organicmaps/freetype
13
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity Actions

[sdf] Make make multi work.

Browse source 
* src/sdf/ftsdf.c: Include `ftbitmap.h`.

* src/sdf/ftsdfcommon.h: Move function bodies to `ftsdfcommon.c`.
Include `ftobjs.h` to get definitions of `FT_LOCAL` and friends.

* src/sdf/ftsdfcommon.c: New file.

* src/sdf/rules.mk, src/sdf/sdf.c: Updated.
This commit is contained in:
Werner Lemberg 2021-06-08 09:06:39 +02:00
parent 36ee71714f
commit 35b21c71e5
6 changed files with 175 additions and 113 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
ChangeLog
View file

@ -1,3 +1,16 @@
2021-06-08 Werner Lemberg <wl@gnu.org>
[sdf] Make `make multi` work.
* src/sdf/ftsdf.c: Include `ftbitmap.h`.
* src/sdf/ftsdfcommon.h: Move function bodies to `ftsdfcommon.c`.
Include `ftobjs.h` to get definitions of `FT_LOCAL` and friends.
* src/sdf/ftsdfcommon.c: New file.
* src/sdf/rules.mk, src/sdf/sdf.c: Updated.
2021-06-08 Anuj Verma <anujv@iitbhilai.ac.in>
[sdf] Use 8 bits for final SDF output instead of 16bits.

1
src/sdf/ftsdf.c
View file

@ -22,6 +22,7 @@
#include <freetype/internal/ftdebug.h>
#include <freetype/ftoutln.h>
#include <freetype/fttrigon.h>
#include <freetype/ftbitmap.h>
#include "ftsdf.h"
#include "ftsdferrs.h"

147
src/sdf/ftsdfcommon.c Normal file
View file

@ -0,0 +1,147 @@
/****************************************************************************
*
* ftsdfcommon.c
*
* Auxiliary data for Signed Distance Field support (body).
*
* Copyright (C) 2020-2021 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* Written by Anuj Verma.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
#include <ftsdf.h>
#include <ftsdfcommon.h>
/**************************************************************************
*
* common functions
*
*/
/*
* Original algorithm:
*
* https://github.com/chmike/fpsqrt
*
* Use this to compute the square root of a 16.16 fixed point number.
*/
FT_LOCAL_DEF( FT_16D16 )
square_root( FT_16D16 val )
{
FT_ULong t, q, b, r;
r = (FT_ULong)val;
b = 0x40000000L;
q = 0;
while ( b > 0x40L )
{
t = q + b;
if ( r >= t )
{
r -= t;
q = t + b;
}
r <<= 1;
b >>= 1;
}
q >>= 8;
return (FT_16D16)q;
}
/**************************************************************************
*
* format and sign manipulating functions
*
*/
/*
* Convert 16.16 fixed point values to the desired output format.
* In this case we reduce 16.16 fixed point values to normalized
* 8-bit values.
*
* The `max_value` in the parameter is the maximum value in the
* distance field map and is equal to the spread. We normalize
* the distances using this value instead of computing the maximum
* value for the entire bitmap.
*
* You can use this function to map the 16.16 signed values to any
* format required. Do note that the output buffer is 8-bit, so only
* use an 8-bit format for `FT_SDFFormat`, or increase the buffer size in
* `ftsdfrend.c`.
*/
FT_LOCAL_DEF( FT_SDFFormat )
map_fixed_to_sdf( FT_16D16 dist,
FT_16D16 max_value )
{
FT_SDFFormat out;
FT_16D16 udist;
/* normalize the distance values */
dist = FT_DivFix( dist, max_value );
udist = dist < 0 ? -dist : dist;
/* Reduce the distance values to 8 bits. */
/* */
/* Since +1/-1 in 16.16 takes the 16th bit, we right-shift */
/* the number by 9 to make it fit into the 7-bit range. */
/* */
/* One bit is reserved for the sign. */
udist >>= 9;
/* Since `char` can only store a maximum positive value */
/* of 127 we need to make sure it does not wrap around and */
/* give a negative value. */
if ( dist > 0 && udist > 127 )
udist = 127;
if ( dist < 0 && udist > 128 )
udist = 128;
/* Output the data; negative values are from [0, 127] and positive */
/* from [128, 255]. One important thing is that negative values */
/* are inverted here, that means [0, 128] maps to [-128, 0] linearly. */
/* More on that in `freetype.h` near the documentation of */
/* `FT_RENDER_MODE_SDF`. */
out = dist < 0 ? 128 - (FT_SDFFormat)udist
: (FT_SDFFormat)udist + 128;
return out;
}
/*
* Invert the signed distance packed into the corresponding format.
* So if the values are negative they will become positive in the
* chosen format.
*
* [Note]: This function should only be used after converting the
* 16.16 signed distance values to `FT_SDFFormat`. If that
* conversion has not been done, then simply invert the sign
* and use the above function to pack the values.
*/
FT_LOCAL_DEF( FT_SDFFormat )
invert_sign( FT_SDFFormat dist )
{
return 255 - dist;
}
/* END */

119
src/sdf/ftsdfcommon.h
View file

@ -2,7 +2,7 @@
*
* ftsdfcommon.h
*
* Auxiliary data for Signed Distance Field support (specification only).
* Auxiliary data for Signed Distance Field support (specification).
*
* Copyright (C) 2020-2021 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
@ -30,7 +30,7 @@
#include <ft2build.h>
#include FT_CONFIG_CONFIG_H
#include <freetype/freetype.h>
#include <freetype/internal/ftobjs.h>
FT_BEGIN_HEADER
@ -120,116 +120,15 @@ FT_BEGIN_HEADER
typedef FT_BBox FT_CBox; /* control box of a curve */
/**************************************************************************
*
* common functions
*
*/
FT_LOCAL( FT_16D16 )
square_root( FT_16D16 val );
/*
* Original algorithm:
*
* https://github.com/chmike/fpsqrt
*
* Use this to compute the square root of a 16.16 fixed point number.
*/
static FT_16D16
square_root( FT_16D16 val )
{
FT_ULong t, q, b, r;
FT_LOCAL( FT_SDFFormat )
map_fixed_to_sdf( FT_16D16 dist,
FT_16D16 max_value );
r = (FT_ULong)val;
b = 0x40000000L;
q = 0;
while ( b > 0x40L )
{
t = q + b;
if ( r >= t )
{
r -= t;
q = t + b;
}
r <<= 1;
b >>= 1;
}
q >>= 8;
return (FT_16D16)q;
}
/**************************************************************************
*
* format and sign manipulating functions
*
*/
/*
* Convert 16.16 fixed point value to the desired output format.
* In this case we reduce 16.16 fixed point value to normalized
* 8-bit values.
* The `max_value` in the parameter is the maximum value in the
* distance field map and is equal to the spread. We normalize
* the distances using this value instead of computing the maximum
* value for the entire bitmap.
* You can use this function to map the 16.16 signed values to any
* format required. Do note that the output buffer is 8-bit, so only
* use 8-bit format for `FT_SDFFormat`, or increase buffer size in
* `ftsdfrend.c`.
*/
static FT_SDFFormat
map_fixed_to_sdf( FT_16D16 dist, FT_16D16 max_value )
{
FT_SDFFormat out;
FT_16D16 udist;
/* normalize the distance values */
dist = FT_DivFix( dist, max_value );
udist = dist < 0 ? -dist : dist;
/* Reduce the distance values to 8 bits, +1/-1 in */
/* 16.16 takes the 16th bit. So we right shift the */
/* number by 9 to make it fit in the 7 bit range. */
/* 1 bit is reserved for the sign. */
udist >>= 9;
/* Since char can only store max positive value */
/* of 127 we need to make sure it does not wrap */
/* around and give a negative value. */
if ( dist > 0 && udist > 127 )
udist = 127;
if ( dist < 0 && udist > 128 )
udist = 128;
/* Output the data; negative values are from [0, 127] and positive */
/* from [128, 255]. One important thing is that negative values */
/* are inverted here, that means [0, 128] maps to [-128, 0] linearly. */
/* More on that in `freetype.h` near `FT_RENDER_MODE_SDF` */
out = dist < 0 ? 128 - (FT_SDFFormat)udist :
(FT_SDFFormat)udist + 128;
return out;
}
/*
* Invert the signed distance packed into the corresponding format.
* So if the values are negative they will become positive in the
* chosen format.
*
* [Note]: This function should only be used after converting the
* 16.16 signed distance values to `FT_SDFFormat`, if that
* conversion has not been done, then simply invert the sign
* and use the above function to pack the values.
*/
static FT_SDFFormat
invert_sign( FT_SDFFormat dist ) {
return 255 - dist;
}
FT_LOCAL( FT_SDFFormat )
invert_sign( FT_SDFFormat dist );
FT_END_HEADER

7
src/sdf/rules.mk
View file

@ -28,9 +28,10 @@ SDF_COMPILE := $(CC) $(ANSIFLAGS) \
# sdf driver sources (i.e., C files)
#
SDF_DRV_SRC := $(SDF_DIR)/ftsdfrend.c \
$(SDF_DIR)/ftsdf.c \
$(SDF_DIR)/ftbsdf.c
SDF_DRV_SRC := $(SDF_DIR)/ftsdfrend.c \
$(SDF_DIR)/ftsdf.c \
$(SDF_DIR)/ftbsdf.c \
$(SDF_DIR)/ftsdfcommon.c
# sdf driver headers

1
src/sdf/sdf.c
View file

@ -21,6 +21,7 @@
#define FT_MAKE_OPTION_SINGLE_OBJECT
#include "ftsdfrend.c"
#include "ftsdfcommon.c"
#include "ftbsdf.c"
#include "ftsdf.c"