+++ /dev/null
-/***************************************************************************/
-/* */
-/* ftbbox.c */
-/* */
-/* FreeType bbox computation (body). */
-/* */
-/* Copyright 1996-2017 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. */
-/* */
-/***************************************************************************/
-
-
- /*************************************************************************/
- /* */
- /* This component has a _single_ role: to compute exact outline bounding */
- /* boxes. */
- /* */
- /*************************************************************************/
-
-
-#include <ft2build.h>
-#include FT_INTERNAL_DEBUG_H
-
-#include FT_BBOX_H
-#include FT_IMAGE_H
-#include FT_OUTLINE_H
-#include FT_INTERNAL_CALC_H
-#include FT_INTERNAL_OBJECTS_H
-
-
- typedef struct TBBox_Rec_
- {
- FT_Vector last;
- FT_BBox bbox;
-
- } TBBox_Rec;
-
-
-#define FT_UPDATE_BBOX( p, bbox ) \
- FT_BEGIN_STMNT \
- if ( p->x < bbox.xMin ) \
- bbox.xMin = p->x; \
- if ( p->x > bbox.xMax ) \
- bbox.xMax = p->x; \
- if ( p->y < bbox.yMin ) \
- bbox.yMin = p->y; \
- if ( p->y > bbox.yMax ) \
- bbox.yMax = p->y; \
- FT_END_STMNT
-
-#define CHECK_X( p, bbox ) \
- ( p->x < bbox.xMin || p->x > bbox.xMax )
-
-#define CHECK_Y( p, bbox ) \
- ( p->y < bbox.yMin || p->y > bbox.yMax )
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Move_To */
- /* */
- /* <Description> */
- /* This function is used as a `move_to' emitter during */
- /* FT_Outline_Decompose(). It simply records the destination point */
- /* in `user->last'. We also update bbox in case contour starts with */
- /* an implicit `on' point. */
- /* */
- /* <Input> */
- /* to :: A pointer to the destination vector. */
- /* */
- /* <InOut> */
- /* user :: A pointer to the current walk context. */
- /* */
- /* <Return> */
- /* Always 0. Needed for the interface only. */
- /* */
- static int
- BBox_Move_To( FT_Vector* to,
- TBBox_Rec* user )
- {
- FT_UPDATE_BBOX( to, user->bbox );
-
- user->last = *to;
-
- return 0;
- }
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Line_To */
- /* */
- /* <Description> */
- /* This function is used as a `line_to' emitter during */
- /* FT_Outline_Decompose(). It simply records the destination point */
- /* in `user->last'; no further computations are necessary because */
- /* bbox already contains both explicit ends of the line segment. */
- /* */
- /* <Input> */
- /* to :: A pointer to the destination vector. */
- /* */
- /* <InOut> */
- /* user :: A pointer to the current walk context. */
- /* */
- /* <Return> */
- /* Always 0. Needed for the interface only. */
- /* */
- static int
- BBox_Line_To( FT_Vector* to,
- TBBox_Rec* user )
- {
- user->last = *to;
-
- return 0;
- }
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Conic_Check */
- /* */
- /* <Description> */
- /* Find the extrema of a 1-dimensional conic Bezier curve and update */
- /* a bounding range. This version uses direct computation, as it */
- /* doesn't need square roots. */
- /* */
- /* <Input> */
- /* y1 :: The start coordinate. */
- /* */
- /* y2 :: The coordinate of the control point. */
- /* */
- /* y3 :: The end coordinate. */
- /* */
- /* <InOut> */
- /* min :: The address of the current minimum. */
- /* */
- /* max :: The address of the current maximum. */
- /* */
- static void
- BBox_Conic_Check( FT_Pos y1,
- FT_Pos y2,
- FT_Pos y3,
- FT_Pos* min,
- FT_Pos* max )
- {
- /* This function is only called when a control off-point is outside */
- /* the bbox that contains all on-points. It finds a local extremum */
- /* within the segment, equal to (y1*y3 - y2*y2)/(y1 - 2*y2 + y3). */
- /* Or, offsetting from y2, we get */
-
- y1 -= y2;
- y3 -= y2;
- y2 += FT_MulDiv( y1, y3, y1 + y3 );
-
- if ( y2 < *min )
- *min = y2;
- if ( y2 > *max )
- *max = y2;
- }
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Conic_To */
- /* */
- /* <Description> */
- /* This function is used as a `conic_to' emitter during */
- /* FT_Outline_Decompose(). It checks a conic Bezier curve with the */
- /* current bounding box, and computes its extrema if necessary to */
- /* update it. */
- /* */
- /* <Input> */
- /* control :: A pointer to a control point. */
- /* */
- /* to :: A pointer to the destination vector. */
- /* */
- /* <InOut> */
- /* user :: The address of the current walk context. */
- /* */
- /* <Return> */
- /* Always 0. Needed for the interface only. */
- /* */
- /* <Note> */
- /* In the case of a non-monotonous arc, we compute directly the */
- /* extremum coordinates, as it is sufficiently fast. */
- /* */
- static int
- BBox_Conic_To( FT_Vector* control,
- FT_Vector* to,
- TBBox_Rec* user )
- {
- /* in case `to' is implicit and not included in bbox yet */
- FT_UPDATE_BBOX( to, user->bbox );
-
- if ( CHECK_X( control, user->bbox ) )
- BBox_Conic_Check( user->last.x,
- control->x,
- to->x,
- &user->bbox.xMin,
- &user->bbox.xMax );
-
- if ( CHECK_Y( control, user->bbox ) )
- BBox_Conic_Check( user->last.y,
- control->y,
- to->y,
- &user->bbox.yMin,
- &user->bbox.yMax );
-
- user->last = *to;
-
- return 0;
- }
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Cubic_Check */
- /* */
- /* <Description> */
- /* Find the extrema of a 1-dimensional cubic Bezier curve and */
- /* update a bounding range. This version uses iterative splitting */
- /* because it is faster than the exact solution with square roots. */
- /* */
- /* <Input> */
- /* p1 :: The start coordinate. */
- /* */
- /* p2 :: The coordinate of the first control point. */
- /* */
- /* p3 :: The coordinate of the second control point. */
- /* */
- /* p4 :: The end coordinate. */
- /* */
- /* <InOut> */
- /* min :: The address of the current minimum. */
- /* */
- /* max :: The address of the current maximum. */
- /* */
- static FT_Pos
- cubic_peak( FT_Pos q1,
- FT_Pos q2,
- FT_Pos q3,
- FT_Pos q4 )
- {
- FT_Pos peak = 0;
- FT_Int shift;
-
-
- /* This function finds a peak of a cubic segment if it is above 0 */
- /* using iterative bisection of the segment, or returns 0. */
- /* The fixed-point arithmetic of bisection is inherently stable */
- /* but may loose accuracy in the two lowest bits. To compensate, */
- /* we upscale the segment if there is room. Large values may need */
- /* to be downscaled to avoid overflows during bisection. */
- /* It is called with either q2 or q3 positive, which is necessary */
- /* for the peak to exist and avoids undefined FT_MSB. */
-
- shift = 27 - FT_MSB( (FT_UInt32)( FT_ABS( q1 ) |
- FT_ABS( q2 ) |
- FT_ABS( q3 ) |
- FT_ABS( q4 ) ) );
-
- if ( shift > 0 )
- {
- /* upscaling too much just wastes time */
- if ( shift > 2 )
- shift = 2;
-
- q1 <<= shift;
- q2 <<= shift;
- q3 <<= shift;
- q4 <<= shift;
- }
- else
- {
- q1 >>= -shift;
- q2 >>= -shift;
- q3 >>= -shift;
- q4 >>= -shift;
- }
-
- /* for a peak to exist above 0, the cubic segment must have */
- /* at least one of its control off-points above 0. */
- while ( q2 > 0 || q3 > 0 )
- {
- /* determine which half contains the maximum and split */
- if ( q1 + q2 > q3 + q4 ) /* first half */
- {
- q4 = q4 + q3;
- q3 = q3 + q2;
- q2 = q2 + q1;
- q4 = q4 + q3;
- q3 = q3 + q2;
- q4 = ( q4 + q3 ) / 8;
- q3 = q3 / 4;
- q2 = q2 / 2;
- }
- else /* second half */
- {
- q1 = q1 + q2;
- q2 = q2 + q3;
- q3 = q3 + q4;
- q1 = q1 + q2;
- q2 = q2 + q3;
- q1 = ( q1 + q2 ) / 8;
- q2 = q2 / 4;
- q3 = q3 / 2;
- }
-
- /* check whether either end reached the maximum */
- if ( q1 == q2 && q1 >= q3 )
- {
- peak = q1;
- break;
- }
- if ( q3 == q4 && q2 <= q4 )
- {
- peak = q4;
- break;
- }
- }
-
- if ( shift > 0 )
- peak >>= shift;
- else
- peak <<= -shift;
-
- return peak;
- }
-
-
- static void
- BBox_Cubic_Check( FT_Pos p1,
- FT_Pos p2,
- FT_Pos p3,
- FT_Pos p4,
- FT_Pos* min,
- FT_Pos* max )
- {
- /* This function is only called when a control off-point is outside */
- /* the bbox that contains all on-points. So at least one of the */
- /* conditions below holds and cubic_peak is called with at least one */
- /* non-zero argument. */
-
- if ( p2 > *max || p3 > *max )
- *max += cubic_peak( p1 - *max, p2 - *max, p3 - *max, p4 - *max );
-
- /* now flip the signs to update the minimum */
- if ( p2 < *min || p3 < *min )
- *min -= cubic_peak( *min - p1, *min - p2, *min - p3, *min - p4 );
- }
-
-
- /*************************************************************************/
- /* */
- /* <Function> */
- /* BBox_Cubic_To */
- /* */
- /* <Description> */
- /* This function is used as a `cubic_to' emitter during */
- /* FT_Outline_Decompose(). It checks a cubic Bezier curve with the */
- /* current bounding box, and computes its extrema if necessary to */
- /* update it. */
- /* */
- /* <Input> */
- /* control1 :: A pointer to the first control point. */
- /* */
- /* control2 :: A pointer to the second control point. */
- /* */
- /* to :: A pointer to the destination vector. */
- /* */
- /* <InOut> */
- /* user :: The address of the current walk context. */
- /* */
- /* <Return> */
- /* Always 0. Needed for the interface only. */
- /* */
- /* <Note> */
- /* In the case of a non-monotonous arc, we don't compute directly */
- /* extremum coordinates, we subdivide instead. */
- /* */
- static int
- BBox_Cubic_To( FT_Vector* control1,
- FT_Vector* control2,
- FT_Vector* to,
- TBBox_Rec* user )
- {
- /* We don't need to check `to' since it is always an on-point, */
- /* thus within the bbox. Only segments with an off-point outside */
- /* the bbox can possibly reach new extreme values. */
-
- if ( CHECK_X( control1, user->bbox ) ||
- CHECK_X( control2, user->bbox ) )
- BBox_Cubic_Check( user->last.x,
- control1->x,
- control2->x,
- to->x,
- &user->bbox.xMin,
- &user->bbox.xMax );
-
- if ( CHECK_Y( control1, user->bbox ) ||
- CHECK_Y( control2, user->bbox ) )
- BBox_Cubic_Check( user->last.y,
- control1->y,
- control2->y,
- to->y,
- &user->bbox.yMin,
- &user->bbox.yMax );
-
- user->last = *to;
-
- return 0;
- }
-
-
- FT_DEFINE_OUTLINE_FUNCS(
- bbox_interface,
-
- (FT_Outline_MoveTo_Func) BBox_Move_To, /* move_to */
- (FT_Outline_LineTo_Func) BBox_Line_To, /* line_to */
- (FT_Outline_ConicTo_Func)BBox_Conic_To, /* conic_to */
- (FT_Outline_CubicTo_Func)BBox_Cubic_To, /* cubic_to */
- 0, /* shift */
- 0 /* delta */
- )
-
-
- /* documentation is in ftbbox.h */
-
- FT_EXPORT_DEF( FT_Error )
- FT_Outline_Get_BBox( FT_Outline* outline,
- FT_BBox *abbox )
- {
- FT_BBox cbox = { 0x7FFFFFFFL, 0x7FFFFFFFL,
- -0x7FFFFFFFL, -0x7FFFFFFFL };
- FT_BBox bbox = { 0x7FFFFFFFL, 0x7FFFFFFFL,
- -0x7FFFFFFFL, -0x7FFFFFFFL };
- FT_Vector* vec;
- FT_UShort n;
-
-
- if ( !abbox )
- return FT_THROW( Invalid_Argument );
-
- if ( !outline )
- return FT_THROW( Invalid_Outline );
-
- /* if outline is empty, return (0,0,0,0) */
- if ( outline->n_points == 0 || outline->n_contours <= 0 )
- {
- abbox->xMin = abbox->xMax = 0;
- abbox->yMin = abbox->yMax = 0;
-
- return 0;
- }
-
- /* We compute the control box as well as the bounding box of */
- /* all `on' points in the outline. Then, if the two boxes */
- /* coincide, we exit immediately. */
-
- vec = outline->points;
-
- for ( n = 0; n < outline->n_points; n++ )
- {
- FT_UPDATE_BBOX( vec, cbox );
-
- if ( FT_CURVE_TAG( outline->tags[n] ) == FT_CURVE_TAG_ON )
- FT_UPDATE_BBOX( vec, bbox );
-
- vec++;
- }
-
- /* test two boxes for equality */
- if ( cbox.xMin < bbox.xMin || cbox.xMax > bbox.xMax ||
- cbox.yMin < bbox.yMin || cbox.yMax > bbox.yMax )
- {
- /* the two boxes are different, now walk over the outline to */
- /* get the Bezier arc extrema. */
-
- FT_Error error;
- TBBox_Rec user;
-
-#ifdef FT_CONFIG_OPTION_PIC
- FT_Outline_Funcs bbox_interface;
-
-
- Init_Class_bbox_interface( &bbox_interface );
-#endif
-
- user.bbox = bbox;
-
- error = FT_Outline_Decompose( outline, &bbox_interface, &user );
- if ( error )
- return error;
-
- *abbox = user.bbox;
- }
- else
- *abbox = bbox;
-
- return FT_Err_Ok;
- }
-
-
-/* END */
projects / reactos.git / blobdiff