src/window.h

   1 /* Window definitions for GNU Emacs.
   2    Copyright (C) 1985, 1986, 1992 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20
  21 /* Windows are allocated as if they were vectors, but then the
  22 Lisp data type is changed to Lisp_Window.  They are garbage
  23 collected along with the vectors.
  24
  25 All windows in use are arranged into a tree, with pointers up and down.
  26
  27 Windows that are leaves of the tree are actually displayed
  28 and show the contents of buffers.  Windows that are not leaves
  29 are used for representing the way groups of leaf windows are
  30 arranged on the frame.  Leaf windows never become non-leaves.
  31 They are deleted only by calling delete-window on them (but
  32 this can be done implicitly).  Combination windows can be created
  33 and deleted at any time.
  34
  35 A leaf window has a non-nil buffer field, and also
  36  has markers in its start and pointm fields.  Non-leaf windows
  37  have nil in these fields.
  38
  39 Non-leaf windows are either vertical or horizontal combinations.
  40
  41 A vertical combination window has children that are arranged on the frame
  42 one above the next.  Its vchild field points to the uppermost child.
  43 The parent field of each of the children points to the vertical
  44 combination window.  The next field of each child points to the
  45 child below it, or is nil for the lowest child.  The prev field
  46 of each child points to the child above it, or is nil for the
  47 highest child.
  48
  49 A horizontal combination window has children that are side by side.
  50 Its hchild field points to the leftmost child.  In each child
  51 the next field points to the child to the right and the prev field
  52 points to the child to the left.
  53
  54 The children of a vertical combination window may be leaf windows
  55 or horizontal combination windows.  The children of a horizontal
  56 combination window may be leaf windows or vertical combination windows.
  57
  58 At the top of the tree are two windows which have nil as parent.
  59 The second of these is minibuf_window.  The first one manages all
  60 the frame area that is not minibuffer, and is called the root window.
  61 Different windows can be the root at different times;
  62 initially the root window is a leaf window, but if more windows
  63 are created then that leaf window ceases to be root and a newly
  64 made combination window becomes root instead.
  65
  66 In any case, on screens which have an ordinary window and a
  67 minibuffer, prev of the minibuf window is the root window and next of
  68 the root window is the minibuf window.  On minibufferless screens or
  69 minibuffer-only screens, the root window and the minibuffer window are
  70 one and the same, so its prev and next members are nil.  */
  71
  72
  73 struct window
  74   {
  75     /* The first two fields are really the header of a vector */
  76     /* The window code does not refer to them.  */
  77     int size;
  78     struct Lisp_Vector *vec_next;
  79     /* The frame this window is on.  */
  80     Lisp_Object frame;
  81     /* t if this window is a minibuffer window.  */
  82     Lisp_Object mini_p;
  83     /* Following child (to right or down) at same level of tree */
  84     Lisp_Object next;
  85     /* Preceding child (to left or up) at same level of tree */
  86     Lisp_Object prev;
  87     /* First child of this window. */
  88     /* vchild is used if this is a vertical combination,
  89        hchild if this is a horizontal combination. */
  90     Lisp_Object hchild, vchild;
  91     /* The window this one is a child of. */
  92     Lisp_Object parent;
  93     /* The upper left corner coordinates of this window,
  94        as integers relative to upper left corner of frame = 0, 0 */
  95     Lisp_Object left;
  96     Lisp_Object top;
  97     /* The size of the window */
  98     Lisp_Object height;
  99     Lisp_Object width;
 100     /* The buffer displayed in this window */
 101     /* Of the fields vchild, hchild and buffer, only one is non-nil.  */
 102     Lisp_Object buffer;
 103     /* A marker pointing to where in the text to start displaying */
 104     Lisp_Object start;
 105     /* A marker pointing to where in the text point is in this window,
 106        used only when the window is not selected.
 107        This exists so that when multiple windows show one buffer
 108        each one can have its own value of point.  */
 109     Lisp_Object pointm;
 110     /* Non-nil means next redisplay must use the value of start
 111        set up for it in advance.  Set by scrolling commands.  */
 112     Lisp_Object force_start;
 113     /* Number of columns display within the window is scrolled to the left.  */
 114     Lisp_Object hscroll;
 115     /* Number saying how recently window was selected */
 116     Lisp_Object use_time;
 117     /* Unique number of window assigned when it was created */
 118     Lisp_Object sequence_number;
 119     /* No permanent meaning; used by save-window-excursion's bookkeeping */
 120     Lisp_Object temslot;
 121     /* text.modified of displayed buffer as of last time display completed */
 122     Lisp_Object last_modified;
 123     /* Value of point at that time */
 124     Lisp_Object last_point;
 125 /* The rest are currently not used or only half used */
 126     /* Frame coords of point at that time */
 127     Lisp_Object last_point_x;
 128     Lisp_Object last_point_y;
 129     /* Frame coords of mark as of last time display completed */
 130     /* May be nil if mark does not exist or was not on frame */
 131     Lisp_Object last_mark_x;
 132     Lisp_Object last_mark_y;
 133     /* Number of characters in buffer past bottom of window,
 134        as of last redisplay that finished. */
 135     Lisp_Object window_end_pos;
 136     /* t if window_end_pos is truly valid.
 137        This is nil if nontrivial redisplay is preempted
 138        since in that case the frame image that window_end_pos
 139        did not get onto the frame.  */
 140     Lisp_Object window_end_valid;
 141     /* Vertical position (relative to window top) of that buffer position
 142        of the first of those characters */
 143     Lisp_Object window_end_vpos;
 144     /* Non-nil means must regenerate mode line of this window */
 145     Lisp_Object update_mode_line;
 146     /* Non-nil means current value of `start'
 147        was the beginning of a line when it was chosen.  */
 148     Lisp_Object start_at_line_beg;
 149     /* Display-table to use for displaying chars in this window.
 150        Nil means use the buffer's own display-table.  */
 151     Lisp_Object display_table;
 152     /* Non-nil means window is marked as dedicated.  */
 153     Lisp_Object dedicated;
 154   };
 155
 156 /* 1 if W is a minibuffer window.  */
 157
 158 #define MINI_WINDOW_P(W)  (!EQ ((W)->mini_p, Qnil))
 159
 160 /* This is the window in which the terminal's cursor should
 161    be left when nothing is being done with it.  This must
 162    always be a leaf window, and its buffer is selected by
 163    the top level editing loop at the end of each command.
 164
 165    This value is always the same as
 166     FRAME_SELECTED_WINDOW (selected_frame).  */
 167
 168 extern Lisp_Object selected_window;
 169
 170 /* This is a time stamp for window selection, so we can find the least
 171    recently used window.  Its only users are Fselect_window,
 172    init_window_once, and make_frame.  */
 173
 174 extern int window_select_count;
 175
 176 /* The minibuffer window of the selected frame.
 177    Note that you cannot test for minibufferness of an arbitrary window
 178    by comparing against this; use the MINI_WINDOW_P macro instead.  */
 179
 180 extern Lisp_Object minibuf_window;
 181
 182 /* Non-nil => window to for C-M-v to scroll
 183    when the minibuffer is selected.  */
 184 extern Lisp_Object Vminibuf_scroll_window;
 185
 186 /* nil or a symbol naming the window system
 187    under which emacs is running
 188    ('x is the only current possibility) */
 189 extern Lisp_Object Vwindow_system;
 190
 191 /* Version number of X windows: 10, 11 or nil.  */
 192 extern Lisp_Object Vwindow_system_version;
 193
 194 /* Window that the mouse is over (nil if no mouse support).  */
 195 extern Lisp_Object Vmouse_window;
 196
 197 /* Last mouse-click event (nil if no mouse support).  */
 198 extern Lisp_Object Vmouse_event;
 199
 200 extern Lisp_Object Fnext_window ();
 201 extern Lisp_Object Fselect_window ();
 202 extern Lisp_Object Fdisplay_buffer ();
 203 extern Lisp_Object Fset_window_buffer ();
 204
 205 /* Prompt to display in front of the minibuffer contents.  */
 206 extern char *minibuf_prompt;
 207
 208 /* The visual width of the above.  */
 209 extern int minibuf_prompt_width;
 210
 211 /* Message to display instead of minibuffer contents.
 212    This is what the functions error and message make,
 213    and command echoing uses it as well. It overrides the
 214    minibuf_prompt as well as the buffer.  */
 215 extern char *echo_area_glyphs;
 216
 217 /* Depth in recursive edits.  */
 218 extern int command_loop_level;
 219
 220 /* Depth in minibuffer invocations.  */
 221 extern int minibuf_level;
 222
 223 /* true iff we should redraw the mode lines on the next redisplay.  */
 224 extern int update_mode_lines;
 225
 226 /* Minimum value of GPT since last redisplay that finished.  */
 227
 228 extern int beg_unchanged;
 229
 230 /* Minimum value of Z - GPT since last redisplay that finished.  */
 231
 232 extern int end_unchanged;
 233
 234 /* MODIFF as of last redisplay that finished;
 235    if it matches MODIFF, beg_unchanged and end_unchangedn
 236    contain no useful information.  */
 237 extern int unchanged_modified;
 238
 239 /* Nonzero if BEGV - BEG or Z - ZV of current buffer has changed
 240    since last redisplay that finished.  */
 241 extern int clip_changed;
 242
 243 /* Nonzero if window sizes or contents have changed
 244  since last redisplay that finished */
 245 extern int windows_or_buffers_changed;
 246
 247 /* Number of windows displaying the selected buffer.
 248    Normally this is 1, but it can be more.  */
 249 extern int buffer_shared;
 250
 251 /* If *ROWS or *COLS are too small a size for FRAME, set them to the
 252    minimum allowable size.  */
 253 extern void check_frame_size ( /* FRAME_PTR frame, int *rows, int *cols */ );