing upside down images.
* src/sdf/ftsdfrend.c (ft_sdf_render): Fixed alignment issues.
2020-06-27 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf] Added function to find shortest distance from

86
src/sdf/ftsdf.c
View File

@ -599,6 +599,38 @@
#endif
/**************************************************************************
*
* math functions
*
*/
/* Original Algorithm: https://github.com/chmike/fpsqrt */
static FT_Fixed
square_root( FT_Fixed val )
{
FT_ULong t, q, b, r;
r = val;
b = 0x40000000;
q = 0;
while( b > 0x40 )
{
t = q + b;
if( r >= t )
{
r -= t;
q = t + b;
}
r <<= 1;
b >>= 1;
}
q >>= 8;
return q;
}
/*************************************************************************/
/*************************************************************************/
/** **/
@ -721,10 +753,8 @@
nearest_point.y = FT_MulFix( FT_26D6_16D16(line_segment.y),
factor );
nearest_point.x = FT_26D6_16D16( a.x ) + nearest_point.x -
FT_26D6_16D16( p.x );
nearest_point.y = FT_26D6_16D16( a.y ) + nearest_point.y -
FT_26D6_16D16( p.y );
nearest_point.x = FT_26D6_16D16( a.x ) + nearest_point.x;
nearest_point.y = FT_26D6_16D16( a.y ) + nearest_point.y;
nearest_vector.x = nearest_point.x - FT_26D6_16D16( p.x );
nearest_vector.y = nearest_point.y - FT_26D6_16D16( p.y );
@ -831,14 +861,16 @@
FT_CALL( sdf_edge_get_min_distance(
(SDF_Edge*)edge_list.head->data,
point, &current_dist ) );
/* [TODO]: *IMPORTANT* Add corner checking function. */
if ( current_dist.squared_distance < min_dist.squared_distance )
if ( current_dist.squared_distance >= 0 &&
current_dist.squared_distance < min_dist.squared_distance )
min_dist = current_dist;
edge_list.head = edge_list.head->next;
}
*out = min_dist;
Exit:
return error;
}
@ -868,11 +900,14 @@
FT_UInt spread,
FT_Bitmap* bitmap )
{
FT_Error error = FT_Err_Ok;
FT_UInt width = 0;
FT_UInt rows = 0;
FT_UInt x = 0; /* used to loop in x direction i.e. width */
FT_UInt y = 0; /* used to loop in y direction i.e. rows */
FT_Error error = FT_Err_Ok;
FT_UInt width = 0;
FT_UInt rows = 0;
FT_UInt x = 0; /* used to loop in x direction i.e. width */
FT_UInt y = 0; /* used to loop in y direction i.e. rows */
FT_UInt sp_sq = 0; /* `spread' * `spread' int 16.16 fixed */
FT_Short* buffer;
if ( !shape || !bitmap )
{
@ -888,6 +923,9 @@
width = bitmap->width;
rows = bitmap->rows;
buffer = (FT_Short*)bitmap->buffer;
sp_sq = FT_INT_16D16( spread * spread );
if ( width == 0 || rows == 0 )
{
@ -911,7 +949,8 @@
FT_INT_26D6( y ) };
SDF_Signed_Distance min_dist = max_sdf;
FT_ListRec contour_list;
FT_UInt index;
FT_Short value;
/* This `grid_point' is at the corner, but we */
/* use the center of the pixel. */
@ -920,6 +959,8 @@
contour_list = shape->contours;
index = ( rows - y - 1 ) * width + x;
/* iterate through all the contours manually */
while ( contour_list.head ) {
SDF_Signed_Distance current_dist = max_sdf;
@ -929,12 +970,27 @@
(SDF_Contour*)contour_list.head->data,
grid_point, &current_dist ) );
if ( current_dist.squared_distance <
min_dist.squared_distance )
if ( current_dist.squared_distance < min_dist.squared_distance )
min_dist = current_dist;
contour_list.head = contour_list.head->next;
}
/* [OPTIMIZATION]: if (min_dist > sp_sq) then simply clamp */
/* the value to spread to avoid square_root */
/* clamp the values to spread */
if ( min_dist.squared_distance > sp_sq )
min_dist.squared_distance = sp_sq;
/* square_root the values and fit in a 6.10 fixed point */
min_dist.squared_distance = square_root( min_dist.squared_distance );
min_dist.squared_distance /= 64; /* convert from 16.16 to 22.10 */
value = min_dist.squared_distance & 0x0000FFFF; /* truncate to 6.10 */
value *= min_dist.sign;
buffer[index] = value;
}
}
@ -1063,8 +1119,6 @@
FT_CALL( sdf_generate( shape, sdf_params->spread,
sdf_params->root.target ) );
sdf_shape_dump( shape );
Exit:
if ( shape )
sdf_shape_done( memory, &shape );

10
src/sdf/ftsdfrend.c
View File

@ -112,8 +112,8 @@
FT_SERVICE_ID_PROPERTIES, &sdf_service_properties )
static FT_Module_Interface
ft_sdf_requester ( FT_Renderer render,
const char* module_interface )
ft_sdf_requester( FT_Renderer render,
const char* module_interface )
{
FT_UNUSED( render );
@ -127,7 +127,7 @@
*/
static FT_Error
ft_sdf_init ( FT_Renderer render )
ft_sdf_init( FT_Renderer render )
{
SDF_Renderer sdf_render = SDF_RENDERER( render );
@ -138,7 +138,7 @@
}
static FT_Error
ft_sdf_done ( FT_Renderer render )
ft_sdf_done( FT_Renderer render )
{
FT_UNUSED( render );
@ -225,7 +225,7 @@
slot->internal->flags |= FT_GLYPH_OWN_BITMAP;
x_shift = 64 * -( slot->bitmap_left + x_pad );
x_shift = 64 * -( slot->bitmap_left - x_pad );
y_shift = 64 * -( slot->bitmap_top + y_pad );
y_shift += 64 * (FT_Int)bitmap->rows;