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Diffstat (limited to 'Build/source/libs/freetype2/freetype-2.5.3/src/base/ftbbox.c')
-rw-r--r-- | Build/source/libs/freetype2/freetype-2.5.3/src/base/ftbbox.c | 487 |
1 files changed, 487 insertions, 0 deletions
diff --git a/Build/source/libs/freetype2/freetype-2.5.3/src/base/ftbbox.c b/Build/source/libs/freetype2/freetype-2.5.3/src/base/ftbbox.c new file mode 100644 index 00000000000..8d3f383b4d6 --- /dev/null +++ b/Build/source/libs/freetype2/freetype-2.5.3/src/base/ftbbox.c @@ -0,0 +1,487 @@ +/***************************************************************************/ +/* */ +/* ftbbox.c */ +/* */ +/* FreeType bbox computation (body). */ +/* */ +/* Copyright 1996-2002, 2004, 2006, 2010, 2013 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; + + + /*************************************************************************/ + /* */ + /* <Function> */ + /* BBox_Move_To */ + /* */ + /* <Description> */ + /* This function is used as a `move_to' and `line_to' emitter during */ + /* FT_Outline_Decompose(). It simply records the destination point */ + /* in `user->last'; no further computations are necessary since we */ + /* use the cbox as the starting bbox which must be refined. */ + /* */ + /* <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 ) + { + user->last = *to; + + return 0; + } + + +#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_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 ) + { + /* we don't need to check `to' since it is always an `on' point, thus */ + /* within the 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 + update_cubic_max( FT_Pos q1, + FT_Pos q2, + FT_Pos q3, + FT_Pos q4, + FT_Pos max ) + { + /* for a cubic segment to possibly reach new maximum, at least */ + /* one of its off-points must stay above the current value */ + while ( q2 > max || q3 > max ) + { + /* 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 ) + { + max = q1; + break; + } + if ( q3 == q4 && q2 <= q4 ) + { + max = q4; + break; + } + } + + return max; + } + + + static void + BBox_Cubic_Check( FT_Pos p1, + FT_Pos p2, + FT_Pos p3, + FT_Pos p4, + FT_Pos* min, + FT_Pos* max ) + { + FT_Pos nmin, nmax; + FT_Int shift; + + + /* 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 using iterative bisection of the segment. */ + /* 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. */ + /* The control off-point outside the bbox is likely to have the top */ + /* absolute value among arguments. */ + + shift = 27 - FT_MSB( FT_ABS( p2 ) | FT_ABS( p3 ) ); + + if ( shift > 0 ) + { + /* upscaling too much just wastes time */ + if ( shift > 2 ) + shift = 2; + + p1 <<= shift; + p2 <<= shift; + p3 <<= shift; + p4 <<= shift; + nmin = *min << shift; + nmax = *max << shift; + } + else + { + p1 >>= -shift; + p2 >>= -shift; + p3 >>= -shift; + p4 >>= -shift; + nmin = *min >> -shift; + nmax = *max >> -shift; + } + + nmax = update_cubic_max( p1, p2, p3, p4, nmax ); + + /* now flip the signs to update the minimum */ + nmin = -update_cubic_max( -p1, -p2, -p3, -p4, -nmin ); + + if ( shift > 0 ) + { + nmin >>= shift; + nmax >>= shift; + } + else + { + nmin <<= -shift; + nmax <<= -shift; + } + + if ( nmin < *min ) + *min = nmin; + if ( nmax > *max ) + *max = nmax; + } + + + /*************************************************************************/ + /* */ + /* <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, + (FT_Outline_LineTo_Func) BBox_Move_To, + (FT_Outline_ConicTo_Func)BBox_Conic_To, + (FT_Outline_CubicTo_Func)BBox_Cubic_To, + 0, 0 + ) + + /* documentation is in ftbbox.h */ + + FT_EXPORT_DEF( FT_Error ) + FT_Outline_Get_BBox( FT_Outline* outline, + FT_BBox *abbox ) + { + FT_BBox cbox; + FT_BBox bbox; + 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; + bbox.xMin = bbox.xMax = cbox.xMin = cbox.xMax = vec->x; + bbox.yMin = bbox.yMax = cbox.yMin = cbox.yMax = vec->y; + vec++; + + for ( n = 1; n < outline->n_points; n++ ) + { + FT_Pos x = vec->x; + FT_Pos y = vec->y; + + + /* update control box */ + if ( x < cbox.xMin ) cbox.xMin = x; + if ( x > cbox.xMax ) cbox.xMax = x; + + if ( y < cbox.yMin ) cbox.yMin = y; + if ( y > cbox.yMax ) cbox.yMax = y; + + if ( FT_CURVE_TAG( outline->tags[n] ) == FT_CURVE_TAG_ON ) + { + /* update bbox for `on' points only */ + if ( x < bbox.xMin ) bbox.xMin = x; + if ( x > bbox.xMax ) bbox.xMax = x; + + if ( y < bbox.yMin ) bbox.yMin = y; + if ( y > bbox.yMax ) bbox.yMax = y; + } + + 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 */ |