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kc3-lang/freetype/src/base/ftbbox.c
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Author :
Oran Agra
Date : 2009-04-05 17:59:26
Hash : 636c294b
Message : Position Independent Code (PIC) support and infrastructure in base. * include/freetype/config/ftoption.h add FT_CONFIG_OPTION_PIC * include/freetype/internal/ftobjs.h Add pic_container member to FT_LibraryRec. Add macros to declare and init instances of FT_CMap_ClassRec. Add macros to init instances of FT_Outline_Funcs and FT_Raster_Funcs. Add macros to declare, allocate and initialize modules (FT_Module_Class). Add macros to declare, allocate and initialize renderers (FT_Renderer_Class). Add macro to init instances of FT_Glyph_Class. Add macros to declare, allocate and initialize drivers (FT_Driver_ClassRec). * include/freetype/internal/ftpic.h new file to declare the FT_PIC_Container struct and the functions to allocate and detroy it. * include/freetype/internal/ftserv.h add macros to allocate and destory arrays of FT_ServiceDescRec. * include/freetype/internal/internal.h define macro to include ftpic.h. New Files: * src/base/ftpic.c implement functions to allocate and destory the global pic_container. * src/base/basepic.h declare struct to hold PIC globals for base and macros to access them. * src/base/basepic.c implement functions to allocate, destroy and initialize PIC globals for base. * src/base/ftinit.c when FT_CONFIG_OPTION_PIC is defined implement functions that allocate and destroy ft_default_modules according to FT_CONFIG_MODULES_H in the pic_container instead of the global scope and use macro from basepic.h to access it. * src/base/ftobjs.c add calls to the functions that allocate and destroy the global pic_container when the library is created and destroyed. * src/base/jamfile add new files to FT2_MULTI build: ftpic.c and basepic.c. * src/base/ftbase.c add new files to build: ftpic.c and basepic.c. * src/base/ftglyph.c when FT_CONFIG_OPTION_PIC is defined ft_bitmap_glyph_class and ft_outline_glyph_class will be allocated in the pic_container instead of the global scope and use macros from basepic.h to access them. * src/base/ftbbox.c allocate bbox_interface stract on the stack instead of the global scope when FT_CONFIG_OPTION_PIC is defined. * src/base/ftstroke.c access ft_outline_glyph_class allocated in ftglyph.c via macros from basepic.h
- src/base/ftbbox.c
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/***************************************************************************/ /* */ /* ftbbox.c */ /* */ /* FreeType bbox computation (body). */ /* */ /* Copyright 1996-2001, 2002, 2004, 2006 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_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> */ /* 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. */ /* */ /* <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 ) { 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; } /*************************************************************************/ /* */ /* <Function> */ /* BBox_Conic_To */ /* */ /* <Description> */ /* This function is used as a `conic_to' emitter during */ /* FT_Raster_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> */ /* 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. */ /* */ /* <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. */ /* */ #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 /*************************************************************************/ /* */ /* <Function> */ /* BBox_Cubic_To */ /* */ /* <Description> */ /* This function is used as a `cubic_to' emitter during */ /* FT_Raster_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 */ 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 */