ref: 64591b765710775d95852eecc3981cc1c865bec3
dir: /src/base/ftstroker.c/
/***************************************************************************/
/* */
/* ftstroker.c */
/* */
/* FreeType path stroker (body). */
/* */
/* Copyright 2002, 2003 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#include <ft2build.h>
#include FT_STROKER_H
#include FT_TRIGONOMETRY_H
#include FT_INTERNAL_MEMORY_H
#include FT_INTERNAL_DEBUG_H
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** BEZIER COMPUTATIONS *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
#define FT_SMALL_CONIC_THRESHOLD ( FT_ANGLE_PI / 6 )
#define FT_SMALL_CUBIC_THRESHOLD ( FT_ANGLE_PI / 6 )
#define FT_EPSILON 2
#define FT_IS_SMALL( x ) ( (x) > -FT_EPSILON && (x) < FT_EPSILON )
static FT_Pos
ft_pos_abs( FT_Pos x )
{
return x >= 0 ? x : -x ;
}
static void
ft_conic_split( FT_Vector* base )
{
FT_Pos a, b;
base[4].x = base[2].x;
b = base[1].x;
a = base[3].x = ( base[2].x + b ) / 2;
b = base[1].x = ( base[0].x + b ) / 2;
base[2].x = ( a + b ) / 2;
base[4].y = base[2].y;
b = base[1].y;
a = base[3].y = ( base[2].y + b ) / 2;
b = base[1].y = ( base[0].y + b ) / 2;
base[2].y = ( a + b ) / 2;
}
static FT_Bool
ft_conic_is_small_enough( FT_Vector* base,
FT_Angle *angle_in,
FT_Angle *angle_out )
{
FT_Vector d1, d2;
FT_Angle theta;
FT_Int close1, close2;
d1.x = base[1].x - base[2].x;
d1.y = base[1].y - base[2].y;
d2.x = base[0].x - base[1].x;
d2.y = base[0].y - base[1].y;
close1 = FT_IS_SMALL( d1.x ) && FT_IS_SMALL( d1.y );
close2 = FT_IS_SMALL( d2.x ) && FT_IS_SMALL( d2.y );
if ( close1 )
{
if ( close2 )
*angle_in = *angle_out = 0;
else
*angle_in = *angle_out = FT_Atan2( d2.x, d2.y );
}
else if ( close2 )
{
*angle_in = *angle_out = FT_Atan2( d1.x, d1.y );
}
else
{
*angle_in = FT_Atan2( d1.x, d1.y );
*angle_out = FT_Atan2( d2.x, d2.y );
}
theta = ft_pos_abs( FT_Angle_Diff( *angle_in, *angle_out ) );
return FT_BOOL( theta < FT_SMALL_CONIC_THRESHOLD );
}
static void
ft_cubic_split( FT_Vector* base )
{
FT_Pos a, b, c, d;
base[6].x = base[3].x;
c = base[1].x;
d = base[2].x;
base[1].x = a = ( base[0].x + c ) / 2;
base[5].x = b = ( base[3].x + d ) / 2;
c = ( c + d ) / 2;
base[2].x = a = ( a + c ) / 2;
base[4].x = b = ( b + c ) / 2;
base[3].x = ( a + b ) / 2;
base[6].y = base[3].y;
c = base[1].y;
d = base[2].y;
base[1].y = a = ( base[0].y + c ) / 2;
base[5].y = b = ( base[3].y + d ) / 2;
c = ( c + d ) / 2;
base[2].y = a = ( a + c ) / 2;
base[4].y = b = ( b + c ) / 2;
base[3].y = ( a + b ) / 2;
}
static FT_Bool
ft_cubic_is_small_enough( FT_Vector* base,
FT_Angle *angle_in,
FT_Angle *angle_mid,
FT_Angle *angle_out )
{
FT_Vector d1, d2, d3;
FT_Angle theta1, theta2;
FT_Int close1, close2, close3;
d1.x = base[2].x - base[3].x;
d1.y = base[2].y - base[3].y;
d2.x = base[1].x - base[2].x;
d2.y = base[1].y - base[2].y;
d3.x = base[0].x - base[1].x;
d3.y = base[0].y - base[1].y;
close1 = FT_IS_SMALL( d1.x ) && FT_IS_SMALL( d1.y );
close2 = FT_IS_SMALL( d2.x ) && FT_IS_SMALL( d2.y );
close3 = FT_IS_SMALL( d3.x ) && FT_IS_SMALL( d3.y );
if ( close1 || close3 )
{
if ( close2 )
{
/* basically a point */
*angle_in = *angle_out = *angle_mid = 0;
}
else if ( close1 )
{
*angle_in = *angle_mid = FT_Atan2( d2.x, d2.y );
*angle_out = FT_Atan2( d3.x, d3.y );
}
else /* close2 */
{
*angle_in = FT_Atan2( d1.x, d1.y );
*angle_mid = *angle_out = FT_Atan2( d2.x, d2.y );
}
}
else if ( close2 )
{
*angle_in = *angle_mid = FT_Atan2( d1.x, d1.y );
*angle_out = FT_Atan2( d3.x, d3.y );
}
else
{
*angle_in = FT_Atan2( d1.x, d1.y );
*angle_mid = FT_Atan2( d2.x, d2.y );
*angle_out = FT_Atan2( d3.x, d3.y );
}
theta1 = ft_pos_abs( FT_Angle_Diff( *angle_in, *angle_mid ) );
theta2 = ft_pos_abs( FT_Angle_Diff( *angle_mid, *angle_out ) );
return FT_BOOL( theta1 < FT_SMALL_CUBIC_THRESHOLD &&
theta2 < FT_SMALL_CUBIC_THRESHOLD );
}
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** STROKE BORDERS *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
typedef enum
{
FT_STROKE_TAG_ON = 1, /* on-curve point */
FT_STROKE_TAG_CUBIC = 2, /* cubic off-point */
FT_STROKE_TAG_BEGIN = 4, /* sub-path start */
FT_STROKE_TAG_END = 8 /* sub-path end */
} FT_StrokeTags;
typedef struct FT_StrokeBorderRec_
{
FT_UInt num_points;
FT_UInt max_points;
FT_Vector* points;
FT_Byte* tags;
FT_Bool movable;
FT_Int start; /* index of current sub-path start point */
FT_Memory memory;
} FT_StrokeBorderRec, *FT_StrokeBorder;
static FT_Error
ft_stroke_border_grow( FT_StrokeBorder border,
FT_UInt new_points )
{
FT_UInt old_max = border->max_points;
FT_UInt new_max = border->num_points + new_points;
FT_Error error = 0;
if ( new_max > old_max )
{
FT_UInt cur_max = old_max;
FT_Memory memory = border->memory;
while ( cur_max < new_max )
cur_max += ( cur_max >> 1 ) + 16;
if ( FT_RENEW_ARRAY( border->points, old_max, cur_max ) ||
FT_RENEW_ARRAY( border->tags, old_max, cur_max ) )
goto Exit;
border->max_points = cur_max;
}
Exit:
return error;
}
static void
ft_stroke_border_close( FT_StrokeBorder border )
{
FT_ASSERT( border->start >= 0 );
/* don't record empty paths! */
if ( border->num_points > (FT_UInt)border->start )
{
border->tags[border->start ] |= FT_STROKE_TAG_BEGIN;
border->tags[border->num_points - 1] |= FT_STROKE_TAG_END;
}
border->start = -1;
border->movable = 0;
}
static FT_Error
ft_stroke_border_lineto( FT_StrokeBorder border,
FT_Vector* to,
FT_Bool movable )
{
FT_Error error = 0;
FT_ASSERT( border->start >= 0 );
if ( border->movable )
{
/* move last point */
border->points[border->num_points - 1] = *to;
}
else
{
/* add one point */
error = ft_stroke_border_grow( border, 1 );
if ( !error )
{
FT_Vector* vec = border->points + border->num_points;
FT_Byte* tag = border->tags + border->num_points;
vec[0] = *to;
tag[0] = FT_STROKE_TAG_ON;
border->num_points += 1;
}
}
border->movable = movable;
return error;
}
static FT_Error
ft_stroke_border_conicto( FT_StrokeBorder border,
FT_Vector* control,
FT_Vector* to )
{
FT_Error error;
FT_ASSERT( border->start >= 0 );
error = ft_stroke_border_grow( border, 2 );
if ( !error )
{
FT_Vector* vec = border->points + border->num_points;
FT_Byte* tag = border->tags + border->num_points;
vec[0] = *control;
vec[1] = *to;
tag[0] = 0;
tag[1] = FT_STROKE_TAG_ON;
border->num_points += 2;
}
border->movable = 0;
return error;
}
static FT_Error
ft_stroke_border_cubicto( FT_StrokeBorder border,
FT_Vector* control1,
FT_Vector* control2,
FT_Vector* to )
{
FT_Error error;
FT_ASSERT( border->start >= 0 );
error = ft_stroke_border_grow( border, 3 );
if ( !error )
{
FT_Vector* vec = border->points + border->num_points;
FT_Byte* tag = border->tags + border->num_points;
vec[0] = *control1;
vec[1] = *control2;
vec[2] = *to;
tag[0] = FT_STROKE_TAG_CUBIC;
tag[1] = FT_STROKE_TAG_CUBIC;
tag[2] = FT_STROKE_TAG_ON;
border->num_points += 3;
}
border->movable = 0;
return error;
}
#define FT_ARC_CUBIC_ANGLE ( FT_ANGLE_PI / 2 )
static FT_Error
ft_stroke_border_arcto( FT_StrokeBorder border,
FT_Vector* center,
FT_Fixed radius,
FT_Angle angle_start,
FT_Angle angle_diff )
{
FT_Angle total, angle, step, rotate, next, theta;
FT_Vector a, b, a2, b2;
FT_Fixed length;
FT_Error error = 0;
/* compute start point */
FT_Vector_From_Polar( &a, radius, angle_start );
a.x += center->x;
a.y += center->y;
total = angle_diff;
angle = angle_start;
rotate = ( angle_diff >= 0 ) ? FT_ANGLE_PI2 : -FT_ANGLE_PI2;
while ( total != 0 )
{
step = total;
if ( step > FT_ARC_CUBIC_ANGLE )
step = FT_ARC_CUBIC_ANGLE;
else if ( step < -FT_ARC_CUBIC_ANGLE )
step = -FT_ARC_CUBIC_ANGLE;
next = angle + step;
theta = step;
if ( theta < 0 )
theta = -theta;
theta >>= 1;
/* compute end point */
FT_Vector_From_Polar( &b, radius, next );
b.x += center->x;
b.y += center->y;
/* compute first and second control points */
length = FT_MulDiv( radius, FT_Sin( theta ) * 4,
( 0x10000L + FT_Cos( theta ) ) * 3 );
FT_Vector_From_Polar( &a2, length, angle + rotate );
a2.x += a.x;
a2.y += a.y;
FT_Vector_From_Polar( &b2, length, next - rotate );
b2.x += b.x;
b2.y += b.y;
/* add cubic arc */
error = ft_stroke_border_cubicto( border, &a2, &b2, &b );
if ( error )
break;
/* process the rest of the arc ?? */
a = b;
total -= step;
angle = next;
}
return error;
}
static FT_Error
ft_stroke_border_moveto( FT_StrokeBorder border,
FT_Vector* to )
{
/* close current open path if any ? */
if ( border->start >= 0 )
ft_stroke_border_close( border );
border->start = border->num_points;
border->movable = 0;
return ft_stroke_border_lineto( border, to, 0 );
}
static void
ft_stroke_border_init( FT_StrokeBorder border,
FT_Memory memory )
{
border->memory = memory;
border->points = NULL;
border->tags = NULL;
border->num_points = 0;
border->max_points = 0;
border->start = -1;
}
static void
ft_stroke_border_reset( FT_StrokeBorder border )
{
border->num_points = 0;
border->start = -1;
}
static void
ft_stroke_border_done( FT_StrokeBorder border )
{
FT_Memory memory = border->memory;
FT_FREE( border->points );
FT_FREE( border->tags );
border->num_points = 0;
border->max_points = 0;
border->start = -1;
}
static FT_Error
ft_stroke_border_get_counts( FT_StrokeBorder border,
FT_UInt *anum_points,
FT_UInt *anum_contours )
{
FT_Error error = 0;
FT_UInt num_points = 0;
FT_UInt num_contours = 0;
FT_UInt count = border->num_points;
FT_Vector* point = border->points;
FT_Byte* tags = border->tags;
FT_Int in_contour = 0;
for ( ; count > 0; count--, num_points++, point++, tags++ )
{
if ( tags[0] & FT_STROKE_TAG_BEGIN )
{
if ( in_contour != 0 )
goto Fail;
in_contour = 1;
}
else if ( in_contour == 0 )
goto Fail;
if ( tags[0] & FT_STROKE_TAG_END )
{
if ( in_contour == 0 )
goto Fail;
in_contour = 0;
num_contours++;
}
}
if ( in_contour != 0 )
goto Fail;
Exit:
*anum_points = num_points;
*anum_contours = num_contours;
return error;
Fail:
num_points = 0;
num_contours = 0;
goto Exit;
}
static void
ft_stroke_border_export( FT_StrokeBorder border,
FT_Outline* outline )
{
/* copy point locations */
FT_MEM_COPY( outline->points + outline->n_points,
border->points,
border->num_points * sizeof ( FT_Vector ) );
/* copy tags */
{
FT_UInt count = border->num_points;
FT_Byte* read = border->tags;
FT_Byte* write = (FT_Byte*)outline->tags + outline->n_points;
for ( ; count > 0; count--, read++, write++ )
{
if ( *read & FT_STROKE_TAG_ON )
*write = FT_CURVE_TAG_ON;
else if ( *read & FT_STROKE_TAG_CUBIC )
*write = FT_CURVE_TAG_CUBIC;
else
*write = FT_CURVE_TAG_CONIC;
}
}
/* copy contours */
{
FT_UInt count = border->num_points;
FT_Byte* tags = border->tags;
FT_Short* write = outline->contours + outline->n_contours;
FT_Short index = (FT_Short)outline->n_points;
for ( ; count > 0; count--, tags++, index++ )
{
if ( *tags & FT_STROKE_TAG_END )
{
*write++ = index;
outline->n_contours++;
}
}
}
outline->n_points = (short)( outline->n_points + border->num_points );
FT_ASSERT( FT_Outline_Check( outline ) == 0 );
}
/***************************************************************************/
/***************************************************************************/
/***** *****/
/***** STROKER *****/
/***** *****/
/***************************************************************************/
/***************************************************************************/
#define FT_SIDE_TO_ROTATE( s ) ( FT_ANGLE_PI2 - (s) * FT_ANGLE_PI )
typedef struct FT_StrokerRec_
{
FT_Angle angle_in;
FT_Angle angle_out;
FT_Vector center;
FT_Bool first_point;
FT_Bool subpath_open;
FT_Angle subpath_angle;
FT_Vector subpath_start;
FT_Stroker_LineCap line_cap;
FT_Stroker_LineJoin line_join;
FT_Fixed miter_limit;
FT_Fixed radius;
FT_Bool valid;
FT_StrokeBorderRec borders[2];
FT_Memory memory;
} FT_StrokerRec;
FT_EXPORT_DEF( FT_Error )
FT_Stroker_New( FT_Memory memory,
FT_Stroker *astroker )
{
FT_Error error;
FT_Stroker stroker;
if ( !FT_NEW( stroker ) )
{
stroker->memory = memory;
ft_stroke_border_init( &stroker->borders[0], memory );
ft_stroke_border_init( &stroker->borders[1], memory );
}
*astroker = stroker;
return error;
}
FT_EXPORT_DEF( void )
FT_Stroker_Set( FT_Stroker stroker,
FT_Fixed radius,
FT_Stroker_LineCap line_cap,
FT_Stroker_LineJoin line_join,
FT_Fixed miter_limit )
{
stroker->radius = radius;
stroker->line_cap = line_cap;
stroker->line_join = line_join;
stroker->miter_limit = miter_limit;
stroker->valid = 0;
ft_stroke_border_reset( &stroker->borders[0] );
ft_stroke_border_reset( &stroker->borders[1] );
}
FT_EXPORT_DEF( void )
FT_Stroker_Done( FT_Stroker stroker )
{
if ( stroker )
{
FT_Memory memory = stroker->memory;
ft_stroke_border_done( &stroker->borders[0] );
ft_stroke_border_done( &stroker->borders[1] );
stroker->memory = NULL;
FT_FREE( stroker );
}
}
/* creates a circular arc at a corner or cap */
static FT_Error
ft_stroker_arcto( FT_Stroker stroker,
FT_Int side )
{
FT_Angle total, rotate;
FT_Fixed radius = stroker->radius;
FT_Error error = 0;
FT_StrokeBorder border = stroker->borders + side;
rotate = FT_SIDE_TO_ROTATE( side );
total = FT_Angle_Diff( stroker->angle_in, stroker->angle_out );
if ( total == FT_ANGLE_PI )
total = -rotate * 2;
error = ft_stroke_border_arcto( border,
&stroker->center,
radius,
stroker->angle_in + rotate,
total );
border->movable = 0;
return error;
}
/* adds a cap at the end of an opened path */
static FT_Error
ft_stroker_cap( FT_Stroker stroker,
FT_Angle angle,
FT_Int side )
{
FT_Error error = 0;
if ( stroker->line_cap == FT_STROKER_LINECAP_ROUND )
{
/* add a round cap */
stroker->angle_in = angle;
stroker->angle_out = angle + FT_ANGLE_PI;
error = ft_stroker_arcto( stroker, side );
}
else if ( stroker->line_cap == FT_STROKER_LINECAP_SQUARE )
{
/* add a square cap */
FT_Vector delta, delta2;
FT_Angle rotate = FT_SIDE_TO_ROTATE( side );
FT_Fixed radius = stroker->radius;
FT_StrokeBorder border = stroker->borders + side;
FT_Vector_From_Polar( &delta2, radius, angle + rotate );
FT_Vector_From_Polar( &delta, radius, angle );
delta.x += stroker->center.x + delta2.x;
delta.y += stroker->center.y + delta2.y;
error = ft_stroke_border_lineto( border, &delta, 0 );
if ( error )
goto Exit;
FT_Vector_From_Polar( &delta2, radius, angle - rotate );
FT_Vector_From_Polar( &delta, radius, angle );
delta.x += delta2.x + stroker->center.x;
delta.y += delta2.y + stroker->center.y;
error = ft_stroke_border_lineto( border, &delta, 0 );
}
Exit:
return error;
}
/* process an inside corner, i.e. compute intersection */
static FT_Error
ft_stroker_inside( FT_Stroker stroker,
FT_Int side)
{
FT_StrokeBorder border = stroker->borders + side;
FT_Angle phi, theta, rotate;
FT_Fixed length, thcos, sigma;
FT_Vector delta;
FT_Error error = 0;
rotate = FT_SIDE_TO_ROTATE( side );
/* compute median angle */
theta = FT_Angle_Diff( stroker->angle_in, stroker->angle_out );
if ( theta == FT_ANGLE_PI )
theta = rotate;
else
theta = theta / 2;
phi = stroker->angle_in + theta;
thcos = FT_Cos( theta );
sigma = FT_MulFix( stroker->miter_limit, thcos );
if ( sigma < 0x10000L )
{
FT_Vector_From_Polar( &delta, stroker->radius,
stroker->angle_out + rotate );
delta.x += stroker->center.x;
delta.y += stroker->center.y;
border->movable = 0;
}
else
{
length = FT_DivFix( stroker->radius, thcos );
FT_Vector_From_Polar( &delta, length, phi + rotate );
delta.x += stroker->center.x;
delta.y += stroker->center.y;
}
error = ft_stroke_border_lineto( border, &delta, 0 );
return error;
}
/* process an outside corner, i.e. compute bevel/miter/round */
static FT_Error
ft_stroker_outside( FT_Stroker stroker,
FT_Int side )
{
FT_StrokeBorder border = stroker->borders + side;
FT_Error error;
FT_Angle rotate;
if ( stroker->line_join == FT_STROKER_LINEJOIN_ROUND )
{
error = ft_stroker_arcto( stroker, side );
}
else
{
/* this is a mitered or beveled corner */
FT_Fixed sigma, radius = stroker->radius;
FT_Angle theta, phi;
FT_Fixed thcos;
FT_Bool miter;
rotate = FT_SIDE_TO_ROTATE( side );
miter = FT_BOOL( stroker->line_join == FT_STROKER_LINEJOIN_MITER );
theta = FT_Angle_Diff( stroker->angle_in, stroker->angle_out );
if ( theta == FT_ANGLE_PI )
{
theta = rotate;
phi = stroker->angle_in;
}
else
{
theta = theta / 2;
phi = stroker->angle_in + theta + rotate;
}
thcos = FT_Cos( theta );
sigma = FT_MulFix( stroker->miter_limit, thcos );
if ( sigma >= 0x10000L )
miter = 0;
if ( miter ) /* this is a miter (broken angle) */
{
FT_Vector middle, delta;
FT_Fixed length;
/* compute middle point */
FT_Vector_From_Polar( &middle,
FT_MulFix( radius, stroker->miter_limit ),
phi );
middle.x += stroker->center.x;
middle.y += stroker->center.y;
/* compute first angle point */
length = FT_MulFix( radius,
FT_DivFix( 0x10000L - sigma,
ft_pos_abs( FT_Sin( theta ) ) ) );
FT_Vector_From_Polar( &delta, length, phi + rotate );
delta.x += middle.x;
delta.y += middle.y;
error = ft_stroke_border_lineto( border, &delta, 0 );
if ( error )
goto Exit;
/* compute second angle point */
FT_Vector_From_Polar( &delta, length, phi - rotate );
delta.x += middle.x;
delta.y += middle.y;
error = ft_stroke_border_lineto( border, &delta, 0 );
if ( error )
goto Exit;
/* finally, add a movable end point */
FT_Vector_From_Polar( &delta, radius, stroker->angle_out + rotate );
delta.x += stroker->center.x;
delta.y += stroker->center.y;
error = ft_stroke_border_lineto( border, &delta, 1 );
}
else /* this is a bevel (intersection) */
{
FT_Fixed length;
FT_Vector delta;
length = FT_DivFix( stroker->radius, thcos );
FT_Vector_From_Polar( &delta, length, phi );
delta.x += stroker->center.x;
delta.y += stroker->center.y;
error = ft_stroke_border_lineto( border, &delta, 0 );
if (error) goto Exit;
/* now add end point */
FT_Vector_From_Polar( &delta, stroker->radius,
stroker->angle_out + rotate );
delta.x += stroker->center.x;
delta.y += stroker->center.y;
error = ft_stroke_border_lineto( border, &delta, 1 );
}
}
Exit:
return error;
}
static FT_Error
ft_stroker_process_corner( FT_Stroker stroker )
{
FT_Error error = 0;
FT_Angle turn;
FT_Int inside_side;
turn = FT_Angle_Diff( stroker->angle_in, stroker->angle_out );
/* no specific corner processing is required if the turn is 0 */
if ( turn == 0 )
goto Exit;
/* when we turn to the right, the inside side is 0 */
inside_side = 0;
/* otherwise, the inside side is 1 */
if ( turn < 0 )
inside_side = 1;
/* process the inside side */
error = ft_stroker_inside( stroker, inside_side );
if ( error )
goto Exit;
/* process the outside side */
error = ft_stroker_outside( stroker, 1 - inside_side );
Exit:
return error;
}
/* add two points to the left and right borders corresponding to the */
/* start of the subpath.. */
static FT_Error
ft_stroker_subpath_start( FT_Stroker stroker,
FT_Angle start_angle )
{
FT_Vector delta;
FT_Vector point;
FT_Error error;
FT_StrokeBorder border;
FT_Vector_From_Polar( &delta, stroker->radius,
start_angle + FT_ANGLE_PI2 );
point.x = stroker->center.x + delta.x;
point.y = stroker->center.y + delta.y;
border = stroker->borders;
error = ft_stroke_border_moveto( border, &point );
if ( error )
goto Exit;
point.x = stroker->center.x - delta.x;
point.y = stroker->center.y - delta.y;
border++;
error = ft_stroke_border_moveto( border, &point );
/* save angle for last cap */
stroker->subpath_angle = start_angle;
stroker->first_point = 0;
Exit:
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Stroker_LineTo( FT_Stroker stroker,
FT_Vector* to )
{
FT_Error error = 0;
FT_StrokeBorder border;
FT_Vector delta;
FT_Angle angle;
FT_Int side;
delta.x = to->x - stroker->center.x;
delta.y = to->y - stroker->center.y;
angle = FT_Atan2( delta.x, delta.y );
FT_Vector_From_Polar( &delta, stroker->radius, angle + FT_ANGLE_PI2 );
/* process corner if necessary */
if ( stroker->first_point )
{
/* This is the first segment of a subpath. We need to */
/* add a point to each border at their respective starting */
/* point locations. */
error = ft_stroker_subpath_start( stroker, angle );
if ( error )
goto Exit;
}
else
{
/* process the current corner */
stroker->angle_out = angle;
error = ft_stroker_process_corner( stroker );
if ( error )
goto Exit;
}
/* now add a line segment to both the "inside" and "outside" paths */
for ( border = stroker->borders, side = 1; side >= 0; side--, border++ )
{
FT_Vector point;
point.x = to->x + delta.x;
point.y = to->y + delta.y;
error = ft_stroke_border_lineto( border, &point, 1 );
if ( error )
goto Exit;
delta.x = -delta.x;
delta.y = -delta.y;
}
stroker->angle_in = angle;
stroker->center = *to;
Exit:
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Stroker_ConicTo( FT_Stroker stroker,
FT_Vector* control,
FT_Vector* to )
{
FT_Error error = 0;
FT_Vector bez_stack[34];
FT_Vector* arc;
FT_Vector* limit = bez_stack + 30;
FT_Angle start_angle;
FT_Bool first_arc = 1;
arc = bez_stack;
arc[0] = *to;
arc[1] = *control;
arc[2] = stroker->center;
while ( arc >= bez_stack )
{
FT_Angle angle_in, angle_out;
angle_in = angle_out = 0; /* remove compiler warnings */
if ( arc < limit &&
!ft_conic_is_small_enough( arc, &angle_in, &angle_out ) )
{
ft_conic_split( arc );
arc += 2;
continue;
}
if ( first_arc )
{
first_arc = 0;
start_angle = angle_in;
/* process corner if necessary */
if ( stroker->first_point )
error = ft_stroker_subpath_start( stroker, start_angle );
else
{
stroker->angle_out = start_angle;
error = ft_stroker_process_corner( stroker );
}
}
/* the arc's angle is small enough; we can add it directly to each */
/* border */
{
FT_Vector ctrl, end;
FT_Angle theta, phi, rotate;
FT_Fixed length;
FT_Int side;
theta = FT_Angle_Diff( angle_in, angle_out ) / 2;
phi = angle_in + theta;
length = FT_DivFix( stroker->radius, FT_Cos( theta ) );
for ( side = 0; side <= 1; side++ )
{
rotate = FT_SIDE_TO_ROTATE( side );
/* compute control point */
FT_Vector_From_Polar( &ctrl, length, phi + rotate );
ctrl.x += arc[1].x;
ctrl.y += arc[1].y;
/* compute end point */
FT_Vector_From_Polar( &end, stroker->radius, angle_out + rotate );
end.x += arc[0].x;
end.y += arc[0].y;
error = ft_stroke_border_conicto( stroker->borders + side,
&ctrl, &end );
if ( error )
goto Exit;
}
}
arc -= 2;
if ( arc < bez_stack )
stroker->angle_in = angle_out;
}
stroker->center = *to;
Exit:
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Stroker_CubicTo( FT_Stroker stroker,
FT_Vector* control1,
FT_Vector* control2,
FT_Vector* to )
{
FT_Error error = 0;
FT_Vector bez_stack[37];
FT_Vector* arc;
FT_Vector* limit = bez_stack + 32;
FT_Angle start_angle;
FT_Bool first_arc = 1;
arc = bez_stack;
arc[0] = *to;
arc[1] = *control2;
arc[2] = *control1;
arc[3] = stroker->center;
while ( arc >= bez_stack )
{
FT_Angle angle_in, angle_mid, angle_out;
/* remove compiler warnings */
angle_in = angle_out = angle_mid = 0;
if ( arc < limit &&
!ft_cubic_is_small_enough( arc, &angle_in,
&angle_mid, &angle_out ) )
{
ft_cubic_split( arc );
arc += 3;
continue;
}
if ( first_arc )
{
first_arc = 0;
/* process corner if necessary */
start_angle = angle_in;
if ( stroker->first_point )
error = ft_stroker_subpath_start( stroker, start_angle );
else
{
stroker->angle_out = start_angle;
error = ft_stroker_process_corner( stroker );
}
if ( error )
goto Exit;
}
/* the arc's angle is small enough; we can add it directly to each */
/* border */
{
FT_Vector ctrl1, ctrl2, end;
FT_Angle theta1, phi1, theta2, phi2, rotate;
FT_Fixed length1, length2;
FT_Int side;
theta1 = ft_pos_abs( angle_mid - angle_in ) / 2;
theta2 = ft_pos_abs( angle_out - angle_mid ) / 2;
phi1 = (angle_mid + angle_in ) / 2;
phi2 = (angle_mid + angle_out ) / 2;
length1 = FT_DivFix( stroker->radius, FT_Cos( theta1 ) );
length2 = FT_DivFix( stroker->radius, FT_Cos(theta2) );
for ( side = 0; side <= 1; side++ )
{
rotate = FT_SIDE_TO_ROTATE( side );
/* compute control points */
FT_Vector_From_Polar( &ctrl1, length1, phi1 + rotate );
ctrl1.x += arc[2].x;
ctrl1.y += arc[2].y;
FT_Vector_From_Polar( &ctrl2, length2, phi2 + rotate );
ctrl2.x += arc[1].x;
ctrl2.y += arc[1].y;
/* compute end point */
FT_Vector_From_Polar( &end, stroker->radius, angle_out + rotate );
end.x += arc[0].x;
end.y += arc[0].y;
error = ft_stroke_border_cubicto( stroker->borders + side,
&ctrl1, &ctrl2, &end );
if ( error )
goto Exit;
}
}
arc -= 3;
if ( arc < bez_stack )
stroker->angle_in = angle_out;
}
stroker->center = *to;
Exit:
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Stroker_BeginSubPath( FT_Stroker stroker,
FT_Vector* to,
FT_Bool open )
{
/* We cannot process the first point, because there is not enough */
/* information regarding its corner/cap. The latter will be processed */
/* in the "end_subpath" routine. */
/* */
stroker->first_point = 1;
stroker->center = *to;
stroker->subpath_open = open;
/* record the subpath start point index for each border */
stroker->subpath_start = *to;
return 0;
}
static FT_Error
ft_stroker_add_reverse_left( FT_Stroker stroker,
FT_Bool open )
{
FT_StrokeBorder right = stroker->borders + 0;
FT_StrokeBorder left = stroker->borders + 1;
FT_Int new_points;
FT_Error error = 0;
FT_ASSERT( left->start >= 0 );
new_points = left->num_points - left->start;
if ( new_points > 0 )
{
error = ft_stroke_border_grow( right, (FT_UInt)new_points );
if ( error )
goto Exit;
{
FT_Vector* dst_point = right->points + right->num_points;
FT_Byte* dst_tag = right->tags + right->num_points;
FT_Vector* src_point = left->points + left->num_points - 1;
FT_Byte* src_tag = left->tags + left->num_points - 1;
while ( src_point >= left->points + left->start )
{
*dst_point = *src_point;
*dst_tag = *src_tag;
if ( open )
dst_tag[0] &= ~( FT_STROKE_TAG_BEGIN | FT_STROKE_TAG_END );
else
{
/* switch begin/end tags if necessary.. */
if ( dst_tag[0] & ( FT_STROKE_TAG_BEGIN | FT_STROKE_TAG_END ) )
dst_tag[0] ^= ( FT_STROKE_TAG_BEGIN | FT_STROKE_TAG_END );
}
src_point--;
src_tag--;
dst_point++;
dst_tag++;
}
}
left->num_points = left->start;
right->num_points += new_points;
right->movable = 0;
left->movable = 0;
}
Exit:
return error;
}
/* there's a lot of magic in this function! */
FT_EXPORT_DEF( FT_Error )
FT_Stroker_EndSubPath( FT_Stroker stroker )
{
FT_Error error = 0;
if ( stroker->subpath_open )
{
FT_StrokeBorder right = stroker->borders;
/* All right, this is an opened path, we need to add a cap between */
/* right & left, add the reverse of left, then add a final cap */
/* between left & right. */
error = ft_stroker_cap( stroker, stroker->angle_in, 0 );
if ( error )
goto Exit;
/* add reversed points from "left" to "right" */
error = ft_stroker_add_reverse_left( stroker, 1 );
if ( error )
goto Exit;
/* now add the final cap */
stroker->center = stroker->subpath_start;
error = ft_stroker_cap( stroker,
stroker->subpath_angle + FT_ANGLE_PI, 0 );
if ( error )
goto Exit;
/* Now end the right subpath accordingly. The left one is */
/* rewind and doesn't need further processing. */
ft_stroke_border_close( right );
}
else
{
FT_Angle turn;
FT_Int inside_side;
/* process the corner */
stroker->angle_out = stroker->subpath_angle;
turn = FT_Angle_Diff( stroker->angle_in,
stroker->angle_out );
/* no specific corner processing is required if the turn is 0 */
if ( turn != 0 )
{
/* when we turn to the right, the inside side is 0 */
inside_side = 0;
/* otherwise, the inside side is 1 */
if ( turn < 0 )
inside_side = 1;
/* IMPORTANT: WE DO NOT PROCESS THE INSIDE BORDER HERE! */
/* process the inside side */
/* error = ft_stroker_inside( stroker, inside_side ); */
/* if ( error ) */
/* goto Exit; */
/* process the outside side */
error = ft_stroker_outside( stroker, 1 - inside_side );
if ( error )
goto Exit;
}
/* we will first end our two subpaths */
ft_stroke_border_close( stroker->borders + 0 );
ft_stroke_border_close( stroker->borders + 1 );
/* now, add the reversed left subpath to "right" */
error = ft_stroker_add_reverse_left( stroker, 0 );
if ( error )
goto Exit;
}
Exit:
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Stroker_GetCounts( FT_Stroker stroker,
FT_UInt *anum_points,
FT_UInt *anum_contours )
{
FT_UInt count1, count2, num_points = 0;
FT_UInt count3, count4, num_contours = 0;
FT_Error error;
error = ft_stroke_border_get_counts( stroker->borders + 0,
&count1, &count2 );
if ( error )
goto Exit;
error = ft_stroke_border_get_counts( stroker->borders + 1,
&count3, &count4 );
if ( error )
goto Exit;
num_points = count1 + count3;
num_contours = count2 + count4;
stroker->valid = 1;
Exit:
*anum_points = num_points;
*anum_contours = num_contours;
return error;
}
FT_EXPORT_DEF( void )
FT_Stroker_Export( FT_Stroker stroker,
FT_Outline* outline )
{
if ( stroker->valid )
{
ft_stroke_border_export( stroker->borders + 0, outline );
ft_stroke_border_export( stroker->borders + 1, outline );
}
}
/*
* The following is very similar to FT_Outline_Decompose, except
* that we do support opened paths, and do not scale the outline.
*/
FT_EXPORT_DEF( FT_Error )
FT_Stroker_ParseOutline( FT_Stroker stroker,
FT_Outline* outline,
FT_Bool opened )
{
FT_Vector v_last;
FT_Vector v_control;
FT_Vector v_start;
FT_Vector* point;
FT_Vector* limit;
char* tags;
FT_Error error;
FT_Int n; /* index of contour in outline */
FT_UInt first; /* index of first point in contour */
FT_Int tag; /* current point's state */
if ( !outline || !stroker )
return FT_Err_Invalid_Argument;
first = 0;
for ( n = 0; n < outline->n_contours; n++ )
{
FT_Int last; /* index of last point in contour */
last = outline->contours[n];
limit = outline->points + last;
v_start = outline->points[first];
v_last = outline->points[last];
v_control = v_start;
point = outline->points + first;
tags = outline->tags + first;
tag = FT_CURVE_TAG( tags[0] );
/* A contour cannot start with a cubic control point! */
if ( tag == FT_CURVE_TAG_CUBIC )
goto Invalid_Outline;
/* check first point to determine origin */
if ( tag == FT_CURVE_TAG_CONIC )
{
/* First point is conic control. Yes, this happens. */
if ( FT_CURVE_TAG( outline->tags[last] ) == FT_CURVE_TAG_ON )
{
/* start at last point if it is on the curve */
v_start = v_last;
limit--;
}
else
{
/* if both first and last points are conic, */
/* start at their middle and record its position */
/* for closure */
v_start.x = ( v_start.x + v_last.x ) / 2;
v_start.y = ( v_start.y + v_last.y ) / 2;
v_last = v_start;
}
point--;
tags--;
}
error = FT_Stroker_BeginSubPath( stroker, &v_start, opened );
if ( error )
goto Exit;
while ( point < limit )
{
point++;
tags++;
tag = FT_CURVE_TAG( tags[0] );
switch ( tag )
{
case FT_CURVE_TAG_ON: /* emit a single line_to */
{
FT_Vector vec;
vec.x = point->x;
vec.y = point->y;
error = FT_Stroker_LineTo( stroker, &vec );
if ( error )
goto Exit;
continue;
}
case FT_CURVE_TAG_CONIC: /* consume conic arcs */
v_control.x = point->x;
v_control.y = point->y;
Do_Conic:
if ( point < limit )
{
FT_Vector vec;
FT_Vector v_middle;
point++;
tags++;
tag = FT_CURVE_TAG( tags[0] );
vec = point[0];
if ( tag == FT_CURVE_TAG_ON )
{
error = FT_Stroker_ConicTo( stroker, &v_control, &vec );
if ( error )
goto Exit;
continue;
}
if ( tag != FT_CURVE_TAG_CONIC )
goto Invalid_Outline;
v_middle.x = ( v_control.x + vec.x ) / 2;
v_middle.y = ( v_control.y + vec.y ) / 2;
error = FT_Stroker_ConicTo( stroker, &v_control, &v_middle );
if ( error )
goto Exit;
v_control = vec;
goto Do_Conic;
}
error = FT_Stroker_ConicTo( stroker, &v_control, &v_start );
goto Close;
default: /* FT_CURVE_TAG_CUBIC */
{
FT_Vector vec1, vec2;
if ( point + 1 > limit ||
FT_CURVE_TAG( tags[1] ) != FT_CURVE_TAG_CUBIC )
goto Invalid_Outline;
point += 2;
tags += 2;
vec1 = point[-2];
vec2 = point[-1];
if ( point <= limit )
{
FT_Vector vec;
vec = point[0];
error = FT_Stroker_CubicTo( stroker, &vec1, &vec2, &vec );
if ( error )
goto Exit;
continue;
}
error = FT_Stroker_CubicTo( stroker, &vec1, &vec2, &v_start );
goto Close;
}
}
}
Close:
if ( error )
goto Exit;
error = FT_Stroker_EndSubPath( stroker );
if ( error )
goto Exit;
first = last + 1;
}
return 0;
Exit:
return error;
Invalid_Outline:
return FT_Err_Invalid_Outline;
}
/* END */