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/* Interface definitions for display code.
Copyright (C) 1985, 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002,
2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */

/* New redisplay written by Gerd Moellmann <gerd@gnu.org>. */

#ifndef DISPEXTERN_H_INCLUDED
#define DISPEXTERN_H_INCLUDED

#ifdef HAVE_X_WINDOWS

#include <X11/Xlib.h>
#ifdef USE_X_TOOLKIT
#include <X11/Intrinsic.h>
#endif /* USE_X_TOOLKIT */

#else /* !HAVE_X_WINDOWS */

/* X-related stuff used by non-X gui code. */

typedef struct {
  unsigned long pixel;
  unsigned short red, green, blue;
  char flags;
  char pad;
} XColor;

#endif /* HAVE_X_WINDOWS */

#ifdef MSDOS
#include "msdos.h"
#endif

#ifdef HAVE_X_WINDOWS
typedef struct x_display_info Display_Info;
typedef XImage * XImagePtr;
typedef XImagePtr XImagePtr_or_DC;
#define NativeRectangle XRectangle
#endif

#ifdef HAVE_NTGUI
#include "w32gui.h"
typedef struct w32_display_info Display_Info;
typedef XImage *XImagePtr;
typedef HDC XImagePtr_or_DC;
#endif

#ifdef HAVE_NS
#include "nsgui.h"
/* Following typedef needed to accommodate the MSDOS port, believe it or not. */
typedef struct ns_display_info Display_Info;
typedef Pixmap XImagePtr;
typedef XImagePtr XImagePtr_or_DC;
#endif

#ifndef NativeRectangle
#define NativeRectangle int
#endif

/* Structure forward declarations. Some are here because function
prototypes below reference structure types before their definition
in this file. Some are here because not every file including
dispextern.h also includes frame.h and windows.h. */

struct glyph;
struct glyph_row;
struct glyph_matrix;
struct glyph_pool;
struct frame;
struct window;


/* Values returned from coordinates_in_window. */

enum window_part
{
  ON_NOTHING,
  ON_TEXT,
  ON_MODE_LINE,
  ON_VERTICAL_BORDER,
  ON_HEADER_LINE,
  ON_LEFT_FRINGE,
  ON_RIGHT_FRINGE,
  ON_LEFT_MARGIN,
  ON_RIGHT_MARGIN,
  ON_SCROLL_BAR
};

/* Number of bits allocated to store fringe bitmap numbers. */
#define FRINGE_ID_BITS 16

/* Number of bits allocated to store fringe bitmap height. */
#define FRINGE_HEIGHT_BITS 8


/***********************************************************************
Debugging
***********************************************************************/

/* If GLYPH_DEBUG is non-zero, additional checks are activated. Turn
it off by defining the macro GLYPH_DEBUG to zero. */

#ifndef GLYPH_DEBUG
#define GLYPH_DEBUG 0
#endif

/* If XASSERTS is non-zero, additional consistency checks are activated.
Turn it off by defining the macro XASSERTS to zero. */

#ifndef XASSERTS
#define XASSERTS 0
#endif

/* Macros to include code only if GLYPH_DEBUG != 0. */

#if GLYPH_DEBUG
#define IF_DEBUG(X) X
#else
#define IF_DEBUG(X) (void) 0
#endif

#if XASSERTS
#define xassert(X) do {if (!(X)) abort ();} while (0)
#else
#define xassert(X) (void) 0
#endif

/* Macro for displaying traces of redisplay. If Emacs was compiled
with GLYPH_DEBUG != 0, the variable trace_redisplay_p can be set to
a non-zero value in debugging sessions to activate traces. */

#if GLYPH_DEBUG

extern int trace_redisplay_p;
#include <stdio.h>

#define TRACE(X) \
if (trace_redisplay_p) \
fprintf X; \
else \
(void) 0

#else /* GLYPH_DEBUG == 0 */

#define TRACE(X) (void) 0

#endif /* GLYPH_DEBUG == 0 */



/***********************************************************************
Text positions
***********************************************************************/

/* Starting with Emacs 20.3, characters from strings and buffers have
both a character and a byte position associated with them. The
following structure holds such a pair of positions. */

struct text_pos
{
  /* Character position. */
  EMACS_INT charpos;

  /* Corresponding byte position. */
  EMACS_INT bytepos;
};

/* Access character and byte position of POS in a functional form. */

#define BYTEPOS(POS) (POS).bytepos
#define CHARPOS(POS) (POS).charpos

/* Set character position of POS to CHARPOS, byte position to BYTEPOS. */

#define SET_TEXT_POS(POS, CHARPOS, BYTEPOS) \
((POS).charpos = (CHARPOS), (POS).bytepos = BYTEPOS)

/* Increment text position POS. */

#define INC_TEXT_POS(POS, MULTIBYTE_P) \
do \
{ \
++(POS).charpos; \
if (MULTIBYTE_P) \
INC_POS ((POS).bytepos); \
else \
++(POS).bytepos; \
} \
while (0)

/* Decrement text position POS. */

#define DEC_TEXT_POS(POS, MULTIBYTE_P) \
do \
{ \
--(POS).charpos; \
if (MULTIBYTE_P) \
DEC_POS ((POS).bytepos); \
else \
--(POS).bytepos; \
} \
while (0)

/* Set text position POS from marker MARKER. */

#define SET_TEXT_POS_FROM_MARKER(POS, MARKER) \
(CHARPOS (POS) = marker_position ((MARKER)), \
BYTEPOS (POS) = marker_byte_position ((MARKER)))

/* Set marker MARKER from text position POS. */

#define SET_MARKER_FROM_TEXT_POS(MARKER, POS) \
set_marker_both ((MARKER), Qnil, CHARPOS ((POS)), BYTEPOS ((POS)))

/* Value is non-zero if character and byte positions of POS1 and POS2
are equal. */

#define TEXT_POS_EQUAL_P(POS1, POS2) \
((POS1).charpos == (POS2).charpos \
&& (POS1).bytepos == (POS2).bytepos)

/* When rendering glyphs, redisplay scans string or buffer text,
overlay strings in that text, and does display table or control
character translations. The following structure captures a
position taking all this into account. */

struct display_pos
{
  /* Buffer or string position. */
  struct text_pos pos;

  /* If this is a position in an overlay string, overlay_string_index
is the index of that overlay string in the sequence of overlay
strings at `pos' in the order redisplay processes them. A value
< 0 means that this is not a position in an overlay string. */
  int overlay_string_index;

  /* If this is a position in an overlay string, string_pos is the
position within that string. */
  struct text_pos string_pos;

  /* If the character at the position above is a control character or
has a display table entry, dpvec_index is an index in the display
table or control character translation of that character. A
value < 0 means this is not a position in such a translation. */
  int dpvec_index;
};



/***********************************************************************
Glyphs
***********************************************************************/

/* Enumeration of glyph types. Glyph structures contain a type field
containing one of the enumerators defined here. */

enum glyph_type
{
  /* Glyph describes a character. */
  CHAR_GLYPH,

  /* Glyph describes a static composition. */
  COMPOSITE_GLYPH,

  /* Glyph describes an image. */
  IMAGE_GLYPH,

  /* Glyph is a space of fractional width and/or height. */
  STRETCH_GLYPH
};


/* Structure describing how to use partial glyphs (images slicing) */

struct glyph_slice
{
  unsigned x : 16;
  unsigned y : 16;
  unsigned width : 16;
  unsigned height : 16;
};


/* Glyphs.

Be extra careful when changing this structure! Esp. make sure that
functions producing glyphs, like append_glyph, fill ALL of the
glyph structure, and that GLYPH_EQUAL_P compares all
display-relevant members of glyphs (not to imply that these are the
only things to check when you add a member). */

struct glyph
{
  /* Position from which this glyph was drawn. If `object' below is a
Lisp string, this is a position in that string. If it is a
buffer, this is a position in that buffer. A value of -1
together with a null object means glyph is a truncation glyph at
the start of a row. */
  EMACS_INT charpos;

  /* Lisp object source of this glyph. Currently either a buffer or
a string, if the glyph was produced from characters which came from
a buffer or a string; or 0 if the glyph was inserted by redisplay
for its own purposes such as padding. */
  Lisp_Object object;

  /* Width in pixels. */
  short pixel_width;

  /* Ascent and descent in pixels. */
  short ascent, descent;

  /* Vertical offset. If < 0, the glyph is displayed raised, if > 0
the glyph is displayed lowered. */
  short voffset;

  /* Which kind of glyph this is---character, image etc. Value
should be an enumerator of type enum glyph_type. */
  unsigned type : 2;

  /* 1 means this glyph was produced from multibyte text. Zero
means it was produced from unibyte text, i.e. charsets aren't
applicable, and encoding is not performed. */
  unsigned multibyte_p : 1;

  /* Non-zero means draw a box line at the left or right side of this
glyph. This is part of the implementation of the face attribute
`:box'. */
  unsigned left_box_line_p : 1;
  unsigned right_box_line_p : 1;

  /* Non-zero means this glyph's physical ascent or descent is greater
than its logical ascent/descent, i.e. it may potentially overlap
glyphs above or below it. */
  unsigned overlaps_vertically_p : 1;

  /* For terminal frames, 1 means glyph is a padding glyph. Padding
glyphs are used for characters whose visual shape consists of
more than one glyph (e.g. Asian characters). All but the first
glyph of such a glyph sequence have the padding_p flag set. This
flag is used only to minimize code changes. A better way would
probably be to use the width field of glyphs to express padding.

For graphic frames, 1 means the pixel width of the glyph in a
font is 0, but 1-pixel is padded on displaying for correct cursor
displaying. The member `pixel_width' above is set to 1. */
  unsigned padding_p : 1;

  /* 1 means the actual glyph is not available, draw a box instead.
This can happen when a font couldn't be loaded, or a character
doesn't have a glyph in a font. */
  unsigned glyph_not_available_p : 1;


  /* Non-zero means don't display cursor here. */
  unsigned avoid_cursor_p : 1;

#define FACE_ID_BITS 20

  /* Face of the glyph. This is a realized face ID,
an index in the face cache of the frame. */
  unsigned face_id : FACE_ID_BITS;

  /* Type of font used to display the character glyph. May be used to
determine which set of functions to use to obtain font metrics
for the glyph. On W32, value should be an enumerator of the type
w32_char_font_type. Otherwise it equals FONT_TYPE_UNKNOWN. */
  unsigned font_type : 3;

  struct glyph_slice slice;

  /* A union of sub-structures for different glyph types. */
  union
  {
    /* Character code for character glyphs (type == CHAR_GLYPH). */
    unsigned ch;

    /* Sub-structures for type == COMPOSITION_GLYPH. */
    struct
    {
      /* Flag to tell if the composition is automatic or not. */
      unsigned automatic : 1;
      /* ID of the composition. */
      unsigned id : 23;
      /* Start and end indices of glyphs of the composition. */
      unsigned from : 4;
      unsigned to : 4;
    } cmp;

    /* Image ID for image glyphs (type == IMAGE_GLYPH). */
    unsigned img_id;

    /* Sub-structure for type == STRETCH_GLYPH. */
    struct
    {
      /* The height of the glyph. */
      unsigned height : 16;

      /* The ascent of the glyph. */
      unsigned ascent : 16;
    }
    stretch;

    /* Used to compare all bit-fields above in one step. */
    unsigned val;
  } u;
};


/* Default value of the glyph font_type field. */

#define FONT_TYPE_UNKNOWN 0

/* Is GLYPH a space? */

#define CHAR_GLYPH_SPACE_P(GLYPH) \
((GLYPH).u.ch == SPACEGLYPH && (GLYPH).face_id == DEFAULT_FACE_ID)

/* Are glyph slices of glyphs *X and *Y equal */

#define GLYPH_SLICE_EQUAL_P(X, Y) \
((X)->slice.x == (Y)->slice.x \
&& (X)->slice.y == (Y)->slice.y \
&& (X)->slice.width == (Y)->slice.width \
&& (X)->slice.height == (Y)->slice.height)

/* Are glyphs *X and *Y displayed equal? */

#define GLYPH_EQUAL_P(X, Y) \
((X)->type == (Y)->type \
&& (X)->u.val == (Y)->u.val \
&& GLYPH_SLICE_EQUAL_P (X, Y) \
&& (X)->face_id == (Y)->face_id \
&& (X)->padding_p == (Y)->padding_p \
&& (X)->left_box_line_p == (Y)->left_box_line_p \
&& (X)->right_box_line_p == (Y)->right_box_line_p \
&& (X)->voffset == (Y)->voffset \
&& (X)->pixel_width == (Y)->pixel_width)

/* Are character codes, faces, padding_ps of glyphs *X and *Y equal? */

#define GLYPH_CHAR_AND_FACE_EQUAL_P(X, Y) \
((X)->u.ch == (Y)->u.ch \
&& (X)->face_id == (Y)->face_id \
&& (X)->padding_p == (Y)->padding_p)

/* Fill a character glyph GLYPH. CODE, FACE_ID, PADDING_P correspond
to the bits defined for the typedef `GLYPH' in lisp.h. */

#define SET_CHAR_GLYPH(GLYPH, CODE, FACE_ID, PADDING_P) \
do \
{ \
(GLYPH).u.ch = (CODE); \
(GLYPH).face_id = (FACE_ID); \
(GLYPH).padding_p = (PADDING_P); \
} \
while (0)

/* Fill a character type glyph GLYPH from a glyph typedef FROM as
defined in lisp.h. */

#define SET_CHAR_GLYPH_FROM_GLYPH(GLYPH, FROM) \
SET_CHAR_GLYPH ((GLYPH), \
GLYPH_CHAR ((FROM)), \
GLYPH_FACE ((FROM)), \
0)

/* Construct a glyph code from a character glyph GLYPH. If the
character is multibyte, return -1 as we can't use glyph table for a
multibyte character. */

#define SET_GLYPH_FROM_CHAR_GLYPH(G, GLYPH) \
do \
{ \
if ((GLYPH).u.ch < 256) \
SET_GLYPH ((G), (GLYPH).u.ch, ((GLYPH).face_id)); \
else \
SET_GLYPH ((G), -1, 0); \
} \
while (0)

#define GLYPH_INVALID_P(GLYPH) (GLYPH_CHAR (GLYPH) < 0)

/* Is GLYPH a padding glyph? */

#define CHAR_GLYPH_PADDING_P(GLYPH) (GLYPH).padding_p




/***********************************************************************
Glyph Pools
***********************************************************************/

/* Glyph Pool.

Glyph memory for frame-based redisplay is allocated from the heap
in one vector kept in a glyph pool structure which is stored with
the frame. The size of the vector is made large enough to cover
all windows on the frame.

Both frame and window glyph matrices reference memory from a glyph
pool in frame-based redisplay.

In window-based redisplay, no glyphs pools exist; windows allocate
and free their glyph memory themselves. */

struct glyph_pool
{
  /* Vector of glyphs allocated from the heap. */
  struct glyph *glyphs;

  /* Allocated size of `glyphs'. */
  int nglyphs;

  /* Number of rows and columns in a matrix. */
  int nrows, ncolumns;
};



/***********************************************************************
Glyph Matrix
***********************************************************************/

/* Glyph Matrix.

Three kinds of glyph matrices exist:

1. Frame glyph matrices. These are used for terminal frames whose
redisplay needs a view of the whole screen due to limited terminal
capabilities. Frame matrices are used only in the update phase
of redisplay. They are built in update_frame and not used after
the update has been performed.

2. Window glyph matrices on frames having frame glyph matrices.
Such matrices are sub-matrices of their corresponding frame matrix,
i.e. frame glyph matrices and window glyph matrices share the same
glyph memory which is allocated in form of a glyph_pool structure.
Glyph rows in such a window matrix are slices of frame matrix rows.

2. Free-standing window glyph matrices managing their own glyph
storage. This form is used in window-based redisplay which
includes variable width and height fonts etc.

The size of a window's row vector depends on the height of fonts
defined on its frame. It is chosen so that the vector is large
enough to describe all lines in a window when it is displayed in
the smallest possible character size. When new fonts are loaded,
or window sizes change, the row vector is adjusted accordingly. */

struct glyph_matrix
{
  /* The pool from which glyph memory is allocated, if any. This is
null for frame matrices and for window matrices managing their
own storage. */
  struct glyph_pool *pool;

  /* Vector of glyph row structures. The row at nrows - 1 is reserved
for the mode line. */
  struct glyph_row *rows;

  /* Number of elements allocated for the vector rows above. */
  int rows_allocated;

  /* The number of rows used by the window if all lines were displayed
with the smallest possible character height. */
  int nrows;

  /* Origin within the frame matrix if this is a window matrix on a
frame having a frame matrix. Both values are zero for
window-based redisplay. */
  int matrix_x, matrix_y;

  /* Width and height of the matrix in columns and rows. */
  int matrix_w, matrix_h;

  /* If this structure describes a window matrix of window W,
window_left_col is the value of W->left_col, window_top_line the
value of W->top_line, window_height and window_width are width and
height of W, as returned by window_box, and window_vscroll is the
value of W->vscroll at the time the matrix was last adjusted.
Only set for window-based redisplay. */
  int window_left_col, window_top_line;
  int window_height, window_width;
  int window_vscroll;

  /* Number of glyphs reserved for left and right marginal areas when
the matrix was last adjusted. */
  int left_margin_glyphs, right_margin_glyphs;

  /* Flag indicating that scrolling should not be tried in
update_window. This flag is set by functions like try_window_id
which do their own scrolling. */
  unsigned no_scrolling_p : 1;

  /* Non-zero means window displayed in this matrix has a top mode
line. */
  unsigned header_line_p : 1;

#ifdef GLYPH_DEBUG
  /* A string identifying the method used to display the matrix. */
  char method[512];
#endif

  /* The buffer this matrix displays. Set in
mark_window_display_accurate_1. */
  struct buffer *buffer;

  /* Values of BEGV and ZV as of last redisplay. Set in
mark_window_display_accurate_1. */
  int begv, zv;
};


/* Check that glyph pointers stored in glyph rows of MATRIX are okay.
This aborts if any pointer is found twice. */

#if GLYPH_DEBUG
void check_matrix_pointer_lossage P_ ((struct glyph_matrix *));
#define CHECK_MATRIX(MATRIX) check_matrix_pointer_lossage ((MATRIX))
#else
#define CHECK_MATRIX(MATRIX) (void) 0
#endif



/***********************************************************************
Glyph Rows
***********************************************************************/

/* Area in window glyph matrix. If values are added or removed, the
function mark_object in alloc.c has to be changed. */

enum glyph_row_area
{
  LEFT_MARGIN_AREA,
  TEXT_AREA,
  RIGHT_MARGIN_AREA,
  LAST_AREA
};


/* Rows of glyphs in a windows or frame glyph matrix.

Each row is partitioned into three areas. The start and end of
each area is recorded in a pointer as shown below.

+--------------------+-------------+---------------------+
| left margin area | text area | right margin area |
+--------------------+-------------+---------------------+
| | | |
glyphs[LEFT_MARGIN_AREA] glyphs[RIGHT_MARGIN_AREA]
| |
glyphs[TEXT_AREA] |
glyphs[LAST_AREA]

Rows in frame matrices reference glyph memory allocated in a frame
glyph pool (see the description of struct glyph_pool). Rows in
window matrices on frames having frame matrices reference slices of
the glyphs of corresponding rows in the frame matrix.

Rows in window matrices on frames having no frame matrices point to
glyphs allocated from the heap via xmalloc;
glyphs[LEFT_MARGIN_AREA] is the start address of the allocated
glyph structure array. */

struct glyph_row
{
  /* Pointers to beginnings of areas. The end of an area A is found at
A + 1 in the vector. The last element of the vector is the end
of the whole row.

Kludge alert: Even if used[TEXT_AREA] == 0, glyphs[TEXT_AREA][0]'s
position field is used. It is -1 if this row does not correspond
to any text; it is some buffer position if the row corresponds to
an empty display line that displays a line end. This is what old
redisplay used to do. (Except in code for terminal frames, this
kludge is no longer used, I believe. --gerd).

See also start, end, displays_text_p and ends_at_zv_p for cleaner
ways to do it. The special meaning of positions 0 and -1 will be
removed some day, so don't use it in new code. */
  struct glyph *glyphs[1 + LAST_AREA];

  /* Number of glyphs actually filled in areas. */
  short used[LAST_AREA];

  /* Window-relative x and y-position of the top-left corner of this
row. If y < 0, this means that eabs (y) pixels of the row are
invisible because it is partially visible at the top of a window.
If x < 0, this means that eabs (x) pixels of the first glyph of
the text area of the row are invisible because the glyph is
partially visible. */
  int x, y;

  /* Width of the row in pixels without taking face extension at the
end of the row into account, and without counting truncation
and continuation glyphs at the end of a row on ttys. */
  int pixel_width;

  /* Logical ascent/height of this line. The value of ascent is zero
and height is 1 on terminal frames. */
  int ascent, height;

  /* Physical ascent/height of this line. If max_ascent > ascent,
this line overlaps the line above it on the display. Otherwise,
if max_height > height, this line overlaps the line beneath it. */
  int phys_ascent, phys_height;

  /* Portion of row that is visible. Partially visible rows may be
found at the top and bottom of a window. This is 1 for tty
frames. It may be < 0 in case of completely invisible rows. */
  int visible_height;

  /* Extra line spacing added after this row. Do not consider this
in last row when checking if row is fully visible. */
  int extra_line_spacing;

  /* Hash code. This hash code is available as soon as the row
is constructed, i.e. after a call to display_line. */
  unsigned hash;

  /* First position in this row. This is the text position, including
overlay position information etc, where the display of this row
started, and can thus be less the position of the first glyph
(e.g. due to invisible text or horizontal scrolling). */
  struct display_pos start;

  /* Text position at the end of this row. This is the position after
the last glyph on this row. It can be greater than the last
glyph position + 1, due to truncation, invisible text etc. In an
up-to-date display, this should always be equal to the start
position of the next row. */
  struct display_pos end;

  /* Non-zero means the overlay arrow bitmap is on this line.
-1 means use default overlay arrow bitmap, else
it specifies actual fringe bitmap number. */
  int overlay_arrow_bitmap;

  /* Left fringe bitmap number (enum fringe_bitmap_type). */
  unsigned left_user_fringe_bitmap : FRINGE_ID_BITS;

  /* Right fringe bitmap number (enum fringe_bitmap_type). */
  unsigned right_user_fringe_bitmap : FRINGE_ID_BITS;

  /* Left fringe bitmap number (enum fringe_bitmap_type). */
  unsigned left_fringe_bitmap : FRINGE_ID_BITS;

  /* Right fringe bitmap number (enum fringe_bitmap_type). */
  unsigned right_fringe_bitmap : FRINGE_ID_BITS;

  /* Face of the left fringe glyph. */
  unsigned left_user_fringe_face_id : FACE_ID_BITS;

  /* Face of the right fringe glyph. */
  unsigned right_user_fringe_face_id : FACE_ID_BITS;

  /* Face of the left fringe glyph. */
  unsigned left_fringe_face_id : FACE_ID_BITS;

  /* Face of the right fringe glyph. */
  unsigned right_fringe_face_id : FACE_ID_BITS;

  /* Vertical offset of the left fringe bitmap. */
  signed left_fringe_offset : FRINGE_HEIGHT_BITS;

  /* Vertical offset of the right fringe bitmap. */
  signed right_fringe_offset : FRINGE_HEIGHT_BITS;

  /* 1 means that at least one of the left and right fringe bitmaps is
periodic and thus depends on the y-position of the row. */
  unsigned fringe_bitmap_periodic_p : 1;

  /* 1 means that we must draw the bitmaps of this row. */
  unsigned redraw_fringe_bitmaps_p : 1;

  /* In a desired matrix, 1 means that this row must be updated. In a
current matrix, 0 means that the row has been invalidated, i.e.
the row's contents do not agree with what is visible on the
screen. */
  unsigned enabled_p : 1;

  /* 1 means row displays a text line that is truncated on the left or
right side. */
  unsigned truncated_on_left_p : 1;
  unsigned truncated_on_right_p : 1;

  /* 1 means that this row displays a continued line, i.e. it has a
continuation mark at the right side. */
  unsigned continued_p : 1;

  /* 0 means that this row does not contain any text, i.e. it is
a blank line at the window and buffer end. */
  unsigned displays_text_p : 1;

  /* 1 means that this line ends at ZV. */
  unsigned ends_at_zv_p : 1;

  /* 1 means the face of the last glyph in the text area is drawn to
the right end of the window. This flag is used in
update_text_area to optimize clearing to the end of the area. */
  unsigned fill_line_p : 1;

  /* Non-zero means display a bitmap on X frames indicating that this
line contains no text and ends in ZV. */
  unsigned indicate_empty_line_p : 1;

  /* 1 means this row contains glyphs that overlap each other because
of lbearing or rbearing. */
  unsigned contains_overlapping_glyphs_p : 1;

  /* 1 means this row is as wide as the window it is displayed in, including
scroll bars, fringes, and internal borders. This also
implies that the row doesn't have marginal areas. */
  unsigned full_width_p : 1;

  /* Non-zero means row is a mode or header-line. */
  unsigned mode_line_p : 1;

  /* 1 in a current row means this row is overlapped by another row. */
  unsigned overlapped_p : 1;

  /* 1 means this line ends in the middle of a character consisting
of more than one glyph. Some glyphs have been put in this row,
the rest are put in rows below this one. */
  unsigned ends_in_middle_of_char_p : 1;

  /* 1 means this line starts in the middle of a character consisting
of more than one glyph. Some glyphs have been put in the
previous row, the rest are put in this row. */
  unsigned starts_in_middle_of_char_p : 1;

  /* 1 in a current row means this row overlaps others. */
  unsigned overlapping_p : 1;

  /* 1 means some glyphs in this row are displayed in mouse-face. */
  unsigned mouse_face_p : 1;

  /* 1 means this row was ended by a newline from a string. */
  unsigned ends_in_newline_from_string_p : 1;

  /* 1 means this row width is exactly the width of the window, and the
final newline character is hidden in the right fringe. */
  unsigned exact_window_width_line_p : 1;

  /* 1 means this row currently shows the cursor in the right fringe. */
  unsigned cursor_in_fringe_p : 1;

  /* 1 means the last glyph in the row is part of an ellipsis. */
  unsigned ends_in_ellipsis_p : 1;

  /* Non-zero means display a bitmap on X frames indicating that this
the first line of the buffer. */
  unsigned indicate_bob_p : 1;

  /* Non-zero means display a bitmap on X frames indicating that this
the top line of the window, but not start of the buffer. */
  unsigned indicate_top_line_p : 1;

  /* Non-zero means display a bitmap on X frames indicating that this
the last line of the buffer. */
  unsigned indicate_eob_p : 1;

  /* Non-zero means display a bitmap on X frames indicating that this
the bottom line of the window, but not end of the buffer. */
  unsigned indicate_bottom_line_p : 1;

  /* Continuation lines width at the start of the row. */
  int continuation_lines_width;

#ifdef HAVE_WINDOW_SYSTEM
  /* Non-NULL means the current clipping area. This is temporarily
set while exposing a region. Coordinates are frame-relative. */
  XRectangle *clip;
#endif
};


/* Get a pointer to row number ROW in matrix MATRIX. If GLYPH_DEBUG
is defined to a non-zero value, the function matrix_row checks that
we don't try to access rows that are out of bounds. */

#if GLYPH_DEBUG
struct glyph_row *matrix_row P_ ((struct glyph_matrix *, int));
#define MATRIX_ROW(MATRIX, ROW) matrix_row ((MATRIX), (ROW))
#else
#define MATRIX_ROW(MATRIX, ROW) ((MATRIX)->rows + (ROW))
#endif

/* Return a pointer to the row reserved for the mode line in MATRIX.
Row MATRIX->nrows - 1 is always reserved for the mode line. */

#define MATRIX_MODE_LINE_ROW(MATRIX) \
((MATRIX)->rows + (MATRIX)->nrows - 1)

/* Return a pointer to the row reserved for the header line in MATRIX.
This is always the first row in MATRIX because that's the only
way that works in frame-based redisplay. */

#define MATRIX_HEADER_LINE_ROW(MATRIX) (MATRIX)->rows

/* Return a pointer to first row in MATRIX used for text display. */

#define MATRIX_FIRST_TEXT_ROW(MATRIX) \
((MATRIX)->rows->mode_line_p ? (MATRIX)->rows + 1 : (MATRIX)->rows)

/* Return a pointer to the first glyph in the text area of a row.
MATRIX is the glyph matrix accessed, and ROW is the row index in
MATRIX. */

#define MATRIX_ROW_GLYPH_START(MATRIX, ROW) \
(MATRIX_ROW ((MATRIX), (ROW))->glyphs[TEXT_AREA])

/* Return the number of used glyphs in the text area of a row. */

#define MATRIX_ROW_USED(MATRIX, ROW) \
(MATRIX_ROW ((MATRIX), (ROW))->used[TEXT_AREA])

/* Return the character/ byte position at which the display of ROW
starts. */

#define MATRIX_ROW_START_CHARPOS(ROW) ((ROW)->start.pos.charpos)
#define MATRIX_ROW_START_BYTEPOS(ROW) ((ROW)->start.pos.bytepos)

/* Return the character/ byte position at which ROW ends. */

#define MATRIX_ROW_END_CHARPOS(ROW) ((ROW)->end.pos.charpos)
#define MATRIX_ROW_END_BYTEPOS(ROW) ((ROW)->end.pos.bytepos)

/* Return the vertical position of ROW in MATRIX. */

#define MATRIX_ROW_VPOS(ROW, MATRIX) ((ROW) - (MATRIX)->rows)

/* Return the last glyph row + 1 in MATRIX on window W reserved for
text. If W has a mode line, the last row in the matrix is reserved
for it. */

#define MATRIX_BOTTOM_TEXT_ROW(MATRIX, W) \
((MATRIX)->rows \
+ (MATRIX)->nrows \
- (WINDOW_WANTS_MODELINE_P ((W)) ? 1 : 0))

/* Non-zero if the face of the last glyph in ROW's text area has
to be drawn to the end of the text area. */

#define MATRIX_ROW_EXTENDS_FACE_P(ROW) ((ROW)->fill_line_p)

/* Set and query the enabled_p flag of glyph row ROW in MATRIX. */

#define SET_MATRIX_ROW_ENABLED_P(MATRIX, ROW, VALUE) \
(MATRIX_ROW ((MATRIX), (ROW))->enabled_p = (VALUE) != 0)

#define MATRIX_ROW_ENABLED_P(MATRIX, ROW) \
(MATRIX_ROW ((MATRIX), (ROW))->enabled_p)

/* Non-zero if ROW displays text. Value is non-zero if the row is
blank but displays a line end. */

#define MATRIX_ROW_DISPLAYS_TEXT_P(ROW) ((ROW)->displays_text_p)


/* Helper macros */

#define MR_PARTIALLY_VISIBLE(ROW) \
((ROW)->height != (ROW)->visible_height)

#define MR_PARTIALLY_VISIBLE_AT_TOP(W, ROW) \
((ROW)->y < WINDOW_HEADER_LINE_HEIGHT ((W)))

#define MR_PARTIALLY_VISIBLE_AT_BOTTOM(W, ROW) \
(((ROW)->y + (ROW)->height - (ROW)->extra_line_spacing) \
> WINDOW_BOX_HEIGHT_NO_MODE_LINE ((W)))

/* Non-zero if ROW is not completely visible in window W. */

#define MATRIX_ROW_PARTIALLY_VISIBLE_P(W, ROW) \
(MR_PARTIALLY_VISIBLE ((ROW)) \
&& (MR_PARTIALLY_VISIBLE_AT_TOP ((W), (ROW)) \
|| MR_PARTIALLY_VISIBLE_AT_BOTTOM ((W), (ROW))))



/* Non-zero if ROW is partially visible at the top of window W. */

#define MATRIX_ROW_PARTIALLY_VISIBLE_AT_TOP_P(W, ROW) \
(MR_PARTIALLY_VISIBLE ((ROW)) \
&& MR_PARTIALLY_VISIBLE_AT_TOP ((W), (ROW)))

/* Non-zero if ROW is partially visible at the bottom of window W. */

#define MATRIX_ROW_PARTIALLY_VISIBLE_AT_BOTTOM_P(W, ROW) \
(MR_PARTIALLY_VISIBLE ((ROW)) \
&& MR_PARTIALLY_VISIBLE_AT_BOTTOM ((W), (ROW)))

/* Return the bottom Y + 1 of ROW. */

#define MATRIX_ROW_BOTTOM_Y(ROW) ((ROW)->y + (ROW)->height)

/* Is ROW the last visible one in the display described by the
iterator structure pointed to by IT?. */

#define MATRIX_ROW_LAST_VISIBLE_P(ROW, IT) \
(MATRIX_ROW_BOTTOM_Y ((ROW)) >= (IT)->last_visible_y)

/* Non-zero if ROW displays a continuation line. */

#define MATRIX_ROW_CONTINUATION_LINE_P(ROW) \
((ROW)->continuation_lines_width > 0)

/* Non-zero if ROW ends in the middle of a character. This is the
case for continued lines showing only part of a display table entry
or a control char, or an overlay string. */

#define MATRIX_ROW_ENDS_IN_MIDDLE_OF_CHAR_P(ROW) \
((ROW)->end.dpvec_index > 0 \
|| (ROW)->end.overlay_string_index >= 0 \
|| (ROW)->ends_in_middle_of_char_p)

/* Non-zero if ROW ends in the middle of an overlay string. */

#define MATRIX_ROW_ENDS_IN_OVERLAY_STRING_P(ROW) \
((ROW)->end.overlay_string_index >= 0)

/* Non-zero if ROW starts in the middle of a character. See above. */

#define MATRIX_ROW_STARTS_IN_MIDDLE_OF_CHAR_P(ROW) \
((ROW)->start.dpvec_index > 0 \
|| (ROW)->starts_in_middle_of_char_p \
|| ((ROW)->start.overlay_string_index >= 0 \
&& (ROW)->start.string_pos.charpos > 0))

/* Non-zero means ROW overlaps its predecessor. */

#define MATRIX_ROW_OVERLAPS_PRED_P(ROW) \
((ROW)->phys_ascent > (ROW)->ascent)

/* Non-zero means ROW overlaps its successor. */

#define MATRIX_ROW_OVERLAPS_SUCC_P(ROW) \
((ROW)->phys_height - (ROW)->phys_ascent \
> (ROW)->height - (ROW)->ascent)

/* Non-zero means that fonts have been loaded since the last glyph
matrix adjustments. The function redisplay_internal adjusts glyph
matrices when this flag is non-zero. */

extern int fonts_changed_p;

/* A glyph for a space. */

extern struct glyph space_glyph;

/* Window being updated by update_window. This is non-null as long as
update_window has not finished, and null otherwise. */

extern struct window *updated_window;

/* Glyph row and area updated by update_window_line. */

extern struct glyph_row *updated_row;
extern int updated_area;

/* Non-zero means reading single-character input with prompt so put
cursor on mini-buffer after the prompt. Positive means at end of
text in echo area; negative means at beginning of line. */

extern int cursor_in_echo_area;

/* Non-zero means last display completed. Zero means it was
preempted. */

extern int display_completed;

/* Non-zero means redisplay has been performed directly (see also
direct_output_for_insert and direct_output_forward_char), so that
no further updating has to be performed. The function
redisplay_internal checks this flag, and does nothing but reset it
to zero if it is non-zero. */

extern int redisplay_performed_directly_p;

/* A temporary storage area, including a row of glyphs. Initialized
in xdisp.c. Used for various purposes, as an example see
direct_output_for_insert. */

extern struct glyph_row scratch_glyph_row;



/************************************************************************
Glyph Strings
************************************************************************/

/* Enumeration for overriding/changing the face to use for drawing
glyphs in draw_glyphs. */

enum draw_glyphs_face
{
  DRAW_NORMAL_TEXT,
  DRAW_INVERSE_VIDEO,
  DRAW_CURSOR,
  DRAW_MOUSE_FACE,
  DRAW_IMAGE_RAISED,
  DRAW_IMAGE_SUNKEN
};

#ifdef HAVE_WINDOW_SYSTEM

/* A sequence of glyphs to be drawn in the same face. */

struct glyph_string
{
  /* X-origin of the string. */
  int x;

  /* Y-origin and y-position of the base line of this string. */
  int y, ybase;

  /* The width of the string, not including a face extension. */
  int width;

  /* The width of the string, including a face extension. */
  int background_width;

  /* The height of this string. This is the height of the line this
string is drawn in, and can be different from the height of the
font the string is drawn in. */
  int height;

  /* Number of pixels this string overwrites in front of its x-origin.
This number is zero if the string has an lbearing >= 0; it is
-lbearing, if the string has an lbearing < 0. */
  int left_overhang;

  /* Number of pixels this string overwrites past its right-most
nominal x-position, i.e. x + width. Zero if the string's
rbearing is <= its nominal width, rbearing - width otherwise. */
  int right_overhang;

  /* The frame on which the glyph string is drawn. */
  struct frame *f;

  /* The window on which the glyph string is drawn. */
  struct window *w;

  /* X display and window for convenience. */
  Display *display;
  Window window;

  /* The glyph row for which this string was built. It determines the
y-origin and height of the string. */
  struct glyph_row *row;

  /* The area within row. */
  enum glyph_row_area area;

  /* Characters to be drawn, and number of characters. */
  XChar2b *char2b;
  int nchars;

  /* A face-override for drawing cursors, mouse face and similar. */
  enum draw_glyphs_face hl;

  /* Face in which this string is to be drawn. */
  struct face *face;

  /* Font in which this string is to be drawn. */
  struct font *font;

  /* Non-null means this string describes (part of) a static
composition. */
  struct composition *cmp;

  /* If not negative, this string describes a compos. */
  int cmp_id;

  /* Start and end glyph indices in a glyph-string. */
  int cmp_from, cmp_to;

  /* 1 means this glyph strings face has to be drawn to the right end
of the window's drawing area. */
  unsigned extends_to_end_of_line_p : 1;

  /* 1 means the background of this string has been drawn. */
  unsigned background_filled_p : 1;

  /* 1 means glyph string must be drawn with 16-bit functions. */
  unsigned two_byte_p : 1;

  /* 1 means that the original font determined for drawing this glyph
string could not be loaded. The member `font' has been set to
the frame's default font in this case. */
  unsigned font_not_found_p : 1;

  /* 1 means that the face in which this glyph string is drawn has a
stipple pattern. */
  unsigned stippled_p : 1;

#define OVERLAPS_PRED (1 << 0)
#define OVERLAPS_SUCC (1 << 1)
#define OVERLAPS_BOTH (OVERLAPS_PRED | OVERLAPS_SUCC)
#define OVERLAPS_ERASED_CURSOR (1 << 2)
  /* Non-zero means only the foreground of this glyph string must be
drawn, and we should use the physical height of the line this
glyph string appears in as clip rect. If the value is
OVERLAPS_ERASED_CURSOR, the clip rect is restricted to the rect
of the erased cursor. OVERLAPS_PRED and OVERLAPS_SUCC mean we
draw overlaps with the preceding and the succeeding rows,
respectively. */
  unsigned for_overlaps : 3;

  /* 1 means that all glyphs in this glyph string has the flag
padding_p set, and thus must be drawn one by one to have 1-pixel
width even though the logical width in the font is zero. */
  unsigned padding_p : 1;

  /* The GC to use for drawing this glyph string. */
#if defined(HAVE_X_WINDOWS)
  GC gc;
#endif
#if defined(HAVE_NTGUI)
  XGCValues *gc;
  HDC hdc;
#endif

  /* A pointer to the first glyph in the string. This glyph
corresponds to char2b[0]. Needed to draw rectangles if
font_not_found_p is 1. */
  struct glyph *first_glyph;

  /* Image, if any. */
  struct image *img;

  /* Slice */
  struct glyph_slice slice;

  /* Non-null means the horizontal clipping region starts from the
left edge of *clip_head, and ends with the right edge of
*clip_tail, not including their overhangs. */
  struct glyph_string *clip_head, *clip_tail;

  /* The current clipping areas. */
  NativeRectangle clip[2];

  /* Number of clipping areas. */
  int num_clips;

  int underline_position;

  int underline_thickness;

  struct glyph_string *next, *prev;
};

#endif /* HAVE_WINDOW_SYSTEM */


/************************************************************************
Display Dimensions
************************************************************************/

/* Return the height of the mode line in glyph matrix MATRIX, or zero
if not known. This macro is called under circumstances where
MATRIX might not have been allocated yet. */

#define MATRIX_MODE_LINE_HEIGHT(MATRIX) \
((MATRIX) && (MATRIX)->rows \
? MATRIX_MODE_LINE_ROW (MATRIX)->height \
: 0)

/* Return the height of the header line in glyph matrix MATRIX, or zero
if not known. This macro is called under circumstances where
MATRIX might not have been allocated yet. */

#define MATRIX_HEADER_LINE_HEIGHT(MATRIX) \
((MATRIX) && (MATRIX)->rows \
? MATRIX_HEADER_LINE_ROW (MATRIX)->height \
: 0)

/* Return the desired face id for the mode line of a window, depending
on whether the window is selected or not, or if the window is the
scrolling window for the currently active minibuffer window.

Due to the way display_mode_lines manipulates with the contents of
selected_window, this macro needs three arguments: SELW which is
compared against the current value of selected_window, MBW which is
compared against minibuf_window (if SELW doesn't match), and SCRW
which is compared against minibuf_selected_window (if MBW matches). */

#define CURRENT_MODE_LINE_FACE_ID_3(SELW, MBW, SCRW) \
((!mode_line_in_non_selected_windows \
|| (SELW) == XWINDOW (selected_window) \
|| (minibuf_level > 0 \
&& !NILP (minibuf_selected_window) \
&& (MBW) == XWINDOW (minibuf_window) \
&& (SCRW) == XWINDOW (minibuf_selected_window))) \
? MODE_LINE_FACE_ID \
: MODE_LINE_INACTIVE_FACE_ID)


/* Return the desired face id for the mode line of window W. */

#define CURRENT_MODE_LINE_FACE_ID(W) \
(CURRENT_MODE_LINE_FACE_ID_3((W), XWINDOW (selected_window), (W)))

/* Return the current height of the mode line of window W. If not
known from current_mode_line_height, look at W's current glyph
matrix, or return a default based on the height of the font of the
face `mode-line'. */

#define CURRENT_MODE_LINE_HEIGHT(W) \
(current_mode_line_height >= 0 \
? current_mode_line_height \
: (MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix) \
? MATRIX_MODE_LINE_HEIGHT ((W)->current_matrix) \
: estimate_mode_line_height (XFRAME ((W)->frame), \
CURRENT_MODE_LINE_FACE_ID (W))))

/* Return the current height of the header line of window W. If not
known from current_header_line_height, look at W's current glyph
matrix, or return an estimation based on the height of the font of
the face `header-line'. */

#define CURRENT_HEADER_LINE_HEIGHT(W) \
(current_header_line_height >= 0 \
? current_header_line_height \
: (MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix) \
? MATRIX_HEADER_LINE_HEIGHT ((W)->current_matrix) \
: estimate_mode_line_height (XFRAME ((W)->frame), \
HEADER_LINE_FACE_ID)))

/* Return the height of the desired mode line of window W. */

#define DESIRED_MODE_LINE_HEIGHT(W) \
MATRIX_MODE_LINE_HEIGHT ((W)->desired_matrix)

/* Return the height of the desired header line of window W. */

#define DESIRED_HEADER_LINE_HEIGHT(W) \
MATRIX_HEADER_LINE_HEIGHT ((W)->desired_matrix)

/* Value is non-zero if window W wants a mode line. */

#define WINDOW_WANTS_MODELINE_P(W) \
(!MINI_WINDOW_P ((W)) \
&& !(W)->pseudo_window_p \
&& FRAME_WANTS_MODELINE_P (XFRAME (WINDOW_FRAME ((W)))) \
&& BUFFERP ((W)->buffer) \
&& !NILP (XBUFFER ((W)->buffer)->mode_line_format) \
&& WINDOW_TOTAL_LINES (W) > 1)


extern Lisp_Object Qwindow_wants_header_line_function,
  Vwindow_wants_header_line_function;

/* Value is non-zero if window W wants a header line. */
#define WINDOW_WANTS_HEADER_LINE_P(W) \
(!MINI_WINDOW_P ((W)) \
&& !(W)->pseudo_window_p \
&& FRAME_WANTS_MODELINE_P (XFRAME (WINDOW_FRAME ((W)))) \
&& BUFFERP ((W)->buffer) \
&& !NILP (XBUFFER ((W)->buffer)->header_line_format) \
&& WINDOW_TOTAL_LINES (W) > 1 + !NILP (XBUFFER ((W)->buffer)->mode_line_format) \
&& !window_header_line_inhibited_p (W))


 
/* Return proper value to be used as baseline offset of font that has
ASCENT and DESCENT to draw characters by the font at the vertical
center of the line of frame F.

Here, our task is to find the value of BOFF in the following figure;

-------------------------+-----------+-
-+-+---------+-+ | |
| | | | | |
| | | | F_ASCENT F_HEIGHT
| | | ASCENT | |
HEIGHT | | | | |
| | |-|-+------+-----------|------- baseline
| | | | BOFF | |
| |---------|-+-+ | |
| | | DESCENT | |
-+-+---------+-+ F_DESCENT |
-------------------------+-----------+-

-BOFF + DESCENT + (F_HEIGHT - HEIGHT) / 2 = F_DESCENT
BOFF = DESCENT + (F_HEIGHT - HEIGHT) / 2 - F_DESCENT
DESCENT = FONT->descent
HEIGHT = FONT_HEIGHT (FONT)
F_DESCENT = (FRAME_FONT (F)->descent
- F->terminal->output_data.x->baseline_offset)
F_HEIGHT = FRAME_LINE_HEIGHT (F)
*/

#define VCENTER_BASELINE_OFFSET(FONT, F) \
(FONT_DESCENT (FONT) \
+ (FRAME_LINE_HEIGHT ((F)) - FONT_HEIGHT ((FONT)) \
+ (FRAME_LINE_HEIGHT ((F)) > FONT_HEIGHT ((FONT)))) / 2 \
- (FONT_DESCENT (FRAME_FONT (F)) - FRAME_BASELINE_OFFSET (F)))


/***********************************************************************
Faces
***********************************************************************/

/* Indices of face attributes in Lisp face vectors. Slot zero is the
symbol `face'. */

enum lface_attribute_index
{
  LFACE_FAMILY_INDEX = 1,
  LFACE_FOUNDRY_INDEX,
  LFACE_SWIDTH_INDEX,
  LFACE_HEIGHT_INDEX,
  LFACE_WEIGHT_INDEX,
  LFACE_SLANT_INDEX,
  LFACE_UNDERLINE_INDEX,
  LFACE_INVERSE_INDEX,
  LFACE_FOREGROUND_INDEX,
  LFACE_BACKGROUND_INDEX,
  LFACE_STIPPLE_INDEX,
  LFACE_OVERLINE_INDEX,
  LFACE_STRIKE_THROUGH_INDEX,
  LFACE_BOX_INDEX,
  LFACE_FONT_INDEX,
  LFACE_INHERIT_INDEX,
  LFACE_FONTSET_INDEX,
  LFACE_VECTOR_SIZE
};


/* Box types of faces. */

enum face_box_type
{
  /* No box around text. */
  FACE_NO_BOX,

  /* Simple box of specified width and color. Default width is 1, and
default color is the foreground color of the face. */
  FACE_SIMPLE_BOX,

  /* Boxes with 3D shadows. Color equals the background color of the
face. Width is specified. */
  FACE_RAISED_BOX,
  FACE_SUNKEN_BOX
};


/* Structure describing a realized face.

For each Lisp face, 0..N realized faces can exist for different
frames and different charsets. Realized faces are built from Lisp
faces and text properties/overlays by merging faces and adding
unspecified attributes from the `default' face. */

struct face
{
  /* The id of this face. The id equals the index of this face in the
vector faces_by_id of its face cache. */
  int id;

#ifdef HAVE_WINDOW_SYSTEM

  /* If non-zero, this is a GC that we can use without modification for
drawing the characters in this face. */
  GC gc;

  /* Background stipple or bitmap used for this face. This is
an id as returned from load_pixmap. */
  int stipple;

#else /* not HAVE_WINDOW_SYSTEM */

  /* Dummy. */
  int stipple;

#endif /* not HAVE_WINDOW_SYSTEM */

  /* Pixel value of foreground color for X frames. Color index
for tty frames. */
  unsigned long foreground;

  /* Pixel value or color index of background color. */
  unsigned long background;

  /* Pixel value or color index of underline color. */
  unsigned long underline_color;

  /* Pixel value or color index of overlined, strike-through, or box
color. */
  unsigned long overline_color;
  unsigned long strike_through_color;
  unsigned long box_color;

  struct font *font;

  /* Fontset ID if for this face's fontset. Non-ASCII faces derived
from the same ASCII face have the same fontset. */
  int fontset;

  /* Pixmap width and height. */
  unsigned int pixmap_w, pixmap_h;

  /* Non-zero means characters in this face have a box that thickness
around them. If it is negative, the absolute value indicates the
thickness, and the horizontal lines of box (top and bottom) are
drawn inside of characters glyph area. The vertical lines of box
(left and right) are drawn as the same way as the case that this
value is positive. */
  int box_line_width;

  /* Type of box drawn. A value of FACE_NO_BOX means no box is drawn
around text in this face. A value of FACE_SIMPLE_BOX means a box
of width box_line_width is drawn in color box_color. A value of
FACE_RAISED_BOX or FACE_SUNKEN_BOX means a 3D box is drawn with
shadow colors derived from the background color of the face. */
  enum face_box_type box;

  /* If `box' above specifies a 3D type, 1 means use box_color for
drawing shadows. */
  unsigned use_box_color_for_shadows_p : 1;

  /* Non-zero if text in this face should be underlined, overlined,
strike-through or have a box drawn around it. */
  unsigned underline_p : 1;
  unsigned overline_p : 1;
  unsigned strike_through_p : 1;

  /* 1 means that the colors specified for this face could not be
loaded, and were replaced by default colors, so they shouldn't be
freed. */
  unsigned foreground_defaulted_p : 1;
  unsigned background_defaulted_p : 1;

  /* 1 means that either no color is specified for underlining or that
the specified color couldn't be loaded. Use the foreground
color when drawing in that case. */
  unsigned underline_defaulted_p : 1;

  /* 1 means that either no color is specified for the corresponding
attribute or that the specified color couldn't be loaded.
Use the foreground color when drawing in that case. */
  unsigned overline_color_defaulted_p : 1;
  unsigned strike_through_color_defaulted_p : 1;
  unsigned box_color_defaulted_p : 1;

  /* TTY appearances. Blinking is not yet implemented. Colors are
found in `lface' with empty color string meaning the default
color of the TTY. */
  unsigned tty_bold_p : 1;
  unsigned tty_dim_p : 1;
  unsigned tty_underline_p : 1;
  unsigned tty_alt_charset_p : 1;
  unsigned tty_reverse_p : 1;
  unsigned tty_blinking_p : 1;

  /* 1 means that colors of this face may not be freed because they
have been copied bitwise from a base face (see
realize_x_face). */
  unsigned colors_copied_bitwise_p : 1;

  /* If non-zero, use overstrike (to simulate bold-face). */
  unsigned overstrike : 1;

/* NOTE: this is not used yet, but eventually this impl should be done
similarly to overstrike */
#ifdef HAVE_NS
  /* If non-zero, use geometric rotation (to simulate italic). */
  unsigned synth_ital : 1;
#endif

  /* The Lisp face attributes this face realizes. All attributes
in this vector are non-nil. */
  Lisp_Object lface[LFACE_VECTOR_SIZE];

  /* The hash value of this face. */
  unsigned hash;

  /* Next and previous face in hash collision list of face cache. */
  struct face *next, *prev;

  /* If this face is an ASCII face, this points to this face itself.
Otherwise, this points to an ASCII face that has the same
attributes except the font. */
  struct face *ascii_face;

  /* Extra member that a font-driver uses privately. */
  void *extra;
};


/* Color index indicating that face uses a terminal's default color. */

#define FACE_TTY_DEFAULT_COLOR ((unsigned long) -1)

/* Color index indicating that face uses an unknown foreground color. */

#define FACE_TTY_DEFAULT_FG_COLOR ((unsigned long) -2)

/* Color index indicating that face uses an unknown background color. */

#define FACE_TTY_DEFAULT_BG_COLOR ((unsigned long) -3)

/* Non-zero if FACE was realized for unibyte use. */

#define FACE_UNIBYTE_P(FACE) ((FACE)->charset < 0)


/* IDs of important faces known by the C face code. These are the IDs
of the faces for CHARSET_ASCII. */

enum face_id
{
  DEFAULT_FACE_ID,
  MODE_LINE_FACE_ID,
  MODE_LINE_INACTIVE_FACE_ID,
  TOOL_BAR_FACE_ID,
  FRINGE_FACE_ID,
  HEADER_LINE_FACE_ID,
  SCROLL_BAR_FACE_ID,
  BORDER_FACE_ID,
  CURSOR_FACE_ID,
  MOUSE_FACE_ID,
  MENU_FACE_ID,
  VERTICAL_BORDER_FACE_ID,
  BASIC_FACE_ID_SENTINEL
};

#define MAX_FACE_ID ((1 << FACE_ID_BITS) - 1)

/* A cache of realized faces. Each frame has its own cache because
Emacs allows different frame-local face definitions. */

struct face_cache
{
  /* Hash table of cached realized faces. */
  struct face **buckets;

  /* Back-pointer to the frame this cache belongs to. */
  struct frame *f;

  /* A vector of faces so that faces can be referenced by an ID. */
  struct face **faces_by_id;

  /* The allocated size, and number of used slots of faces_by_id. */
  int size, used;

  /* Flag indicating that attributes of the `menu' face have been
changed. */
  unsigned menu_face_changed_p : 1;
};


/* Prepare face FACE for use on frame F. This must be called before
using X resources of FACE. */

#define PREPARE_FACE_FOR_DISPLAY(F, FACE) \
if ((FACE)->gc == 0) \
prepare_face_for_display ((F), (FACE)); \
else \
(void) 0

/* Return a pointer to the face with ID on frame F, or null if such a
face doesn't exist. */

#define FACE_FROM_ID(F, ID) \
(((unsigned) (ID) < FRAME_FACE_CACHE (F)->used) \
? FRAME_FACE_CACHE (F)->faces_by_id[ID] \
: NULL)

#ifdef HAVE_WINDOW_SYSTEM

/* Non-zero if FACE is suitable for displaying character CHAR. */

#define FACE_SUITABLE_FOR_CHAR_P(FACE, CHAR) \
(ASCII_CHAR_P (CHAR) \
? (FACE) == (FACE)->ascii_face \
: face_suitable_for_char_p ((FACE), (CHAR)))

/* Return the id of the realized face on frame F that is like the face
with id ID but is suitable for displaying character CHAR.
This macro is only meaningful for multibyte character CHAR. */

#define FACE_FOR_CHAR(F, FACE, CHAR, POS, OBJECT) \
((ASCII_CHAR_P (CHAR) || CHAR_BYTE8_P (CHAR)) \
? (FACE)->ascii_face->id \
: face_for_char ((F), (FACE), (CHAR), (POS), (OBJECT)))

#else /* not HAVE_WINDOW_SYSTEM */

#define FACE_SUITABLE_FOR_CHAR_P(FACE, CHAR) 1
#define FACE_FOR_CHAR(F, FACE, CHAR, POS, OBJECT) ((FACE)->id)

#endif /* not HAVE_WINDOW_SYSTEM */

/* Non-zero means face attributes have been changed since the last
redisplay. Used in redisplay_internal. */

extern int face_change_count;




/***********************************************************************
Fringes
***********************************************************************/

/* Structure used to describe where and how to draw a fringe bitmap.
WHICH is the fringe bitmap to draw. WD and H is the (adjusted)
width and height of the bitmap, DH is the height adjustment (if
bitmap is periodic). X and Y are frame coordinates of the area to
display the bitmap, DY is relative offset of the bitmap into that
area. BX, NX, BY, NY specifies the area to clear if the bitmap
does not fill the entire area. FACE is the fringe face. */

struct draw_fringe_bitmap_params
{
  int which; /* enum fringe_bitmap_type */
  unsigned short *bits;
  int wd, h, dh;
  int x, y;
  int bx, nx, by, ny;
  unsigned cursor_p : 1;
  unsigned overlay_p : 1;
  struct face *face;
};

#define MAX_FRINGE_BITMAPS (1<<FRINGE_ID_BITS)


/***********************************************************************
Display Iterator
***********************************************************************/

/* Iteration over things to display in current_buffer or in a string.

The iterator handles:

1. Overlay strings (after-string, before-string).
2. Face properties.
3. Invisible text properties.
4. Selective display.
5. Translation of characters via display tables.
6. Translation of control characters to the forms `\003' or `^C'.
7. `glyph' and `space-width' properties.

Iterators are initialized by calling init_iterator or one of the
equivalent functions below. A call to get_next_display_element
loads the iterator structure with information about what next to
display. A call to set_iterator_to_next increments the iterator's
position.

Characters from overlay strings, display table entries or control
character translations are returned one at a time. For example, if
we have a text of `a\x01' where `a' has a display table definition
of `cd' and the control character is displayed with a leading
arrow, then the iterator will return:

Call Return Source Call next
-----------------------------------------------------------------
next c display table move
next d display table move
next ^ control char move
next A control char move

The same mechanism is also used to return characters for ellipses
displayed at the end of invisible text.

CAVEAT: Under some circumstances, move_.* functions can be called
asynchronously, e.g. when computing a buffer position from an x and
y pixel position. This means that these functions and functions
called from them SHOULD NOT USE xmalloc and alike. See also the
comment at the start of xdisp.c. */

/* Enumeration describing what kind of display element an iterator is
loaded with after a call to get_next_display_element. */

enum display_element_type
{
  /* A normal character. */
  IT_CHARACTER,

  /* A composition (static and automatic). */
  IT_COMPOSITION,

  /* An image. */
  IT_IMAGE,

  /* A flexible width and height space. */
  IT_STRETCH,

  /* End of buffer or string. */
  IT_EOB,

  /* Truncation glyphs. Never returned by get_next_display_element.
Used to get display information about truncation glyphs via
produce_glyphs. */
  IT_TRUNCATION,

  /* Continuation glyphs. See the comment for IT_TRUNCATION. */
  IT_CONTINUATION
};


/* An enumerator for each text property that has a meaning for display
purposes. */

enum prop_idx
{
  FONTIFIED_PROP_IDX,
  FACE_PROP_IDX,
  INVISIBLE_PROP_IDX,
  DISPLAY_PROP_IDX,
  COMPOSITION_PROP_IDX,

  /* Not a property. Used to indicate changes in overlays. */
  OVERLAY_PROP_IDX,

  /* Sentinel. */
  LAST_PROP_IDX
};

/* An enumerator for the method of wrapping long lines. */

enum line_wrap_method
{
  TRUNCATE,
  WORD_WRAP,
  WINDOW_WRAP
};

struct it_slice
{
  Lisp_Object x;
  Lisp_Object y;
  Lisp_Object width;
  Lisp_Object height;
};

/* Input sources for fetching characters or data to display.
The input source is found in the `method' field. */

enum it_method {
  GET_FROM_BUFFER = 0,
  GET_FROM_DISPLAY_VECTOR,
  GET_FROM_STRING,
  GET_FROM_C_STRING,
  GET_FROM_IMAGE,
  GET_FROM_STRETCH,
  NUM_IT_METHODS
};

#define IT_STACK_SIZE 4

/* Iterator for composition (both for static and automatic). */
struct composition_it
{
  /* Next position at which to check the composition. */
  EMACS_INT stop_pos;
  /* ID number of the composition or glyph-string. If negative, we
are not iterating over a composition now. */
  int id;
  /* If non-negative, character that triggers the automatic
composition at `stop_pos', and this is an automatic composition.
If negative, this is a static composition. This is set to -2
temporarily if searching of composition reach a limit or a
newline. */
  int ch;
  /* If this an automatic composition, how many characters to look back
from the position where a character triggering the composition