Add su[pport for symbol fonts

Adds FC_SYMBOL.

This affects fonts having a cmap with platform 3 encoding 0.
We now map their glyphs from the PUA area to the Latin1 area.

See thread "Webdings and other MS symbol fonts don't display"
on the mailing list.

Test before/after with:
$ pango-view --markup --text='<span fallback="false">&#xd7;&#xf0d7;</span>' --font=Wingdings

doc/fontconfig-devel.sgml

@@ -177,6 +177,7 @@ convenience for the application's rendering mechanism.
     scalable       FC_SCALABLE            Bool    Whether glyphs can be scaled
     scale          FC_SCALE               Double  Scale factor for point->pixel
                                                   conversions (deprecated)
+    symbol         FC_SYMBOL              Bool    Whether font uses MS symbol-font encoding
     color          FC_COLOR               Bool    Whether any glyphs have color
     dpi            FC_DPI                 Double  Target dots per inch
     rgba           FC_RGBA                Int     unknown, rgb, bgr, vrgb,

fontconfig/fontconfig.h

@@ -96,6 +96,7 @@ typedef int		FcBool;
 #define FC_SCALABLE	    "scalable"		/* Bool */
 #define FC_COLOR	    "color"		/* Bool */
 #define FC_SCALE	    "scale"		/* double (deprecated) */
+#define FC_SYMBOL	    "symbol"		/* Bool */
 #define FC_DPI		    "dpi"		/* double */
 #define FC_RGBA		    "rgba"		/* Int */
 #define FC_MINSPACE	    "minspace"		/* Bool use minimum line spacing */

src/fcdefault.c

@@ -38,6 +38,7 @@ static const struct {
     { FC_GLOBAL_ADVANCE_OBJECT,    FcTrue	},  /* !FC_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH */
     { FC_EMBEDDED_BITMAP_OBJECT,   FcTrue 	},  /* !FC_LOAD_NO_BITMAP */
     { FC_DECORATIVE_OBJECT,	   FcFalse	},
+    { FC_SYMBOL_OBJECT,		   FcFalse	},
 };
 
 #define NUM_FC_BOOL_DEFAULTS	(int) (sizeof FcBoolDefaults / sizeof FcBoolDefaults[0])

src/fcfreetype.c

@@ -1201,6 +1201,8 @@ FcFreeTypeQueryFace (const FT_Face  face,
     FcRange	    *r = NULL;
     double	    lower_size = 0.0L, upper_size = DBL_MAX;
 
+    FcBool	    symbol = FcFalse;
+
     FcInitDebug (); /* We might be called with no initizalization whatsoever. */
 
     pat = FcPatternCreate ();
@@ -1803,6 +1805,11 @@ FcFreeTypeQueryFace (const FT_Face  face,
     if (!cs)
 	goto bail1;
 
+    /* The FcFreeTypeCharSetAndSpacing() chose the encoding; test it for symbol. */
+    symbol = face->charmap && face->charmap->encoding == FT_ENCODING_MS_SYMBOL;
+    if (!FcPatternAddBool (pat, FC_SYMBOL, symbol))
+	goto bail1;
+
 #if HAVE_FT_GET_BDF_PROPERTY
     /* For PCF fonts, override the computed spacing with the one from
        the property */
@@ -1835,9 +1842,18 @@ FcFreeTypeQueryFace (const FT_Face  face,
     if (!FcPatternAddCharSet (pat, FC_CHARSET, cs))
 	goto bail2;
 
-    ls = FcFreeTypeLangSet (cs, exclusiveLang);
-    if (!ls)
-	goto bail2;
+    if (!symbol)
+    {
+	ls = FcFreeTypeLangSet (cs, exclusiveLang);
+	if (!ls)
+	    goto bail2;
+    }
+    else
+    {
+	/* Symbol fonts don't cover any language, even though they
+	 * claim to support Latin1 range. */
+	ls = FcLangSetCreate ();
+    }
 
     if (!FcPatternAddLangSet (pat, FC_LANG, ls))
     {
@@ -2093,6 +2109,22 @@ FcFreeTypeCharIndex (FT_Face face, FcChar32 ucs4)
 	glyphindex = FT_Get_Char_Index (face, (FT_ULong) ucs4);
 	if (glyphindex)
 	    return glyphindex;
+	if (ucs4 < 0x100 && face->charmap &&
+	    face->charmap->encoding == FT_ENCODING_MS_SYMBOL)
+	{
+	    /* For symbol-encoded OpenType fonts, we duplicate the
+	     * U+F000..F0FF range at U+0000..U+00FF.  That's what
+	     * Windows seems to do, and that's hinted about at:
+	     * http://www.microsoft.com/typography/otspec/recom.htm
+	     * under "Non-Standard (Symbol) Fonts".
+	     *
+	     * See thread with subject "Webdings and other MS symbol
+	     * fonts don't display" on mailing list from May 2015.
+	     */
+	    glyphindex = FT_Get_Char_Index (face, (FT_ULong) ucs4 + 0xF000);
+	    if (glyphindex)
+		return glyphindex;
+	}
     }
 #if HAVE_FT_HAS_PS_GLYPH_NAMES
     /*
@@ -2253,6 +2285,23 @@ FcFreeTypeCharSetAndSpacingForSize (FT_Face face, FcBlanks *blanks, int *spacing
 		}
 		ucs4 = FT_Get_Next_Char (face, ucs4, &glyph);
 	    }
+	    if (fcFontEncodings[o] == FT_ENCODING_MS_SYMBOL)
+	    {
+		/* For symbol-encoded OpenType fonts, we duplicate the
+		 * U+F000..F0FF range at U+0000..U+00FF.  That's what
+		 * Windows seems to do, and that's hinted about at:
+		 * http://www.microsoft.com/typography/otspec/recom.htm
+		 * under "Non-Standard (Symbol) Fonts".
+		 *
+		 * See thread with subject "Webdings and other MS symbol
+		 * fonts don't display" on mailing list from May 2015.
+		 */
+		for (ucs4 = 0xF000; ucs4 < 0xF100; ucs4++)
+		{
+		    if (FcCharSetHasChar (fcs, ucs4))
+			FcCharSetAddChar (fcs, ucs4 - 0xF000);
+		}
+	    }
 #ifdef CHECK
 	    for (ucs4 = 0; ucs4 < 0x10000; ucs4++)
 	    {
@@ -2267,6 +2316,8 @@ FcFreeTypeCharSetAndSpacingForSize (FT_Face face, FcBlanks *blanks, int *spacing
 	    }
 #endif
 	}
+
+       break;
     }
 #if HAVE_FT_HAS_PS_GLYPH_NAMES
     /*

src/fcmatch.c

@@ -292,6 +292,7 @@ typedef enum _FcMatcherPriority {
     PRI1(LANG),
     PRI_FAMILY_WEAK,
     PRI_POSTSCRIPT_NAME_WEAK,
+    PRI1(SYMBOL),
     PRI1(SPACING),
     PRI1(SIZE),
     PRI1(PIXEL_SIZE),

src/fcobjs.h

@@ -69,4 +69,5 @@ FC_OBJECT (PRGNAME,		FcTypeString,	NULL)
 FC_OBJECT (HASH,		FcTypeString,	NULL)	/* deprecated */
 FC_OBJECT (POSTSCRIPT_NAME,	FcTypeString,	FcComparePostScript)
 FC_OBJECT (COLOR,		FcTypeBool,	FcCompareBool)
+FC_OBJECT (SYMBOL,		FcTypeBool,	FcCompareBool)
 /* ^-------------- Add new objects here. */