diff options
Diffstat (limited to 'src/3rdparty/freetype/src/base/ftbbox.c')
-rw-r--r-- | src/3rdparty/freetype/src/base/ftbbox.c | 512 |
1 files changed, 178 insertions, 334 deletions
diff --git a/src/3rdparty/freetype/src/base/ftbbox.c b/src/3rdparty/freetype/src/base/ftbbox.c index 4b8e9112fe..f9a17517ec 100644 --- a/src/3rdparty/freetype/src/base/ftbbox.c +++ b/src/3rdparty/freetype/src/base/ftbbox.c @@ -4,7 +4,7 @@ /* */ /* FreeType bbox computation (body). */ /* */ -/* Copyright 1996-2001, 2002, 2004, 2006, 2010 by */ +/* Copyright 1996-2002, 2004, 2006, 2010, 2013, 2014 by */ /* David Turner, Robert Wilhelm, and Werner Lemberg. */ /* */ /* This file is part of the FreeType project, and may only be used */ @@ -25,6 +25,8 @@ #include <ft2build.h> +#include FT_INTERNAL_DEBUG_H + #include FT_BBOX_H #include FT_IMAGE_H #include FT_OUTLINE_H @@ -40,16 +42,35 @@ } 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' and `line_to' emitter during */ + /* This function is used as a `move_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. */ + /* in `user->last'. We also update bbox in case contour starts with */ + /* an implicit `on' point. */ /* */ /* <Input> */ /* to :: A pointer to the destination vector. */ @@ -64,17 +85,42 @@ BBox_Move_To( FT_Vector* to, TBBox_Rec* user ) { + FT_UPDATE_BBOX( to, user->bbox ); + user->last = *to; return 0; } -#define CHECK_X( p, bbox ) \ - ( p->x < bbox.xMin || p->x > bbox.xMax ) + /*************************************************************************/ + /* */ + /* <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; -#define CHECK_Y( p, bbox ) \ - ( p->y < bbox.yMin || p->y > bbox.yMax ) + return 0; + } /*************************************************************************/ @@ -83,7 +129,7 @@ /* BBox_Conic_Check */ /* */ /* <Description> */ - /* Finds the extrema of a 1-dimensional conic Bezier curve and update */ + /* 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. */ /* */ @@ -106,30 +152,19 @@ 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; + /* 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; } @@ -164,8 +199,8 @@ FT_Vector* to, TBBox_Rec* user ) { - /* we don't need to check `to' since it is always an `on' point, thus */ - /* within the bbox */ + /* 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, @@ -193,9 +228,9 @@ /* BBox_Cubic_Check */ /* */ /* <Description> */ - /* 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. */ + /* 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. */ @@ -211,294 +246,117 @@ /* */ /* 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 ) + static FT_Pos + cubic_peak( FT_Pos q1, + FT_Pos q2, + FT_Pos q3, + FT_Pos q4 ) { - FT_Pos stack[32*3 + 1], *arc; - - - arc = stack; - - arc[0] = p1; - arc[1] = p2; - arc[2] = p3; - arc[3] = p4; - - do + 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_ABS( q1 ) | FT_ABS( q2 ) | FT_ABS( q3 ) | FT_ABS( q4 ) ); + + if ( shift > 0 ) { - FT_Pos y1 = arc[0]; - FT_Pos y2 = arc[1]; - FT_Pos y3 = arc[2]; - FT_Pos y4 = arc[3]; - + /* 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; + } - if ( y1 == y4 ) + /* 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 */ { - if ( y1 == y2 && y1 == y3 ) /* flat */ - goto Test; + 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 if ( y1 < y4 ) + else /* second half */ { - if ( y2 >= y1 && y2 <= y4 && y3 >= y1 && y3 <= y4 ) /* ascending */ - goto Test; + 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; } - else + + /* check whether either end reached the maximum */ + if ( q1 == q2 && q1 >= q3 ) { - if ( y2 >= y4 && y2 <= y1 && y3 >= y4 && y3 <= y1 ) /* descending */ - { - y2 = y1; - y1 = y4; - y4 = y2; - goto Test; - } + peak = q1; + break; } + if ( q3 == q4 && q2 <= q4 ) + { + peak = q4; + break; + } + } - /* 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 ( shift > 0 ) + peak >>= shift; + else + peak <<= -shift; - if ( y < *min ) *min = y; - if ( y > *max ) *max = y; - } + return peak; } static void - BBox_Cubic_Check( FT_Pos y1, - FT_Pos y2, - FT_Pos y3, - FT_Pos y4, + BBox_Cubic_Check( FT_Pos p1, + FT_Pos p2, + FT_Pos p3, + FT_Pos p4, FT_Pos* min, FT_Pos* max ) { - /* always compare first and last points */ - if ( y1 < *min ) *min = y1; - else if ( y1 > *max ) *max = y1; + /* 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 ( y4 < *min ) *min = y4; - else if ( y4 > *max ) *max = y4; + if ( p2 > *max || p3 > *max ) + *max += cubic_peak( p1 - *max, p2 - *max, p3 - *max, p4 - *max ); - /* 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 ); - } - } - } + /* now flip the signs to update the minimum */ + if ( p2 < *min || p3 < *min ) + *min -= cubic_peak( *min - p1, *min - p2, *min - p3, *min - p4 ); } -#endif - /*************************************************************************/ /* */ @@ -534,8 +392,9 @@ FT_Vector* to, TBBox_Rec* user ) { - /* we don't need to check `to' since it is always an `on' point, thus */ - /* within the bbox */ + /* 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 ) ) @@ -560,31 +419,35 @@ return 0; } -FT_DEFINE_OUTLINE_FUNCS(bbox_interface, + + FT_DEFINE_OUTLINE_FUNCS(bbox_interface, (FT_Outline_MoveTo_Func) BBox_Move_To, - (FT_Outline_LineTo_Func) BBox_Move_To, + (FT_Outline_LineTo_Func) BBox_Line_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_BBox cbox = { 0x7FFFFFFFL, 0x7FFFFFFFL, + -0x7FFFFFFFL, -0x7FFFFFFFL }; + FT_BBox bbox = { 0x7FFFFFFFL, 0x7FFFFFFFL, + -0x7FFFFFFFL, -0x7FFFFFFFL }; FT_Vector* vec; FT_UShort n; if ( !abbox ) - return FT_Err_Invalid_Argument; + return FT_THROW( Invalid_Argument ); if ( !outline ) - return FT_Err_Invalid_Outline; + return FT_THROW( Invalid_Outline ); /* if outline is empty, return (0,0,0,0) */ if ( outline->n_points == 0 || outline->n_contours <= 0 ) @@ -599,32 +462,13 @@ FT_DEFINE_OUTLINE_FUNCS(bbox_interface, /* 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++ ) + for ( n = 0; 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; + FT_UPDATE_BBOX( vec, cbox); 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; - } + FT_UPDATE_BBOX( vec, bbox); vec++; } |