source/texk/web2c/luatexdir/tex/packaging.h

   1 /* packaging.h
   2
   3    Copyright 2009 Taco Hoekwater <taco@luatex.org>
   4
   5    This file is part of LuaTeX.
   6
   7    LuaTeX is free software; you can redistribute it and/or modify it under
   8    the terms of the GNU General Public License as published by the Free
   9    Software Foundation; either version 2 of the License, or (at your
  10    option) any later version.
  11
  12    LuaTeX is distributed in the hope that it will be useful, but WITHOUT
  13    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  15    License for more details.
  16
  17    You should have received a copy of the GNU General Public License along
  18    with LuaTeX; if not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #ifndef PACKAGING_H
  22 #  define PACKAGING_H
  23
  24 /* We define some constants used when calling |hpack| to deal with font expansion. */
  25
  26 typedef enum {
  27     exactly = 0,      /*a box dimension is pre-specified */
  28     additional,       /*a box dimension is increased from the natural one */
  29     cal_expand_ratio, /* calculate amount for font expansion after breaking paragraph into lines */
  30     subst_ex_font     /* substitute fonts */
  31 } hpack_subtypes;
  32
  33 #  define substituted 3 /* |subtype| of kern nodes that should be substituted */
  34
  35 extern void scan_spec(group_code c);
  36 extern void scan_full_spec(group_code c, int spec_direction, int justpack);
  37
  38 extern scaled total_stretch[5];
  39 extern scaled total_shrink[5];        /* glue found by |hpack| or |vpack| */
  40 extern int last_badness;              /* badness of the most recently packaged box */
  41 extern halfword adjust_tail;          /* tail of adjustment list */
  42 extern halfword pre_adjust_tail;
  43 extern int font_expand_ratio;         /* current expansion ratio */
  44 extern halfword last_leftmost_char;
  45 extern halfword last_rightmost_char;
  46 extern halfword next_char_p;          /* pointer to the next char of an implicit kern */
  47 extern halfword prev_char_p;          /* pointer to the previous char of an implicit kern */
  48
  49 extern void set_prev_char_p(halfword p);
  50 extern scaled char_stretch(halfword p);
  51 extern scaled char_shrink(halfword p);
  52 extern scaled kern_stretch(halfword p);
  53 extern scaled kern_shrink(halfword p);
  54 extern void do_subst_font(halfword p, int ex_ratio);
  55 extern scaled char_pw(halfword p, int side);
  56 extern halfword new_margin_kern(scaled w, halfword p, int side);
  57
  58 #  define update_adjust_list(A) do { \
  59         if (A == null) \
  60             normal_error("pre vadjust", "adjust_tail or pre_adjust_tail is null"); \
  61         vlink(A) = adjust_ptr(p); \
  62         while (vlink(A) != null) \
  63             A = vlink(A); \
  64     } while (0)
  65
  66 extern halfword filtered_hpack(halfword p, halfword qt, scaled w, int m, int grp, int d, int just_pack);
  67 extern scaled_whd natural_sizes(halfword p, halfword pp, glue_ratio g_mult, int g_sign, int g_order, int d);
  68 extern halfword hpack(halfword p, scaled w, int m, int d);
  69
  70 extern int pack_begin_line;
  71
  72 extern halfword vpackage(halfword p, scaled h, int m, scaled l, int d);
  73 extern halfword filtered_vpackage(halfword p, scaled h, int m, scaled l, int grp, int d, int just_pack);
  74 extern void finish_vcenter(void);
  75 extern void package(int c);
  76 extern void append_to_vlist(halfword b, int location);
  77
  78 # define vpack(A,B,C,D) vpackage(A,B,C,max_dimen,D) /* special case of unconstrained depth */
  79
  80 extern halfword prune_page_top(halfword p, boolean s);
  81 extern scaled active_height[10];        /* distance from first active node to~|cur_p| */
  82
  83 #  define cur_height active_height[1]   /* the natural height */
  84 #  define awful_bad 07777777777         /* more than a billion demerits */
  85 #  define deplorable 100000             /* more than |inf_bad|, but less than |awful_bad| */
  86
  87 extern scaled best_height_plus_depth;   /* height of the best box, without stretching or shrinking */
  88
  89 extern halfword vert_break(halfword p, scaled h, scaled d);
  90 extern halfword vsplit(halfword n, scaled h, int m); /* extracts a page of height |h| from box |n| */
  91
  92 #  define box_code      0 /* |chr_code| for `\.{\\box}' */
  93 #  define copy_code     1 /* |chr_code| for `\.{\\copy}' */
  94 #  define last_box_code 2 /* |chr_code| for `\.{\\lastbox}' */
  95 #  define vsplit_code   3 /* |chr_code| for `\.{\\vsplit}' */
  96 #  define tpack_code    4
  97 #  define vpack_code    5
  98 #  define hpack_code    6
  99 #  define vtop_code     7 /* |chr_code| for `\.{\\vtop}' */
 100
 101 #  define tail_page_disc disc_ptr[copy_code] /* last item removed by page builder */
 102 #  define page_disc disc_ptr[last_box_code]  /* first item removed by page builder */
 103 #  define split_disc disc_ptr[vsplit_code]   /* first item removed by \.{\\vsplit} */
 104
 105 extern halfword disc_ptr[(vsplit_code + 1)]; /* list pointers */
 106
 107 /*
 108
 109 Now let's turn to the question of how \.{\\hbox} is treated. We actually need to
 110 consider also a slightly larger context, since constructions like
 111
 112 `\.{\\setbox3=}\penalty0\.{\\hbox...}' and
 113 `\.{\\leaders}\penalty0\.{\\hbox...}' and
 114 `\.{\\lower3.8pt\\hbox...}'
 115
 116 are supposed to invoke quite different actions after the box has been packaged.
 117 Conversely, constructions like `\.{\\setbox3=}' can be followed by a variety of
 118 different kinds of boxes, and we would like to encode such things in an efficient
 119 way.
 120
 121 In other words, there are two problems: To represent the context of a box, and to
 122 represent its type. The first problem is solved by putting a ``context code'' on
 123 the |save_stack|, just below the two entries that give the dimensions produced by
 124 |scan_spec|. The context code is either a (signed) shift amount, or it is a large
 125 integer |>=box_flag|, where |box_flag=@t$2^{30}$@>|. Codes |box_flag| through
 126 |box_flag+biggest_reg| represent `\.{\\setbox0}' through
 127 `\.{\\setbox}|biggest_reg|'; codes |box_flag+biggest_reg+1| through
 128 |box_flag+2*biggest_reg| represent `\.{\\global\\setbox0}' through
 129 `\.{\\global\\setbox}|biggest_reg|'; code |box_flag+2*number_regs| represents
 130 `\.{\\shipout}'; and codes |box_flag+2*number_regs+1| through
 131 |box_flag+2*number_regs+3| represent `\.{\\leaders}', `\.{\\cleaders}', and
 132 `\.{\\xleaders}'.
 133
 134 The second problem is solved by giving the command code |make_box| to all control
 135 sequences that produce a box, and by using the following |chr_code| values to
 136 distinguish between them: |box_code|, |copy_code|, |last_box_code|,
 137 |vsplit_code|, |vtop_code|, |vtop_code+vmode|, and |vtop_code+hmode|, where the
 138 latter two are used denote \.{\\vbox} and \.{\\hbox}, respectively.
 139
 140 */
 141
 142 #  define box_flag            010000000000                  /* context code for `\.{\\setbox0}' */
 143 #  define global_box_flag     (box_flag+number_regs)        /* context code for `\.{\\global\\setbox0}' */
 144 #  define max_global_box_flag (global_box_flag+number_regs)
 145 #  define ship_out_flag       (max_global_box_flag+1)       /* context code for `\.{\\shipout}' */
 146 #  define leader_flag         ship_out_flag+1               /* context code for `\.{\\leaders}' */
 147
 148 extern void begin_box(int box_context);
 149
 150 #endif