src/window.h

   1 /* Window definitions for GNU Emacs.
   2    Copyright (C) 1985, 1986, 1993, 1995 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, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22 /* Windows are allocated as if they were vectors, but then the
  23 Lisp data type is changed to Lisp_Window.  They are garbage
  24 collected along with the vectors.
  25
  26 All windows in use are arranged into a tree, with pointers up and down.
  27
  28 Windows that are leaves of the tree are actually displayed
  29 and show the contents of buffers.  Windows that are not leaves
  30 are used for representing the way groups of leaf windows are
  31 arranged on the frame.  Leaf windows never become non-leaves.
  32 They are deleted only by calling delete-window on them (but
  33 this can be done implicitly).  Combination windows can be created
  34 and deleted at any time.
  35
  36 A leaf window has a non-nil buffer field, and also
  37  has markers in its start and pointm fields.  Non-leaf windows
  38  have nil in these fields.
  39
  40 Non-leaf windows are either vertical or horizontal combinations.
  41
  42 A vertical combination window has children that are arranged on the frame
  43 one above the next.  Its vchild field points to the uppermost child.
  44 The parent field of each of the children points to the vertical
  45 combination window.  The next field of each child points to the
  46 child below it, or is nil for the lowest child.  The prev field
  47 of each child points to the child above it, or is nil for the
  48 highest child.
  49
  50 A horizontal combination window has children that are side by side.
  51 Its hchild field points to the leftmost child.  In each child
  52 the next field points to the child to the right and the prev field
  53 points to the child to the left.
  54
  55 The children of a vertical combination window may be leaf windows
  56 or horizontal combination windows.  The children of a horizontal
  57 combination window may be leaf windows or vertical combination windows.
  58
  59 At the top of the tree are two windows which have nil as parent.
  60 The second of these is minibuf_window.  The first one manages all
  61 the frame area that is not minibuffer, and is called the root window.
  62 Different windows can be the root at different times;
  63 initially the root window is a leaf window, but if more windows
  64 are created then that leaf window ceases to be root and a newly
  65 made combination window becomes root instead.
  66
  67 In any case, on screens which have an ordinary window and a
  68 minibuffer, prev of the minibuf window is the root window and next of
  69 the root window is the minibuf window.  On minibufferless screens or
  70 minibuffer-only screens, the root window and the minibuffer window are
  71 one and the same, so its prev and next members are nil.
  72
  73 A dead window has its buffer, hchild, and vchild windows all nil.  */
  74
  75 struct window
  76   {
  77     /* The first two fields are really the header of a vector */
  78     /* The window code does not refer to them.  */
  79     EMACS_INT size;
  80     struct Lisp_Vector *vec_next;
  81     /* The frame this window is on.  */
  82     Lisp_Object frame;
  83     /* t if this window is a minibuffer window.  */
  84     Lisp_Object mini_p;
  85     /* Following child (to right or down) at same level of tree */
  86     Lisp_Object next;
  87     /* Preceding child (to left or up) at same level of tree */
  88     Lisp_Object prev;
  89     /* First child of this window. */
  90     /* vchild is used if this is a vertical combination,
  91        hchild if this is a horizontal combination. */
  92     Lisp_Object hchild, vchild;
  93     /* The window this one is a child of. */
  94     Lisp_Object parent;
  95     /* The upper left corner coordinates of this window,
  96        as integers relative to upper left corner of frame = 0, 0 */
  97     Lisp_Object left;
  98     Lisp_Object top;
  99     /* The size of the window */
 100     Lisp_Object height;
 101     Lisp_Object width;
 102     /* The buffer displayed in this window */
 103     /* Of the fields vchild, hchild and buffer, only one is non-nil.  */
 104     Lisp_Object buffer;
 105     /* A marker pointing to where in the text to start displaying */
 106     Lisp_Object start;
 107     /* A marker pointing to where in the text point is in this window,
 108        used only when the window is not selected.
 109        This exists so that when multiple windows show one buffer
 110        each one can have its own value of point.  */
 111     Lisp_Object pointm;
 112     /* Non-nil means next redisplay must use the value of start
 113        set up for it in advance.  Set by scrolling commands.  */
 114     Lisp_Object force_start;
 115     /* Number of columns display within the window is scrolled to the left.  */
 116     Lisp_Object hscroll;
 117     /* Number saying how recently window was selected */
 118     Lisp_Object use_time;
 119     /* Unique number of window assigned when it was created */
 120     Lisp_Object sequence_number;
 121     /* No permanent meaning; used by save-window-excursion's bookkeeping */
 122     Lisp_Object temslot;
 123     /* text.modified of displayed buffer as of last time display completed */
 124     Lisp_Object last_modified;
 125     /* Value of point at that time */
 126     Lisp_Object last_point;
 127     /* Non-nil if the buffer was "modified" when the window
 128        was last updated.  */
 129     Lisp_Object last_had_star;
 130     /* This window's vertical scroll bar.  This field is only for use
 131        by the window-system-dependent code which implements the
 132        scroll bars; it can store anything it likes here.  If this
 133        window is newly created and we haven't displayed a scroll bar in
 134        it yet, or if the frame doesn't have any scroll bars, this is nil.  */
 135     Lisp_Object vertical_scroll_bar;
 136
 137 /* The rest are currently not used or only half used */
 138     /* Frame coords of point at that time */
 139     Lisp_Object last_point_x;
 140     Lisp_Object last_point_y;
 141     /* Frame coords of mark as of last time display completed */
 142     /* May be nil if mark does not exist or was not on frame */
 143     Lisp_Object last_mark_x;
 144     Lisp_Object last_mark_y;
 145     /* Number of characters in buffer past bottom of window,
 146        as of last redisplay that finished. */
 147     Lisp_Object window_end_pos;
 148     /* t if window_end_pos is truly valid.
 149        This is nil if nontrivial redisplay is preempted
 150        since in that case the frame image that window_end_pos
 151        did not get onto the frame.  */
 152     Lisp_Object window_end_valid;
 153     /* Vertical position (relative to window top) of that buffer position
 154        of the first of those characters */
 155     Lisp_Object window_end_vpos;
 156     /* Non-nil means must regenerate mode line of this window */
 157     Lisp_Object update_mode_line;
 158     /* Non-nil means current value of `start'
 159        was the beginning of a line when it was chosen.  */
 160     Lisp_Object start_at_line_beg;
 161     /* Display-table to use for displaying chars in this window.
 162        Nil means use the buffer's own display-table.  */
 163     Lisp_Object display_table;
 164     /* Non-nil means window is marked as dedicated.  */
 165     Lisp_Object dedicated;
 166     /* Line number and position of a line somewhere above the
 167        top of the screen.  */
 168     /* If this field is nil, it means we don't have a base line.  */
 169     Lisp_Object base_line_number;
 170     /* If this field is nil, it means we don't have a base line.
 171        If it is a buffer, it means don't display the line number
 172        as long as the window shows that buffer.  */
 173     Lisp_Object base_line_pos;
 174     /* If we have highlighted the region (or any part of it),
 175        this is the mark position that we used, as an integer.  */
 176     Lisp_Object region_showing;
 177     /* The column number currently displayed in this window's mode line,
 178        or nil if column numbers are not being displayed.  */
 179     Lisp_Object column_number_displayed;
 180     /* If redisplay in this window goes beyond this buffer position,
 181        must run the redisplay-end-trigger-hook.  */
 182     Lisp_Object redisplay_end_trigger;
 183   };
 184
 185 /* 1 if W is a minibuffer window.  */
 186
 187 #define MINI_WINDOW_P(W)  (!EQ ((W)->mini_p, Qnil))
 188
 189 /* This is the window in which the terminal's cursor should
 190    be left when nothing is being done with it.  This must
 191    always be a leaf window, and its buffer is selected by
 192    the top level editing loop at the end of each command.
 193
 194    This value is always the same as
 195     FRAME_SELECTED_WINDOW (selected_frame).  */
 196
 197 extern Lisp_Object selected_window;
 198
 199 /* This is a time stamp for window selection, so we can find the least
 200    recently used window.  Its only users are Fselect_window,
 201    init_window_once, and make_frame.  */
 202
 203 extern int window_select_count;
 204
 205 /* The minibuffer window of the selected frame.
 206    Note that you cannot test for minibufferness of an arbitrary window
 207    by comparing against this; use the MINI_WINDOW_P macro instead.  */
 208
 209 extern Lisp_Object minibuf_window;
 210
 211 /* Non-nil => window to for C-M-v to scroll
 212    when the minibuffer is selected.  */
 213 extern Lisp_Object Vminibuf_scroll_window;
 214
 215 /* nil or a symbol naming the window system
 216    under which emacs is running
 217    ('x is the only current possibility) */
 218 extern Lisp_Object Vwindow_system;
 219
 220 /* Version number of X windows: 10, 11 or nil.  */
 221 extern Lisp_Object Vwindow_system_version;
 222
 223 /* Window that the mouse is over (nil if no mouse support).  */
 224 extern Lisp_Object Vmouse_window;
 225
 226 /* Last mouse-click event (nil if no mouse support).  */
 227 extern Lisp_Object Vmouse_event;
 228
 229 extern Lisp_Object Fnext_window ();
 230 extern Lisp_Object Fselect_window ();
 231 extern Lisp_Object Fdisplay_buffer ();
 232 extern Lisp_Object Fset_window_buffer ();
 233 extern Lisp_Object make_window ();
 234 extern Lisp_Object window_from_coordinates ();
 235 extern Lisp_Object Fwindow_dedicated_p ();
 236
 237 /* Prompt to display in front of the minibuffer contents.  */
 238 extern Lisp_Object minibuf_prompt;
 239
 240 /* The visual width of the above.  */
 241 extern int minibuf_prompt_width;
 242
 243 /* Message to display instead of minibuffer contents.
 244    This is what the functions error and message make,
 245    and command echoing uses it as well. It overrides the
 246    minibuf_prompt as well as the buffer.  */
 247 extern char *echo_area_glyphs;
 248
 249 /* This is the length of the message in echo_area_glyphs.  */
 250 extern int echo_area_glyphs_length;
 251
 252 /* Value of echo_area_glyphs when it was last acted on.
 253   If this is nonzero, there is a message on the frame
 254   in the minibuffer and it should be erased as soon
 255   as it is no longer requested to appear. */
 256 extern char *previous_echo_glyphs;
 257
 258 /* This is the window where the echo area message was displayed.
 259    It is always a minibuffer window, but it may not be the
 260    same window currently active as a minibuffer.  */
 261 extern Lisp_Object echo_area_window;
 262
 263 /* Depth in recursive edits.  */
 264 extern int command_loop_level;
 265
 266 /* Depth in minibuffer invocations.  */
 267 extern int minibuf_level;
 268
 269 /* true iff we should redraw the mode lines on the next redisplay.  */
 270 extern int update_mode_lines;
 271
 272 /* Minimum value of GPT - BEG since last redisplay that finished.  */
 273
 274 extern int beg_unchanged;
 275
 276 /* Minimum value of Z - GPT since last redisplay that finished.  */
 277
 278 extern int end_unchanged;
 279
 280 /* MODIFF as of last redisplay that finished;
 281    if it matches MODIFF, beg_unchanged and end_unchanged
 282    contain no useful information.  */
 283 extern int unchanged_modified;
 284
 285 /* Nonzero if BEGV - BEG or Z - ZV of current buffer has changed
 286    since last redisplay that finished.  */
 287 extern int clip_changed;
 288
 289 /* Nonzero if window sizes or contents have changed
 290  since last redisplay that finished */
 291 extern int windows_or_buffers_changed;
 292
 293 /* Number of windows displaying the selected buffer.
 294    Normally this is 1, but it can be more.  */
 295 extern int buffer_shared;
 296
 297 /* If *ROWS or *COLS are too small a size for FRAME, set them to the
 298    minimum allowable size.  */
 299 extern void check_frame_size ( /* FRAME_PTR frame, int *rows, int *cols */ );