freetype2/[GSoC]ChangeLog

2020-08-15  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Added a basic overview of the `bsdf' rasterizer.

	* src/sdf/ftbsdf.c: Added the citation of the original paper
	  and added a overview of the process for generating SDF
	  from bitmaps.

2020-08-15  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added a basic overview of the `sdf' rasterizer.

	* src/sdf/ftsdf.c: Added the citation of the original paper
	  and added a overview of the process for generating SDF
	  from outlines.

	* src/sdf/ftsdf.c (sdf_generate_subdivision): Added comment
	  explaining how the optimization works.

2020-08-13  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Fix gcc compiler warnings.

	* src/sdf/ftsdf.c, src/sdf/ftbsdf.c (*): Fix
	  various compiler warnings, which were caused
	  mainly due to unused variables and unused functions.

2020-08-13  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Bug fix.

	* src/sdf/ftsdf.c (sdf_generate_with_overlaps): The
	  outside sign will always be 1. And added a missing
	  `else'.

2020-08-12  Anuj Verma  <anujv@iitbhilai.ac.in>

	[base] Fix memory leaks due to FreeType internals.

	* src/base/ftobjs.c (ft_remove_renderer): Similar to
	  `ft_add_renderer', remover raster's `glyph_format'
	  check. Due to this the rasterizers which do not have
	  `glyph_format' of `FT_GLYPH_FORMAT_OUTLINE' won't get
	  deallocated (the `raster_done' function is no called).

2020-08-12  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Fix memory leaks.

	* src/sdf/ftsdf.c (sdf_generate_with_overlaps): Deallocate
	  the temporary bitmaps, and all the rest of the arrays.
	  And also handle the `shape' appropriately so as to not
	  cause memory leaks.

2020-08-12  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Handle Post-Script fonts for overlap.

	* src/sdf/ftsdf.c (sdf_generate_with_overlaps): Handle
	  Handle Post-Script fonts for overlap support. Simply
	  flip the orientation while combining all the separate
	  SDF.
	  Also, handle the `flip_sign' property separately so as
	  to avoid handling extra cases.

2020-08-12  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added overlap support (currently only for TrueType).

	* src/sdf/ftsdfrend.h (SDF_Renderer_Module): Removed the
	  expermental `optimization' property.
	  Added another property `overlaps', which can be used to
	  turn on the overlap support.

	* src/sdf/ftsdf.h (SDF_Raster_Params): Ditto as above.

	* src/sdf/ftsdfrend.c (*): Added functionality to set
	  and get the new `overlaps' property.

	* src/sdf/ftsdf.c (sdf_raster_render):
	  Removed support for all the optimization modes and
	  only keep the subdivision optimization and the new
	  overlap support function.

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Turned
	  off until we can find a way to make it faster.

	* src/sdf/ftsdf.c (sdf_generate_with_overlaps): Added
	  a function to generate SDF for shapes with overlapping
	  contours. It basically generate SDF for separate contours
	  in seperate bitmaps and then combine them to remove
	  overlaps.

2020-08-7  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf, bsdf] Added better documentation.

	* src/sdf/ftsdf.c, src/sdf/ftbsdf.c (*): Added documentation
	  of the structs and enums for both the renderers.

2020-08-6  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added function to get contour orientation.

	* src/sdf/ftsdf.c (SDF_Contour_Orientation): Added
	  enum to hold the different orientations of a contour.

	* src/sdf/ftsdf.c (get_contour_orientation): Added
	  function which can be used to compute the orientation
	  of a contour.

	* src/sdf/ftbsdf.c (*): Remove completed `[TODO]'s.

2020-08-6  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Added documentation for functions of the `bsdf' renderer.

	* src/sdf/ftbsdf.c (*) Added function documentation for
	  function of the `bsdf' renderer.

2020-08-6  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added documentation for function of the `sdf' renderer.

	* src/sdf/ftsdf.c (*): Added function documentation for
	  function of the `sdf' renderer, and fixed grammar at a
	  few places.

2020-08-5  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added documentation for some structs.

	* src/sdf/ftsdfrend.h
	      .../ftsdfrend.c
	      .../ftsdfcommon.h
	      .../ftsdf.h
	  : Added documentation for a few structs.

2020-08-5  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Extended to work with monochrome bitmaps.

	* src/sdf/ftbsdf.c (bsdf_init_distance_map): Handle
	  monochrome bitmaps and convert them to the internal
	  intermediate format, which can then be used to
	  generate SDF.

2020-08-3  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfrend.c (ft_bsdf_render): Initialize
	  the target bitmap so as to avoid crashes due to
	  uninitialized memory.

2020-08-3  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Fixed memory leak.

	* src/sdf/ftbsdf.c (bsdf_raster_render): Release the
	  allocated distance map.
	  Also, added a log of total memory allocated for
	  generating SDF from bitmap.

2020-08-2  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Fixed a bug with `finalize_sdf'.

	* src/sdf/ftbsdf.c (finalize_sdf): First check if the
	  value is withing [-spread, spread] and then cast it
	  to 6.10 short, otherwise the value can overflow and
	  give negative result.
	  Also, flip the sign if the property `flip_sign' is
	  set to true.

2020-08-1  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Added option to use squared distances.

	* src/sdf/ftbsdf.c (bsdf_is_edge): Modified the function
	  to use distance map rather than the alpha values from
	  the source image.

	* src/sdf/ftbsdf.c (bsdf_approximate_edge): Only calculate
	  approximate edges for edge pixels. Use `bsdf_is_edge' is
	  to check for edge pixels. For non edge pixel assgn far
	  away distances.

	* src/sdf/ftbsdf.c (finalize_sdf): Handle distances in case
	  of squared distances.
	  And also use the macro `VECTOR_LENGTH_16D16' in the entire
	  code to compute vector length. This takes care of squared
	  distances.

	* src/sdf/ftsdfcommon.c (VECTOR_LENGTH_16D16): Move the macro
	  `VECTOR_LENGTH_16D16' from `ftsdf.c' to this file because
	  it is also used by the `bsdf' renderer.

2020-08-1  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c (compare_neighbor): Fix bug.

2020-08-1  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Optimized a bit.

	* src/sdf/ftbsdf.c (ED: sign => alpha): Renamed sign
	  to alphas. This is used to store the alpha of the current
	  pixel mapped to the source image. This let's us store
	  additional information without increasing memory usage.

	* src/sdf/ftbsdf.c (bsdf_init_distance_map): Removed any/all
	  kind of edge approximation and edge check from the function.
	  The function simply copy the source bitmap to the distance
	  map now, preserving alpha values.

	* src/sdf/ftbsdf.c (compute_edge_distance): Use the new `alpha'
	  parameter to compute gradient and approximate distance.
	  Previously we were using the `dist' variable to store alpha
	  values, which restricts modifying the `dist' variable because
	  we need alpha values of neighbor to compute the gradient.

	* src/sdf/ftbsdf.c (bsdf_approximate_edge): Now that we can
	  modify the `dist' variable of the distance map, we can
	  combine the two nested loops.

	* src/sdf/ftbsdf.c (finalize_sdf): Move the `sign' determination
	  and assignment to this function.

2020-07-31  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c (compute_edge_distance): Grammer fix.

2020-07-31  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Add explanation of the approximation.

	* src/sdf/ftbsdf.c (compute_gradient => compute_edge_distance):
	  Renamed to make sense of what the function does.
	  Also, added the explanation of the algorithm used
	  and a high level view of how it works.

	* src/sdf/ftbsdf.c (compare_neighbor): Fix a bug related
	  to value approximation before calling `FT_Vector_Length'.

2020-07-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfcommon.h (*): Fix line endings.

	Always use LF line endings.

2020-07-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf,bsdf] Put common propertied and functions in one file.

	* src/sdf/ftsdfcommon.h: Added new file which contains
	  common function, macros, properties for both `sdf' and
	  `bsdf' renderer.

	* src/sdf/ftsdf.c, src/sdf/ftsdf.h, src/sdf/ftbsdf.c:
	  Remove common properties and include `ftsdfcommon.h'.

	* src/sdf/rules.mk (SDF_DRV_H): Add the new `ftsdfcommon.h'
	  file to include list.

2020-07-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c (compute_gradient): Use root(2)
	  for the filter. Also, use the computed gradient
	  to approximate the edge distance from a pixel's
	  position according to the Gustavson's algorithm.

2020-07-29  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Added function to approximate edge distance.

	* src/sdf/ftbsdf.c (bsdf_approximate_edge): The function
	  uses the Gustavson's algorithm to approximate the edge
	  from pixel values.

	* src/sdf/ftbsdf.c (compute_gradient): The function uses
	  Sobel's operator to compute the gradient at a pixel.
	  The is used to detect edge direction.

2020-07-28  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c (_pass): Use function for repetitive task.

	Use function `compare_neighbor' for comparing the
	neighbors. Makes it easier to tweak the algorithm
	and looks better.

	* src/sdf/ftbsdf.c (compare_neighbor): Added function
	  to compare the neighbors and assign values if the
	  new distance is the shortest.

2020-07-27  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c (bsdf_is_edge): Use macros to
	  make it look cleaner.

	  Use `CHECK_NEIGHBOR' macro to check neighbors while
	  finding edges. Make the code more readable and look
	  cleaner.

2020-07-27  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Fix edge detection bug.

	* src/sdf/ftbsdf.c (bsdf_is_edge): [BUG] Check all
	  neighbors including the diagonal neighbors to
	  properly determine the edge.

2020-07-27  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Added edge detection algorithm.

	Added edge detection algorithm. It works by checking
	the neighboring pixels and if any neighbor is not
	filled (i.e. belongs to background) we mark the
	pixel as edge by setting it's distance to 0.

	* src/sdf/ftbsdf.c (bsdf_is_edge): Added function to
	  detect if the pixel is an edge.

2020-07-27  Anuj Verma  <anujv@iitbhilai.ac.in>

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

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

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

2020-07-26  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf] Optimize the first pass of the 8SED.

	* src/sdf/ftbsdf.c (first_pass): Optimize the first
	  pass by first approximating the neighbor's distance
	  by adding an offset. The offset will be max root(2)
	  because the maximum be add to a vector is (1, 1).
	  By approximating we can reduce the number of
	  `FT_Vector_Length' calls and thus make the process
	  faster.

2020-07-26  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Fix GNU Make build.

	* src/sdf/rules.mk (SDF_DRV_H): Manually add source files
	  as there is a `ftbsdf.c' file without any `ftbsdf.h'.

	* src/sdf/ftbsdf.c: Include `fttrigon.h' for `multi' builds.

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'.

	`SDF_TRaster' is for the `sdf' renderer.

2020-07-25  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftbsdf.c: Typo. `FT_16D16' is 16.16 representation.

2020-07-25  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf renderer] Hold a refrence to `FT_Memory'.

	Due to the way the 8SED algorithm works we need to keep
	a track of distances and nearest point of all the pixels/
	grid points.

	* src/sdf/ftbsdf.c (BSDF_TRaster): Added struct to
	  hold the `FT_Memory' reference, to be used to allocate
	  memory.

	* src/sdf/ftbsdf.c (ED, BSDF_Worker): Added few more
	  essential struct. `ED' contains infomation about the
	  nearest point. `BSDF_Worker' is used to combine all
	  the essentail parameters to functions.

	* src/sdf/ftbsdf.c (bsdf_copy_source_to_target => 
	  bsdf_init_distance_map): Renamed.

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

	* src/sdf/sdf.c: Change the order of source include
	  because `ftsdf.c' change some internal freetype
	  defines which are required in `ftbsdf.c'.

2020-07-25  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf -> bsdf renderer] Convert 8bit bitmap to 16bit.

	* src/sdf/ftbsdf.c (bsdf_copy_source_to_target): Added
	  extra parameter to flip the bitmap vertically.

	* src/sdf/ftbsdf.c (bsdf_copy_source_to_target):
	  Implemented functionality to convert 8bits per
	  pixel bitmap to a 16bits per pixel bitmap, which
	  will be used to generate SDF.

2020-07-24  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Started the `bsdf' rasterier.

	* src/sdf/ftbsdf.c (*): Fix line endings.

	* src/sdf/ftbsdf.c (bsdf_copy_source_to_target): Added
	  function to copy the source bitmap to the center of
	  the target bitmap and also convert it to normalized
	  16 bits per pixel bitmap.

2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added interface functions for `bsdf' converter.

	* src/base/ftobjs.c (FT_Render_Glyph_Internal): Remove
	  the bitmap check which prevent calling renderers
	  if the glyph is already a bitmap. The `bsdf' renderer
	  requires a bitmap for conversion.

	* src/base/ftobjs.c (ft_add_renderer): Remove the glyph
	  format check which ensures that the glyph format for
	  a renderer is `FT_GLYPH_FORMAT_OUTLINE', again the `bsdf'
	  renderer has `FT_GLYPH_FORMAT_BITMAP' as a glyph format,
	  so we need to remove the condition to initialize the
	  renderer properly.

	* src/sdf/ftbsdf.c (*): Added a rasterizer for the
	  `bsdf' renderer and created necessary functions.

	* src/sdf/ftbsdf.h: Add forward declaration of the
	  rasterizer.

	* src/sdf/ftsdfrend.c (ft_bitmap_sdf_renderer_class):
	  Define the new `bsdf' rendere and add the
	  `FT_Renderer_RenderFunc' function, the rest is
	  same as the `sdf' renderer.

	* src/sdf/ftsdfrend.h: Add forward declaration of the
	  renderer.

	* src/sdf/rules.mk (SDF_DRV_SRC): Add the new `ftbsdf.c'
	  file to the compile list.

	* src/sdf/sdf.c: Inclue the `ftbsdf.c' file if making
	  single object.

2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Add alloc/free functions.

	* src/sdf/ftsdf.c (*): Add `sdf_alloc' and `sdf_free'
	  to allocate and deallocate memory respectively.
	  By using function we can directly use them in the
	  conditional statements, which is not possible when
	  using `do {} while ( 0 )'.

	* src/sdf/ftsdf.c (SDF_MEMORY_TRACKER_): When not
	  debugging don't leave the macros empty otherwise
	  some compiler may emit warning because of empty
	  `;' semi-colon.

2020-07-19  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added new renderer `bsdf'.

	* src/sdf/ftsdfrend.* (*): Added new renderer
	  named `bsdf' which basically convert bitmap
	  to signed distance fields. This is a part of
	  the `sdf' module and not a separate module on
	  it's own.

	* src/sdf/module.mk (FTMODULE_H_COMMANDS): Add
	  the new renderer to the list of modules.

	* include/freetype/config/ftmodule.h: Add the
	  new renderer to default list of modules when
	  not compiling with GNU Make.

2020-07-18  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Only track memory in debug mode.

	* src/sdf/ftsdf.c (*): Disable total memory
	  usage tracking if the program is not in
	  debug mode.

2020-07-18  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdfb] Removed Module.

	Remove sdfb module. Instead of a new module
	simply create a new renderer in the `sdf'
	module for converting bitmaps to SDF.

2020-07-18  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdfb] Fix GNU Make build.

	* src/sdfb/rules.mk (SDFB_DRV_H): Fix name of
	  the module specific error file `ftsdfberrs.h'.

	* src/sdf/ftsdf.h (Optimizations): Fix warning.
	  `warning: comma at end of enumerator list [-Wpedantic]'

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Remove
	  unused variable `cindex', causes warning.
	  `warning: unused variable 'cindex' [-Wunused-variable]'

2020-07-17  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdfb] Added new module to generate SDF from bitmap.

	* src/sdfb/sdfb.c, src/sdfb/ftsdfbrend.c,
	  src/sdfb/ftsdfb.c, src/sdfb/ftsdfbrend.h,
	  src/sdfb/ftsdfb.h, src/sdfb/ftsdfberrs.h:
	  Added files required by the `sdfb' renderer module.

	* src/sdfb/rules.mk, src/sdfb/module.mk: Added
	  files required to build the `sdfb' module using
	  the default build system.

	* CMakeLists.txt (BASE_SRCS): Add `src/sdfb/sdfb.c'
	  to the variable.

	* include/freetype/config/ftmodule.h: Added `sdfb'
	  module declaration so that the module can be compiled 
	  when not compiling with GNU make.

	* modules.cfg (RASTER_MODULES): Include `sdfb' module
	  to the default rasterizer module list.

	* include/freetype/ftmoderr.h: sdfb module error define

	* src/sdf/rules.mk: Add EOF.

2020-07-17  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added memory tracker.

	* src/sdf/ftsdf.c (SDF_MemoryUser): Added struct
	  which is used in place of `FT_Memory::user'.

	* src/sdf/ftsdf.c (SDF_ALLOC, SDF_FREE): Added macros
	  for allocating and deallocating memory. These macros
	  restore the old `FT_Memory::user' before calling the
	  relevant allocation/deallocation functions so as to
	  not cause errors while debugging memory. And later
	  they add the allocated memory size in a variable.

	* src/sdf/ftsdf.c (*): Use `SDF_ALLOC', `SDF_FREE'
	  instead of the `FT_' variant.

2020-07-15  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfrend.c (sdf_property_set): Minor fix.

2020-07-14  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Temporary change.

	Added new property to dynamically change the
	optimization to be used to generate the SDF.
	This can be used to compare the performance of
	different optimization techniques without going
	and recompiling the program.
	And will also be used in the demo to check the
	performance.

2020-07-13  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added more properties.

	Added two properties:
	- `flip_y': To flip the generated SDF along the y axis.
	- `flip_sign': By default outside is treated to have
	   negative sign, setting `flip_sign' to 1 the outside
	   pixels will have positive sign.

	* src/sdf/ftsdf.* (*): Use the newly added properties.

	* src/sdf/ftsdfrend.* (*): Add the newly added properties,
	  and add functionality to set them using `FT_Property_Set'.

2020-07-13  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Check for left or right fill.

	* src/sdf/ftsdf.c (SDF_Params): Added struct which
	  contains some internal data required by the rater-
	  izer (such as left/right fill).

	* src/sdf/ftsdf.c (sdf_raster_render): Determine the
	  fill side and pass it to the `sdf_generate_' funcs.

	* src/sdf/ftsdf.c (sdf_generate_): Use the new `SDF_Params'
	  to generate SDF accordingly.

2020-07-12  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Optimize the coarse grid optimization.

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Merge
	  the relevant edge finding loop and shortest dist-
	  ance search loop. We can find the relevant edges
	  of a coarse grid and immediately use them to find
	  the shortest distance of the points in the coarse
	  grid. This drastically reduce memory usage and 
	  performance.
	  Also, do the sign assignment of the edges which was
	  missing.

2020-07-11  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (*): Fixed warnings.

	Fixed various warnings and other few errors.

2020-07-11  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Comments.

	Add more comments explaining the step by step
	process of using coarse grid to increase the
	performance of nearest distance search.

2020-07-11  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Memory leak.

	Release the allocated lists for the coarse grid after
	we are done using them.

2020-07-11  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Completed the coarse grid optimization.

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Fixed
	  an issue with position calculation and upside down
	  images.

2020-07-10  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Partially completed the coarse grid optimization.

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): Added
	  functionality to check distances of all edges from
	  the coarse grid and add the relevant edges to the 
	  list.
	  [Note]: The function is not complete yet.

2020-07-10  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added the coarse grid optimization function.

	* src/sdf/ftsdf.c (sdf_generate_coarse_grid): The
	  function uses coarse grid to optimize nearest edge
	  search performance.

2020-07-10  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Remove use of `FT_List'.

	Simply use a `next' pointer inside `SDF_Edge' and
	`SDF_Contour' to create a linked list. This reduces
	the number of allocations due to `FT_ListNode', also
	we don't need a doubly linked list.

	* src/sdf/ftsdf.c (SDF_Edge, SDF_Contour): Remove the
	  `FT_List' and use a `next' pointer to create the
	  linked list.

	* src/sdf/ftsdf.c(sdf_edge_destructor, sdf_contour_destructor):
	  Removed, not needed any more.

	* src/sdf/ftsdf.c (*): Remove the use of `FT_List_'
	  functions wherever necessary and sync with the new
	  list.

2020-07-09  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added subdivision optimization.

	* src/sdf/ftsdf.c (sdf_generate_subdivision): The
	  function generate SDF just like the `sdf_generate'
	  function, but subdivide the curve into a number of
	  lines and then use the `sdf_generate_bounding_box'
	  function to generate SDF.

2020-07-09  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added functions to subdivide a cubic curve.

	* src/sdf/ftsdf.c (split_cubic, split_sdf_cubic):
	  These functions can be used to subdivide a
	  cubic bezier curve into line segments which can
	  then be used to generate the SDF.

	* src/sdf/ftsdf.c (split_sdf_shape): Added function
	  to split a cubic into a line segments.

	* src/sdf/ftsdf.c (sdf_shape_done): No need to pass
	  `FT_Memory' as a parameter, it can be accessed
	  from the `shape' struct.

2020-07-09  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (split_sdf_shape): Typo.

2020-07-08  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (split_sdf_shape): Memory leak.
	  After recursion the edges variable becomes `NULL'
	  so reassign it to deallocate the list completely.

2020-07-08  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added functions to subdivide a conic curve.

	* src/sdf/ftsdf.c (split_conic, split_sdf_conic):
	  These functions can be used to subdivide a
	  conic bezier curve into line segments which can
	  then be used to generate the SDF.

	* src/sdf/ftsdf.c (split_sdf_shape): Added function
	  to split a outline into a line segments.

2020-07-06  Anuj Verma  <anujv@iitbhilai.ac.in>

	* [GSoC]ChangLog: Fixed typos.

2020-07-06  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfrend.c (sdf_generate_bounding_box): Due to
	  the way we use the bounding box, we need to keep a track
	  of signed distances of each pixel so later the sign can
	  be determined properly. The method is certainly faster
	  then checking all the pixels against all the edges,
	  but also require a decent amount of memory to work.

2020-07-06  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Precompute the orthogonality.

	* src/sdf/ftsdf.c (SDF_Signed_Distance): Remove unused
	  fields.

	* src/sdf/ftsdf.c (resolve_corner): The function can be
	  simplified to a single line. Instead of computing
	  orthogonality here, we precompute it in the corresponding
	  `get_min_distance_' functions more efficiently.

	* src/sdf/ftsdf.c (get_min_distance_): Precompute orthogonality/
	  cross product of direction and the distance vector. Since
	  in these function we know that weather the distance vector
	  and the direction are perpendicular, we can simply set
	  the cross to 1 (sin(90) = 1) in case they are perpendicular.
	  This can reduce the number of `FT_Vector_NormLen' calls.

2020-07-05  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added bounding box optimization.

	* src/sdf/ftsdfrend.c (sdf_generate_bounding_box): The
	  function generate SDF just like the `sdf_generate'
	  function, but uses bounding box to check pixels
	  efficiently.

	* src/sdf/ftsdfrend.c (get_control_box): Added function
	  to get control box of a `SDF_Edge'.

2020-07-04  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfrend.c (sdf_shape_dump): Use `%ld' to
	  printf `signed long' otherwise it gives wrong output.

2020-07-04  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdfrend.c (ft_sdf_render): Don't negate
	  unsigned integers.

2020-07-03  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c: Use ASCII single quote (') instead
	  of back tick (`) for derivatives. Looks cleaner.

2020-07-03  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added function to find shortest distance from a
	point to a cubic bezier. Now the sdf module can render
	all types of fonts, but still has some issues.

	* src/sdf/ftsdf.c (get_min_distance_cubic): The function
	  calculates shortest distance from a point to a cubic
	  bezier curve.

	* src/sdf/ftsdf.c (sdf_edge_get_min_distance): Add the
	  `get_min_distance_cubic' function call.

2020-07-03  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (resolve_corner): [Bug] Remove the
	  nearest_point check. Two distances can be same and
	  can give opposite sign, but they may not have a
	  common nearest_point. Also remove distance check
	  because due to precision errors the two distances can
	  be really really close. Therefore use epsilon instead.

	* src/sdf/ftsdf.c (sdf_contour_get_min_distance): Use
	  epsilon for comparing distances.

2020-07-03  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (sdf_shape_dump): Add more info
	  to the debug output.

2020-07-03  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (MAX_NEWTON_ITERATION => MAX_NEWTON_DIVISIONS):
	  Renamed to avoid confusion.

2020-07-02  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added Newton's method for shortest distance
	from a point to a conic.

	* src/sdf/ftsdf.c (get_min_distance_conic): Created
	  a new function with same name which uses Newton's
	  iteration for finding shortest distance from a point
	  to a conic curve. This doesn't causes underflow.

	* src/sdf/ftsdf.c (USE_NEWTON_FOR_CONIC): This macro
	  can be used to toggle between Newton or analytical
	  cubic solving method.

2020-07-01	Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (get_min_distance_conic): Add more
	  details to why we clamp the roots.

	* src/sdf/ftsdf.c: Make sure preprocessor # is always
	  on the first line.

2020-07-01	Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Make squared distances toggleable.

	* src/sdf/ftsdf.c (SDF_Signed_Distance): Renamed 
	  squared_distance to distance. It can now represent
	  both squared as well as actual distances.

	* src/sdf/ftsdf.c (USE_SQUARED_DISTANCES): Added macro
	  which control weather to do computation is squared
	  distances or actual distances. This can be used to
	  avoid overflow when generating large SDF bitmaps.

	* src/sdf/ftsdf.c: Make sure not to exceed line length
	  of 78.

2020-07-01	Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (get_min_distance_conic): In case
	  the cubic equation returns zero root, use endpoints
	  for calculating the shortest distance.

2020-07-01	Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added function to find shortest distance from a
	point to a conic bezier. Now the sdf module can render
	ttf fonts or fonts with line and conic segments.

	* src/sdf/ftsdf.c (get_min_distance_conic): The function
	  calculates shortest distance from a point to a conic
	  bezier curve.

	* src/sdf/ftsdf.c (sdf_edge_get_min_distance): Add the
	  `get_min_distance_conic' function call.

2020-07-01	Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (get_min_distance_line): First check
	  pointer before using or dereferencing them.

2020-06-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c: Avoid parentheses if there is only
	  one statement inside a control-flow statement.

2020-06-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added functions to solve polynomial equations.

	* src/sdf/ftsdf.c (solve_quadratic_equation, 
	  solve_cubic_equation): Added functions to solve
	  quadratic and cubic equations. These will be used for
	  conic bezier curves only.

2020-06-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (square_root, cube_root, arc_cos):
	  Use FT_16D16 instead of FT_Fixed to avoid confusion.

2020-06-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (cube_root, arc_cos): Added a few
	  essential math functions.

2020-06-30  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Fixed compilation under gnumake.

	* src/sdf/rules.mk (DRV_OBJ_ => DRV_OBJS_): Fixed variable
	  name so that the sdf can compile.

	* src/sdf/module.mk: Fixed spacing.

	* src/sdf/*.c: Fixed all compiler warnings.

	* [GSoC]ChangLog: Fixed dates.

2020-06-29  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added function to resolve corners in case of
	ambiguity.

	* src/sdf/ftsdf.c (resolve_corner): Added function
	  to determine the correct sign in case there are
	  two sign for the same shortest distance (happens
	  around corners).

	* src/sdf/ftsdf.c: Typo neartest_point -> nearest_point.

2020-06-29  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.

2020-06-28  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added function to find shortest distance from
	a point to a line.

	* src/sdf/ftsdf.c (get_min_distance_line): The function
	  calculate the shortest signed distance from a point
	  to a line segment.

	* src/sdf/ftsdf.c (sdf_contour_get_min_distance): Typo.

	* src/sdf/ftsdf.c (SDF_Signed_Distance): Use squared
	  distance instead of actual distance for performance.

2020-06-28  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (SDF_Iterator_IO): Removed.

	* src/sdf/ftsdf.c (sdf_edge_iterator_func => sdf_edge_get_min_distance
	  sdf_contour_iterator_func => sdf_contour_get_min_distance): Renamed.
	  Manually iterate through the lists instead of `FT_List_Iterate' to
	  avoid io structs and looks a bit cleaner.

2020-06-28  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added basic outline of the functions required to
	generate sdf.

	* src/sdf/ftsdf.c (SDF_Signed_Distance): Added struct which
	  represent a complete signed distance and can be used to
	  get cross, dot, sign etc.

	* src/sdf/ftsdf.c (SDF_Iterator_IO): This struct will be used
	  while `FT_List_Iterate'.

	* src/sdf/ftsdf.c (sdf_generate): Added function which generate
	  SDF from `SDF_Shape'.

	* src/sdf/ftsdf.c (sdf_edge_iterator_func,
	                   sdf_contour_iterator_func): Added functions
	  which iterate through contours and edges and return the shortest
	  distance.
	  

2020-06-27  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added `SDF_Raster_Params' struct which extends
	`FT_Raster_Params' and has a few extra fields. This is done
	to pass extra data to the sdf rasterizer which is required
	while rasterizing.

	* src/sdf/ftsdf.h (SDF_Raster_Params): Added a struct which
	  extends `FT_Raster_Params' and has the `spread' parameter.
	  Also moved the max, min and default spread values to this
	  header file.

	* src/sdf/ftsdf.c (sdf_raster_render): Added parameter and
	  attribute checking in order to pick errors and return
	  early.

	* src//sdf/ftsdfrend.c (ft_sdf_render): Setup the `SDF_Raster_Params'
	  and pass it to the rasterizer instead of `FT_Raster_Params'.

2020-06-27  Anuj Verma  <anujv@iitbhilai.ac.in>

	* include/freetype/ftimage.h (FT_RASTER_FLAG_): Added
	  a new raster flag `FT_RASTER_FLAG_SDF'. The `ftsdf'
	  rasterizer will only render if this flag is set.

	* src/sdf/ftsdfrend.c (ft_sdf_render): Set the `flags' field
	  of `FT_Raster_Params' to `FT_RASTER_FLAG_SDF'.
	  
2020-06-26  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (sdf_shape_dump): Use `FT_TRACEX'
	  instead of `printf'.

2020-06-26  Anuj Verma  <anujv@iitbhilai.ac.in>

	* src/sdf/ftsdf.c (sdf_shape_dump): Added function to
	  dump the `SDF_Shape' on the console for debugging.

2020-06-26  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added functions to de-allocate `SDF_' structs.

	* src/sdf/ftsdf.c (SDF_Contour, SDF_Shape): Use `FT_ListRec'
	  instead of `FT_List' to avoid a few extra allocations.

	* src/sdf/ftsdf.c (SDF_Edge, SDF_Contour, SDF_Shape): Added
	  functions to de-allocate these structs and their members.

	* src/sdf/ftsdfrenc.c: Typo.

2020-06-25  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Decompose outline and store it in a temporary
	`SDF_Shape' object for easy iteration and pre-computing
	some variables.

	* src/sdf/ftsdf.c (sdf_outline_decompose): Added function
	  to decompost outline and store it in a `SDF_Shape' object.
	  This allows us to pre-compute some variable.

2020-06-25  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added essential enums and structs required.

	* src/freetype/internal/fttrace.h: Remove tabs.

	* src/sdf/ftsdfrend.c (ft_sdf_render): Calculate padding
	  using the `spread'.

	* src/sdf/ftsdf.c (SDF_Edge_Type, SDF_Edge, SDF_Contour,
	  SDF_Shape): Added structures and their initializer
	  functions.

2020-06-23  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added functionality to set and get module properties.
	Also added a `spread' property.

	* src/freetype/internal/fttrace.h: Added sdf module trace
	  define.

	* src/sdf/ftsdf.c (sdf_TRaster => SDF_TRaster): Use capital
	  character for structs.

	* src/sdf/ftsdfrend.h (SDF_Renderer_Module): Added a struct
	  which extends the `FT_RendererRec' and added the `spread'
	  property.

	* src/sdf/ftsdfrend.c: Synchronized the code to use the new
	  `SDF_Renderer_Module' and added functions to get/set the
	  properties.


2020-06-20  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Implemented a few functions required by a renderer
	module.

	* src/sdf/ftsdf.c (sdf_TRaster_): Added new structure to hold
	  the memory allocator `FT_Memory'.

	* src/sdf/ftsdf.c (ft_sdf_raster): Implemented a few essential
	  functions required by `FT_Raster'.

	* src/sdf/ftsdfrend.c (ft_sdf_renderer_class): Implemented a few
	  essential functions required by `FT_Renderer'.

	* src/sdf/ftsdfrend.c (ft_sdf_render): Added functionality to
	  compute shift and padding before rendering the outline.

2020-06-19  Anuj Verma  <anujv@iitbhilai.ac.in>

	* include/freetype/ftimage.h (FT_Render_Mode_): Added new
	  pixel mode `FT_PIXEL_MODE_GRAY16' which will be used
	  to represent signed values while rendering to SDF bitmap.

2020-06-19  Anuj Verma  <anujv@iitbhilai.ac.in>

	* include/freetype/freetype.h (FT_Render_Mode_): Added new
	  rendermode `FT_RENDER_MODE_SDF' which will be used by the
	  `sdf' module to generate signed distance fields from glyph's
	  outline.

	* src/sdf/ftsdfrend.h, src/sdf/module.mk, src/sdf/rules.mk:
	  Add a new line at the end of files.

2020-06-18  Anuj Verma  <anujv@iitbhilai.ac.in>

	[sdf] Added the structure of a new module to render
	signed distance fields.

	* src/sdf/sdf.c, src/sdf/ftsdfrend.c, src/sdf/ftsdf.c,
	  src/sdf/ftsdfrend.h, src/sdf/ftsdf.h, src/sdf/ftsdferrs.h:
	  Added files required by the `sdf' renderer module and added
	  the basic structure and functions required.

	* src/sdf/rules.mk, src/sdf/module.mk: Added files required to
	  build the `sdf' module using the default build system.

	* CMakeLists.txt (BASE_SRCS): Add `src/sdf/sdf.c' to the variable.

	* include/freetype/config/ftmodule.h: Added `sdf' module 
	  declaration so that the module can be compiled when not compiling
	  with GNU make.

	* modules.cfg (RASTER_MODULES): Include `sdf' module to the default
	  rasterizer module list.

	* include/freetype/ftmoderr.h: sdf module error define