forked from minhngoc25a/freetype2
[sdf, bsdf] Added better documentation.
* src/sdf/ftsdf.c, src/sdf/ftbsdf.c (*): Added documentation of the structs and enums for both the renderers.
This commit is contained in:
parent
06bbff76b9
commit
307b0cbd6f
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@ -1,3 +1,10 @@
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2020-08-7 Anuj Verma <anujv@iitbhilai.ac.in>
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[sdf, bsdf] Added better documentation.
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* src/sdf/ftsdf.c, src/sdf/ftbsdf.c (*): Added documentation
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of the structs and enums for both the renderers.
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2020-08-6 Anuj Verma <anujv@iitbhilai.ac.in>
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2020-08-6 Anuj Verma <anujv@iitbhilai.ac.in>
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[sdf] Added function to get contour orientation.
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[sdf] Added function to get contour orientation.
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@ -22,22 +22,87 @@
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*
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*
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*/
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*/
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/**************************************************************************
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*
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* @Struct:
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* BSDF_TRaster
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*
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* @Description:
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* This struct is used in place of `FT_Raster' and is stored within
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* the internal freetype renderer struct. While rasterizing this is
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* passed to the `FT_Raster_Render_Func' function, which then can be
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* used however we want.
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*
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* @Fields:
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* memory ::
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* Used internally to allocate intermediate memory while raterizing.
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*
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*/
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typedef struct BSDF_TRaster_
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typedef struct BSDF_TRaster_
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{
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{
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FT_Memory memory; /* used internally to allocate memory */
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FT_Memory memory;
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} BSDF_TRaster;
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} BSDF_TRaster;
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/* Euclidean distance used for euclidean distance transform */
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/**************************************************************************
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/* can also be interpreted as edge distance. */
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*
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* @Struct:
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* ED
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*
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* @Description:
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* Euclidean distance used for euclidean distance transform can also be
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* interpreted as edge distance.
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*
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* @Fields:
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* dist ::
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* Vector length of the `near' parameter. Can be squared or absolute
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* depending on the `USE_SQUARED_DISTANCES' parameter defined in
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* `ftsdfcommon.h'.
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*
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* near ::
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* Vector to the nearest edge. Can also be interpreted as shortest
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* distance of a point.
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*
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* alpha ::
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* Alpha value of the original bitmap from which we generate SDF.
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* While computing the gradient and determining the proper sign
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* of a pixel this field is used.
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*
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*/
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typedef struct ED_
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typedef struct ED_
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{
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{
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FT_16D16 dist; /* distance at `near' */
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FT_16D16 dist;
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FT_16D16_Vec near; /* nearest point */
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FT_16D16_Vec near;
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FT_Byte alpha; /* alpha of the source */
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FT_Byte alpha;
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} ED;
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} ED;
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/**************************************************************************
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*
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* @Struct:
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* BSDF_Worker
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*
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* @Description:
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* Just a convenient struct which is passed to most of the functions
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* while generating SDF. This makes it easier to pass parameters because
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* most functions require the same parameters.
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*
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* @Fields:
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* distance_map ::
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* A 1D array which is interpreted as 2D array. This array contains
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* the Euclidean distance of all the points of the bitmap.
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*
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* width ::
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* Width of the above `distance_map'.
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*
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* rows ::
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* Number of rows in the above `distance_map'.
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*
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* params ::
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* Internal params and properties required by the rasterizer. See
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* `ftsdf.h' for the fields of this struct.
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*
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*/
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typedef struct BSDF_Worker_
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typedef struct BSDF_Worker_
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{
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{
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ED* distance_map;
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ED* distance_map;
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*
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*
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*/
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*/
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/* called when adding a new module through `FT_Add_Module' */
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static FT_Error
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static FT_Error
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bsdf_raster_new( FT_Memory memory,
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bsdf_raster_new( FT_Memory memory,
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FT_Raster* araster)
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FT_Raster* araster)
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return error;
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return error;
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}
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}
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/* unused */
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static void
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static void
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bsdf_raster_reset( FT_Raster raster,
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bsdf_raster_reset( FT_Raster raster,
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unsigned char* pool_base,
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unsigned char* pool_base,
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FT_UNUSED( pool_size );
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FT_UNUSED( pool_size );
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}
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}
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/* unused */
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static FT_Error
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static FT_Error
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bsdf_raster_set_mode( FT_Raster raster,
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bsdf_raster_set_mode( FT_Raster raster,
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unsigned long mode,
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unsigned long mode,
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return FT_Err_Ok;
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return FT_Err_Ok;
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}
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}
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/* called while rendering through `FT_Render_Glyph' */
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static FT_Error
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static FT_Error
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bsdf_raster_render( FT_Raster raster,
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bsdf_raster_render( FT_Raster raster,
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const FT_Raster_Params* params )
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const FT_Raster_Params* params )
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return error;
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return error;
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}
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}
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/* called while deleting a `FT_Library' only if the module is added */
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static void
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static void
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bsdf_raster_done( FT_Raster raster )
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bsdf_raster_done( FT_Raster raster )
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{
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{
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259
src/sdf/ftsdf.c
259
src/sdf/ftsdf.c
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@ -143,6 +143,8 @@
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/* then they will be checked for corner if they have ambiguity. */
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/* then they will be checked for corner if they have ambiguity. */
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#define CORNER_CHECK_EPSILON 32
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#define CORNER_CHECK_EPSILON 32
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/* Coarse grid dimension. Probably will be removed in the future cause */
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/* coarse grid optimization is the slowest. */
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#define CG_DIMEN 8
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#define CG_DIMEN 8
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/**************************************************************************
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/**************************************************************************
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@ -161,101 +163,258 @@
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*
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*
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*/
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*/
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/**************************************************************************
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*
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* @Struct:
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* SDF_TRaster
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*
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* @Description:
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* This struct is used in place of `FT_Raster' and is stored within
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* the internal freetype renderer struct. While rasterizing this is
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* passed to the `FT_Raster_Render_Func' function, which then can be
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* used however we want.
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*
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* @Fields:
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* memory ::
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* Used internally to allocate intermediate memory while raterizing.
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*
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*/
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typedef struct SDF_TRaster_
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typedef struct SDF_TRaster_
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{
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{
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FT_Memory memory; /* used internally to allocate memory */
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FT_Memory memory;
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} SDF_TRaster;
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} SDF_TRaster;
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/* enumeration of all the types of curve present in vector fonts */
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/**************************************************************************
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*
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* @Enum:
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* SDF_Edge_Type
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*
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* @Description:
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* Enumeration of all the types of curve present in fonts.
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*
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* @Fields:
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* SDF_EDGE_UNDEFINED ::
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* Undefined edge, simply used to initialize and detect errors.
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*
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* SDF_EDGE_LINE ::
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* Line segment with start and end point.
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*
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* SDF_EDGE_CONIC ::
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* A conic/quadratic bezier curve with start, end and on control
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* point.
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*
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* SDF_EDGE_CUBIC ::
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* A cubic bezier curve with start, end and two control points.
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*
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*/
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typedef enum SDF_Edge_Type_
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typedef enum SDF_Edge_Type_
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{
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{
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SDF_EDGE_UNDEFINED = 0, /* undefined, used to initialize */
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SDF_EDGE_UNDEFINED = 0,
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SDF_EDGE_LINE = 1, /* straight line segment */
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SDF_EDGE_LINE = 1,
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SDF_EDGE_CONIC = 2, /* second order bezier curve */
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SDF_EDGE_CONIC = 2,
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SDF_EDGE_CUBIC = 3 /* third order bezier curve */
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SDF_EDGE_CUBIC = 3
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} SDF_Edge_Type;
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} SDF_Edge_Type;
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/* Enumeration for the orientation of a contour, remember */
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/**************************************************************************
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/* the orientation is independent of the fill rule. */
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*
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* @Enum:
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* SDF_Contour_Orientation
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*
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* @Description:
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* Enumeration of all the orientation of a contour. We determine the
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* orientation by calculating the area covered by a contour.
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*
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* @Fields:
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* SDF_ORIENTATION_NONE ::
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* Undefined orientation, simply used to initialize and detect errors.
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*
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* SDF_ORIENTATION_CW ::
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* Clockwise orientation. (positive area covered)
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*
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* SDF_ORIENTATION_ACW ::
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* Anti-clockwise orientation. (negative area covered)
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*
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* @Note:
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* The orientation is independent of the fill rule of a `FT_Outline',
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* that means the fill will be different for different font formats.
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* For example, for TrueType fonts clockwise contours are filled, while
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* for OpenType fonts anti-clockwise contours are filled. To determine
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* the propert fill rule use `FT_Outline_Get_Orientation'.
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*
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*/
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typedef enum SDF_Contour_Orientation_
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typedef enum SDF_Contour_Orientation_
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{
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{
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SDF_ORIENTATION_NONE = 0, /* undefined, used to initialize */
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SDF_ORIENTATION_NONE = 0,
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SDF_ORIENTATION_CW = 0, /* clockwise orientation */
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SDF_ORIENTATION_CW = 0,
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SDF_ORIENTATION_ACW = 0, /* anti-clockwise orientation */
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SDF_ORIENTATION_ACW = 0
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} SDF_Contour_Orientation;
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} SDF_Contour_Orientation;
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/* represent a single edge in a contour */
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/**************************************************************************
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*
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* @Enum:
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* SDF_Edge
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*
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* @Description:
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* Represent an edge of a contour.
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*
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* @Fields:
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* start_pos ::
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* Start position of an edge. Valid for all types of edges.
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*
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* end_pos ::
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* Etart position of an edge. Valid for all types of edges.
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*
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* control_a ::
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* A control point of the edge. Valid only for `SDF_EDGE_CONIC'
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* and `SDF_EDGE_CUBIC'.
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*
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* control_b ::
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* Another control point of the edge. Valid only for `SDF_EDGE_CONIC'.
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*
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* edge_type ::
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* Type of the edge, see `SDF_Edge_Type' for all possible edge types.
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*
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* next ::
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* Used to create a singly linked list, which can be interpreted
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* as a contour.
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*
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*/
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typedef struct SDF_Edge_
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typedef struct SDF_Edge_
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{
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{
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FT_26D6_Vec start_pos; /* start position of the edge */
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FT_26D6_Vec start_pos;
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FT_26D6_Vec end_pos; /* end position of the edge */
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FT_26D6_Vec end_pos;
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FT_26D6_Vec control_a; /* first control point of a bezier curve */
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FT_26D6_Vec control_a;
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FT_26D6_Vec control_b; /* second control point of a bezier curve */
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FT_26D6_Vec control_b;
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SDF_Edge_Type edge_type; /* edge identifier */
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SDF_Edge_Type edge_type;
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struct SDF_Edge_* next; /* to create linked list */
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struct SDF_Edge_* next;
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} SDF_Edge;
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} SDF_Edge;
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/* A contour represent a set of edges which make a closed */
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/**************************************************************************
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/* loop. */
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*
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* @Enum:
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* SDF_Contour
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*
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* @Description:
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* Represent a complete contour, which contains a list of edges.
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*
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* @Fields:
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* last_pos ::
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* Contains the position of the `end_pos' of the last edge
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* in the list of edges. Useful while decomposing the outline
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* using `FT_Outline_Decompose'.
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*
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* edges ::
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* Linked list of all the edges that make the contour.
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*
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* next ::
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* Used to create a singly linked list, which can be interpreted
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* as a complete shape or `FT_Outline'.
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*
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*/
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typedef struct SDF_Contour_
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typedef struct SDF_Contour_
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{
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{
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FT_26D6_Vec last_pos; /* end position of the last edge */
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FT_26D6_Vec last_pos;
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SDF_Edge* edges; /* list of all edges in the contour */
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SDF_Edge* edges;
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|
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struct SDF_Contour_* next; /* to create linked list */
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struct SDF_Contour_* next;
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} SDF_Contour;
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} SDF_Contour;
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/* Represent a set a contours which makes up a complete */
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/**************************************************************************
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/* glyph outline. */
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*
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* @Enum:
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* SDF_Shape
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*
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* @Description:
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* Represent a complete shape which is the decomposition of `FT_Outline'.
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*
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* @Fields:
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* memory ::
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* Used internally to allocate memory.
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*
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* contours ::
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* Linked list of all the contours that make the shape.
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*
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*/
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typedef struct SDF_Shape_
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typedef struct SDF_Shape_
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{
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{
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FT_Memory memory; /* used internally to allocate memory */
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FT_Memory memory;
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SDF_Contour* contours; /* list of all contours in the outline */
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SDF_Contour* contours;
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} SDF_Shape;
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} SDF_Shape;
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/**************************************************************************
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*
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* @Enum:
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* SDF_Signed_Distance
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*
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* @Description:
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* Represent signed distance of a point, i.e. the distance of the
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* edge nearest to the point.
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*
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* @Fields:
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* distance ::
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* Distance of the point from the nearest edge. Can be squared or
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* absolute depending on the `USE_SQUARED_DISTANCES' parameter
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* defined in `ftsdfcommon.h'.
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*
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* cross ::
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* Cross product of the shortest distance vector (i.e. the vector
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* the point to the nearest edge) and the direction of the edge
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* at the nearest point. This is used to resolve any ambiguity
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* in the sign.
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*
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* sign ::
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* Represent weather the distance vector is outside or inside the
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* contour corresponding to the edge.
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*
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* @Note:
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* The `sign' may or may not be correct, therefore it must be checked
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* properly in case there is an ambiguity.
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*
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*/
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typedef struct SDF_Signed_Distance_
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typedef struct SDF_Signed_Distance_
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{
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{
|
||||||
/* Unsigned shortest distance from the point to */
|
|
||||||
/* the above `nearest_point'. */
|
|
||||||
/* [NOTE]: This can represent both squared as or */
|
|
||||||
/* actual distance. This is controlled by the */
|
|
||||||
/* `USE_SQUARED_DISTANCES' macro. */
|
|
||||||
FT_16D16 distance;
|
FT_16D16 distance;
|
||||||
|
|
||||||
/* The cross product of distance vector and the */
|
|
||||||
/* direction. ( aka orthogonality ) */
|
|
||||||
FT_16D16 cross;
|
FT_16D16 cross;
|
||||||
|
|
||||||
/* Represent weather the distance vector is outside */
|
|
||||||
/* or inside the contour corresponding to the edge. */
|
|
||||||
/* [note]: This sign may or may not be correct, */
|
|
||||||
/* therefore it must be checked properly in */
|
|
||||||
/* case there is an ambiguity. */
|
|
||||||
FT_Char sign;
|
FT_Char sign;
|
||||||
|
|
||||||
} SDF_Signed_Distance;
|
} SDF_Signed_Distance;
|
||||||
|
|
||||||
|
/**************************************************************************
|
||||||
|
*
|
||||||
|
* @Enum:
|
||||||
|
* SDF_Params
|
||||||
|
*
|
||||||
|
* @Description:
|
||||||
|
* Yet another internal parameters required by the rasterizer.
|
||||||
|
*
|
||||||
|
* @Fields:
|
||||||
|
* orientation ::
|
||||||
|
* This is not the `SDF_Contour_Orientation', this is the
|
||||||
|
* `FT_Orientation', which determine weather clockwise is to
|
||||||
|
* be filled or anti-clockwise.
|
||||||
|
*
|
||||||
|
* flip_sign ::
|
||||||
|
* Simply flip the sign if this is true. By default the points
|
||||||
|
* filled by the outline are positive.
|
||||||
|
*
|
||||||
|
* flip_y ::
|
||||||
|
* If set to true the output bitmap will be upside down. Can be
|
||||||
|
* useful because OpenGL and DirectX have different coordinate
|
||||||
|
* system for textures.
|
||||||
|
*
|
||||||
|
*/
|
||||||
typedef struct SDF_Params_
|
typedef struct SDF_Params_
|
||||||
{
|
{
|
||||||
/* Used to properly assign sign to the pixels. In */
|
|
||||||
/* truetype the right should be inside but in post */
|
|
||||||
/* script left should be inside. */
|
|
||||||
FT_Orientation orientation;
|
FT_Orientation orientation;
|
||||||
|
|
||||||
/* Simply flip the sign if this is true. */
|
|
||||||
FT_Bool flip_sign;
|
FT_Bool flip_sign;
|
||||||
|
|
||||||
/* If set to true the output will be upside down. */
|
|
||||||
/* Can be useful because OpenGL and DirectX have */
|
|
||||||
/* different coordinate system for textures. */
|
|
||||||
FT_Bool flip_y;
|
FT_Bool flip_y;
|
||||||
|
|
||||||
} SDF_Params;
|
} SDF_Params;
|
||||||
|
|
Loading…
Reference in New Issue