w32font.c

/* Font backend for the Microsoft Windows API.
   Copyright (C) 2007-2019 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 <https://www.gnu.org/licenses/>.  */

#include <config.h>
#include <windows.h>
#include <stdio.h>
#include <math.h>
#include <ctype.h>
#include <commdlg.h>

#include "lisp.h"
#include "w32term.h"
#include "frame.h"
#include "coding.h"	/* for ENCODE_SYSTEM, DECODE_SYSTEM */
#include "w32font.h"
#ifdef WINDOWSNT
#include "w32common.h"
#include "w32.h"
#endif

#include "pdumper.h"

/* Cleartype available on Windows XP, cleartype_natural from XP SP1.
   The latter does not try to fit cleartype smoothed fonts into the
   same bounding box as the non-antialiased version of the font.
 */
#ifndef CLEARTYPE_QUALITY
#define CLEARTYPE_QUALITY 5
#endif
#ifndef CLEARTYPE_NATURAL_QUALITY
#define CLEARTYPE_NATURAL_QUALITY 6
#endif

/* VIETNAMESE_CHARSET and JOHAB_CHARSET are not defined in some versions
   of MSVC headers.  */
#ifndef VIETNAMESE_CHARSET
#define VIETNAMESE_CHARSET 163
#endif
#ifndef JOHAB_CHARSET
#define JOHAB_CHARSET 130
#endif

static void fill_in_logfont (struct frame *, LOGFONT *, Lisp_Object);

static BYTE w32_antialias_type (Lisp_Object);
static Lisp_Object lispy_antialias_type (BYTE);

static Lisp_Object font_supported_scripts (FONTSIGNATURE *);
static int w32font_full_name (LOGFONT *, Lisp_Object, int, char *, int);
static void compute_metrics (HDC, struct w32font_info *, unsigned int,
                             struct w32_metric_cache *);

static Lisp_Object w32_registry (LONG, DWORD);

/* EnumFontFamiliesEx callbacks.  */
static int CALLBACK ALIGN_STACK add_font_entity_to_list (ENUMLOGFONTEX *,
							 NEWTEXTMETRICEX *,
							 DWORD, LPARAM);
static int CALLBACK ALIGN_STACK add_one_font_entity_to_list (ENUMLOGFONTEX *,
							     NEWTEXTMETRICEX *,
							     DWORD, LPARAM);
static int CALLBACK ALIGN_STACK add_font_name_to_list (ENUMLOGFONTEX *,
						       NEWTEXTMETRICEX *,
						       DWORD, LPARAM);

/* struct passed in as LPARAM arg to EnumFontFamiliesEx, for keeping track
   of what we really want.  */
struct font_callback_data
{
  /* The logfont we are matching against. EnumFontFamiliesEx only matches
     face name and charset, so we need to manually match everything else
     in the callback function.  */
  LOGFONT pattern;
  /* The original font spec or entity.  */
  Lisp_Object orig_font_spec;
  /* The frame the font is being loaded on.  */
  Lisp_Object frame;
  /* Fonts known to support the font spec, or nil if none.  */
  Lisp_Object known_fonts;
  /* The list to add matches to.  */
  Lisp_Object list;
  /* Whether to match only opentype fonts.  */
  bool opentype_only;
};

/* Handles the problem that EnumFontFamiliesEx will not return all
   style variations if the font name is not specified.  */
static void list_all_matching_fonts (struct font_callback_data *);

#ifdef WINDOWSNT

static BOOL g_b_init_get_outline_metrics_w;
static BOOL g_b_init_get_text_metrics_w;
static BOOL g_b_init_get_glyph_outline_w;
static BOOL g_b_init_get_char_width_32_w;

typedef UINT (WINAPI * GetOutlineTextMetricsW_Proc) (
   HDC hdc,
   UINT cbData,
   LPOUTLINETEXTMETRICW lpotmw);
typedef BOOL (WINAPI * GetTextMetricsW_Proc) (
   HDC hdc,
   LPTEXTMETRICW lptmw);
typedef DWORD (WINAPI * GetGlyphOutlineW_Proc) (
   HDC hdc,
   UINT uChar,
   UINT uFormat,
   LPGLYPHMETRICS lpgm,
   DWORD cbBuffer,
   LPVOID lpvBuffer,
   const MAT2 *lpmat2);
typedef BOOL (WINAPI * GetCharWidth32W_Proc) (
   HDC hdc,
   UINT uFirstChar,
   UINT uLastChar,
   LPINT lpBuffer);

/* Several "wide" functions we use to support the font backends are
   unavailable on Windows 9X, unless UNICOWS.DLL is installed (their
   versions in the default libraries are non-functional stubs).  On NT
   and later systems, these functions are in GDI32.DLL.  The following
   helper function attempts to load UNICOWS.DLL on Windows 9X, and
   refuses to let Emacs start up if that library is not found.  On NT
   and later versions, it simply loads GDI32.DLL, which should always
   be available.  */
static HMODULE
w32_load_unicows_or_gdi32 (void)
{
  return maybe_load_unicows_dll ();
}

/* The following 3 functions call the problematic "wide" APIs via
   function pointers, to avoid linking against the non-standard
   libunicows on W9X.  */
static UINT WINAPI
get_outline_metrics_w(HDC hdc, UINT cbData, LPOUTLINETEXTMETRICW lpotmw)
{
  static GetOutlineTextMetricsW_Proc s_pfn_Get_Outline_Text_MetricsW = NULL;
  HMODULE hm_unicows = NULL;
  if (g_b_init_get_outline_metrics_w == 0)
    {
      g_b_init_get_outline_metrics_w = 1;
      hm_unicows = w32_load_unicows_or_gdi32 ();
      if (hm_unicows)
	s_pfn_Get_Outline_Text_MetricsW = (GetOutlineTextMetricsW_Proc)
	  get_proc_addr (hm_unicows, "GetOutlineTextMetricsW");
    }
  eassert (s_pfn_Get_Outline_Text_MetricsW != NULL);
  return s_pfn_Get_Outline_Text_MetricsW (hdc, cbData, lpotmw);
}

static BOOL WINAPI
get_text_metrics_w(HDC hdc, LPTEXTMETRICW lptmw)
{
  static GetTextMetricsW_Proc s_pfn_Get_Text_MetricsW = NULL;
  HMODULE hm_unicows = NULL;
  if (g_b_init_get_text_metrics_w == 0)
    {
      g_b_init_get_text_metrics_w = 1;
      hm_unicows = w32_load_unicows_or_gdi32 ();
      if (hm_unicows)
	s_pfn_Get_Text_MetricsW = (GetTextMetricsW_Proc)
	  get_proc_addr (hm_unicows, "GetTextMetricsW");
    }
  eassert (s_pfn_Get_Text_MetricsW != NULL);
  return s_pfn_Get_Text_MetricsW (hdc, lptmw);
}

static DWORD WINAPI
get_glyph_outline_w (HDC hdc, UINT uChar, UINT uFormat, LPGLYPHMETRICS lpgm,
		     DWORD cbBuffer, LPVOID lpvBuffer, const MAT2 *lpmat2)
{
  static GetGlyphOutlineW_Proc s_pfn_Get_Glyph_OutlineW = NULL;
  HMODULE hm_unicows = NULL;
  if (g_b_init_get_glyph_outline_w == 0)
    {
      g_b_init_get_glyph_outline_w = 1;
      hm_unicows = w32_load_unicows_or_gdi32 ();
      if (hm_unicows)
	s_pfn_Get_Glyph_OutlineW = (GetGlyphOutlineW_Proc)
	  get_proc_addr (hm_unicows, "GetGlyphOutlineW");
    }
  eassert (s_pfn_Get_Glyph_OutlineW != NULL);
  return s_pfn_Get_Glyph_OutlineW (hdc, uChar, uFormat, lpgm, cbBuffer,
				   lpvBuffer, lpmat2);
}

static DWORD WINAPI
get_char_width_32_w (HDC hdc, UINT uFirstChar, UINT uLastChar, LPINT lpBuffer)
{
  static GetCharWidth32W_Proc s_pfn_Get_Char_Width_32W = NULL;
  HMODULE hm_unicows = NULL;
  if (g_b_init_get_char_width_32_w == 0)
    {
      g_b_init_get_char_width_32_w = 1;
      hm_unicows = w32_load_unicows_or_gdi32 ();
      if (hm_unicows)
	s_pfn_Get_Char_Width_32W = (GetCharWidth32W_Proc)
	  get_proc_addr (hm_unicows, "GetCharWidth32W");
    }
  eassert (s_pfn_Get_Char_Width_32W != NULL);
  return s_pfn_Get_Char_Width_32W (hdc, uFirstChar, uLastChar, lpBuffer);
}

#else  /* Cygwin */

/* Cygwin doesn't support Windows 9X, and links against GDI32.DLL, so
   it can just call these functions directly.  */
#define get_outline_metrics_w(h,d,o)   GetOutlineTextMetricsW(h,d,o)
#define get_text_metrics_w(h,t)        GetTextMetricsW(h,t)
#define get_glyph_outline_w(h,uc,f,gm,b,v,m) \
                                       GetGlyphOutlineW(h,uc,f,gm,b,v,m)
#define get_char_width_32_w(h,fc,lc,b) GetCharWidth32W(h,fc,lc,b)

#endif	/* Cygwin */

static int
memq_no_quit (Lisp_Object elt, Lisp_Object list)
{
  while (CONSP (list) && ! EQ (XCAR (list), elt))
    list = XCDR (list);
  return (CONSP (list));
}

Lisp_Object
intern_font_name (char * string)
{
  Lisp_Object str = DECODE_SYSTEM (build_string (string));
  ptrdiff_t len = SCHARS (str);
  Lisp_Object obarray = check_obarray (Vobarray);
  Lisp_Object tem = oblookup (obarray, SSDATA (str), len, len);
  /* This code is similar to intern function from lread.c.  */
  return SYMBOLP (tem) ? tem : intern_driver (str, obarray, tem);
}

/* w32 implementation of get_cache for font backend.
   Return a cache of font-entities on FRAME.  The cache must be a
   cons whose cdr part is the actual cache area.  */
Lisp_Object
w32font_get_cache (struct frame *f)
{
  struct w32_display_info *dpyinfo = FRAME_DISPLAY_INFO (f);

  return (dpyinfo->name_list_element);
}

/* w32 implementation of list for font backend.
   List fonts exactly matching with FONT_SPEC on FRAME.  The value
   is a vector of font-entities.  This is the sole API that
   allocates font-entities.  */
static Lisp_Object
w32font_list (struct frame *f, Lisp_Object font_spec)
{
  Lisp_Object fonts = w32font_list_internal (f, font_spec, 0);
  FONT_ADD_LOG ("w32font-list", font_spec, fonts);
  return fonts;
}

/* w32 implementation of match for font backend.
   Return a font entity most closely matching with FONT_SPEC on
   FRAME.  The closeness is determined by the font backend, thus
   `face-font-selection-order' is ignored here.  */
static Lisp_Object
w32font_match (struct frame *f, Lisp_Object font_spec)
{
  Lisp_Object entity = w32font_match_internal (f, font_spec, 0);
  FONT_ADD_LOG ("w32font-match", font_spec, entity);
  return entity;
}

/* w32 implementation of list_family for font backend.
   List available families.  The value is a list of family names
   (symbols).  */
static Lisp_Object
w32font_list_family (struct frame *f)
{
  Lisp_Object list = Qnil;
  Lisp_Object prev_quit = Vinhibit_quit;
  LOGFONT font_match_pattern;
  HDC dc;

  memset (&font_match_pattern, 0, sizeof (font_match_pattern));
  font_match_pattern.lfCharSet = DEFAULT_CHARSET;

  /* Prevent quitting while EnumFontFamiliesEx runs and conses the
     list it will return.  That's because get_frame_dc acquires the
     critical section, so we cannot quit before we release it in
     release_frame_dc.  */
  Vinhibit_quit = Qt;
  dc = get_frame_dc (f);

  EnumFontFamiliesEx (dc, &font_match_pattern,
                      (FONTENUMPROC) add_font_name_to_list,
                      (LPARAM) &list, 0);
  release_frame_dc (f, dc);
  Vinhibit_quit = prev_quit;

  return list;
}

/* w32 implementation of open for font backend.
   Open a font specified by FONT_ENTITY on frame F.
   If the font is scalable, open it with PIXEL_SIZE.  */
static Lisp_Object
w32font_open (struct frame *f, Lisp_Object font_entity, int pixel_size)
{
  Lisp_Object font_object
    = font_make_object (VECSIZE (struct w32font_info),
                        font_entity, pixel_size);
  struct w32font_info *w32_font
    = (struct w32font_info *) XFONT_OBJECT (font_object);

  ASET (font_object, FONT_TYPE_INDEX, Qgdi);

  if (!w32font_open_internal (f, font_entity, pixel_size, font_object))
    {
      return Qnil;
    }

  /* GDI backend does not use glyph indices.  */
  w32_font->glyph_idx = 0;

  return font_object;
}

/* w32 implementation of close for font_backend.  */
void
w32font_close (struct font *font)
{
  struct w32font_info *w32_font = (struct w32font_info *) font;

  if (w32_font->hfont)
    {
      /* Delete the GDI font object.  */
      DeleteObject (w32_font->hfont);
      w32_font->hfont = NULL;

      /* Free all the cached metrics.  */
      if (w32_font->cached_metrics)
	{
	  int i;

	  for (i = 0; i < w32_font->n_cache_blocks; i++)
	      xfree (w32_font->cached_metrics[i]);
	  xfree (w32_font->cached_metrics);
	  w32_font->cached_metrics = NULL;
	}
    }
}

/* w32 implementation of has_char for font backend.
   Optional.
   If FONT_ENTITY has a glyph for character C (Unicode code point),
   return 1.  If not, return 0.  If a font must be opened to check
   it, return -1.  */
int
w32font_has_char (Lisp_Object entity, int c)
{
  /* We can't be certain about which characters a font will support until
     we open it.  Checking the scripts that the font supports turns out
     to not be reliable.  */
  return -1;

#if 0
  Lisp_Object supported_scripts, extra, script;
  DWORD mask;

  extra = AREF (entity, FONT_EXTRA_INDEX);
  if (!CONSP (extra))
    return -1;

  supported_scripts = assq_no_quit (QCscript, extra);
  /* If font doesn't claim to support any scripts, then we can't be certain
     until we open it.  */
  if (!CONSP (supported_scripts))
    return -1;

  supported_scripts = XCDR (supported_scripts);

  script = CHAR_TABLE_REF (Vchar_script_table, c);

  /* If we don't know what script the character is from, then we can't be
     certain until we open it.  Also if the font claims support for the script
     the character is from, it may only have partial coverage, so we still
     can't be certain until we open the font.  */
  if (NILP (script) || memq_no_quit (script, supported_scripts))
    return -1;

  /* Font reports what scripts it supports, and none of them are the script
     the character is from. But we still can't be certain, as some fonts
     will contain some/most/all of the characters in that script without
     claiming support for it.  */
  return -1;
#endif
}

/* w32 implementation of encode_char for font backend.
   Return a glyph code of FONT for character C (Unicode code point).
   If FONT doesn't have such a glyph, return FONT_INVALID_CODE.

   For speed, the gdi backend uses Unicode (Emacs calls encode_char
   far too often for it to be efficient). But we still need to detect
   which characters are not supported by the font.
  */
static unsigned
w32font_encode_char (struct font *font, int c)
{
  struct w32font_info * w32_font = (struct w32font_info *)font;

  if (c < w32_font->metrics.tmFirstChar
      || c > w32_font->metrics.tmLastChar)
    return FONT_INVALID_CODE;
  else
    return c;
}

/* w32 implementation of text_extents for font backend.
   Perform the size computation of glyphs of FONT and fillin members
   of METRICS.  The glyphs are specified by their glyph codes in
   CODE (length NGLYPHS).  Apparently metrics can be NULL, in this
   case just return the overall width.  */
void
w32font_text_extents (struct font *font, const unsigned *code,
		      int nglyphs, struct font_metrics *metrics)
{
  int i;
  HFONT old_font = NULL;
  HDC dc = NULL;
  struct frame * f UNINIT;
  int total_width = 0;
  WORD *wcode;
  SIZE size;
  bool first;
  Lisp_Object prev_quit = Vinhibit_quit;

  struct w32font_info *w32_font = (struct w32font_info *) font;

  memset (metrics, 0, sizeof (struct font_metrics));

  for (i = 0, first = true; i < nglyphs; i++)
    {
      struct w32_metric_cache *char_metric;
      int block = *(code + i) / CACHE_BLOCKSIZE;
      int pos_in_block = *(code + i) % CACHE_BLOCKSIZE;

      if (block >= w32_font->n_cache_blocks)
	{
	  if (!w32_font->cached_metrics)
	    w32_font->cached_metrics
	      = xmalloc ((block + 1)
			 * sizeof (struct w32_metric_cache *));
	  else
	    w32_font->cached_metrics
	      = xrealloc (w32_font->cached_metrics,
			  (block + 1)
			  * sizeof (struct w32_metric_cache *));
	  memset (w32_font->cached_metrics + w32_font->n_cache_blocks, 0,
		  ((block + 1 - w32_font->n_cache_blocks)
		   * sizeof (struct w32_metric_cache *)));
	  w32_font->n_cache_blocks = block + 1;
	}

      if (!w32_font->cached_metrics[block])
	{
	  w32_font->cached_metrics[block]
	    = xzalloc (CACHE_BLOCKSIZE * sizeof (struct w32_metric_cache));
	}

      char_metric = w32_font->cached_metrics[block] + pos_in_block;

      if (char_metric->status == W32METRIC_NO_ATTEMPT)
	{
	  if (dc == NULL)
	    {
	      /* TODO: Frames can come and go, and their fonts
		 outlive them. So we can't cache the frame in the
		 font structure.  Use selected_frame until the API
		 is updated to pass in a frame.  */
	      f = XFRAME (selected_frame);

	      /* Prevent quitting while EnumFontFamiliesEx runs and
		 conses the list it will return.  That's because
		 get_frame_dc acquires the critical section, so we
		 cannot quit before we release it in release_frame_dc.  */
	      prev_quit = Vinhibit_quit;
	      Vinhibit_quit = Qt;
	      dc = get_frame_dc (f);
	      old_font = SelectObject (dc, w32_font->hfont);
	    }
	  compute_metrics (dc, w32_font, *(code + i), char_metric);
	}

      if (char_metric->status == W32METRIC_SUCCESS)
	{
	  if (first)
	    {
	      metrics->lbearing = char_metric->lbearing;
	      metrics->rbearing = char_metric->rbearing;
	      metrics->width    = 0;
	      metrics->ascent   = char_metric->ascent;
	      metrics->descent  = char_metric->descent;
	      first = false;
	    }
	  if (metrics->lbearing > char_metric->lbearing)
	    metrics->lbearing = char_metric->lbearing;
	  if (metrics->rbearing < char_metric->rbearing)
	    metrics->rbearing = char_metric->rbearing;
	  metrics->width += char_metric->width;
	  if (metrics->ascent < char_metric->ascent)
	    metrics->ascent = char_metric->ascent;
	  if (metrics->descent < char_metric->descent)
	    metrics->descent = char_metric->descent;
	}
      else
	/* If we couldn't get metrics for a char,
	   use alternative method.  */
	break;
    }
  /* If we got through everything, return.  */
  if (i == nglyphs)
    {
      if (dc != NULL)
	{
	  /* Restore state and release DC.  */
	  SelectObject (dc, old_font);
	  release_frame_dc (f, dc);
	  Vinhibit_quit = prev_quit;
	}
      return;
    }

  /* For non-truetype fonts, GetGlyphOutlineW is not supported, so
     fallback on other methods that will at least give some of the metric
     information.  */

  /* Make array big enough to hold surrogates.  */
  eassume (0 <= nglyphs);	/* pacify GCC warning on next line */
  wcode = alloca (nglyphs * sizeof (WORD) * 2);
  for (i = 0; i < nglyphs; i++)
    {
      if (code[i] < 0x10000)
        wcode[i] = code[i];
      else
        {
          DWORD surrogate = code[i] - 0x10000;

          /* High surrogate: U+D800 - U+DBFF.  */
          wcode[i++] = 0xD800 + ((surrogate >> 10) & 0x03FF);
          /* Low surrogate: U+DC00 - U+DFFF.  */
          wcode[i] = 0xDC00 + (surrogate & 0x03FF);
          /* An extra glyph. wcode is already double the size of code to
             cope with this.  */
          nglyphs++;
        }
    }

  if (dc == NULL)
    {
      /* TODO: Frames can come and go, and their fonts outlive
	 them. So we can't cache the frame in the font structure.  Use
	 selected_frame until the API is updated to pass in a
	 frame.  */
      f = XFRAME (selected_frame);

      /* Prevent quitting while EnumFontFamiliesEx runs and conses the
	 list it will return.  That's because get_frame_dc acquires
	 the critical section, so we cannot quit before we release it
	 in release_frame_dc.  */
      prev_quit = Vinhibit_quit;
      Vinhibit_quit = Qt;
      dc = get_frame_dc (f);
      old_font = SelectObject (dc, w32_font->hfont);
    }

  if (GetTextExtentPoint32W (dc, wcode, nglyphs, &size))
    {
      total_width = size.cx;
    }

  /* On 95/98/ME, only some Unicode functions are available, so fallback
     on doing a dummy draw to find the total width.  */
  if (!total_width)
    {
      RECT rect;
      rect.top = 0; rect.bottom = font->height; rect.left = 0; rect.right = 1;
      DrawTextW (dc, wcode, nglyphs, &rect,
                 DT_CALCRECT | DT_NOPREFIX | DT_SINGLELINE);
      total_width = rect.right;
    }

  /* Give our best estimate of the metrics, based on what we know.  */
  metrics->width = total_width - w32_font->metrics.tmOverhang;
  metrics->lbearing = 0;
  metrics->rbearing = total_width;
  metrics->ascent = font->ascent;
  metrics->descent = font->descent;

  /* Restore state and release DC.  */
  SelectObject (dc, old_font);
  release_frame_dc (f, dc);
  Vinhibit_quit = prev_quit;
}

/* w32 implementation of draw for font backend.
   Optional.
   Draw glyphs between FROM and TO of S->char2b at (X Y) pixel
   position of frame F with S->FACE and S->GC.  If WITH_BACKGROUND,
   fill the background in advance.  It is assured that WITH_BACKGROUND
   is false when (FROM > 0 || TO < S->nchars).

   TODO: Currently this assumes that the colors and fonts are already
   set in the DC. This seems to be true now, but maybe only due to
   the old font code setting it up. It may be safer to resolve faces
   and fonts in here and set them explicitly
*/

int
w32font_draw (struct glyph_string *s, int from, int to,
	      int x, int y, bool with_background)
{
  UINT options;
  HRGN orig_clip = NULL;
  int len = to - from;
  struct w32font_info *w32font = (struct w32font_info *) s->font;

  options = w32font->glyph_idx;

  if (s->num_clips > 0)
    {
      HRGN new_clip = CreateRectRgnIndirect (s->clip);

      /* Save clip region for later restoration.  */
      orig_clip = CreateRectRgn (0, 0, 0, 0);
      if (!GetClipRgn (s->hdc, orig_clip))
	{
	  DeleteObject (orig_clip);
	  orig_clip = NULL;
	}

      if (s->num_clips > 1)
        {
          HRGN clip2 = CreateRectRgnIndirect (s->clip + 1);

          CombineRgn (new_clip, new_clip, clip2, RGN_OR);
          DeleteObject (clip2);
        }

      SelectClipRgn (s->hdc, new_clip);
      DeleteObject (new_clip);
    }

  /* Using OPAQUE background mode can clear more background than expected
     when Cleartype is used.  Draw the background manually to avoid this.  */
  SetBkMode (s->hdc, TRANSPARENT);
  if (with_background)
    {
      HBRUSH brush;
      RECT rect;
      struct font *font = s->font;
      int ascent = font->ascent, descent = font->descent;

      /* Font's global ascent and descent values might be
	 preposterously large for some fonts.  We fix here the case
	 when those fonts are used for display of glyphless
	 characters, because drawing background with font dimensions
	 in those cases makes the display illegible.  There's only one
	 more call to the draw method with with_background set to
	 true, and that's in w32_draw_glyph_string_foreground, when
	 drawing the cursor, where we have no such heuristics
	 available.  FIXME.  */
      if (s->first_glyph->type == GLYPHLESS_GLYPH
	  && (s->first_glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEX_CODE
	      || s->first_glyph->u.glyphless.method == GLYPHLESS_DISPLAY_ACRONYM))
	{
	  ascent =
	    s->first_glyph->slice.glyphless.lower_yoff
	    - s->first_glyph->slice.glyphless.upper_yoff;
	  descent = 0;
	}
      brush = CreateSolidBrush (s->gc->background);
      rect.left = x;
      rect.top = y - ascent;
      rect.right = x + s->width;
      rect.bottom = y + descent;
      FillRect (s->hdc, &rect, brush);
      DeleteObject (brush);
    }

  if (s->padding_p)
    {
      int i;

      for (i = 0; i < len; i++)
	{
	  WCHAR c = s->char2b[from + i] & 0xFFFF;
	  ExtTextOutW (s->hdc, x + i, y, options, NULL, &c, 1, NULL);
	}
    }
  else
    {
      /* The number of glyphs in a glyph_string cannot be larger than
	 the maximum value of the 'used' member of a glyph_row, so we
	 are OK using alloca here.  */
      eassert (len <= SHRT_MAX);
      WCHAR *chars = alloca (len * sizeof (WCHAR));
      int j;
      for (j = 0; j < len; j++)
	chars[j] = s->char2b[from + j] & 0xFFFF;
      ExtTextOutW (s->hdc, x, y, options, NULL, chars, len, NULL);
    }

  /* Restore clip region.  */
  if (s->num_clips > 0)
    SelectClipRgn (s->hdc, orig_clip);

  if (orig_clip)
    DeleteObject (orig_clip);

  return len;
}

/* w32 implementation of free_entity for font backend.
   Optional.
   Free FONT_EXTRA_INDEX field of FONT_ENTITY.
static void
w32font_free_entity (Lisp_Object entity);
  */

/* w32 implementation of prepare_face for font backend.
   Optional (if FACE->extra is not used).
   Prepare FACE for displaying characters by FONT on frame F by
   storing some data in FACE->extra.  If successful, return 0.
   Otherwise, return -1.
static int
w32font_prepare_face (struct frame *f, struct face *face);
  */
/* w32 implementation of done_face for font backend.
   Optional.
   Done FACE for displaying characters by FACE->font on frame F.
static void
w32font_done_face (struct frame *f, struct face *face);  */

/* w32 implementation of get_bitmap for font backend.
   Optional.
   Store bitmap data for glyph-code CODE of FONT in BITMAP.  It is
   intended that this method is called from the other font-driver
   for actual drawing.
static int
w32font_get_bitmap (struct font *font, unsigned code,
                    struct font_bitmap *bitmap, int bits_per_pixel);
  */
/* w32 implementation of free_bitmap for font backend.
   Optional.
   Free bitmap data in BITMAP.
static void
w32font_free_bitmap (struct font *font, struct font_bitmap *bitmap);
  */
/* w32 implementation of anchor_point for font backend.
   Optional.
   Get coordinates of the INDEXth anchor point of the glyph whose
   code is CODE.  Store the coordinates in *X and *Y.  Return 0 if
   the operations was successful.  Otherwise return -1.
static int
w32font_anchor_point (struct font *font, unsigned code,
                                 int index, int *x, int *y);
  */
/* w32 implementation of otf_capability for font backend.
   Optional.
   Return a list describing which scripts/languages FONT
   supports by which GSUB/GPOS features of OpenType tables.
static Lisp_Object
w32font_otf_capability (struct font *font);
  */
/* w32 implementation of otf_drive for font backend.
   Optional.
   Apply FONT's OTF-FEATURES to the glyph string.

   FEATURES specifies which OTF features to apply in this format:
      (SCRIPT LANGSYS GSUB-FEATURE GPOS-FEATURE)
   See the documentation of `font-drive-otf' for the detail.

   This method applies the specified features to the codes in the
   elements of GSTRING-IN (between FROMth and TOth).  The output
   codes are stored in GSTRING-OUT at the IDXth element and the
   following elements.

   Return the number of output codes.  If none of the features are
   applicable to the input data, return 0.  If GSTRING-OUT is too
   short, return -1.
static int
w32font_otf_drive (struct font *font, Lisp_Object features,
                   Lisp_Object gstring_in, int from, int to,
                   Lisp_Object gstring_out, int idx,
                   bool alternate_subst);
  */

/* Internal implementation of w32font_list.
   Additional parameter opentype_only restricts the returned fonts to
   opentype fonts, which can be used with the Uniscribe backend.  */
Lisp_Object
w32font_list_internal (struct frame *f, Lisp_Object font_spec,
		       bool opentype_only)
{
  struct font_callback_data match_data;
  HDC dc;

  match_data.orig_font_spec = font_spec;
  match_data.list = Qnil;
  XSETFRAME (match_data.frame, f);

  memset (&match_data.pattern, 0, sizeof (LOGFONT));
  fill_in_logfont (f, &match_data.pattern, font_spec);

  /* If the charset is unrecognized, then we won't find a font, so don't
     waste time looking for one.  */
  if (match_data.pattern.lfCharSet == DEFAULT_CHARSET)
    {
      Lisp_Object spec_charset = AREF (font_spec, FONT_REGISTRY_INDEX);
      if (!NILP (spec_charset)
	  && !EQ (spec_charset, Qiso10646_1)
	  && !EQ (spec_charset, Qunicode_bmp)
	  && !EQ (spec_charset, Qunicode_sip)
	  && !EQ (spec_charset, Qunknown)
	  && !EQ (spec_charset, Qascii_0))
	return Qnil;
    }

  match_data.opentype_only = opentype_only;
  if (opentype_only)
    match_data.pattern.lfOutPrecision = OUT_OUTLINE_PRECIS;
  match_data.known_fonts = Qnil;
  Lisp_Object vw32_non_USB_fonts = Fsymbol_value (Qw32_non_USB_fonts), val;
  if (CONSP (vw32_non_USB_fonts))
    {
      Lisp_Object extra;
      for (extra = AREF (font_spec, FONT_EXTRA_INDEX);
	   CONSP (extra); extra = XCDR (extra))
	{
	  Lisp_Object tem = XCAR (extra);
	  if (CONSP (tem)
	      && EQ (XCAR (tem), QCscript)
	      && SYMBOLP (XCDR (tem))
	      && !NILP (val = assq_no_quit (XCDR (tem), vw32_non_USB_fonts)))
	    {
	      match_data.known_fonts = XCDR (val);
	      break;
	    }
	}
    }

  if (match_data.pattern.lfFaceName[0] == '\0')
    {
      /* EnumFontFamiliesEx does not take other fields into account if
         font name is blank, so need to use two passes.  */
      list_all_matching_fonts (&match_data);
    }
  else
    {
      Lisp_Object prev_quit = Vinhibit_quit;

      /* Prevent quitting while EnumFontFamiliesEx runs and conses the
	 list it will return.  That's because get_frame_dc acquires
	 the critical section, so we cannot quit before we release it
	 in release_frame_dc.  */
      Vinhibit_quit = Qt;
      dc = get_frame_dc (f);

      EnumFontFamiliesEx (dc, &match_data.pattern,
                          (FONTENUMPROC) add_font_entity_to_list,
                          (LPARAM) &match_data, 0);
      release_frame_dc (f, dc);
      Vinhibit_quit = prev_quit;
    }

  return match_data.list;
}

/* Internal implementation of w32font_match.
   Additional parameter opentype_only restricts the returned fonts to
   opentype fonts, which can be used with the Uniscribe backend.  */
Lisp_Object
w32font_match_internal (struct frame *f, Lisp_Object font_spec,
			bool opentype_only)
{
  struct font_callback_data match_data;
  HDC dc;

  match_data.orig_font_spec = font_spec;
  XSETFRAME (match_data.frame, f);
  match_data.list = Qnil;

  memset (&match_data.pattern, 0, sizeof (LOGFONT));
  fill_in_logfont (f, &match_data.pattern, font_spec);

  match_data.opentype_only = opentype_only;
  if (opentype_only)
    match_data.pattern.lfOutPrecision = OUT_OUTLINE_PRECIS;

  match_data.known_fonts = Qnil;
  Lisp_Object vw32_non_USB_fonts = Fsymbol_value (Qw32_non_USB_fonts), val;
  if (CONSP (vw32_non_USB_fonts))
    {
      Lisp_Object extra;
      for (extra = AREF (font_spec, FONT_EXTRA_INDEX);
	   CONSP (extra); extra = XCDR (extra))
	{
	  Lisp_Object tem = XCAR (extra);
	  if (CONSP (tem)
	      && EQ (XCAR (tem), QCscript)
	      && SYMBOLP (XCDR (tem))
	      && !NILP (val = assq_no_quit (XCDR (tem), vw32_non_USB_fonts)))
	    {
	      match_data.known_fonts = XCDR (val);
	      break;
	    }
	}
    }

  /* Prevent quitting while EnumFontFamiliesEx runs and conses the
     list it will return.  That's because get_frame_dc acquires the
     critical section, so we cannot quit before we release it in
     release_frame_dc.  */
  Lisp_Object prev_quit = Vinhibit_quit;
  Vinhibit_quit = Qt;
  dc = get_frame_dc (f);

  EnumFontFamiliesEx (dc, &match_data.pattern,
                      (FONTENUMPROC) add_one_font_entity_to_list,
                      (LPARAM) &match_data, 0);
  release_frame_dc (f, dc);
  Vinhibit_quit = prev_quit;

  return NILP (match_data.list) ? Qnil : XCAR (match_data.list);
}

int
w32font_open_internal (struct frame *f, Lisp_Object font_entity,
		       int pixel_size, Lisp_Object font_object)
{
  int len, size;
  LOGFONT logfont;
  HDC dc;
  HFONT hfont, old_font;
  Lisp_Object val;
  struct w32font_info *w32_font;
  struct font * font;
  OUTLINETEXTMETRICW* metrics = NULL;

  w32_font = (struct w32font_info *) XFONT_OBJECT (font_object);
  font = (struct font *) w32_font;

  if (!font)
    return 0;

  memset (&logfont, 0, sizeof (logfont));
  fill_in_logfont (f, &logfont, font_entity);

  /* Prefer truetype fonts, to avoid known problems with type1 fonts, and
     limitations in bitmap fonts.  */
  val = AREF (font_entity, FONT_FOUNDRY_INDEX);
  if (!EQ (val, Qraster))
    logfont.lfOutPrecision = OUT_TT_PRECIS;

  size = XFIXNUM (AREF (font_entity, FONT_SIZE_INDEX));
  if (!size)
    size = pixel_size;

  logfont.lfHeight = -size;
  hfont = CreateFontIndirect (&logfont);

  if (hfont == NULL)
    return 0;

  /* Get the metrics for this font.  */
  dc = get_frame_dc (f);
  old_font = SelectObject (dc, hfont);

  /* Try getting the outline metrics (only works for truetype fonts).  */
  len = get_outline_metrics_w (dc, 0, NULL);
  if (len)
    {
      metrics = (OUTLINETEXTMETRICW *) alloca (len);
      if (get_outline_metrics_w (dc, len, metrics))
        memcpy (&w32_font->metrics, &metrics->otmTextMetrics,
		sizeof (TEXTMETRICW));
      else
        metrics = NULL;
    }

  if (!metrics)