ref: 2de1b5630d7717f5fc5401a7ca3aa756d3c204fd
dir: /src/sdf/ftsdf.c/
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftdebug.h>
#include <freetype/fttrigon.h>
#include "ftsdf.h"
#include "ftsdferrs.h"
/**************************************************************************
*
* for tracking used memory
*
*/
/* The memory tracker only works when `FT_DEBUG_MEMORY` is defined; */
/* we need some variables such as `_ft_debug_file`, which aren't */
/* available otherwise. */
#if defined( FT_DEBUG_LEVEL_TRACE ) && defined( FT_DEBUG_MEMORY )
#undef FT_DEBUG_INNER
#undef FT_ASSIGNP_INNER
#define FT_DEBUG_INNER( exp ) ( _ft_debug_file = __FILE__, \
_ft_debug_lineno = line, \
(exp) )
#define FT_ASSIGNP_INNER( p, exp ) ( _ft_debug_file = __FILE__, \
_ft_debug_lineno = line, \
FT_ASSIGNP( p, exp ) )
/* To be used with `FT_Memory::user' in order to track */
/* memory allocations. */
typedef struct SDF_MemoryUser_
{
void* prev_user;
FT_Long total_usage;
} SDF_MemoryUser;
/*
* These functions are used while allocating and deallocating memory.
* They restore the previous user pointer before calling the allocation
* functions.
*/
static FT_Pointer
sdf_alloc( FT_Memory memory,
FT_Long size,
FT_Error* err,
FT_Int line )
{
SDF_MemoryUser* current_user;
FT_Pointer ptr;
FT_Error error;
current_user = (SDF_MemoryUser*)memory->user;
memory->user = current_user->prev_user;
if ( !FT_QALLOC( ptr, size ) )
current_user->total_usage += size;
memory->user = (void*)current_user;
*err = error;
return ptr;
}
static void
sdf_free( FT_Memory memory,
FT_Pointer ptr,
FT_Int line )
{
SDF_MemoryUser* current_user;
current_user = (SDF_MemoryUser*)memory->user;
memory->user = current_user->prev_user;
FT_FREE( ptr );
memory->user = (void*)current_user;
}
#define SDF_ALLOC( ptr, size ) \
( ptr = sdf_alloc( memory, size, \
&error, __LINE__ ), \
error != 0 )
#define SDF_FREE( ptr ) \
sdf_free( memory, ptr, __LINE__ )
#define SDF_MEMORY_TRACKER_DECLARE() SDF_MemoryUser sdf_memory_user
#define SDF_MEMORY_TRACKER_SETUP() \
sdf_memory_user.prev_user = memory->user; \
sdf_memory_user.total_usage = 0; \
memory->user = &sdf_memory_user
#define SDF_MEMORY_TRACKER_DONE() \
memory->user = sdf_memory_user.prev_user; \
\
FT_TRACE0(( "[sdf] sdf_raster_render:" \
" Total memory used = %ld\n", \
sdf_memory_user.total_usage ))
#else /* !FT_DEBUG_LEVEL_TRACE */
#define SDF_ALLOC FT_QALLOC
#define SDF_FREE FT_FREE
#define SDF_MEMORY_TRACKER_DECLARE() FT_DUMMY_STMNT
#define SDF_MEMORY_TRACKER_SETUP() FT_DUMMY_STMNT
#define SDF_MEMORY_TRACKER_DONE() FT_DUMMY_STMNT
#endif /* !FT_DEBUG_LEVEL_TRACE */
/**************************************************************************
*
* definitions
*
*/
/*
* If set to 1, the rasterizer uses Newton-Raphson's method for finding
* the shortest distance from a point to a conic curve.
*
* If set to 0, an analytical method gets used instead, which computes the
* roots of a cubic polynomial to find the shortest distance. However,
* the analytical method can currently underflow; we thus use Newton's
* method by default.
*/
#ifndef USE_NEWTON_FOR_CONIC
#define USE_NEWTON_FOR_CONIC 1
#endif
/*
* The number of intervals a Bezier curve gets sampled and checked to find
* the shortest distance.
*/
#define MAX_NEWTON_DIVISIONS 4
/*
* The number of steps of Newton's iterations in each interval of the
* Bezier curve. Basically, we run Newton's approximation
*
* x -= Q(t) / Q'(t)
*
* for each division to get the shortest distance.
*/
#define MAX_NEWTON_STEPS 4
/*
* The epsilon distance (in 16.16 fractional units) used for corner
* resolving. If the difference of two distances is less than this value
* they will be checked for a corner if they are ambiguous.
*/
#define CORNER_CHECK_EPSILON 32
#if 0
/*
* Coarse grid dimension. Will probably be removed in the future because
* coarse grid optimization is the slowest algorithm.
*/
#define CG_DIMEN 8
#endif
/**************************************************************************
*
* macros
*
*/
#define MUL_26D6( a, b ) ( ( ( a ) * ( b ) ) / 64 )
#define VEC_26D6_DOT( p, q ) ( MUL_26D6( p.x, q.x ) + \
MUL_26D6( p.y, q.y ) )
/**************************************************************************
*
* structures and enums
*
*/
/**************************************************************************
*
* @Struct:
* SDF_TRaster
*
* @Description:
* This struct is used in place of @FT_Raster and is stored within the
* internal FreeType renderer struct. While rasterizing it is passed to
* the @FT_Raster_RenderFunc function, which then can be used however we
* want.
*
* @Fields:
* memory ::
* Used internally to allocate intermediate memory while raterizing.
*
*/
typedef struct SDF_TRaster_
{
FT_Memory memory;
} SDF_TRaster;
/**************************************************************************
*
* @Enum:
* SDF_Edge_Type
*
* @Description:
* Enumeration of all curve types present in fonts.
*
* @Fields:
* SDF_EDGE_UNDEFINED ::
* Undefined edge, simply used to initialize and detect errors.
*
* SDF_EDGE_LINE ::
* Line segment with start and end point.
*
* SDF_EDGE_CONIC ::
* A conic/quadratic Bezier curve with start, end, and one control
* point.
*
* SDF_EDGE_CUBIC ::
* A cubic Bezier curve with start, end, and two control points.
*
*/
typedef enum SDF_Edge_Type_
{
SDF_EDGE_UNDEFINED = 0,
SDF_EDGE_LINE = 1,
SDF_EDGE_CONIC = 2,
SDF_EDGE_CUBIC = 3
} SDF_Edge_Type;
/**************************************************************************
*
* @Enum:
* SDF_Contour_Orientation
*
* @Description:
* Enumeration of all orientation values of a contour. We determine the
* orientation by calculating the area covered by a contour. Contrary
* to values returned by @FT_Outline_Get_Orientation,
* `SDF_Contour_Orientation` is independent of the fill rule, which can
* be different for different font formats.
*
* @Fields:
* SDF_ORIENTATION_NONE ::
* Undefined orientation, used for initialization and error detection.
*
* SDF_ORIENTATION_CW ::
* Clockwise orientation (positive area covered).
*
* SDF_ORIENTATION_ACW ::
* Anti-clockwise orientation (negative area covered).
*
* @Note:
* See @FT_Outline_Get_Orientation for more details.
*
*/
typedef enum SDF_Contour_Orientation_
{
SDF_ORIENTATION_NONE = 0,
SDF_ORIENTATION_CW = 1,
SDF_ORIENTATION_ACW = 2
} SDF_Contour_Orientation;
/**************************************************************************
*
* @Struct:
* SDF_Edge
*
* @Description:
* Represent an edge of a contour.
*
* @Fields:
* start_pos ::
* Start position of an edge. Valid for all types of edges.
*
* end_pos ::
* Etart position of an edge. Valid for all types of edges.
*
* control_a ::
* A control point of the edge. Valid only for `SDF_EDGE_CONIC`
* and `SDF_EDGE_CUBIC`.
*
* control_b ::
* Another control point of the edge. Valid only for
* `SDF_EDGE_CONIC`.
*
* edge_type ::
* Type of the edge, see @SDF_Edge_Type for all possible edge types.
*
* next ::
* Used to create a singly linked list, which can be interpreted
* as a contour.
*
*/
typedef struct SDF_Edge_
{
FT_26D6_Vec start_pos;
FT_26D6_Vec end_pos;
FT_26D6_Vec control_a;
FT_26D6_Vec control_b;
SDF_Edge_Type edge_type;
struct SDF_Edge_* next;
} SDF_Edge;
/**************************************************************************
*
* @Struct:
* SDF_Contour
*
* @Description:
* Represent a complete contour, which contains a list of edges.
*
* @Fields:
* last_pos ::
* Contains the value of `end_pos' of the last edge in the list of
* edges. Useful while decomposing the outline with
* @FT_Outline_Decompose.
*
* edges ::
* Linked list of all the edges that make the contour.
*
* next ::
* Used to create a singly linked list, which can be interpreted as a
* complete shape or @FT_Outline.
*
*/
typedef struct SDF_Contour_
{
FT_26D6_Vec last_pos;
SDF_Edge* edges;
struct SDF_Contour_* next;
} SDF_Contour;
/**************************************************************************
*
* @Struct:
* SDF_Shape
*
* @Description:
* Represent a complete shape, which is the decomposition of
* @FT_Outline.
*
* @Fields:
* memory ::
* Used internally to allocate memory.
*
* contours ::
* Linked list of all the contours that make the shape.
*
*/
typedef struct SDF_Shape_
{
FT_Memory memory;
SDF_Contour* contours;
} SDF_Shape;
/**************************************************************************
*
* @Struct:
* SDF_Signed_Distance
*
* @Description:
* Represent signed distance of a point, i.e., the distance of the edge
* nearest to the point.
*
* @Fields:
* distance ::
* Distance of the point from the nearest edge. Can be squared or
* absolute depending on the `USE_SQUARED_DISTANCES` macro defined in
* file `ftsdfcommon.h`.
*
* cross ::
* Cross product of the shortest distance vector (i.e., the vector
* from the point to the nearest edge) and the direction of the edge
* at the nearest point. This is used to resolve ambiguities of
* `sign`.
*
* sign ::
* A value used to indicate whether the distance vector is outside or
* inside the contour corresponding to the edge.
*
* @Note:
* `sign` may or may not be correct, therefore it must be checked
* properly in case there is an ambiguity.
*
*/
typedef struct SDF_Signed_Distance_
{
FT_16D16 distance;
FT_16D16 cross;
FT_Char sign;
} SDF_Signed_Distance;
/**************************************************************************
*
* @Struct:
* SDF_Params
*
* @Description:
* Yet another internal parameters required by the rasterizer.
*
* @Fields:
* orientation ::
* This is not the @SDF_Contour_Orientation value but @FT_Orientation,
* which determines whether clockwise-oriented outlines are to be
* filled or anti-clockwise-oriented ones.
*
* flip_sign ::
* If set to true, flip the sign. By default the points filled by the
* outline are positive.
*
* flip_y ::
* If set to true the output bitmap is upside-down. Can be useful
* because OpenGL and DirectX use different coordinate systems for
* textures.
*
* overload_sign ::
* In the subdivision and bounding box optimization, the default
* outside sign is taken as -1. This parameter can be used to modify
* that behaviour. For example, while generating SDF for a single
* counter-clockwise contour, the outside sign should be 1.
*
*/
typedef struct SDF_Params_
{
FT_Orientation orientation;
FT_Bool flip_sign;
FT_Bool flip_y;
FT_Int overload_sign;
} SDF_Params;
/**************************************************************************
*
* constants, initializer, and destructor
*
*/
static
const FT_Vector zero_vector = { 0, 0 };
static
const SDF_Edge null_edge = { { 0, 0 }, { 0, 0 },
{ 0, 0 }, { 0, 0 },
SDF_EDGE_UNDEFINED, NULL };
static
const SDF_Contour null_contour = { { 0, 0 }, NULL, NULL };
static
const SDF_Shape null_shape = { NULL, NULL };
static
const SDF_Signed_Distance max_sdf = { INT_MAX, 0, 0 };
/* Create a new @SDF_Edge on the heap and assigns the `edge` */
/* pointer to the newly allocated memory. */
static FT_Error
sdf_edge_new( FT_Memory memory,
SDF_Edge** edge )
{
FT_Error error = FT_Err_Ok;
SDF_Edge* ptr = NULL;
if ( !memory || !edge )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( !SDF_ALLOC( ptr, sizeof ( *ptr ) ) )
{
*ptr = null_edge;
*edge = ptr;
}
Exit:
return error;
}
/* Free the allocated `edge` variable. */
static void
sdf_edge_done( FT_Memory memory,
SDF_Edge** edge )
{
if ( !memory || !edge || !*edge )
return;
SDF_FREE( *edge );
}
/* Create a new @SDF_Contour on the heap and assign */
/* the `contour` pointer to the newly allocated memory. */
static FT_Error
sdf_contour_new( FT_Memory memory,
SDF_Contour** contour )
{
FT_Error error = FT_Err_Ok;
SDF_Contour* ptr = NULL;
if ( !memory || !contour )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( !SDF_ALLOC( ptr, sizeof ( *ptr ) ) )
{
*ptr = null_contour;
*contour = ptr;
}
Exit:
return error;
}
/* Free the allocated `contour` variable. */
/* Also free the list of edges. */
static void
sdf_contour_done( FT_Memory memory,
SDF_Contour** contour )
{
SDF_Edge* edges;
SDF_Edge* temp;
if ( !memory || !contour || !*contour )
return;
edges = (*contour)->edges;
/* release all edges */
while ( edges )
{
temp = edges;
edges = edges->next;
sdf_edge_done( memory, &temp );
}
SDF_FREE( *contour );
}
/* Create a new @SDF_Shape on the heap and assign */
/* the `shape` pointer to the newly allocated memory. */
static FT_Error
sdf_shape_new( FT_Memory memory,
SDF_Shape** shape )
{
FT_Error error = FT_Err_Ok;
SDF_Shape* ptr = NULL;
if ( !memory || !shape )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
if ( !SDF_ALLOC( ptr, sizeof ( *ptr ) ) )
{
*ptr = null_shape;
ptr->memory = memory;
*shape = ptr;
}
Exit:
return error;
}
/* Free the allocated `shape` variable. */
/* Also free the list of contours. */
static void
sdf_shape_done( SDF_Shape** shape )
{
FT_Memory memory;
SDF_Contour* contours;
SDF_Contour* temp;
if ( !shape || !*shape )
return;
memory = (*shape)->memory;
contours = (*shape)->contours;
if ( !memory )
return;
/* release all contours */
while ( contours )
{
temp = contours;
contours = contours->next;
sdf_contour_done( memory, &temp );
}
/* release the allocated shape struct */
SDF_FREE( *shape );
}
/**************************************************************************
*
* shape decomposition functions
*
*/
/* This function is called when starting a new contour at `to`, */
/* which gets added to the shape's list. */
static FT_Error
sdf_move_to( const FT_26D6_Vec* to,
void* user )
{
SDF_Shape* shape = ( SDF_Shape* )user;
SDF_Contour* contour = NULL;
FT_Error error = FT_Err_Ok;
FT_Memory memory = shape->memory;
if ( !to || !user )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
FT_CALL( sdf_contour_new( memory, &contour ) );
contour->last_pos = *to;
contour->next = shape->contours;
shape->contours = contour;
Exit:
return error;
}
/* This function is called when there is a line in the */
/* contour. The line starts at the previous edge point and */
/* stops at `to`. */
static FT_Error
sdf_line_to( const FT_26D6_Vec* to,
void* user )
{
SDF_Shape* shape = ( SDF_Shape* )user;
SDF_Edge* edge = NULL;
SDF_Contour* contour = NULL;
FT_Error error = FT_Err_Ok;
FT_Memory memory = shape->memory;
if ( !to || !user )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
contour = shape->contours;
if ( contour->last_pos.x == to->x &&
contour->last_pos.y == to->y )
goto Exit;
FT_CALL( sdf_edge_new( memory, &edge ) );
edge->edge_type = SDF_EDGE_LINE;
edge->start_pos = contour->last_pos;
edge->end_pos = *to;
edge->next = contour->edges;
contour->edges = edge;
contour->last_pos = *to;
Exit:
return error;
}
/* This function is called when there is a conic Bezier curve */
/* in the contour. The curve starts at the previous edge point */
/* and stops at `to`, with control point `control_1`. */
static FT_Error
sdf_conic_to( const FT_26D6_Vec* control_1,
const FT_26D6_Vec* to,
void* user )
{
SDF_Shape* shape = ( SDF_Shape* )user;
SDF_Edge* edge = NULL;
SDF_Contour* contour = NULL;
FT_Error error = FT_Err_Ok;
FT_Memory memory = shape->memory;
if ( !control_1 || !to || !user )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
contour = shape->contours;
FT_CALL( sdf_edge_new( memory, &edge ) );
edge->edge_type = SDF_EDGE_CONIC;
edge->start_pos = contour->last_pos;
edge->control_a = *control_1;
edge->end_pos = *to;
edge->next = contour->edges;
contour->edges = edge;
contour->last_pos = *to;
Exit:
return error;
}
/* This function is called when there is a cubic Bezier curve */
/* in the contour. The curve starts at the previous edge point */
/* and stops at `to`, with two control points `control_1` and */
/* `control_2`. */
static FT_Error
sdf_cubic_to( const FT_26D6_Vec* control_1,
const FT_26D6_Vec* control_2,
const FT_26D6_Vec* to,
void* user )
{
SDF_Shape* shape = ( SDF_Shape* )user;
SDF_Edge* edge = NULL;
SDF_Contour* contour = NULL;
FT_Error error = FT_Err_Ok;
FT_Memory memory = shape->memory;
if ( !control_2 || !control_1 || !to || !user )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
contour = shape->contours;
FT_CALL( sdf_edge_new( memory, &edge ) );
edge->edge_type = SDF_EDGE_CUBIC;
edge->start_pos = contour->last_pos;
edge->control_a = *control_1;
edge->control_b = *control_2;
edge->end_pos = *to;
edge->next = contour->edges;
contour->edges = edge;
contour->last_pos = *to;
Exit:
return error;
}
/* Construct the structure to hold all four outline */
/* decomposition functions. */
FT_DEFINE_OUTLINE_FUNCS(
sdf_decompose_funcs,
(FT_Outline_MoveTo_Func) sdf_move_to, /* move_to */
(FT_Outline_LineTo_Func) sdf_line_to, /* line_to */
(FT_Outline_ConicTo_Func)sdf_conic_to, /* conic_to */
(FT_Outline_CubicTo_Func)sdf_cubic_to, /* cubic_to */
0, /* shift */
0 /* delta */
)
/* Decompose `outline` and put it into the `shape` structure. */
static FT_Error
sdf_outline_decompose( FT_Outline* outline,
SDF_Shape* shape )
{
FT_Error error = FT_Err_Ok;
if ( !outline || !shape )
{
error = FT_THROW( Invalid_Argument );
goto Exit;
}
error = FT_Outline_Decompose( outline,
&sdf_decompose_funcs,
(void*)shape );
Exit:
return error;
}
/* END */