src/window.h

   1 /* Window definitions for GNU Emacs.
   2    Copyright (C) 1985, 1986, 1993 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 A dead window has its buffer, hchild, and vchild windows all nil.  */
  73
  74 struct window
  75   {
  76     /* The first two fields are really the header of a vector */
  77     /* The window code does not refer to them.  */
  78     int size;
  79     struct Lisp_Vector *vec_next;
  80     /* The frame this window is on.  */
  81     Lisp_Object frame;
  82     /* t if this window is a minibuffer window.  */
  83     Lisp_Object mini_p;
  84     /* Following child (to right or down) at same level of tree */
  85     Lisp_Object next;
  86     /* Preceding child (to left or up) at same level of tree */
  87     Lisp_Object prev;
  88     /* First child of this window. */
  89     /* vchild is used if this is a vertical combination,
  90        hchild if this is a horizontal combination. */
  91     Lisp_Object hchild, vchild;
  92     /* The window this one is a child of. */
  93     Lisp_Object parent;
  94     /* The upper left corner coordinates of this window,
  95        as integers relative to upper left corner of frame = 0, 0 */
  96     Lisp_Object left;
  97     Lisp_Object top;
  98     /* The size of the window */
  99     Lisp_Object height;
 100     Lisp_Object width;
 101     /* The buffer displayed in this window */
 102     /* Of the fields vchild, hchild and buffer, only one is non-nil.  */
 103     Lisp_Object buffer;
 104     /* A marker pointing to where in the text to start displaying */
 105     Lisp_Object start;
 106     /* A marker pointing to where in the text point is in this window,
 107        used only when the window is not selected.
 108        This exists so that when multiple windows show one buffer
 109        each one can have its own value of point.  */
 110     Lisp_Object pointm;
 111     /* Non-nil means next redisplay must use the value of start
 112        set up for it in advance.  Set by scrolling commands.  */
 113     Lisp_Object force_start;
 114     /* Number of columns display within the window is scrolled to the left.  */
 115     Lisp_Object hscroll;
 116     /* Number saying how recently window was selected */
 117     Lisp_Object use_time;
 118     /* Unique number of window assigned when it was created */
 119     Lisp_Object sequence_number;
 120     /* No permanent meaning; used by save-window-excursion's bookkeeping */
 121     Lisp_Object temslot;
 122     /* text.modified of displayed buffer as of last time display completed */
 123     Lisp_Object last_modified;
 124     /* Value of point at that time */
 125     Lisp_Object last_point;
 126     /* This window's vertical scroll bar.  This field is only for use
 127        by the window-system-dependent code which implements the
 128        scroll bars; it can store anything it likes here.  If this
 129        window is newly created and we haven't displayed a scroll bar in
 130        it yet, or if the frame doesn't have any scroll bars, this is nil.  */
 131     Lisp_Object vertical_scroll_bar;
 132
 133 /* The rest are currently not used or only half used */
 134     /* Frame coords of point at that time */
 135     Lisp_Object last_point_x;
 136     Lisp_Object last_point_y;
 137     /* Frame coords of mark as of last time display completed */
 138     /* May be nil if mark does not exist or was not on frame */
 139     Lisp_Object last_mark_x;
 140     Lisp_Object last_mark_y;
 141     /* Number of characters in buffer past bottom of window,
 142        as of last redisplay that finished. */
 143     Lisp_Object window_end_pos;
 144     /* t if window_end_pos is truly valid.
 145        This is nil if nontrivial redisplay is preempted
 146        since in that case the frame image that window_end_pos
 147        did not get onto the frame.  */
 148     Lisp_Object window_end_valid;
 149     /* Vertical position (relative to window top) of that buffer position
 150        of the first of those characters */
 151     Lisp_Object window_end_vpos;
 152     /* Non-nil means must regenerate mode line of this window */
 153     Lisp_Object update_mode_line;
 154     /* Non-nil means current value of `start'
 155        was the beginning of a line when it was chosen.  */
 156     Lisp_Object start_at_line_beg;
 157     /* Display-table to use for displaying chars in this window.
 158        Nil means use the buffer's own display-table.  */
 159     Lisp_Object display_table;
 160     /* Non-nil means window is marked as dedicated.  */
 161     Lisp_Object dedicated;
 162     /* Line number and position of a line somewhere above the
 163        top of the screen.  */
 164     /* If this field is nil, it means we don't have a base line.  */
 165     Lisp_Object base_line_number;
 166     /* If this field is nil, it means we don't have a base line.
 167        If it is a buffer, it means don't display the line number
 168        as long as the window shows that buffer.  */
 169     Lisp_Object base_line_pos;
 170     /* If we have highlighted the region (or any part of it),
 171        this is the mark position that we used, as an integer.  */
 172     Lisp_Object region_showing;
 173   };
 174
 175 /* 1 if W is a minibuffer window.  */
 176
 177 #define MINI_WINDOW_P(W)  (!EQ ((W)->mini_p, Qnil))
 178
 179 /* This is the window in which the terminal's cursor should
 180    be left when nothing is being done with it.  This must
 181    always be a leaf window, and its buffer is selected by
 182    the top level editing loop at the end of each command.
 183
 184    This value is always the same as
 185     FRAME_SELECTED_WINDOW (selected_frame).  */
 186
 187 extern Lisp_Object selected_window;
 188
 189 /* This is a time stamp for window selection, so we can find the least
 190    recently used window.  Its only users are Fselect_window,
 191    init_window_once, and make_frame.  */
 192
 193 extern int window_select_count;
 194
 195 /* The minibuffer window of the selected frame.
 196    Note that you cannot test for minibufferness of an arbitrary window
 197    by comparing against this; use the MINI_WINDOW_P macro instead.  */
 198
 199 extern Lisp_Object minibuf_window;
 200
 201 /* Non-nil => window to for C-M-v to scroll
 202    when the minibuffer is selected.  */
 203 extern Lisp_Object Vminibuf_scroll_window;
 204
 205 /* nil or a symbol naming the window system
 206    under which emacs is running
 207    ('x is the only current possibility) */
 208 extern Lisp_Object Vwindow_system;
 209
 210 /* Version number of X windows: 10, 11 or nil.  */
 211 extern Lisp_Object Vwindow_system_version;
 212
 213 /* Window that the mouse is over (nil if no mouse support).  */
 214 extern Lisp_Object Vmouse_window;
 215
 216 /* Last mouse-click event (nil if no mouse support).  */
 217 extern Lisp_Object Vmouse_event;
 218
 219 extern Lisp_Object Fnext_window ();
 220 extern Lisp_Object Fselect_window ();
 221 extern Lisp_Object Fdisplay_buffer ();
 222 extern Lisp_Object Fset_window_buffer ();
 223 extern Lisp_Object make_window ();
 224 extern Lisp_Object window_from_coordinates ();
 225 extern Lisp_Object Fwindow_dedicated_p ();
 226
 227 /* Prompt to display in front of the minibuffer contents.  */
 228 extern char *minibuf_prompt;
 229
 230 /* The visual width of the above.  */
 231 extern int minibuf_prompt_width;
 232
 233 /* Message to display instead of minibuffer contents.
 234    This is what the functions error and message make,
 235    and command echoing uses it as well. It overrides the
 236    minibuf_prompt as well as the buffer.  */
 237 extern char *echo_area_glyphs;
 238
 239 /* This is the length of the message in echo_area_glyphs.  */
 240 extern int echo_area_glyphs_length;
 241
 242 /* Value of echo_area_glyphs when it was last acted on.
 243   If this is nonzero, there is a message on the frame
 244   in the minibuffer and it should be erased as soon
 245   as it is no longer requested to appear. */
 246 extern char *previous_echo_glyphs;
 247
 248 /* Depth in recursive edits.  */
 249 extern int command_loop_level;
 250
 251 /* Depth in minibuffer invocations.  */
 252 extern int minibuf_level;
 253
 254 /* true iff we should redraw the mode lines on the next redisplay.  */
 255 extern int update_mode_lines;
 256
 257 /* Minimum value of GPT since last redisplay that finished.  */
 258
 259 extern int beg_unchanged;
 260
 261 /* Minimum value of Z - GPT since last redisplay that finished.  */
 262
 263 extern int end_unchanged;
 264
 265 /* MODIFF as of last redisplay that finished;
 266    if it matches MODIFF, beg_unchanged and end_unchangedn
 267    contain no useful information.  */
 268 extern int unchanged_modified;
 269
 270 /* Nonzero if BEGV - BEG or Z - ZV of current buffer has changed
 271    since last redisplay that finished.  */
 272 extern int clip_changed;
 273
 274 /* Nonzero if window sizes or contents have changed
 275  since last redisplay that finished */
 276 extern int windows_or_buffers_changed;
 277
 278 /* Number of windows displaying the selected buffer.
 279    Normally this is 1, but it can be more.  */
 280 extern int buffer_shared;
 281
 282 /* If *ROWS or *COLS are too small a size for FRAME, set them to the
 283    minimum allowable size.  */
 284 extern void check_frame_size ( /* FRAME_PTR frame, int *rows, int *cols */ );