* include/freetype/config/ftmodule.h: Add both the 'sfd' and 'bsfd'
renderers to the list of modules.
* CMakeLists.txt (BASE_SRCS): Add 'sdf' single-object module.
* src/sdf/module.mk, src/sfd/rules.mk: New files.
* src/sdf/ftsdf.h (ft_sdf_raster): New forward declaration.
* include/freetype/ftmoderr.h (FT_MODERRDEF): Add error definition
for the 'sdf' module.
* include/freetype/internal/fttrace.h (FT_TRACE_DEF): Add trace
definition for the `sdf' module.
* modules.cfg (RASTER_MODULES): Add the `sdf' module to the list of
rasterizers.
* src/sdf/ftsdf.c (sdf_generate_bounding_box): New function, which
is an optimized version of `sdf_generate`.
(sdf_generate_subdivision): New function.
* src/sdf/ftsdf.c (sdf_generate): New function, currently disabled.
This is a proof-of-concept implementation: It doesn't use any
optimization, it simply checks all grid points against all contours.
* src/sdf/ftsdf.c (get_min_distance_line, get_min_distance_conic,
get_min_distance_cubic): New functions. Note that
`get_min_distance_conic` comes with two implementations (using an
analytical and an iterative method, to be controlled with the
`USE_NEWTON_FOR_CONIC` macro).
* src/sdf/ftsdf.c (FT_DEBUG_INNER, FT_ASSIGNP_INNER)
[FT_DEBUG_LEVEL_TRACE && FT_DEBUG_MEMORY]: New macros.
(SDF_MemoryUser) [FT_DEBUG_LEVEL_TRACE && FT_DEBUG_MEMORY]: New
struct for memory usage tracing.
(sdf_alloc, sdf_free) [FT_DEBUG_LEVEL_TRACE && FT_DEBUG_MEMORY]: New
functions for memory usage tracing.
(SDF_ALLOC, SDF_FREE): New macros for memory management.
(SDF_MEMORY_TRACKER_DECLARE, SDF_MEMORY_TRACKER_SETUP,
SDF_MEMORY_TRACKER_DONE): New macros to set up memory usage tracing.
(USE_NEWTON_FOR_CONIC, MAX_NEWTON_DIVISIONS, MAX_NEWTON_STEPS,
CORNER_CHECK_EPSILON, CG_DIMEN): New configuration macros for
controlling the process of finding the shortest distance.
(MUL_26D6, VEC_26D6_DOT): New auxiliary macros.
(SDF_TRaster, SDF_Edge, SDF_Contour, SDF_Shape, SDF_Signed_Distance,
SDF_Params): New structs for setting up SDF data.
(SDF_Edge_Type, SDF_Contour_Orientation): New enums for SDF data.
(zero_vector, null_edge, null_contour, null_shape, max_sdf): Useful
constants.
(sdf_edge_new, sdf_edge_done, sdf_contour_new, sdf_contour_done,
sdf_shape_new, sdf_shape_done): New constructors and destructors.
Here is a breakdown of what the files will contain.
* src/sdf/ftsdfrend.c, src/sdf/ftsdfrend.h: The 'sdf' and 'bsdf'
renderers.
* src/sdf/ftsdf.c, src/sdf/ftsdf.h: The rasterizer for the 'sdf'
renderer.
* src/sdf/ftbsdf.c, src/sdf/ftbsdf.h: The rasterizer for the 'bsdf'
renderer.
* src/sdf/ftsdfcommon.h: Commmon properties and functions for both
rasterizers.
* src/sdf/ftsdferrs.h: Common error defines.
* src/sdf/sdf.c: For building a single object of the entire module.
* src/base/ftobjs.c (FT_Render_Glyph_Internal): Do not return if the
glyph's slot format is `FT_GLYPH_FORMAT_BITMAP`. The forthcoming
'bsdf' renderer will require bitmaps for processing.
* src/base/ftobjs.c (ft_add_renderer, ft_remove_renderer): Remove
renderer's glyph format check before adding and removing them. The
'bsdf' renderer will have a format `FT_GLYPH_FORMAT_BITMAP`.
* include/freetype/freetype.h (FT_Render_Mode): Add new render mode
`FT_RENDER_MODE_SDF`, which will be used to generate SDF.
* include/freetype/ftimage.h (FT_Pixel_Mode): Add new pixel mode
`FT_PIXEL_MODE_GRAY16`, which will be the output of the 'sdf'
module.
(FT_RASTER_FLAG_SDF): New raster flag to be used internally by the
'sdf' module.
* include/freetype/fttypes.h (FT_F6Dot10): New data type.
* src/base/ftobjs.c (FT_Render_Glyph_Internal): Do not return if the
glyph's slot format is `FT_GLYPH_FORMAT_BITMAP`. The forthcoming
'bsdf' renderer will require bitmaps for processing.
* src/base/ftobjs.c (ft_add_renderer, ft_remove_renderer): Remove
renderer's glyph format check before adding and removing them. The
'bsdf' renderer will have a format `FT_GLYPH_FORMAT_BITMAP`.
The old code used to divide the darkening amount by em_ratio twice,
leading to unnecessarily bold stems on certain fonts with higher
units per em (e.g. Inter). This patch fixes it.
The return value of af_loader_compute_darkening was also changed to
use 16.16 fixed point to get rid of a redundant truncation operation.
This should slightly improve the precision, although it's still
bottlenecked by the emboldening function, which uses 26.6 fixed point.
* src/autofit/afloader.[ch]
(af_loader_compute_darkening): Return FT_Fixed.
(af_loader_embolden_glyph_in_slot): Revise calculations.
* src/truetype/ttgload.c (tt_get_metrics, load_truetype_glyph):
Previously, the code would populate the phantom points before
calling the `get_glyph_metrics` callback. For formats like PCL XL
format 1, class 2 downloaded fonts (where metrics are removed from
the TTF header), this causes problems when the hinting program uses
the phantom points (misplaced and distorted glyphs) due to the
metrics being unset (all zeros).
(tt_get_metrics_incr_overrides): Renamed to...
(tt_get_metrics_incremental): ... this. Updated caller
* include/freetype/ftincrem.h: Update the documentation to make it
clearer that `get_glyph_metrics` is to retrieve metrics from a
non-standard source, but *not* for the purpose of imposing custom
metrics.
