Re: Emacs 22.1 Windows ClearType Support

[Juanma Barranquero]

On Nov 22, 2007 4:51 PM, Ng, Andrew <anng@ptc.com> wrote:

> I have been having a go at fixing up the issues related to ClearType in
> Emacs 22.1.
>
> I think I have pretty much sorted out the major issues and everything
> appears to work fine now. I've tried as much as possible not to alter
> the non-ClearType code path.
>
> I've also added an environment variable "EMACS_CLEARTYPE". If present
> this will disable ClearType if its value is 0 and will enable ClearType
> if its value is non-zero. Otherwise, ClearType is enabled according to
> the system settings.
>
> I've attached a patch file for my changes.
>
> Thank you.
>
> Regards,
>
> Andrew Ng

Here's the patch, adapted to the current trunk.

             Juanma


Index: src/dispnew.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/dispnew.c,v
retrieving revision 1.398
diff -u -r1.398 dispnew.c
--- src/dispnew.c       21 Nov 2007 03:46:31 -0000      1.398
+++ src/dispnew.c       22 Nov 2007 21:27:53 -0000
@@ -4525,9 +4525,7 @@
                 taken care of by draw_glyphs.  */
              if (overlapping_glyphs_p
                  && i > 0
-                 && i < current_row->used[TEXT_AREA]
-                 && (current_row->used[TEXT_AREA]
-                     != desired_row->used[TEXT_AREA]))
+                 && i < current_row->used[TEXT_AREA])
                {
                  int left, right;

Index: src/w32fns.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/w32fns.c,v
retrieving revision 1.307
diff -u -r1.307 w32fns.c
--- src/w32fns.c        14 Nov 2007 17:33:36 -0000      1.307
+++ src/w32fns.c        22 Nov 2007 21:23:32 -0000
@@ -4571,6 +4571,8 @@
     int codepage;
     int i;

+    const char *env;
+
     if (!fontname || !x_to_w32_font (fontname, &lf))
       return (NULL);

@@ -4582,7 +4584,12 @@
            ended up with. */
       return NULL;

-    lf.lfQuality = DEFAULT_QUALITY;
+#ifndef CLEARTYPE_QUALITY
+#define CLEARTYPE_QUALITY 5
+#endif
+
+    env = getenv ("EMACS_CLEARTYPE");
+    lf.lfQuality = env ? (atoi (env) ? CLEARTYPE_QUALITY :
ANTIALIASED_QUALITY) : DEFAULT_QUALITY;

     font = (XFontStruct *) xmalloc (sizeof (XFontStruct));
     bzero (font, sizeof (*font));
Index: src/w32term.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/w32term.c,v
retrieving revision 1.276
diff -u -r1.276 w32term.c
--- src/w32term.c       9 Nov 2007 12:19:55 -0000       1.276
+++ src/w32term.c       22 Nov 2007 21:33:15 -0000
@@ -948,7 +948,7 @@
 #endif
          if (cleartype_active)
            {
-             /* Cleartype antialiasing causes characters to overhang
+             /* Cleartype antialiasing can cause characters to overhang
                 by a pixel on each side compared with what GetCharABCWidths
                 reports.  */
              char_widths.abcA -= 1;
@@ -1086,7 +1086,8 @@
       if (((font->tm.tmPitchAndFamily & TMPF_FIXED_PITCH) != 0)
           /* Some fonts (eg DBCS fonts) are marked as fixed width even
              though they contain characters of different widths. */
-          || (font->tm.tmMaxCharWidth != font->tm.tmAveCharWidth))
+          || (font->tm.tmMaxCharWidth != font->tm.tmAveCharWidth)
+          || cleartype_active)
        {
          /* Font is not fixed pitch, so cache per_char info for the
              ASCII characters.  It would be much more work, and probably
@@ -1483,9 +1484,42 @@
 w32_compute_glyph_string_overhangs (s)
      struct glyph_string *s;
 {
-  /* TODO: Windows does not appear to have a method for
-     getting this info without getting the ABC widths for each
-     individual character and working it out manually. */
+  if (s->cmp == NULL
+      && s->first_glyph->type == CHAR_GLYPH
+      && s->nchars > 0)
+    {
+      XFontStruct *font = s->font;
+      const int    font_type = s->first_glyph->font_type;
+
+      wchar_t  *ws = s->char2b;
+      const int nc = s->nchars;
+      int       i, pos, mn, mx;
+      if (nc == 1)
+        {
+          XCharStruct *pcm = w32_per_char_metric (font, ws, font_type);
+
+          s->right_overhang = pcm->rbearing > pcm->width ?
pcm->rbearing - pcm->width : 0;
+          s->left_overhang  = pcm->lbearing < 0 ? -pcm->lbearing : 0;
+          return;
+        }
+
+      pos = mn = mx = 0;
+      for (i = 0; i < nc; ++i, ++ws)
+        {
+          XCharStruct *pcm = w32_per_char_metric (font, ws, font_type);
+
+          const int rp = pos + pcm->rbearing;
+          const int lp = pos + pcm->lbearing;
+
+          if (rp > mx) mx = rp;
+          if (lp < mn) mn = lp;
+
+          pos += pcm->width;
+        }
+
+      s->right_overhang = mx > pos ? mx - pos : 0;
+      s->left_overhang  = mn < 0 ? -mn : 0;
+    }
 }


@@ -1582,7 +1616,7 @@
 x_draw_glyph_string_foreground (s)
      struct glyph_string *s;
 {
-  int i, x;
+  int i, x, ct_clear = 0;
   HFONT old_font;

   /* If first glyph of S has a left box line, start drawing the text
@@ -1595,6 +1629,11 @@

   if (s->for_overlaps || (s->background_filled_p && s->hl != DRAW_CURSOR))
     SetBkMode (s->hdc, TRANSPARENT);
+  else if (cleartype_active)
+    {
+      ct_clear = 1;
+      SetBkMode (s->hdc, TRANSPARENT);
+    }
   else
     SetBkMode (s->hdc, OPAQUE);

@@ -1632,6 +1671,21 @@
           char1b[i] = XCHAR2B_BYTE2 (&s->char2b[i]);

       /* Draw text with TextOut and friends. */
+      if (ct_clear)
+        {
+          HBRUSH hb;
+          RECT   r;
+
+          r.left = x;
+          r.top  = s->y;
+          r.right  = x + s->background_width;
+          r.bottom = s->y + s->height;
+
+          hb = CreateSolidBrush (s->gc->background);
+          FillRect (s->hdc, &r, hb);
+          DeleteObject (hb);
+        }
+
       w32_text_out (s, x, s->ybase - boff, s->char2b, s->nchars);

       if (s->face->overstrike)
@@ -6292,7 +6346,7 @@
   w32_destroy_fringe_bitmap,
   w32_per_char_metric,
   w32_encode_char,
-  NULL, /* w32_compute_glyph_string_overhangs */
+  w32_compute_glyph_string_overhangs,
   x_draw_glyph_string,
   w32_define_frame_cursor,
   w32_clear_frame_area,
@@ -6592,6 +6646,8 @@
     UINT smoothing_type;
     BOOL smoothing_enabled;

+    const char *env;
+
     /* If using proportional scroll bars, ensure handle is at least 5 pixels;
        otherwise use the fixed height.  */
     vertical_scroll_bar_min_handle = 5;
@@ -6617,11 +6673,13 @@
        the char metric calculations which adds extra pixels to
        compensate for the "sub-pixels" that are not counted by the
        system APIs. */
+    env = getenv ("EMACS_CLEARTYPE");
     cleartype_active =
-      SystemParametersInfo (SPI_GETFONTSMOOTHING, 0, &smoothing_enabled, 0)
-      && smoothing_enabled
-      && SystemParametersInfo (SPI_GETFONTSMOOTHINGTYPE, 0, &smoothing_type, 0)
-      && smoothing_type == FE_FONTSMOOTHINGCLEARTYPE;
+      env ? (atoi (env) != 0) :
+      (SystemParametersInfo (SPI_GETFONTSMOOTHING, 0, &smoothing_enabled, 0)
+       && smoothing_enabled
+       && SystemParametersInfo (SPI_GETFONTSMOOTHINGTYPE, 0,
&smoothing_type, 0)
+       && smoothing_type == FE_FONTSMOOTHINGCLEARTYPE);
   }
 }