ref: c962db28ea59225f0105c03d907d4a9b71765687
dir: /src/base/ftoutln.c/
/****************************************************************************
*
* ftoutln.c
*
* FreeType outline management (body).
*
* Copyright 1996-2018 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.
*
*/
/**************************************************************************
*
* All functions are declared in freetype.h.
*
*/
#include <ft2build.h>
#include FT_OUTLINE_H
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_CALC_H
#include FT_INTERNAL_DEBUG_H
#include FT_TRIGONOMETRY_H
/**************************************************************************
*
* The macro FT_COMPONENT is used in trace mode. It is an implicit
* parameter of the FT_TRACE() and FT_ERROR() macros, used to print/log
* messages during execution.
*/
#undef FT_COMPONENT
#define FT_COMPONENT outline
static
const FT_Outline null_outline = { 0, 0, NULL, NULL, NULL, 0 };
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Decompose( FT_Outline* outline,
const FT_Outline_Funcs* func_interface,
void* user )
{
#undef SCALED
#define SCALED( x ) ( ( (x) < 0 ? -( -(x) << shift ) \
: ( (x) << shift ) ) - delta )
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 */
FT_Int shift;
FT_Pos delta;
if ( !outline )
return FT_THROW( Invalid_Outline );
if ( !func_interface )
return FT_THROW( Invalid_Argument );
shift = func_interface->shift;
delta = func_interface->delta;
first = 0;
for ( n = 0; n < outline->n_contours; n++ )
{
FT_Int last; /* index of last point in contour */
FT_TRACE5(( "FT_Outline_Decompose: Outline %d\n", n ));
last = outline->contours[n];
if ( last < 0 )
goto Invalid_Outline;
limit = outline->points + last;
v_start = outline->points[first];
v_start.x = SCALED( v_start.x );
v_start.y = SCALED( v_start.y );
v_last = outline->points[last];
v_last.x = SCALED( v_last.x );
v_last.y = SCALED( v_last.y );
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--;
}
FT_TRACE5(( " move to (%.2f, %.2f)\n",
v_start.x / 64.0, v_start.y / 64.0 ));
error = func_interface->move_to( &v_start, user );
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 = SCALED( point->x );
vec.y = SCALED( point->y );
FT_TRACE5(( " line to (%.2f, %.2f)\n",
vec.x / 64.0, vec.y / 64.0 ));
error = func_interface->line_to( &vec, user );
if ( error )
goto Exit;
continue;
}
case FT_CURVE_TAG_CONIC: /* consume conic arcs */
v_control.x = SCALED( point->x );
v_control.y = SCALED( point->y );
Do_Conic:
if ( point < limit )
{
FT_Vector vec;
FT_Vector v_middle;
point++;
tags++;
tag = FT_CURVE_TAG( tags[0] );
vec.x = SCALED( point->x );
vec.y = SCALED( point->y );
if ( tag == FT_CURVE_TAG_ON )
{
FT_TRACE5(( " conic to (%.2f, %.2f)"
" with control (%.2f, %.2f)\n",
vec.x / 64.0, vec.y / 64.0,
v_control.x / 64.0, v_control.y / 64.0 ));
error = func_interface->conic_to( &v_control, &vec, user );
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;
FT_TRACE5(( " conic to (%.2f, %.2f)"
" with control (%.2f, %.2f)\n",
v_middle.x / 64.0, v_middle.y / 64.0,
v_control.x / 64.0, v_control.y / 64.0 ));
error = func_interface->conic_to( &v_control, &v_middle, user );
if ( error )
goto Exit;
v_control = vec;
goto Do_Conic;
}
FT_TRACE5(( " conic to (%.2f, %.2f)"
" with control (%.2f, %.2f)\n",
v_start.x / 64.0, v_start.y / 64.0,
v_control.x / 64.0, v_control.y / 64.0 ));
error = func_interface->conic_to( &v_control, &v_start, user );
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.x = SCALED( point[-2].x );
vec1.y = SCALED( point[-2].y );
vec2.x = SCALED( point[-1].x );
vec2.y = SCALED( point[-1].y );
if ( point <= limit )
{
FT_Vector vec;
vec.x = SCALED( point->x );
vec.y = SCALED( point->y );
FT_TRACE5(( " cubic to (%.2f, %.2f)"
" with controls (%.2f, %.2f) and (%.2f, %.2f)\n",
vec.x / 64.0, vec.y / 64.0,
vec1.x / 64.0, vec1.y / 64.0,
vec2.x / 64.0, vec2.y / 64.0 ));
error = func_interface->cubic_to( &vec1, &vec2, &vec, user );
if ( error )
goto Exit;
continue;
}
FT_TRACE5(( " cubic to (%.2f, %.2f)"
" with controls (%.2f, %.2f) and (%.2f, %.2f)\n",
v_start.x / 64.0, v_start.y / 64.0,
vec1.x / 64.0, vec1.y / 64.0,
vec2.x / 64.0, vec2.y / 64.0 ));
error = func_interface->cubic_to( &vec1, &vec2, &v_start, user );
goto Close;
}
}
}
/* close the contour with a line segment */
FT_TRACE5(( " line to (%.2f, %.2f)\n",
v_start.x / 64.0, v_start.y / 64.0 ));
error = func_interface->line_to( &v_start, user );
Close:
if ( error )
goto Exit;
first = (FT_UInt)last + 1;
}
FT_TRACE5(( "FT_Outline_Decompose: Done\n", n ));
return FT_Err_Ok;
Invalid_Outline:
error = FT_THROW( Invalid_Outline );
/* fall through */
Exit:
FT_TRACE5(( "FT_Outline_Decompose: Error 0x%x\n", error ));
return error;
}
FT_EXPORT_DEF( FT_Error )
FT_Outline_New_Internal( FT_Memory memory,
FT_UInt numPoints,
FT_Int numContours,
FT_Outline *anoutline )
{
FT_Error error;
if ( !anoutline || !memory )
return FT_THROW( Invalid_Argument );
*anoutline = null_outline;
if ( numContours < 0 ||
(FT_UInt)numContours > numPoints )
return FT_THROW( Invalid_Argument );
if ( numPoints > FT_OUTLINE_POINTS_MAX )
return FT_THROW( Array_Too_Large );
if ( FT_NEW_ARRAY( anoutline->points, numPoints ) ||
FT_NEW_ARRAY( anoutline->tags, numPoints ) ||
FT_NEW_ARRAY( anoutline->contours, numContours ) )
goto Fail;
anoutline->n_points = (FT_Short)numPoints;
anoutline->n_contours = (FT_Short)numContours;
anoutline->flags |= FT_OUTLINE_OWNER;
return FT_Err_Ok;
Fail:
anoutline->flags |= FT_OUTLINE_OWNER;
FT_Outline_Done_Internal( memory, anoutline );
return error;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_New( FT_Library library,
FT_UInt numPoints,
FT_Int numContours,
FT_Outline *anoutline )
{
if ( !library )
return FT_THROW( Invalid_Library_Handle );
return FT_Outline_New_Internal( library->memory, numPoints,
numContours, anoutline );
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Check( FT_Outline* outline )
{
if ( outline )
{
FT_Int n_points = outline->n_points;
FT_Int n_contours = outline->n_contours;
FT_Int end0, end;
FT_Int n;
/* empty glyph? */
if ( n_points == 0 && n_contours == 0 )
return FT_Err_Ok;
/* check point and contour counts */
if ( n_points <= 0 || n_contours <= 0 )
goto Bad;
end0 = end = -1;
for ( n = 0; n < n_contours; n++ )
{
end = outline->contours[n];
/* note that we don't accept empty contours */
if ( end <= end0 || end >= n_points )
goto Bad;
end0 = end;
}
if ( end != n_points - 1 )
goto Bad;
/* XXX: check the tags array */
return FT_Err_Ok;
}
Bad:
return FT_THROW( Invalid_Argument );
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Copy( const FT_Outline* source,
FT_Outline *target )
{
FT_Int is_owner;
if ( !source || !target )
return FT_THROW( Invalid_Outline );
if ( source->n_points != target->n_points ||
source->n_contours != target->n_contours )
return FT_THROW( Invalid_Argument );
if ( source == target )
return FT_Err_Ok;
if ( source->n_points )
{
FT_ARRAY_COPY( target->points, source->points, source->n_points );
FT_ARRAY_COPY( target->tags, source->tags, source->n_points );
}
if ( source->n_contours )
FT_ARRAY_COPY( target->contours, source->contours, source->n_contours );
/* copy all flags, except the `FT_OUTLINE_OWNER' one */
is_owner = target->flags & FT_OUTLINE_OWNER;
target->flags = source->flags;
target->flags &= ~FT_OUTLINE_OWNER;
target->flags |= is_owner;
return FT_Err_Ok;
}
FT_EXPORT_DEF( FT_Error )
FT_Outline_Done_Internal( FT_Memory memory,
FT_Outline* outline )
{
if ( !outline )
return FT_THROW( Invalid_Outline );
if ( !memory )
return FT_THROW( Invalid_Argument );
if ( outline->flags & FT_OUTLINE_OWNER )
{
FT_FREE( outline->points );
FT_FREE( outline->tags );
FT_FREE( outline->contours );
}
*outline = null_outline;
return FT_Err_Ok;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Done( FT_Library library,
FT_Outline* outline )
{
/* check for valid `outline' in FT_Outline_Done_Internal() */
if ( !library )
return FT_THROW( Invalid_Library_Handle );
return FT_Outline_Done_Internal( library->memory, outline );
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( void )
FT_Outline_Get_CBox( const FT_Outline* outline,
FT_BBox *acbox )
{
FT_Pos xMin, yMin, xMax, yMax;
if ( outline && acbox )
{
if ( outline->n_points == 0 )
{
xMin = 0;
yMin = 0;
xMax = 0;
yMax = 0;
}
else
{
FT_Vector* vec = outline->points;
FT_Vector* limit = vec + outline->n_points;
xMin = xMax = vec->x;
yMin = yMax = vec->y;
vec++;
for ( ; vec < limit; vec++ )
{
FT_Pos x, y;
x = vec->x;
if ( x < xMin ) xMin = x;
if ( x > xMax ) xMax = x;
y = vec->y;
if ( y < yMin ) yMin = y;
if ( y > yMax ) yMax = y;
}
}
acbox->xMin = xMin;
acbox->xMax = xMax;
acbox->yMin = yMin;
acbox->yMax = yMax;
}
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( void )
FT_Outline_Translate( const FT_Outline* outline,
FT_Pos xOffset,
FT_Pos yOffset )
{
FT_UShort n;
FT_Vector* vec;
if ( !outline )
return;
vec = outline->points;
for ( n = 0; n < outline->n_points; n++ )
{
vec->x = ADD_LONG( vec->x, xOffset );
vec->y = ADD_LONG( vec->y, yOffset );
vec++;
}
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( void )
FT_Outline_Reverse( FT_Outline* outline )
{
FT_UShort n;
FT_Int first, last;
if ( !outline )
return;
first = 0;
for ( n = 0; n < outline->n_contours; n++ )
{
last = outline->contours[n];
/* reverse point table */
{
FT_Vector* p = outline->points + first;
FT_Vector* q = outline->points + last;
FT_Vector swap;
while ( p < q )
{
swap = *p;
*p = *q;
*q = swap;
p++;
q--;
}
}
/* reverse tags table */
{
char* p = outline->tags + first;
char* q = outline->tags + last;
while ( p < q )
{
char swap;
swap = *p;
*p = *q;
*q = swap;
p++;
q--;
}
}
first = last + 1;
}
outline->flags ^= FT_OUTLINE_REVERSE_FILL;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Render( FT_Library library,
FT_Outline* outline,
FT_Raster_Params* params )
{
FT_Error error;
FT_Renderer renderer;
FT_ListNode node;
FT_BBox cbox;
if ( !library )
return FT_THROW( Invalid_Library_Handle );
if ( !outline )
return FT_THROW( Invalid_Outline );
if ( !params )
return FT_THROW( Invalid_Argument );
FT_Outline_Get_CBox( outline, &cbox );
if ( cbox.xMin < -0x1000000L || cbox.yMin < -0x1000000L ||
cbox.xMax > 0x1000000L || cbox.yMax > 0x1000000L )
return FT_THROW( Invalid_Outline );
renderer = library->cur_renderer;
node = library->renderers.head;
params->source = (void*)outline;
error = FT_ERR( Cannot_Render_Glyph );
while ( renderer )
{
error = renderer->raster_render( renderer->raster, params );
if ( !error || FT_ERR_NEQ( error, Cannot_Render_Glyph ) )
break;
/* FT_Err_Cannot_Render_Glyph is returned if the render mode */
/* is unsupported by the current renderer for this glyph image */
/* format */
/* now, look for another renderer that supports the same */
/* format */
renderer = FT_Lookup_Renderer( library, FT_GLYPH_FORMAT_OUTLINE,
&node );
}
return error;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Get_Bitmap( FT_Library library,
FT_Outline* outline,
const FT_Bitmap *abitmap )
{
FT_Raster_Params params;
if ( !abitmap )
return FT_THROW( Invalid_Argument );
/* other checks are delayed to `FT_Outline_Render' */
params.target = abitmap;
params.flags = 0;
if ( abitmap->pixel_mode == FT_PIXEL_MODE_GRAY ||
abitmap->pixel_mode == FT_PIXEL_MODE_LCD ||
abitmap->pixel_mode == FT_PIXEL_MODE_LCD_V )
params.flags |= FT_RASTER_FLAG_AA;
return FT_Outline_Render( library, outline, ¶ms );
}
/* documentation is in freetype.h */
FT_EXPORT_DEF( void )
FT_Vector_Transform( FT_Vector* vector,
const FT_Matrix* matrix )
{
FT_Pos xz, yz;
if ( !vector || !matrix )
return;
xz = FT_MulFix( vector->x, matrix->xx ) +
FT_MulFix( vector->y, matrix->xy );
yz = FT_MulFix( vector->x, matrix->yx ) +
FT_MulFix( vector->y, matrix->yy );
vector->x = xz;
vector->y = yz;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( void )
FT_Outline_Transform( const FT_Outline* outline,
const FT_Matrix* matrix )
{
FT_Vector* vec;
FT_Vector* limit;
if ( !outline || !matrix )
return;
vec = outline->points;
limit = vec + outline->n_points;
for ( ; vec < limit; vec++ )
FT_Vector_Transform( vec, matrix );
}
#if 0
#define FT_OUTLINE_GET_CONTOUR( outline, c, first, last ) \
do \
{ \
(first) = ( c > 0 ) ? (outline)->points + \
(outline)->contours[c - 1] + 1 \
: (outline)->points; \
(last) = (outline)->points + (outline)->contours[c]; \
} while ( 0 )
/* Is a point in some contour? */
/* */
/* We treat every point of the contour as if it */
/* it were ON. That is, we allow false positives, */
/* but disallow false negatives. (XXX really?) */
static FT_Bool
ft_contour_has( FT_Outline* outline,
FT_Short c,
FT_Vector* point )
{
FT_Vector* first;
FT_Vector* last;
FT_Vector* a;
FT_Vector* b;
FT_UInt n = 0;
FT_OUTLINE_GET_CONTOUR( outline, c, first, last );
for ( a = first; a <= last; a++ )
{
FT_Pos x;
FT_Int intersect;
b = ( a == last ) ? first : a + 1;
intersect = ( a->y - point->y ) ^ ( b->y - point->y );
/* a and b are on the same side */
if ( intersect >= 0 )
{
if ( intersect == 0 && a->y == point->y )
{
if ( ( a->x <= point->x && b->x >= point->x ) ||
( a->x >= point->x && b->x <= point->x ) )
return 1;
}
continue;
}
x = a->x + ( b->x - a->x ) * (point->y - a->y ) / ( b->y - a->y );
if ( x < point->x )
n++;
else if ( x == point->x )
return 1;
}
return n & 1;
}
static FT_Bool
ft_contour_enclosed( FT_Outline* outline,
FT_UShort c )
{
FT_Vector* first;
FT_Vector* last;
FT_Short i;
FT_OUTLINE_GET_CONTOUR( outline, c, first, last );
for ( i = 0; i < outline->n_contours; i++ )
{
if ( i != c && ft_contour_has( outline, i, first ) )
{
FT_Vector* pt;
for ( pt = first + 1; pt <= last; pt++ )
if ( !ft_contour_has( outline, i, pt ) )
return 0;
return 1;
}
}
return 0;
}
/* This version differs from the public one in that each */
/* part (contour not enclosed in another contour) of the */
/* outline is checked for orientation. This is */
/* necessary for some buggy CJK fonts. */
static FT_Orientation
ft_outline_get_orientation( FT_Outline* outline )
{
FT_Short i;
FT_Vector* first;
FT_Vector* last;
FT_Orientation orient = FT_ORIENTATION_NONE;
first = outline->points;
for ( i = 0; i < outline->n_contours; i++, first = last + 1 )
{
FT_Vector* point;
FT_Vector* xmin_point;
FT_Pos xmin;
last = outline->points + outline->contours[i];
/* skip degenerate contours */
if ( last < first + 2 )
continue;
if ( ft_contour_enclosed( outline, i ) )
continue;
xmin = first->x;
xmin_point = first;
for ( point = first + 1; point <= last; point++ )
{
if ( point->x < xmin )
{
xmin = point->x;
xmin_point = point;
}
}
/* check the orientation of the contour */
{
FT_Vector* prev;
FT_Vector* next;
FT_Orientation o;
prev = ( xmin_point == first ) ? last : xmin_point - 1;
next = ( xmin_point == last ) ? first : xmin_point + 1;
if ( FT_Atan2( prev->x - xmin_point->x, prev->y - xmin_point->y ) >
FT_Atan2( next->x - xmin_point->x, next->y - xmin_point->y ) )
o = FT_ORIENTATION_POSTSCRIPT;
else
o = FT_ORIENTATION_TRUETYPE;
if ( orient == FT_ORIENTATION_NONE )
orient = o;
else if ( orient != o )
return FT_ORIENTATION_NONE;
}
}
return orient;
}
#endif /* 0 */
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_Embolden( FT_Outline* outline,
FT_Pos strength )
{
return FT_Outline_EmboldenXY( outline, strength, strength );
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Error )
FT_Outline_EmboldenXY( FT_Outline* outline,
FT_Pos xstrength,
FT_Pos ystrength )
{
FT_Vector* points;
FT_Int c, first, last;
FT_Orientation orientation;
if ( !outline )
return FT_THROW( Invalid_Outline );
xstrength /= 2;
ystrength /= 2;
if ( xstrength == 0 && ystrength == 0 )
return FT_Err_Ok;
orientation = FT_Outline_Get_Orientation( outline );
if ( orientation == FT_ORIENTATION_NONE )
{
if ( outline->n_contours )
return FT_THROW( Invalid_Argument );
else
return FT_Err_Ok;
}
points = outline->points;
first = 0;
for ( c = 0; c < outline->n_contours; c++ )
{
FT_Vector in, out, anchor, shift;
FT_Fixed l_in, l_out, l_anchor = 0, l, q, d;
FT_Int i, j, k;
l_in = 0;
last = outline->contours[c];
/* pacify compiler */
in.x = in.y = anchor.x = anchor.y = 0;
/* Counter j cycles though the points; counter i advances only */
/* when points are moved; anchor k marks the first moved point. */
for ( i = last, j = first, k = -1;
j != i && i != k;
j = j < last ? j + 1 : first )
{
if ( j != k )
{
out.x = points[j].x - points[i].x;
out.y = points[j].y - points[i].y;
l_out = (FT_Fixed)FT_Vector_NormLen( &out );
if ( l_out == 0 )
continue;
}
else
{
out = anchor;
l_out = l_anchor;
}
if ( l_in != 0 )
{
if ( k < 0 )
{
k = i;
anchor = in;
l_anchor = l_in;
}
d = FT_MulFix( in.x, out.x ) + FT_MulFix( in.y, out.y );
/* shift only if turn is less than ~160 degrees */
if ( d > -0xF000L )
{
d = d + 0x10000L;
/* shift components along lateral bisector in proper orientation */
shift.x = in.y + out.y;
shift.y = in.x + out.x;
if ( orientation == FT_ORIENTATION_TRUETYPE )
shift.x = -shift.x;
else
shift.y = -shift.y;
/* restrict shift magnitude to better handle collapsing segments */
q = FT_MulFix( out.x, in.y ) - FT_MulFix( out.y, in.x );
if ( orientation == FT_ORIENTATION_TRUETYPE )
q = -q;
l = FT_MIN( l_in, l_out );
/* non-strict inequalities avoid divide-by-zero when q == l == 0 */
if ( FT_MulFix( xstrength, q ) <= FT_MulFix( l, d ) )
shift.x = FT_MulDiv( shift.x, xstrength, d );
else
shift.x = FT_MulDiv( shift.x, l, q );
if ( FT_MulFix( ystrength, q ) <= FT_MulFix( l, d ) )
shift.y = FT_MulDiv( shift.y, ystrength, d );
else
shift.y = FT_MulDiv( shift.y, l, q );
}
else
shift.x = shift.y = 0;
for ( ;
i != j;
i = i < last ? i + 1 : first )
{
points[i].x += xstrength + shift.x;
points[i].y += ystrength + shift.y;
}
}
else
i = j;
in = out;
l_in = l_out;
}
first = last + 1;
}
return FT_Err_Ok;
}
/* documentation is in ftoutln.h */
FT_EXPORT_DEF( FT_Orientation )
FT_Outline_Get_Orientation( FT_Outline* outline )
{
FT_BBox cbox = { 0, 0, 0, 0 };
FT_Int xshift, yshift;
FT_Vector* points;
FT_Vector v_prev, v_cur;
FT_Int c, n, first;
FT_Pos area = 0;
if ( !outline || outline->n_points <= 0 )
return FT_ORIENTATION_TRUETYPE;
/* We use the nonzero winding rule to find the orientation. */
/* Since glyph outlines behave much more `regular' than arbitrary */
/* cubic or quadratic curves, this test deals with the polygon */
/* only that is spanned up by the control points. */
FT_Outline_Get_CBox( outline, &cbox );
/* Handle collapsed outlines to avoid undefined FT_MSB. */
if ( cbox.xMin == cbox.xMax || cbox.yMin == cbox.yMax )
return FT_ORIENTATION_NONE;
xshift = FT_MSB( (FT_UInt32)( FT_ABS( cbox.xMax ) |
FT_ABS( cbox.xMin ) ) ) - 14;
xshift = FT_MAX( xshift, 0 );
yshift = FT_MSB( (FT_UInt32)( cbox.yMax - cbox.yMin ) ) - 14;
yshift = FT_MAX( yshift, 0 );
points = outline->points;
first = 0;
for ( c = 0; c < outline->n_contours; c++ )
{
FT_Int last = outline->contours[c];
v_prev.x = points[last].x >> xshift;
v_prev.y = points[last].y >> yshift;
for ( n = first; n <= last; n++ )
{
v_cur.x = points[n].x >> xshift;
v_cur.y = points[n].y >> yshift;
area = ADD_LONG( area,
( v_cur.y - v_prev.y ) * ( v_cur.x + v_prev.x ) );
v_prev = v_cur;
}
first = last + 1;
}
if ( area > 0 )
return FT_ORIENTATION_POSTSCRIPT;
else if ( area < 0 )
return FT_ORIENTATION_TRUETYPE;
else
return FT_ORIENTATION_NONE;
}
/* END */