Add HarfBuzz-to-Qt bridging code

Change-Id: I2f61566fe69d18b80d5831238beb27b34b7be1c8
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

4 files changed, 861 insertions, 0 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 9e6b8d6ffd..d561fcf823 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -48,6 +48,11 @@
 #include "qvarlengtharray.h"
 #include <qmath.h>
 #include <qendian.h>
+
+#ifdef QT_ENABLE_HARFBUZZ_NG
+#  include "qharfbuzzng_p.h"
+#  include <harfbuzz/hb-ot.h>
+#endif
 #include <private/qharfbuzz_p.h>
 
 #include <algorithm>
@@ -73,6 +78,10 @@ static inline bool qtransform_equals_no_translate(const QTransform &a, const QTr
 
 // Harfbuzz helper functions
 
+#ifdef QT_ENABLE_HARFBUZZ_NG
+bool useHarfbuzzNG = qgetenv("QT_HARFBUZZ") != "old";
+#endif
+
 Q_STATIC_ASSERT(sizeof(HB_Glyph) == sizeof(glyph_t));
 Q_STATIC_ASSERT(sizeof(HB_Fixed) == sizeof(QFixed));
 
@@ -253,6 +262,10 @@ QFixed QFontEngine::underlinePosition() const
 
 void *QFontEngine::harfbuzzFont() const
 {
+#ifdef QT_ENABLE_HARFBUZZ_NG
+    if (useHarfbuzzNG)
+        qFatal("Called QFontEngine::harfbuzzFont() in Harfbuzz-NG mode!");
+#endif
     if (!font_) {
         HB_FontRec *hbFont = (HB_FontRec *) malloc(sizeof(HB_FontRec));
         Q_CHECK_PTR(hbFont);
@@ -277,6 +290,10 @@ void *QFontEngine::harfbuzzFont() const
 
 void *QFontEngine::harfbuzzFace() const
 {
+#ifdef QT_ENABLE_HARFBUZZ_NG
+    if (useHarfbuzzNG)
+        qFatal("Called QFontEngine::harfbuzzFace() in Harfbuzz-NG mode!");
+#endif
     if (!face_) {
         HB_Face hbFace = qHBNewFace(const_cast<QFontEngine *>(this), hb_getSFntTable);
         Q_CHECK_PTR(hbFace);
@@ -292,6 +309,26 @@ void *QFontEngine::harfbuzzFace() const
 
 bool QFontEngine::supportsScript(QChar::Script script) const
 {
+#ifdef QT_ENABLE_HARFBUZZ_NG
+    if (useHarfbuzzNG) {
+        bool ret = false;
+        if (hb_face_t *face = hb_qt_face_get_for_engine(const_cast<QFontEngine *>(this))) {
+            hb_tag_t script_tag_1, script_tag_2;
+            hb_ot_tags_from_script(hb_qt_script_to_script(script), &script_tag_1, &script_tag_2);
+
+            unsigned int script_index = -1;
+            ret = hb_ot_layout_table_find_script(face, HB_OT_TAG_GSUB, script_tag_1, &script_index);
+            if (!ret) {
+                ret = hb_ot_layout_table_find_script(face, HB_OT_TAG_GSUB, script_tag_2, &script_index);
+                if (!ret && script_tag_2 != HB_OT_TAG_DEFAULT_SCRIPT)
+                    ret = hb_ot_layout_table_find_script(face, HB_OT_TAG_GSUB, HB_OT_TAG_DEFAULT_SCRIPT, &script_index);
+            }
+
+            hb_face_destroy(face);
+        }
+        return ret;
+    }
+#endif
     HB_Face hbFace = (HB_Face)harfbuzzFace();
     return hbFace->supported_scripts[script_to_hbscript(script)];
 }
diff --git a/src/gui/text/qharfbuzzng.cpp b/src/gui/text/qharfbuzzng.cpp
new file mode 100644
index 0000000000..96a1cff889
--- /dev/null
+++ b/src/gui/text/qharfbuzzng.cpp
@@ -0,0 +1,730 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2013 Konstantin Ritt
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qharfbuzzng_p.h"
+
+#include <qstring.h>
+#include <qvector.h>
+
+#include "qfontengine_p.h"
+
+QT_BEGIN_NAMESPACE
+
+// Unicode routines
+
+static const hb_script_t _qtscript_to_hbscript[] = {
+    HB_SCRIPT_UNKNOWN,
+    HB_SCRIPT_INHERITED,
+    HB_SCRIPT_COMMON,
+
+    HB_SCRIPT_LATIN,
+    HB_SCRIPT_GREEK,
+    HB_SCRIPT_CYRILLIC,
+    HB_SCRIPT_ARMENIAN,
+    HB_SCRIPT_HEBREW,
+    HB_SCRIPT_ARABIC,
+    HB_SCRIPT_SYRIAC,
+    HB_SCRIPT_THAANA,
+    HB_SCRIPT_DEVANAGARI,
+    HB_SCRIPT_BENGALI,
+    HB_SCRIPT_GURMUKHI,
+    HB_SCRIPT_GUJARATI,
+    HB_SCRIPT_ORIYA,
+    HB_SCRIPT_TAMIL,
+    HB_SCRIPT_TELUGU,
+    HB_SCRIPT_KANNADA,
+    HB_SCRIPT_MALAYALAM,
+    HB_SCRIPT_SINHALA,
+    HB_SCRIPT_THAI,
+    HB_SCRIPT_LAO,
+    HB_SCRIPT_TIBETAN,
+    HB_SCRIPT_MYANMAR,
+    HB_SCRIPT_GEORGIAN,
+    HB_SCRIPT_HANGUL,
+    HB_SCRIPT_ETHIOPIC,
+    HB_SCRIPT_CHEROKEE,
+    HB_SCRIPT_CANADIAN_ABORIGINAL,
+    HB_SCRIPT_OGHAM,
+    HB_SCRIPT_RUNIC,
+    HB_SCRIPT_KHMER,
+    HB_SCRIPT_MONGOLIAN,
+    HB_SCRIPT_HIRAGANA,
+    HB_SCRIPT_KATAKANA,
+    HB_SCRIPT_BOPOMOFO,
+    HB_SCRIPT_HAN,
+    HB_SCRIPT_YI,
+    HB_SCRIPT_OLD_ITALIC,
+    HB_SCRIPT_GOTHIC,
+    HB_SCRIPT_DESERET,
+    HB_SCRIPT_TAGALOG,
+    HB_SCRIPT_HANUNOO,
+    HB_SCRIPT_BUHID,
+    HB_SCRIPT_TAGBANWA,
+    HB_SCRIPT_COPTIC,
+    HB_SCRIPT_LIMBU,
+    HB_SCRIPT_TAI_LE,
+    HB_SCRIPT_LINEAR_B,
+    HB_SCRIPT_UGARITIC,
+    HB_SCRIPT_SHAVIAN,
+    HB_SCRIPT_OSMANYA,
+    HB_SCRIPT_CYPRIOT,
+    HB_SCRIPT_BRAILLE,
+    HB_SCRIPT_BUGINESE,
+    HB_SCRIPT_NEW_TAI_LUE,
+    HB_SCRIPT_GLAGOLITIC,
+    HB_SCRIPT_TIFINAGH,
+    HB_SCRIPT_SYLOTI_NAGRI,
+    HB_SCRIPT_OLD_PERSIAN,
+    HB_SCRIPT_KHAROSHTHI,
+    HB_SCRIPT_BALINESE,
+    HB_SCRIPT_CUNEIFORM,
+    HB_SCRIPT_PHOENICIAN,
+    HB_SCRIPT_PHAGS_PA,
+    HB_SCRIPT_NKO,
+    HB_SCRIPT_SUNDANESE,
+    HB_SCRIPT_LEPCHA,
+    HB_SCRIPT_OL_CHIKI,
+    HB_SCRIPT_VAI,
+    HB_SCRIPT_SAURASHTRA,
+    HB_SCRIPT_KAYAH_LI,
+    HB_SCRIPT_REJANG,
+    HB_SCRIPT_LYCIAN,
+    HB_SCRIPT_CARIAN,
+    HB_SCRIPT_LYDIAN,
+    HB_SCRIPT_CHAM,
+    HB_SCRIPT_TAI_THAM,
+    HB_SCRIPT_TAI_VIET,
+    HB_SCRIPT_AVESTAN,
+    HB_SCRIPT_EGYPTIAN_HIEROGLYPHS,
+    HB_SCRIPT_SAMARITAN,
+    HB_SCRIPT_LISU,
+    HB_SCRIPT_BAMUM,
+    HB_SCRIPT_JAVANESE,
+    HB_SCRIPT_MEETEI_MAYEK,
+    HB_SCRIPT_IMPERIAL_ARAMAIC,
+    HB_SCRIPT_OLD_SOUTH_ARABIAN,
+    HB_SCRIPT_INSCRIPTIONAL_PARTHIAN,
+    HB_SCRIPT_INSCRIPTIONAL_PAHLAVI,
+    HB_SCRIPT_OLD_TURKIC,
+    HB_SCRIPT_KAITHI,
+    HB_SCRIPT_BATAK,
+    HB_SCRIPT_BRAHMI,
+    HB_SCRIPT_MANDAIC,
+    HB_SCRIPT_CHAKMA,
+    HB_SCRIPT_MEROITIC_CURSIVE,
+    HB_SCRIPT_MEROITIC_HIEROGLYPHS,
+    HB_SCRIPT_MIAO,
+    HB_SCRIPT_SHARADA,
+    HB_SCRIPT_SORA_SOMPENG,
+    HB_SCRIPT_TAKRI
+};
+Q_STATIC_ASSERT(QChar::ScriptCount == sizeof(_qtscript_to_hbscript) / sizeof(_qtscript_to_hbscript[0]));
+
+hb_script_t hb_qt_script_to_script(QChar::Script script)
+{
+    return _qtscript_to_hbscript[script];
+}
+
+QChar::Script hb_qt_script_from_script(hb_script_t script)
+{
+    uint i = QChar::ScriptCount - 1;
+    while (i > QChar::Script_Unknown && _qtscript_to_hbscript[i] != script)
+        --i;
+    return QChar::Script(i);
+}
+
+
+static hb_unicode_combining_class_t
+_hb_qt_unicode_combining_class(hb_unicode_funcs_t * /*ufuncs*/,
+                               hb_codepoint_t unicode,
+                               void * /*user_data*/)
+{
+    return hb_unicode_combining_class_t(QChar::combiningClass(unicode));
+}
+
+static unsigned int
+_hb_qt_unicode_eastasian_width(hb_unicode_funcs_t * /*ufuncs*/,
+                               hb_codepoint_t /*unicode*/,
+                               void * /*user_data*/)
+{
+    qCritical("hb_qt_unicode_eastasian_width: not implemented!");
+    return 1;
+}
+
+static const hb_unicode_general_category_t _qtcategory_to_hbcategory[] = {
+    HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK,    //   Mn
+    HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK,        //   Mc
+    HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK,      //   Me
+
+    HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER,      //   Nd
+    HB_UNICODE_GENERAL_CATEGORY_LETTER_NUMBER,       //   Nl
+    HB_UNICODE_GENERAL_CATEGORY_OTHER_NUMBER,        //   No
+
+    HB_UNICODE_GENERAL_CATEGORY_SPACE_SEPARATOR,     //   Zs
+    HB_UNICODE_GENERAL_CATEGORY_LINE_SEPARATOR,      //   Zl
+    HB_UNICODE_GENERAL_CATEGORY_PARAGRAPH_SEPARATOR, //   Zp
+
+    HB_UNICODE_GENERAL_CATEGORY_CONTROL,             //   Cc
+    HB_UNICODE_GENERAL_CATEGORY_FORMAT,              //   Cf
+    HB_UNICODE_GENERAL_CATEGORY_SURROGATE,           //   Cs
+    HB_UNICODE_GENERAL_CATEGORY_PRIVATE_USE,         //   Co
+    HB_UNICODE_GENERAL_CATEGORY_UNASSIGNED,          //   Cn
+
+    HB_UNICODE_GENERAL_CATEGORY_UPPERCASE_LETTER,    //   Lu
+    HB_UNICODE_GENERAL_CATEGORY_LOWERCASE_LETTER,    //   Ll
+    HB_UNICODE_GENERAL_CATEGORY_TITLECASE_LETTER,    //   Lt
+    HB_UNICODE_GENERAL_CATEGORY_MODIFIER_LETTER,     //   Lm
+    HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER,        //   Lo
+
+    HB_UNICODE_GENERAL_CATEGORY_CONNECT_PUNCTUATION, //   Pc
+    HB_UNICODE_GENERAL_CATEGORY_DASH_PUNCTUATION,    //   Pd
+    HB_UNICODE_GENERAL_CATEGORY_OPEN_PUNCTUATION,    //   Ps
+    HB_UNICODE_GENERAL_CATEGORY_CLOSE_PUNCTUATION,   //   Pe
+    HB_UNICODE_GENERAL_CATEGORY_INITIAL_PUNCTUATION, //   Pi
+    HB_UNICODE_GENERAL_CATEGORY_FINAL_PUNCTUATION,   //   Pf
+    HB_UNICODE_GENERAL_CATEGORY_OTHER_PUNCTUATION,   //   Po
+
+    HB_UNICODE_GENERAL_CATEGORY_MATH_SYMBOL,         //   Sm
+    HB_UNICODE_GENERAL_CATEGORY_CURRENCY_SYMBOL,     //   Sc
+    HB_UNICODE_GENERAL_CATEGORY_MODIFIER_SYMBOL,     //   Sk
+    HB_UNICODE_GENERAL_CATEGORY_OTHER_SYMBOL         //   So
+};
+
+static hb_unicode_general_category_t
+_hb_qt_unicode_general_category(hb_unicode_funcs_t * /*ufuncs*/,
+                                hb_codepoint_t unicode,
+                                void * /*user_data*/)
+{
+    return _qtcategory_to_hbcategory[QChar::category(unicode)];
+}
+
+static hb_codepoint_t
+_hb_qt_unicode_mirroring(hb_unicode_funcs_t * /*ufuncs*/,
+                         hb_codepoint_t unicode,
+                         void * /*user_data*/)
+{
+    return QChar::mirroredChar(unicode);
+}
+
+static hb_script_t
+_hb_qt_unicode_script(hb_unicode_funcs_t * /*ufuncs*/,
+                      hb_codepoint_t unicode,
+                      void * /*user_data*/)
+{
+    return _qtscript_to_hbscript[QChar::script(unicode)];
+}
+
+static hb_bool_t
+_hb_qt_unicode_compose(hb_unicode_funcs_t * /*ufuncs*/,
+                       hb_codepoint_t a, hb_codepoint_t b,
+                       hb_codepoint_t *ab,
+                       void * /*user_data*/)
+{
+    // ### optimize
+    QString s = QString::fromUcs4(&a, 1) + QString::fromUcs4(&b, 1);
+    QString normalized = s.normalized(QString::NormalizationForm_C);
+    if (normalized.isEmpty())
+        return false;
+
+    QVector<uint> ucs4str = normalized.toUcs4();
+    if (ucs4str.size() == 1) {
+        *ab = ucs4str.at(0);
+        return true;
+    }
+
+    return false;
+}
+
+static hb_bool_t
+_hb_qt_unicode_decompose(hb_unicode_funcs_t * /*ufuncs*/,
+                         hb_codepoint_t ab,
+                         hb_codepoint_t *a, hb_codepoint_t *b,
+                         void * /*user_data*/)
+{
+    // ### optimize
+    if (QChar::decompositionTag(ab) != QChar::Canonical) // !NFD
+        return false;
+
+    QString normalized = QChar::decomposition(ab);
+    Q_ASSERT(!normalized.isEmpty());
+
+    const QVector<uint> ucs4str = normalized.toUcs4();
+    Q_ASSERT(ucs4str.size() <= HB_UNICODE_MAX_DECOMPOSITION_LEN);
+
+    if (ucs4str.size() == 1) {
+        *a = ucs4str.at(0);
+        *b = 0;
+        return *a != ab;
+    }
+
+    if (ucs4str.size() == 2) {
+        *a = ucs4str.at(0);
+        *b = ucs4str.at(1);
+
+        // Here's the ugly part: if ab decomposes to a single character and
+        // that character decomposes again, we have to detect that and undo
+        // the second part :-(
+        QString recomposed = normalized.normalized(QString::NormalizationForm_C);
+        if (recomposed.isEmpty() || recomposed == normalized)
+            return false;
+
+        hb_codepoint_t c = recomposed.toUcs4().at(0);
+        if (c != *a && c != ab) {
+            *a = c;
+            *b = 0;
+        }
+        return true;
+    }
+
+    // If decomposed to more than two characters, take the last one,
+    // and recompose the rest to get the first component
+    *b = ucs4str.last();
+    normalized.chop(1);
+    QString recomposed = normalized.normalized(QString::NormalizationForm_C);
+    if (recomposed.isEmpty() || recomposed == normalized)
+        return false;
+
+    // We expect that recomposed has exactly one character now
+    *a = recomposed.toUcs4().at(0);
+
+    return true;
+}
+
+static unsigned int
+_hb_qt_unicode_decompose_compatibility(hb_unicode_funcs_t * /*ufuncs*/,
+                                       hb_codepoint_t u,
+                                       hb_codepoint_t *decomposed,
+                                       void * /*user_data*/)
+{
+    if (QChar::decompositionTag(u) == QChar::NoDecomposition) // !NFKD
+        return 0;
+
+    const QString normalized = QChar::decomposition(u);
+
+    uint outlen = 0;
+
+    // ### replace with QCharIterator
+    const ushort *p = reinterpret_cast<const ushort *>(normalized.unicode());
+    const ushort *const e = p + normalized.size();
+    for ( ; p != e; ++p) {
+        uint ucs4 = *p;
+        if (QChar::isHighSurrogate(ucs4) && p + 1 != e && QChar::isLowSurrogate(p[1]))
+            ucs4 = QChar::surrogateToUcs4(ucs4, *++p);
+        Q_ASSERT(outlen < HB_UNICODE_MAX_DECOMPOSITION_LEN);
+        decomposed[outlen++] = ucs4;
+    }
+
+    return outlen;
+}
+
+
+struct _hb_unicode_funcs_t {
+    _hb_unicode_funcs_t()
+    {
+        funcs = hb_unicode_funcs_create(NULL);
+        hb_unicode_funcs_set_combining_class_func(funcs, _hb_qt_unicode_combining_class, NULL, NULL);
+        hb_unicode_funcs_set_eastasian_width_func(funcs, _hb_qt_unicode_eastasian_width, NULL, NULL);
+        hb_unicode_funcs_set_general_category_func(funcs, _hb_qt_unicode_general_category, NULL, NULL);
+        hb_unicode_funcs_set_mirroring_func(funcs, _hb_qt_unicode_mirroring, NULL, NULL);
+        hb_unicode_funcs_set_script_func(funcs, _hb_qt_unicode_script, NULL, NULL);
+        hb_unicode_funcs_set_compose_func(funcs, _hb_qt_unicode_compose, NULL, NULL);
+        hb_unicode_funcs_set_decompose_func(funcs, _hb_qt_unicode_decompose, NULL, NULL);
+        hb_unicode_funcs_set_decompose_compatibility_func(funcs, _hb_qt_unicode_decompose_compatibility, NULL, NULL);
+    }
+    ~_hb_unicode_funcs_t()
+    {
+        hb_unicode_funcs_destroy(funcs);
+    }
+
+    hb_unicode_funcs_t *funcs;
+};
+
+Q_GLOBAL_STATIC(_hb_unicode_funcs_t, qt_ufuncs)
+
+hb_unicode_funcs_t *hb_qt_get_unicode_funcs()
+{
+    return qt_ufuncs()->funcs;
+}
+
+
+// Font routines
+
+static hb_bool_t
+_hb_qt_font_get_glyph(hb_font_t * /*font*/, void *font_data,
+                      hb_codepoint_t unicode, hb_codepoint_t /*variation_selector*/,
+                      hb_codepoint_t *glyph,
+                      void * /*user_data*/)
+{
+    QFontEngine *fe = (QFontEngine *)font_data;
+    Q_ASSERT(fe);
+
+    glyph_t glyphs[2] = { 0, 0 };
+
+    QGlyphLayout g;
+    g.numGlyphs = 2;
+    g.glyphs = glyphs;
+
+    QChar chars[4];
+    int numChars = 0;
+    if (Q_UNLIKELY(QChar::requiresSurrogates(unicode))) {
+        chars[numChars++] = QChar(QChar::highSurrogate(unicode));
+        chars[numChars++] = QChar(QChar::lowSurrogate(unicode));
+    } else {
+        chars[numChars++] = QChar(unicode);
+    }
+#if 0
+    if (Q_UNLIKELY(variation_selector != 0)) {
+        if (Q_UNLIKELY(QChar::requiresSurrogates(variation_selector))) {
+            chars[numChars++] = QChar(QChar::highSurrogate(variation_selector));
+            chars[numChars++] = QChar(QChar::lowSurrogate(variation_selector));
+        } else {
+            chars[numChars++] = QChar(variation_selector);
+        }
+    }
+#endif
+
+    int numGlyphs = g.numGlyphs;
+    bool ok = fe->stringToCMap(chars, numChars, &g, &numGlyphs, QFontEngine::GlyphIndicesOnly);
+    Q_ASSERT(ok); Q_UNUSED(ok)
+
+    *glyph = g.glyphs[0];
+
+    return true;
+}
+
+static hb_position_t
+_hb_qt_font_get_glyph_h_advance(hb_font_t *font, void *font_data,
+                                hb_codepoint_t glyph,
+                                void * /*user_data*/)
+{
+    QFontEngine *fe = (QFontEngine *)font_data;
+    Q_ASSERT(fe);
+
+    QFixed advance_x;
+    QFixed advance_y;
+
+    QGlyphLayout g;
+    g.numGlyphs = 1;
+    g.glyphs = &glyph;
+    g.advances_x = &advance_x;
+    g.advances_y = &advance_y;
+
+    fe->recalcAdvances(&g, QFontEngine::ShaperFlags(hb_qt_font_get_use_design_metrics(font)));
+
+    return g.advances_x[0].value();
+}
+
+static hb_position_t
+_hb_qt_font_get_glyph_v_advance(hb_font_t * /*font*/, void * /*font_data*/,
+                                hb_codepoint_t /*glyph*/,
+                                void * /*user_data*/)
+{
+    qCritical("hb_qt_font_get_glyph_v_advance: vertical writing isn't supported!");
+    return 0;
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_h_origin(hb_font_t * /*font*/, void * /*font_data*/,
+                               hb_codepoint_t /*glyph*/,
+                               hb_position_t * /*x*/, hb_position_t * /*y*/,
+                               void * /*user_data*/)
+{
+    return true; // we always work in the horizontal coordinates
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_v_origin(hb_font_t * /*font*/, void * /*font_data*/,
+                               hb_codepoint_t /*glyph*/,
+                               hb_position_t * /*x*/, hb_position_t * /*y*/,
+                               void * /*user_data*/)
+{
+    qCritical("hb_qt_get_glyph_v_origin: vertical writing isn't supported!");
+    return false;
+}
+
+static hb_position_t
+_hb_qt_font_get_glyph_h_kerning(hb_font_t *font, void *font_data,
+                                hb_codepoint_t first_glyph, hb_codepoint_t second_glyph,
+                                void * /*user_data*/)
+{
+    QFontEngine *fe = (QFontEngine *)font_data;
+    Q_ASSERT(fe);
+
+    glyph_t glyphs[2] = { first_glyph, second_glyph };
+    QFixed advance_x;
+    QFixed advance_y;
+
+    QGlyphLayout g;
+    g.numGlyphs = 2;
+    g.glyphs = glyphs;
+    g.advances_x = &advance_x;
+    g.advances_y = &advance_y;
+
+    fe->doKerning(&g, QFontEngine::ShaperFlags(hb_qt_font_get_use_design_metrics(font)));
+
+    return g.advances_x[0].value();
+}
+
+static hb_position_t
+_hb_qt_font_get_glyph_v_kerning(hb_font_t * /*font*/, void * /*font_data*/,
+                                hb_codepoint_t /*first_glyph*/, hb_codepoint_t /*second_glyph*/,
+                                void * /*user_data*/)
+{
+    qCritical("hb_qt_get_glyph_v_kerning: vertical writing isn't supported!");
+    return 0;
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_extents(hb_font_t * /*font*/, void *font_data,
+                              hb_codepoint_t glyph,
+                              hb_glyph_extents_t *extents,
+                              void * /*user_data*/)
+{
+    QFontEngine *fe = (QFontEngine *)font_data;
+    Q_ASSERT(fe);
+
+    glyph_metrics_t gm = fe->boundingBox(glyph);
+
+    extents->x_bearing = gm.x.value();
+    extents->y_bearing = gm.y.value();
+    extents->width = gm.width.value();
+    extents->height = gm.height.value();
+
+    return true;
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_contour_point(hb_font_t * /*font*/, void *font_data,
+                                    hb_codepoint_t glyph,
+                                    unsigned int point_index, hb_position_t *x, hb_position_t *y,
+                                    void * /*user_data*/)
+{
+    QFontEngine *fe = (QFontEngine *)font_data;
+    Q_ASSERT(fe);
+
+    QFixed xpos, ypos;
+    quint32 numPoints = 1;
+    if (Q_LIKELY(fe->getPointInOutline(glyph, 0, point_index, &xpos, &ypos, &numPoints) == 0)) {
+        *x = xpos.value();
+        *y = ypos.value();
+        return true;
+    }
+
+    *x = *y = 0;
+    return false;
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_name(hb_font_t * /*font*/, void * /*font_data*/,
+                           hb_codepoint_t /*glyph*/,
+                           char *name, unsigned int size,
+                           void * /*user_data*/)
+{
+    qCritical("hb_qt_font_get_glyph_name: not implemented!");
+    if (size)
+        *name = '\0';
+    return false;
+}
+
+static hb_bool_t
+_hb_qt_font_get_glyph_from_name(hb_font_t * /*font*/, void * /*font_data*/,
+                                const char * /*name*/, int /*len*/,
+                                hb_codepoint_t *glyph,
+                                void * /*user_data*/)
+{
+    qCritical("hb_qt_font_get_glyph_from_name: not implemented!");
+    *glyph = 0;
+    return false;
+}
+
+
+static hb_user_data_key_t _useDesignMetricsKey;
+
+void hb_qt_font_set_use_design_metrics(hb_font_t *font, uint value)
+{
+    hb_font_set_user_data(font, &_useDesignMetricsKey, (void *)value, NULL, true);
+}
+
+uint hb_qt_font_get_use_design_metrics(hb_font_t *font)
+{
+    return uint(hb_font_get_user_data(font, &_useDesignMetricsKey));
+}
+
+
+struct _hb_qt_font_funcs_t {
+    _hb_qt_font_funcs_t()
+    {
+        funcs = hb_font_funcs_create();
+        hb_font_funcs_set_glyph_func(funcs, _hb_qt_font_get_glyph, NULL, NULL);
+        hb_font_funcs_set_glyph_h_advance_func(funcs, _hb_qt_font_get_glyph_h_advance, NULL, NULL);
+        hb_font_funcs_set_glyph_v_advance_func(funcs, _hb_qt_font_get_glyph_v_advance, NULL, NULL);
+        hb_font_funcs_set_glyph_h_origin_func(funcs, _hb_qt_font_get_glyph_h_origin, NULL, NULL);
+        hb_font_funcs_set_glyph_v_origin_func(funcs, _hb_qt_font_get_glyph_v_origin, NULL, NULL);
+        hb_font_funcs_set_glyph_h_kerning_func(funcs, _hb_qt_font_get_glyph_h_kerning, NULL, NULL);
+        hb_font_funcs_set_glyph_v_kerning_func(funcs, _hb_qt_font_get_glyph_v_kerning, NULL, NULL);
+        hb_font_funcs_set_glyph_extents_func(funcs, _hb_qt_font_get_glyph_extents, NULL, NULL);
+        hb_font_funcs_set_glyph_contour_point_func(funcs, _hb_qt_font_get_glyph_contour_point, NULL, NULL);
+        hb_font_funcs_set_glyph_name_func(funcs, _hb_qt_font_get_glyph_name, NULL, NULL);
+        hb_font_funcs_set_glyph_from_name_func(funcs, _hb_qt_font_get_glyph_from_name, NULL, NULL);
+    }
+    ~_hb_qt_font_funcs_t()
+    {
+        hb_font_funcs_destroy(funcs);
+    }
+
+    hb_font_funcs_t *funcs;
+};
+
+Q_GLOBAL_STATIC(_hb_qt_font_funcs_t, qt_ffuncs)
+
+hb_font_funcs_t *hb_qt_get_font_funcs()
+{
+    return qt_ffuncs()->funcs;
+}
+
+
+static hb_blob_t *
+_hb_qt_get_font_table(hb_face_t * /*face*/, hb_tag_t tag, void *user_data)
+{
+    QFontEngine *fe = (QFontEngine *)user_data;
+    Q_ASSERT(fe);
+
+    uint length = 0;
+    if (Q_UNLIKELY(!fe->getSfntTableData(tag, 0, &length) || length == 0))
+        return hb_blob_get_empty();
+
+    char *buffer = (char *)malloc(length);
+    Q_CHECK_PTR(buffer);
+
+    if (Q_UNLIKELY(!fe->getSfntTableData(tag, reinterpret_cast<uchar *>(buffer), &length)))
+        length = 0;
+
+    return hb_blob_create(const_cast<const char *>(buffer), length,
+                          HB_MEMORY_MODE_WRITABLE,
+                          buffer, free);
+}
+
+static inline hb_face_t *
+_hb_qt_face_create(QFontEngine *fe)
+{
+    hb_face_t *face;
+
+    face = hb_face_create_for_tables(_hb_qt_get_font_table, (void *)fe, NULL);
+    if (Q_UNLIKELY(hb_face_is_immutable(face))) {
+        hb_face_destroy(face);
+        return NULL;
+    }
+
+    hb_face_set_index(face, fe->faceId().index);
+    hb_face_set_upem(face, fe->emSquareSize().truncate());
+
+    return face;
+}
+
+static void
+_hb_qt_face_release(void *user_data)
+{
+    if (Q_LIKELY(user_data))
+        hb_face_destroy((hb_face_t *)user_data);
+}
+
+hb_face_t *hb_qt_face_get_for_engine(QFontEngine *fe)
+{
+    if (Q_UNLIKELY(!fe->face_)) {
+        fe->face_ = _hb_qt_face_create(fe);
+        if (Q_UNLIKELY(!fe->face_))
+            return NULL;
+        fe->face_destroy_func = _hb_qt_face_release;
+    }
+
+    return hb_face_reference((hb_face_t *)fe->face_);
+}
+
+
+static inline hb_font_t *
+_hb_qt_font_create(QFontEngine *fe)
+{
+    Q_ASSERT(fe);
+
+    hb_face_t *face = hb_qt_face_get_for_engine(fe);
+    if (Q_UNLIKELY(!face))
+        return NULL;
+
+    hb_font_t *font = hb_font_create(face);
+
+    hb_face_destroy(face); // ref-ed in hb_qt_face_get_for_engine()
+
+    if (Q_UNLIKELY(hb_font_is_immutable(font))) {
+        hb_font_destroy(font);
+        return NULL;
+    }
+
+    const int y_ppem = fe->fontDef.pixelSize;
+    const int x_ppem = (fe->fontDef.pixelSize * fe->fontDef.stretch) / 100;
+
+    hb_font_set_funcs(font, hb_qt_get_font_funcs(), (void *)fe, NULL);
+    hb_font_set_scale(font, QFixed(x_ppem).value(), -QFixed(y_ppem).value());
+    hb_font_set_ppem(font, x_ppem, y_ppem);
+
+    return font;
+}
+
+static void
+_hb_qt_font_release(void *user_data)
+{
+    if (Q_LIKELY(user_data))
+        hb_font_destroy((hb_font_t *)user_data);
+}
+
+hb_font_t *hb_qt_font_get_for_engine(QFontEngine *fe)
+{
+    if (Q_UNLIKELY(!fe->font_)) {
+        fe->font_ = _hb_qt_font_create(fe);
+        if (Q_UNLIKELY(!fe->font_))
+            return NULL;
+        fe->font_destroy_func = _hb_qt_font_release;
+    }
+
+    return hb_font_reference((hb_font_t *)fe->font_);
+}
+
+QT_END_NAMESPACE
diff --git a/src/gui/text/qharfbuzzng_p.h b/src/gui/text/qharfbuzzng_p.h
new file mode 100644
index 0000000000..10cac69875
--- /dev/null
+++ b/src/gui/text/qharfbuzzng_p.h
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
+** Copyright (C) 2013 Konstantin Ritt
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QHARFBUZZNG_P_H
+#define QHARFBUZZNG_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qchar.h>
+
+#include <harfbuzz/hb.h>
+
+QT_BEGIN_NAMESPACE
+
+class QFontEngine;
+
+// Unicode
+
+Q_GUI_EXPORT hb_script_t hb_qt_script_to_script(QChar::Script script);
+Q_GUI_EXPORT QChar::Script hb_qt_script_from_script(hb_script_t script);
+
+Q_GUI_EXPORT hb_unicode_funcs_t *hb_qt_get_unicode_funcs();
+
+
+// Font
+
+Q_GUI_EXPORT hb_font_funcs_t *hb_qt_get_font_funcs();
+
+Q_GUI_EXPORT hb_face_t *hb_qt_face_get_for_engine(QFontEngine *fe);
+Q_GUI_EXPORT hb_font_t *hb_qt_font_get_for_engine(QFontEngine *fe);
+
+Q_GUI_EXPORT void hb_qt_font_set_use_design_metrics(hb_font_t *font, uint value);
+Q_GUI_EXPORT uint hb_qt_font_get_use_design_metrics(hb_font_t *font);
+
+QT_END_NAMESPACE
+
+#endif // QHARFBUZZNG_P_H
diff --git a/src/gui/text/text.pri b/src/gui/text/text.pri
index e9ea2a3f83..59a6f346e2 100644
--- a/src/gui/text/text.pri
+++ b/src/gui/text/text.pri
@@ -84,3 +84,12 @@ SOURCES += \
 
 HEADERS += \
       text/qplatformfontdatabase.h
+
+contains(QT_CONFIG, harfbuzz)|contains(QT_CONFIG, system-harfbuzz) {
+    DEFINES += QT_ENABLE_HARFBUZZ_NG
+
+    include($$PWD/../../3rdparty/harfbuzz.pri)
+
+    SOURCES += text/qharfbuzzng.cpp
+    HEADERS += text/qharfbuzzng_p.h
+}