diff -r 92af50454cf2 -r 8054d9d775fd misc/libfreetype/src/base/ftbbox.c --- a/misc/libfreetype/src/base/ftbbox.c Fri Oct 11 11:55:31 2013 +0200 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,662 +0,0 @@ -/***************************************************************************/ -/* */ -/* ftbbox.c */ -/* */ -/* FreeType bbox computation (body). */ -/* */ -/* Copyright 1996-2001, 2002, 2004, 2006, 2010 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 -#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; - - - /*************************************************************************/ - /* */ - /* */ - /* BBox_Move_To */ - /* */ - /* */ - /* 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. */ - /* */ - /* */ - /* to :: A pointer to the destination vector. */ - /* */ - /* */ - /* user :: A pointer to the current walk context. */ - /* */ - /* */ - /* 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 ) - - - /*************************************************************************/ - /* */ - /* */ - /* BBox_Conic_Check */ - /* */ - /* */ - /* Finds 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. */ - /* */ - /* */ - /* y1 :: The start coordinate. */ - /* */ - /* y2 :: The coordinate of the control point. */ - /* */ - /* y3 :: The end coordinate. */ - /* */ - /* */ - /* 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 ) - { - if ( y1 <= y3 && y2 == y1 ) /* flat arc */ - goto Suite; - - if ( y1 < y3 ) - { - if ( y2 >= y1 && y2 <= y3 ) /* ascending arc */ - goto Suite; - } - else - { - if ( y2 >= y3 && y2 <= y1 ) /* descending arc */ - { - y2 = y1; - y1 = y3; - y3 = y2; - goto Suite; - } - } - - y1 = y3 = y1 - FT_MulDiv( y2 - y1, y2 - y1, y1 - 2*y2 + y3 ); - - Suite: - if ( y1 < *min ) *min = y1; - if ( y3 > *max ) *max = y3; - } - - - /*************************************************************************/ - /* */ - /* */ - /* BBox_Conic_To */ - /* */ - /* */ - /* 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. */ - /* */ - /* */ - /* control :: A pointer to a control point. */ - /* */ - /* to :: A pointer to the destination vector. */ - /* */ - /* */ - /* user :: The address of the current walk context. */ - /* */ - /* */ - /* Always 0. Needed for the interface only. */ - /* */ - /* */ - /* 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; - } - - - /*************************************************************************/ - /* */ - /* */ - /* BBox_Cubic_Check */ - /* */ - /* */ - /* Finds the extrema of a 1-dimensional cubic Bezier curve and */ - /* updates a bounding range. This version uses splitting because we */ - /* don't want to use square roots and extra accuracy. */ - /* */ - /* */ - /* p1 :: The start coordinate. */ - /* */ - /* p2 :: The coordinate of the first control point. */ - /* */ - /* p3 :: The coordinate of the second control point. */ - /* */ - /* p4 :: The end coordinate. */ - /* */ - /* */ - /* min :: The address of the current minimum. */ - /* */ - /* max :: The address of the current maximum. */ - /* */ - -#if 0 - - 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 stack[32*3 + 1], *arc; - - - arc = stack; - - arc[0] = p1; - arc[1] = p2; - arc[2] = p3; - arc[3] = p4; - - do - { - FT_Pos y1 = arc[0]; - FT_Pos y2 = arc[1]; - FT_Pos y3 = arc[2]; - FT_Pos y4 = arc[3]; - - - if ( y1 == y4 ) - { - if ( y1 == y2 && y1 == y3 ) /* flat */ - goto Test; - } - else if ( y1 < y4 ) - { - if ( y2 >= y1 && y2 <= y4 && y3 >= y1 && y3 <= y4 ) /* ascending */ - goto Test; - } - else - { - if ( y2 >= y4 && y2 <= y1 && y3 >= y4 && y3 <= y1 ) /* descending */ - { - y2 = y1; - y1 = y4; - y4 = y2; - goto Test; - } - } - - /* unknown direction -- split the arc in two */ - arc[6] = y4; - arc[1] = y1 = ( y1 + y2 ) / 2; - arc[5] = y4 = ( y4 + y3 ) / 2; - y2 = ( y2 + y3 ) / 2; - arc[2] = y1 = ( y1 + y2 ) / 2; - arc[4] = y4 = ( y4 + y2 ) / 2; - arc[3] = ( y1 + y4 ) / 2; - - arc += 3; - goto Suite; - - Test: - if ( y1 < *min ) *min = y1; - if ( y4 > *max ) *max = y4; - arc -= 3; - - Suite: - ; - } while ( arc >= stack ); - } - -#else - - static void - test_cubic_extrema( FT_Pos y1, - FT_Pos y2, - FT_Pos y3, - FT_Pos y4, - FT_Fixed u, - FT_Pos* min, - FT_Pos* max ) - { - /* FT_Pos a = y4 - 3*y3 + 3*y2 - y1; */ - FT_Pos b = y3 - 2*y2 + y1; - FT_Pos c = y2 - y1; - FT_Pos d = y1; - FT_Pos y; - FT_Fixed uu; - - FT_UNUSED ( y4 ); - - - /* The polynomial is */ - /* */ - /* P(x) = a*x^3 + 3b*x^2 + 3c*x + d , */ - /* */ - /* dP/dx = 3a*x^2 + 6b*x + 3c . */ - /* */ - /* However, we also have */ - /* */ - /* dP/dx(u) = 0 , */ - /* */ - /* which implies by subtraction that */ - /* */ - /* P(u) = b*u^2 + 2c*u + d . */ - - if ( u > 0 && u < 0x10000L ) - { - uu = FT_MulFix( u, u ); - y = d + FT_MulFix( c, 2*u ) + FT_MulFix( b, uu ); - - if ( y < *min ) *min = y; - if ( y > *max ) *max = y; - } - } - - - static void - BBox_Cubic_Check( FT_Pos y1, - FT_Pos y2, - FT_Pos y3, - FT_Pos y4, - FT_Pos* min, - FT_Pos* max ) - { - /* always compare first and last points */ - if ( y1 < *min ) *min = y1; - else if ( y1 > *max ) *max = y1; - - if ( y4 < *min ) *min = y4; - else if ( y4 > *max ) *max = y4; - - /* now, try to see if there are split points here */ - if ( y1 <= y4 ) - { - /* flat or ascending arc test */ - if ( y1 <= y2 && y2 <= y4 && y1 <= y3 && y3 <= y4 ) - return; - } - else /* y1 > y4 */ - { - /* descending arc test */ - if ( y1 >= y2 && y2 >= y4 && y1 >= y3 && y3 >= y4 ) - return; - } - - /* There are some split points. Find them. */ - { - FT_Pos a = y4 - 3*y3 + 3*y2 - y1; - FT_Pos b = y3 - 2*y2 + y1; - FT_Pos c = y2 - y1; - FT_Pos d; - FT_Fixed t; - - - /* We need to solve `ax^2+2bx+c' here, without floating points! */ - /* The trick is to normalize to a different representation in order */ - /* to use our 16.16 fixed point routines. */ - /* */ - /* We compute FT_MulFix(b,b) and FT_MulFix(a,c) after normalization. */ - /* These values must fit into a single 16.16 value. */ - /* */ - /* We normalize a, b, and c to `8.16' fixed float values to ensure */ - /* that its product is held in a `16.16' value. */ - - { - FT_ULong t1, t2; - int shift = 0; - - - /* The following computation is based on the fact that for */ - /* any value `y', if `n' is the position of the most */ - /* significant bit of `abs(y)' (starting from 0 for the */ - /* least significant bit), then `y' is in the range */ - /* */ - /* -2^n..2^n-1 */ - /* */ - /* We want to shift `a', `b', and `c' concurrently in order */ - /* to ensure that they all fit in 8.16 values, which maps */ - /* to the integer range `-2^23..2^23-1'. */ - /* */ - /* Necessarily, we need to shift `a', `b', and `c' so that */ - /* the most significant bit of its absolute values is at */ - /* _most_ at position 23. */ - /* */ - /* We begin by computing `t1' as the bitwise `OR' of the */ - /* absolute values of `a', `b', `c'. */ - - t1 = (FT_ULong)( ( a >= 0 ) ? a : -a ); - t2 = (FT_ULong)( ( b >= 0 ) ? b : -b ); - t1 |= t2; - t2 = (FT_ULong)( ( c >= 0 ) ? c : -c ); - t1 |= t2; - - /* Now we can be sure that the most significant bit of `t1' */ - /* is the most significant bit of either `a', `b', or `c', */ - /* depending on the greatest integer range of the particular */ - /* variable. */ - /* */ - /* Next, we compute the `shift', by shifting `t1' as many */ - /* times as necessary to move its MSB to position 23. This */ - /* corresponds to a value of `t1' that is in the range */ - /* 0x40_0000..0x7F_FFFF. */ - /* */ - /* Finally, we shift `a', `b', and `c' by the same amount. */ - /* This ensures that all values are now in the range */ - /* -2^23..2^23, i.e., they are now expressed as 8.16 */ - /* fixed-float numbers. This also means that we are using */ - /* 24 bits of precision to compute the zeros, independently */ - /* of the range of the original polynomial coefficients. */ - /* */ - /* This algorithm should ensure reasonably accurate values */ - /* for the zeros. Note that they are only expressed with */ - /* 16 bits when computing the extrema (the zeros need to */ - /* be in 0..1 exclusive to be considered part of the arc). */ - - if ( t1 == 0 ) /* all coefficients are 0! */ - return; - - if ( t1 > 0x7FFFFFUL ) - { - do - { - shift++; - t1 >>= 1; - - } while ( t1 > 0x7FFFFFUL ); - - /* this loses some bits of precision, but we use 24 of them */ - /* for the computation anyway */ - a >>= shift; - b >>= shift; - c >>= shift; - } - else if ( t1 < 0x400000UL ) - { - do - { - shift++; - t1 <<= 1; - - } while ( t1 < 0x400000UL ); - - a <<= shift; - b <<= shift; - c <<= shift; - } - } - - /* handle a == 0 */ - if ( a == 0 ) - { - if ( b != 0 ) - { - t = - FT_DivFix( c, b ) / 2; - test_cubic_extrema( y1, y2, y3, y4, t, min, max ); - } - } - else - { - /* solve the equation now */ - d = FT_MulFix( b, b ) - FT_MulFix( a, c ); - if ( d < 0 ) - return; - - if ( d == 0 ) - { - /* there is a single split point at -b/a */ - t = - FT_DivFix( b, a ); - test_cubic_extrema( y1, y2, y3, y4, t, min, max ); - } - else - { - /* there are two solutions; we need to filter them */ - d = FT_SqrtFixed( (FT_Int32)d ); - t = - FT_DivFix( b - d, a ); - test_cubic_extrema( y1, y2, y3, y4, t, min, max ); - - t = - FT_DivFix( b + d, a ); - test_cubic_extrema( y1, y2, y3, y4, t, min, max ); - } - } - } - } - -#endif - - - /*************************************************************************/ - /* */ - /* */ - /* BBox_Cubic_To */ - /* */ - /* */ - /* 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. */ - /* */ - /* */ - /* control1 :: A pointer to the first control point. */ - /* */ - /* control2 :: A pointer to the second control point. */ - /* */ - /* to :: A pointer to the destination vector. */ - /* */ - /* */ - /* user :: The address of the current walk context. */ - /* */ - /* */ - /* Always 0. Needed for the interface only. */ - /* */ - /* */ - /* 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 */ - - 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_Err_Invalid_Argument; - - if ( !outline ) - return FT_Err_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 */