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[sdf -> bsdf] Added first pass of the '8SED' algorithm. 

Added the first pass of the 8SED algorithm. The first pass
transverse the bitmap from top to bottom and for each row
it sweeps forward and backward assigning distances to the
grid points.

* src/sdf/ftbsdf.c (ED): Added additional parameter `sign'.

* src/sdf/ftbsdf.c (edt8): Added function to convert bitmap
  to SDF using the 8SED algorithm.

* src/sdf/ftbsdf.c (first_pass): Added function to do the
  first pass of the 8SED algorithm on the bitmap.

* src/sdf/ftbsdf.c (finalize_sdf): Added function to assign
  the final SDF data to the target bitmap.

* src/sdf/ftbsdf.c (*): Various minor or experimental changes.

* src/sdf/ftsdfrend.c (ft_bsdf_render): Fix spacing.
This commit is contained in:
Anuj Verma 2020-07-26 10:38:15 +05:30 committed by anujverma
parent 59d340878a
commit 470131db91
3 changed files with 284 additions and 14 deletions
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24
[GSoC]ChangeLog
View File

@ -1,3 +1,27 @@
2020-07-26 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf -> bsdf] Added first pass of the '8SED' algorithm.
Added the first pass of the 8SED algorithm. The first pass
transverse the bitmap from top to bottom and for each row
it sweeps forward and backward assigning distances to the
grid points.
* src/sdf/ftbsdf.c (ED): Added additional parameter `sign'.
* src/sdf/ftbsdf.c (edt8): Added function to convert bitmap
to SDF using the 8SED algorithm.
* src/sdf/ftbsdf.c (first_pass): Added function to do the
first pass of the 8SED algorithm on the bitmap.
* src/sdf/ftbsdf.c (finalize_sdf): Added function to assign
the final SDF data to the target bitmap.
* src/sdf/ftbsdf.c (*): Various minor or experimental changes.
* src/sdf/ftsdfrend.c (ft_bsdf_render): Fix spacing.
2020-07-25 Anuj Verma <anujv@iitbhilai.ac.in>
* src/sdf/ftbsdf.c (*): Rename `SDF_TRaster' => `BSDF_TRaster'.

266
src/sdf/ftbsdf.c
View File

@ -21,6 +21,8 @@
goto Exit; \
} while ( 0 )
#define ONE 65536 /* 1 in 16.16 */
/**************************************************************************
*
* typedefs
@ -48,7 +50,8 @@
typedef struct ED_
{
FT_16D16 dist; /* distance at `near' */
FT_16D16_Vec near; /* nearest point */
FT_16D16_Vec near; /* nearest point */
FT_Char sign; /* outside or inside */
} ED;
@ -63,6 +66,15 @@
} BSDF_Worker;
/**************************************************************************
*
* initializer
*
*/
static
const ED zero_ed = { 0, { 0, 0 }, 0 };
/**************************************************************************
*
* rasterizer functions
@ -180,17 +192,22 @@
{
FT_Int t_index = t_j * t_width + t_i;
FT_Int s_index;
FT_Short pixel_value;
FT_Byte pixel_value;
t[t_index] = zero_ed;
s_i = t_i - x_diff;
s_j = t_j - y_diff;
/* assign INT_MAX to the padding */
/* Assign 0 to padding similar to */
/* the source bitmap. */
if ( s_i < 0 || s_i >= s_width ||
s_j < 0 || s_j >= s_rows )
{
t[t_index].dist = FT_INT_MAX;
t[t_index].near.x = 100000;
t[t_index].near.y = 100000;
t[t_index].dist = 100000;
continue;
}
@ -199,7 +216,9 @@
else
s_index = s_j * s_width + s_i;
pixel_value = (FT_Short)s[s_index];
pixel_value = s[s_index];
#if 0
/* to make the fractional value 1 */
/* for completely filled pixels */
@ -211,7 +230,17 @@
/* shift the value by 8. */
pixel_value <<= 8;
t[t_index].dist = pixel_value;
#else
if ( pixel_value )
t[t_index].dist = 0;
else
{
t[t_index].near.x = 100000;
t[t_index].near.y = 100000;
t[t_index].dist = 100000;
}
#endif
}
}
@ -227,7 +256,222 @@
Exit:
return error;
}
/**************************************************************************
*
* @Function:
* first_pass
*
* @Description:
* [TODO]
*
* @Input:
* [TODO]
*
* @Return:
* [TODO]
*/
static void
first_pass( BSDF_Worker* worker )
{
FT_Int i, j; /* iterators */
FT_Int w, r; /* width, rows */
ED* dm; /* distance map */
dm = worker->distance_map;
w = worker->width;
r = worker->rows;
/* Start scanning from top to bottom and sweep each */
/* row back and forth comparing the distances of the */
/* neighborhood. Leave the first row as it has no top */
/* neighbor, it will be covered in the 2nd scan of */
/* the image, that is from bottom to top. */
for ( j = 1; j < r; j++ )
{
FT_Int index;
FT_16D16 dist;
FT_16D16_Vec dist_vec;
ED* to_check;
ED* current;
/* Forward pass of rows (left -> right), leave, the */
/* first column, will be covered in backward pass. */
for ( i = 1; i < w; i++ )
{
index = j * w + i;
current = dm + index;
/* left-up */
to_check = current - w - 1;
dist_vec = to_check->near;
dist_vec.x -= ONE;
dist_vec.y -= ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
/* up */
to_check = current - w;
dist_vec = to_check->near;
dist_vec.y -= ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
/* up-right */
to_check = current - w + 1;
dist_vec = to_check->near;
dist_vec.x += ONE;
dist_vec.y -= ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
/* left */
to_check = current - 1;
dist_vec = to_check->near;
dist_vec.x -= ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
/* Backward pass of rows (right -> left), leave, the */
/* last column, already covered in the forward pass. */
for ( i = w - 2; i >= 0; i-- )
{
index = j * w + i;
current = dm + index;
/* right */
to_check = current + 1;
dist_vec = to_check->near;
dist_vec.x += ONE;
dist = FT_Vector_Length( &dist_vec );
if ( dist < current->dist )
{
current->dist = dist;
current->near = dist_vec;
}
}
}
}
/**************************************************************************
*
* @Function:
* edt8
*
* @Description:
* [TODO]
*
* @Input:
* [TODO]
*
* @Return:
* [TODO]
*/
static FT_Error
edt8( BSDF_Worker* worker )
{
FT_Error error = FT_Err_Ok;
if ( !worker || !worker->distance_map )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
/* first scan of the image */
first_pass( worker );
/* second scan of the image */
/* [TODO] */
Exit:
return error;
}
/**************************************************************************
*
* @Function:
* finalize_sdf
*
* @Description:
* [TODO]
*
* @Input:
* [TODO]
*
* @Return:
* [TODO]
*/
static FT_Error
finalize_sdf( BSDF_Worker* worker,
FT_Bitmap* target )
{
FT_Error error = FT_Err_Ok;
FT_Int w, r;
FT_Int i, j;
FT_6D10* t_buffer;
if ( !worker || !target )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
w = target->width;
r = target->rows;
t_buffer = (FT_6D10*)target->buffer;
if ( w != worker->width ||
r != worker->rows )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
for ( j = 0; j < r; j++ )
{
for ( i = 0; i < w; i++ )
{
FT_Int index;
FT_16D16 dist;
FT_6D10 final_dist;
index = j * w + i;
dist = worker->distance_map[index].dist;
/* convert from 16.16 to 6.10 */
dist /= 64;
final_dist = (FT_6D10)(dist & 0x0000FFFF);
/* [TODO]: Assing the sign properly. */
t_buffer[index] = final_dist;
}
}
Exit:
return error;
}
/**************************************************************************
*
@ -338,7 +582,7 @@
" Also, you must pass `SDF_Raster_Params' instead of the\n"
" default `FT_Raster_Params' while calling this function\n"
" and set the fields properly.\n"
, MIN_SPREAD, MAX_SPREAD) );
, MIN_SPREAD, MAX_SPREAD ));
error = FT_THROW( Invalid_Argument );
goto Exit;
}
@ -346,8 +590,8 @@
/* setup the worker */
/* allocate the distance map */
if ( !FT_QALLOC_MULT( worker.distance_map, target->rows,
target->width * sizeof( *worker.distance_map ) ) )
if ( FT_QALLOC_MULT( worker.distance_map, target->rows,
target->width * sizeof( *worker.distance_map ) ) )
goto Exit;
worker.width = target->width;
@ -355,6 +599,8 @@
worker.params = *sdf_params;
FT_CALL( bsdf_init_distance_map( source, &worker ) );
FT_CALL( edt8( &worker ) );
FT_CALL( finalize_sdf( &worker, target ) );
Exit:
return error;

8
src/sdf/ftsdfrend.c
View File

@ -404,10 +404,10 @@
/* generate signed distance field from glyph's bitmap */
static FT_Error
ft_bsdf_render( FT_Renderer module,
FT_GlyphSlot slot,
FT_Render_Mode mode,
const FT_Vector* origin )
ft_bsdf_render( FT_Renderer module,
FT_GlyphSlot slot,
FT_Render_Mode mode,
const FT_Vector* origin )
{
FT_Error error = FT_Err_Ok;
FT_Bitmap* bitmap = &slot->bitmap;