gecko-dev/gfx/thebes/src/gfxFontUtils.cpp

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is thebes gfx code.
 *
 * The Initial Developer of the Original Code is Mozilla Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2007
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Stuart Parmenter <stuart@mozilla.com>
 *   John Daggett <jdaggett@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "gfxFontUtils.h"

#include "nsIPref.h"  // for pref handling code
#include "nsServiceManagerUtils.h"

#include "nsIPrefBranch.h"
#include "nsIPrefService.h"
#include "nsIPrefLocalizedString.h"
#include "nsISupportsPrimitives.h"

#define NO_RANGE_FOUND 126 // bit 126 in the font unicode ranges is required to be 0

/* Unicode subrange table
 *   from: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/intl/unicode_63ub.asp
 *
 * Use something like:
 * perl -pi -e 's/^(\d+)\s+([\dA-Fa-f]+)\s+-\s+([\dA-Fa-f]+)\s+\b(.*)/    { \1, 0x\2, 0x\3,\"\4\" },/' < unicoderanges.txt
 * to generate the below list.
 */
struct UnicodeRangeTableEntry
{
    PRUint8 bit;
    PRUint32 start;
    PRUint32 end;
    const char *info;
};

static const struct UnicodeRangeTableEntry gUnicodeRanges[] = {
    { 0, 0x0000, 0x007F, "Basic Latin" },
    { 1, 0x0080, 0x00FF, "Latin-1 Supplement" },
    { 2, 0x0100, 0x017F, "Latin Extended-A" },
    { 3, 0x0180, 0x024F, "Latin Extended-B" },
    { 4, 0x0250, 0x02AF, "IPA Extensions" },
    { 4, 0x1D00, 0x1D7F, "Phonetic Extensions" },
    { 4, 0x1D80, 0x1DBF, "Phonetic Extensions Supplement" },
    { 5, 0x02B0, 0x02FF, "Spacing Modifier Letters" },
    { 5, 0xA700, 0xA71F, "Modifier Tone Letters" },
    { 6, 0x0300, 0x036F, "Spacing Modifier Letters" },
    { 6, 0x1DC0, 0x1DFF, "Combining Diacritical Marks Supplement" },
    { 7, 0x0370, 0x03FF, "Greek and Coptic" },
    { 8, 0x2C80, 0x2CFF, "Coptic" },
    { 9, 0x0400, 0x04FF, "Cyrillic" },
    { 9, 0x0500, 0x052F, "Cyrillic Supplementary" },
    { 10, 0x0530, 0x058F, "Armenian" },
    { 11, 0x0590, 0x05FF, "Basic Hebrew" },
    /* 12 - reserved */
    { 13, 0x0600, 0x06FF, "Basic Arabic" },
    { 13, 0x0750, 0x077F, "Arabic Supplement" },
    { 14, 0x07C0, 0x07FF, "N'Ko" },
    { 15, 0x0900, 0x097F, "Devanagari" },
    { 16, 0x0980, 0x09FF, "Bengali" },
    { 17, 0x0A00, 0x0A7F, "Gurmukhi" },
    { 18, 0x0A80, 0x0AFF, "Gujarati" },
    { 19, 0x0B00, 0x0B7F, "Oriya" },
    { 20, 0x0B80, 0x0BFF, "Tamil" },
    { 21, 0x0C00, 0x0C7F, "Telugu" },
    { 22, 0x0C80, 0x0CFF, "Kannada" },
    { 23, 0x0D00, 0x0D7F, "Malayalam" },
    { 24, 0x0E00, 0x0E7F, "Thai" },
    { 25, 0x0E80, 0x0EFF, "Lao" },
    { 26, 0x10A0, 0x10FF, "Georgian" },
    { 26, 0x2D00, 0x2D2F, "Georgian Supplement" },
    { 27, 0x1B00, 0x1B7F, "Balinese" },
    { 28, 0x1100, 0x11FF, "Hangul Jamo" },
    { 29, 0x1E00, 0x1EFF, "Latin Extended Additional" },
    { 29, 0x2C60, 0x2C7F, "Latin Extended-C" },
    { 30, 0x1F00, 0x1FFF, "Greek Extended" },
    { 31, 0x2000, 0x206F, "General Punctuation" },
    { 31, 0x2E00, 0x2E7F, "Supplemental Punctuation" },
    { 32, 0x2070, 0x209F, "Subscripts and Superscripts" },
    { 33, 0x20A0, 0x20CF, "Currency Symbols" },
    { 34, 0x20D0, 0x20FF, "Combining Diacritical Marks for Symbols" },
    { 35, 0x2100, 0x214F, "Letter-like Symbols" },
    { 36, 0x2150, 0x218F, "Number Forms" },
    { 37, 0x2190, 0x21FF, "Arrows" },
    { 37, 0x27F0, 0x27FF, "Supplemental Arrows-A" },
    { 37, 0x2900, 0x297F, "Supplemental Arrows-B" },
    { 37, 0x2B00, 0x2BFF, "Miscellaneous Symbols and Arrows" },
    { 38, 0x2200, 0x22FF, "Mathematical Operators" },
    { 38, 0x27C0, 0x27EF, "Miscellaneous Mathematical Symbols-A" },
    { 38, 0x2980, 0x29FF, "Miscellaneous Mathematical Symbols-B" },
    { 38, 0x2A00, 0x2AFF, "Supplemental Mathematical Operators" },
    { 39, 0x2300, 0x23FF, "Miscellaneous Technical" },
    { 40, 0x2400, 0x243F, "Control Pictures" },
    { 41, 0x2440, 0x245F, "Optical Character Recognition" },
    { 42, 0x2460, 0x24FF, "Enclosed Alphanumerics" },
    { 43, 0x2500, 0x257F, "Box Drawing" },
    { 44, 0x2580, 0x259F, "Block Elements" },
    { 45, 0x25A0, 0x25FF, "Geometric Shapes" },
    { 46, 0x2600, 0x26FF, "Miscellaneous Symbols" },
    { 47, 0x2700, 0x27BF, "Dingbats" },
    { 48, 0x3000, 0x303F, "Chinese, Japanese, and Korean (CJK) Symbols and Punctuation" },
    { 49, 0x3040, 0x309F, "Hiragana" },
    { 50, 0x30A0, 0x30FF, "Katakana" },
    { 50, 0x31F0, 0x31FF, "Katakana Phonetic Extensions" },
    { 51, 0x3100, 0x312F, "Bopomofo" },
    { 51, 0x31A0, 0x31BF, "Extended Bopomofo" },
    { 52, 0x3130, 0x318F, "Hangul Compatibility Jamo" },
    { 53, 0xA840, 0xA87F, "Phags-pa" },
    { 54, 0x3200, 0x32FF, "Enclosed CJK Letters and Months" },
    { 55, 0x3300, 0x33FF, "CJK Compatibility" },
    { 56, 0xAC00, 0xD7A3, "Hangul" },
    { 57, 0xD800, 0xDFFF, "Surrogates. Note that setting this bit implies that there is at least one supplementary code point beyond the Basic Multilingual Plane (BMP) that is supported by this font. See Surrogates and Supplementary Characters." },
    { 58, 0x10900, 0x1091F, "Phoenician" },
    { 59, 0x2E80, 0x2EFF, "CJK Radicals Supplement" },
    { 59, 0x2F00, 0x2FDF, "Kangxi Radicals" },
    { 59, 0x2FF0, 0x2FFF, "Ideographic Description Characters" },
    { 59, 0x3190, 0x319F, "Kanbun" },
    { 59, 0x3400, 0x4DBF, "CJK Unified Ideographs Extension A" },
    { 59, 0x4E00, 0x9FFF, "CJK Unified Ideographs" },
    { 59, 0x20000, 0x2A6DF, "CJK Unified Ideographs Extension B" },
    { 60, 0xE000, 0xF8FF, "Private Use (Plane 0)" },
    { 61, 0x31C0, 0x31EF, "CJK Base Strokes" },
    { 61, 0xF900, 0xFAFF, "CJK Compatibility Ideographs" },
    { 61, 0x2F800, 0x2FA1F, "CJK Compatibility Ideographs Supplement" },
    { 62, 0xFB00, 0xFB4F, "Alphabetical Presentation Forms" },
    { 63, 0xFB50, 0xFDFF, "Arabic Presentation Forms-A" },
    { 64, 0xFE20, 0xFE2F, "Combining Half Marks" },
    { 65, 0xFE10, 0xFE1F, "Vertical Forms" },
    { 65, 0xFE30, 0xFE4F, "CJK Compatibility Forms" },
    { 66, 0xFE50, 0xFE6F, "Small Form Variants" },
    { 67, 0xFE70, 0xFEFE, "Arabic Presentation Forms-B" },
    { 68, 0xFF00, 0xFFEF, "Halfwidth and Fullwidth Forms" },
    { 69, 0xFFF0, 0xFFFF, "Specials" },
    { 70, 0x0F00, 0x0FFF, "Tibetan" },
    { 71, 0x0700, 0x074F, "Syriac" },
    { 72, 0x0780, 0x07BF, "Thaana" },
    { 73, 0x0D80, 0x0DFF, "Sinhala" },
    { 74, 0x1000, 0x109F, "Myanmar" },
    { 75, 0x1200, 0x137F, "Ethiopic" },
    { 75, 0x1380, 0x139F, "Ethiopic Supplement" },
    { 75, 0x2D80, 0x2DDF, "Ethiopic Extended" },
    { 76, 0x13A0, 0x13FF, "Cherokee" },
    { 77, 0x1400, 0x167F, "Canadian Aboriginal Syllabics" },
    { 78, 0x1680, 0x169F, "Ogham" },
    { 79, 0x16A0, 0x16FF, "Runic" },
    { 80, 0x1780, 0x17FF, "Khmer" },
    { 80, 0x19E0, 0x19FF, "Khmer Symbols" },
    { 81, 0x1800, 0x18AF, "Mongolian" },
    { 82, 0x2800, 0x28FF, "Braille" },
    { 83, 0xA000, 0xA48F, "Yi" },
    { 83, 0xA490, 0xA4CF, "Yi Radicals" },
    { 84, 0x1700, 0x171F, "Tagalog" },
    { 84, 0x1720, 0x173F, "Hanunoo" },
    { 84, 0x1740, 0x175F, "Buhid" },
    { 84, 0x1760, 0x177F, "Tagbanwa" },
    { 85, 0x10300, 0x1032F, "Old Italic" },
    { 86, 0x10330, 0x1034F, "Gothic" },
    { 87, 0x10440, 0x1044F, "Deseret" },
    { 88, 0x1D000, 0x1D0FF, "Byzantine Musical Symbols" },
    { 88, 0x1D100, 0x1D1FF, "Musical Symbols" },
    { 88, 0x1D200, 0x1D24F, "Ancient Greek Musical Notation" },
    { 89, 0x1D400, 0x1D7FF, "Mathematical Alphanumeric Symbols" },
    { 90, 0xFF000, 0xFFFFD, "Private Use (Plane 15)" },
    { 90, 0x100000, 0x10FFFD, "Private Use (Plane 16)" },
    { 91, 0xFE00, 0xFE0F, "Variation Selectors" },
    { 91, 0xE0100, 0xE01EF, "Variation Selectors Supplement" },
    { 92, 0xE0000, 0xE007F, "Tags" },
    { 93, 0x1900, 0x194F, "Limbu" },
    { 94, 0x1950, 0x197F, "Tai Le" },
    { 95, 0x1980, 0x19DF, "New Tai Lue" },
    { 96, 0x1A00, 0x1A1F, "Buginese" },
    { 97, 0x2C00, 0x2C5F, "Glagolitic" },
    { 98, 0x2D40, 0x2D7F, "Tifinagh" },
    { 99, 0x4DC0, 0x4DFF, "Yijing Hexagram Symbols" },
    { 100, 0xA800, 0xA82F, "Syloti Nagri" },
    { 101, 0x10000, 0x1007F, "Linear B Syllabary" },
    { 101, 0x10080, 0x100FF, "Linear B Ideograms" },
    { 101, 0x10100, 0x1013F, "Aegean Numbers" },
    { 102, 0x10140, 0x1018F, "Ancient Greek Numbers" },
    { 103, 0x10380, 0x1039F, "Ugaritic" },
    { 104, 0x103A0, 0x103DF, "Old Persian" },
    { 105, 0x10450, 0x1047F, "Shavian" },
    { 106, 0x10480, 0x104AF, "Osmanya" },
    { 107, 0x10800, 0x1083F, "Cypriot Syllabary" },
    { 108, 0x10A00, 0x10A5F, "Kharoshthi" },
    { 109, 0x1D300, 0x1D35F, "Tai Xuan Jing Symbols" },
    { 110, 0x12000, 0x123FF, "Cuneiform" },
    { 110, 0x12400, 0x1247F, "Cuneiform Numbers and Punctuation" },
    { 111, 0x1D360, 0x1D37F, "Counting Rod Numerals" }
};


nsresult
gfxFontUtils::ReadCMAPTableFormat12(PRUint8 *aBuf, PRInt32 aLength, gfxSparseBitSet& aCharacterMap) 
{
    enum {
        OffsetFormat = 0,
        OffsetReserved = 2,
        OffsetTableLength = 4,
        OffsetLanguage = 8,
        OffsetNumberGroups = 12,
        OffsetGroups = 16,

        SizeOfGroup = 12,

        GroupOffsetStartCode = 0,
        GroupOffsetEndCode = 4
    };
    NS_ENSURE_TRUE(aLength >= 16, NS_ERROR_FAILURE);

    NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetFormat) == 12, NS_ERROR_FAILURE);
    NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetReserved) == 0, NS_ERROR_FAILURE);

    PRUint32 tablelen = ReadLongAt(aBuf, OffsetTableLength);
    NS_ENSURE_TRUE(tablelen <= aLength, NS_ERROR_FAILURE);
    NS_ENSURE_TRUE(tablelen >= 16, NS_ERROR_FAILURE);

    NS_ENSURE_TRUE(ReadLongAt(aBuf, OffsetLanguage) == 0, NS_ERROR_FAILURE);

    const PRUint32 numGroups  = ReadLongAt(aBuf, OffsetNumberGroups);
    NS_ENSURE_TRUE(tablelen >= 16 + (12 * numGroups), NS_ERROR_FAILURE);

    const PRUint8 *groups = aBuf + OffsetGroups;
    for (PRUint32 i = 0; i < numGroups; i++, groups += SizeOfGroup) {
        const PRUint32 startCharCode = ReadLongAt(groups, GroupOffsetStartCode);
        const PRUint32 endCharCode = ReadLongAt(groups, GroupOffsetEndCode);
        aCharacterMap.SetRange(startCharCode, endCharCode);
    }

    return NS_OK;
}

nsresult 
gfxFontUtils::ReadCMAPTableFormat4(PRUint8 *aBuf, PRInt32 aLength, gfxSparseBitSet& aCharacterMap)
{
    enum {
        OffsetFormat = 0,
        OffsetLength = 2,
        OffsetLanguage = 4,
        OffsetSegCountX2 = 6
    };

    NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetFormat) == 4, NS_ERROR_FAILURE);
    PRUint16 tablelen = ReadShortAt(aBuf, OffsetLength);
    NS_ENSURE_TRUE(tablelen <= aLength, NS_ERROR_FAILURE);
    NS_ENSURE_TRUE(tablelen > 16, NS_ERROR_FAILURE);
    
    // some buggy fonts on Mac OS report lang = English (e.g. Arial Narrow Bold, v. 1.1 (Tiger))
#if defined(XP_WIN)
    NS_ENSURE_TRUE(ReadShortAt(aBuf, OffsetLanguage) == 0, NS_ERROR_FAILURE);
#endif

    PRUint16 segCountX2 = ReadShortAt(aBuf, OffsetSegCountX2);
    NS_ENSURE_TRUE(tablelen >= 16 + (segCountX2 * 4), NS_ERROR_FAILURE);

    const PRUint16 segCount = segCountX2 / 2;

    const PRUint16 *endCounts = (PRUint16*)(aBuf + 14);
    const PRUint16 *startCounts = endCounts + 1 /* skip one uint16 for reservedPad */ + segCount;
    const PRUint16 *idDeltas = startCounts + segCount;
    const PRUint16 *idRangeOffsets = idDeltas + segCount;
    for (PRUint16 i = 0; i < segCount; i++) {
        const PRUint16 endCount = ReadShortAt16(endCounts, i);
        const PRUint16 startCount = ReadShortAt16(startCounts, i);
        const PRUint16 idRangeOffset = ReadShortAt16(idRangeOffsets, i);
        if (idRangeOffset == 0) {
            aCharacterMap.SetRange(startCount, endCount);
        } else {
            const PRUint16 idDelta = ReadShortAt16(idDeltas, i);
            for (PRUint32 c = startCount; c <= endCount; ++c) {
                if (c == 0xFFFF)
                    break;

                const PRUint16 *gdata = (idRangeOffset/2 
                                         + (c - startCount)
                                         + &idRangeOffsets[i]);

                NS_ENSURE_TRUE((PRUint8*)gdata > aBuf && (PRUint8*)gdata < aBuf + aLength, NS_ERROR_FAILURE);

                // make sure we have a glyph
                if (*gdata != 0) {
                    // The glyph index at this point is:
                    // glyph = (ReadShortAt16(idDeltas, i) + *gdata) % 65536;

                    aCharacterMap.set(c);
                }
            }
        }
    }

    return NS_OK;
}

// Windows requires fonts to have a format-4 cmap with a Microsoft ID (3).  On the Mac, fonts either have
// a format-4 cmap with Microsoft platform/encoding id or they have one with a platformID == Unicode (0)
// For fonts with two format-4 tables, the first one (Unicode platform) is preferred on the Mac.

#if defined(XP_MACOSX)
    #define acceptablePlatform(p)       ((p) == PlatformIDUnicode || (p) == PlatformIDMicrosoft)
    #define acceptableFormat4(p,e,k)      ( ((p) == PlatformIDMicrosoft && (e) == EncodingIDMicrosoft && (k) != 4) || \
                                            ((p) == PlatformIDUnicode) )
    #define isSymbol(p,e)               ((p) == PlatformIDMicrosoft && (e) == EncodingIDSymbol)
#else
    #define acceptablePlatform(p)       ((p) == PlatformIDMicrosoft)
    #define acceptableFormat4(p,e,k)      ((e) == EncodingIDMicrosoft)
    #define isSymbol(p,e)               ((e) == EncodingIDSymbol)
#endif

#define acceptableUCS4Encoding(p, e) \
    ((platformID == PlatformIDMicrosoft && encodingID == EncodingIDUCS4ForMicrosoftPlatform) || \
     (platformID == PlatformIDUnicode   && encodingID == EncodingIDUCS4ForUnicodePlatform))

nsresult
gfxFontUtils::ReadCMAP(PRUint8 *aBuf, PRUint32 aBufLength, gfxSparseBitSet& aCharacterMap, 
                       PRPackedBool& aUnicodeFont, PRPackedBool& aSymbolFont)
{
    enum {
        OffsetVersion = 0,
        OffsetNumTables = 2,
        SizeOfHeader = 4,

        TableOffsetPlatformID = 0,
        TableOffsetEncodingID = 2,
        TableOffsetOffset = 4,
        SizeOfTable = 8,

        SubtableOffsetFormat = 0
    };
    enum {
        PlatformIDUnicode = 0,
        PlatformIDMicrosoft = 3
    };
    enum {
        EncodingIDSymbol = 0,
        EncodingIDMicrosoft = 1,
        EncodingIDUCS4ForUnicodePlatform = 3,
        EncodingIDUCS4ForMicrosoftPlatform = 10
    };

    PRUint16 version = ReadShortAt(aBuf, OffsetVersion);
    PRUint16 numTables = ReadShortAt(aBuf, OffsetNumTables);

    // save the format and offset we want here
    PRUint32 keepOffset = 0;
    PRUint32 keepFormat = 0;

    PRUint8 *table = aBuf + SizeOfHeader;
    for (PRUint16 i = 0; i < numTables; ++i, table += SizeOfTable) {
        const PRUint16 platformID = ReadShortAt(table, TableOffsetPlatformID);
        if (!acceptablePlatform(platformID))
            continue;

        const PRUint16 encodingID = ReadShortAt(table, TableOffsetEncodingID);
        const PRUint32 offset = ReadLongAt(table, TableOffsetOffset);

        NS_ASSERTION(offset < aBufLength, "cmap table offset is longer than table size");
        NS_ENSURE_TRUE(offset < aBufLength, NS_ERROR_FAILURE);

        const PRUint8 *subtable = aBuf + offset;
        const PRUint16 format = ReadShortAt(subtable, SubtableOffsetFormat);

        if (isSymbol(platformID, encodingID)) {
            aUnicodeFont = PR_FALSE;
            aSymbolFont = PR_TRUE;
            keepFormat = format;
            keepOffset = offset;
            break;
        } else if (format == 4 && acceptableFormat4(platformID, encodingID, keepFormat)) {
            aUnicodeFont = PR_TRUE;
            aSymbolFont = PR_FALSE;
            keepFormat = format;
            keepOffset = offset;
        } else if (format == 12 && acceptableUCS4Encoding(platformID, encodingID)) {
            aUnicodeFont = PR_TRUE;
            aSymbolFont = PR_FALSE;
            keepFormat = format;
            keepOffset = offset;
            break; // we don't want to try anything else when this format is available.
        }
    }

    nsresult rv = NS_ERROR_FAILURE;

    if (keepFormat == 12)
        rv = ReadCMAPTableFormat12(aBuf + keepOffset, aBufLength - keepOffset, aCharacterMap);
    else if (keepFormat == 4)
        rv = ReadCMAPTableFormat4(aBuf + keepOffset, aBufLength - keepOffset, aCharacterMap);

    return rv;
}

PRUint8 gfxFontUtils::CharRangeBit(PRUint32 ch) {
    const PRUint32 n = sizeof(gUnicodeRanges) / sizeof(struct UnicodeRangeTableEntry);

    for (PRUint32 i = 0; i < n; ++i)
        if (ch >= gUnicodeRanges[i].start && ch <= gUnicodeRanges[i].end)
            return gUnicodeRanges[i].bit;

    return NO_RANGE_FOUND;
}

void gfxFontUtils::GetPrefsFontList(const char *aPrefName, nsTArray<nsString>& aFontList)
{
    const PRUnichar kComma = PRUnichar(',');
    
    aFontList.Clear();
    
    // get the list of single-face font families
    nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));

    nsAutoString fontlistValue;
    if (prefs) {
        nsCOMPtr<nsISupportsString> prefString;
        prefs->GetComplexValue(aPrefName, NS_GET_IID(nsISupportsString), getter_AddRefs(prefString));
        if (!prefString) 
            return;
        prefString->GetData(fontlistValue);
    }
    
    // append each font name to the list
    nsAutoString fontname;
    nsPromiseFlatString fonts(fontlistValue);
    const PRUnichar *p, *p_end;
    fonts.BeginReading(p);
    fonts.EndReading(p_end);

     while (p < p_end) {
        const PRUnichar *nameStart = p;
        while (++p != p_end && *p != kComma)
        /* nothing */ ;

        // pull out a single name and clean out leading/trailing whitespace        
        fontname = Substring(nameStart, p);
        fontname.CompressWhitespace(PR_TRUE, PR_TRUE);
        
        // append it to the list
        aFontList.AppendElement(fontname);
        ++p;
    }

}