Get rid of HB dependency in FT font engine

Instead of loading HB face in QFreetypeFace::getFace(), defer allocation
until the first FT font engine for that face gets initialized;
then, QFreetypeFace "reparents" and manages the loaded HB face.

Change-Id: I2ac8ead4c6ed25d341af9c9cf0c34dfb979f8390
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

5 files changed, 42 insertions, 61 deletions

diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index 6a6e67abb0..d8a8e34b0b 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -143,7 +143,7 @@ int QFontEngine::getPointInOutline(glyph_t glyph, int flags, quint32 point, QFix
     Q_UNUSED(xpos)
     Q_UNUSED(ypos)
     Q_UNUSED(nPoints)
-    return HB_Err_Not_Covered;
+    return Err_Not_Covered;
 }
 
 static HB_Error hb_getPointInOutline(HB_Font font, HB_Glyph glyph, int flags, hb_uint32 point, HB_Fixed *xpos, HB_Fixed *ypos, hb_uint32 *nPoints)
@@ -203,17 +203,6 @@ QFontEngine::QFontEngine()
     fsType = 0;
     symbol = false;
 
-    {
-        HB_FontRec *hbFont = (HB_FontRec *) malloc(sizeof(HB_FontRec));
-        Q_CHECK_PTR(hbFont);
-        memset(hbFont, 0, sizeof(HB_FontRec));
-        hbFont->klass = &hb_fontClass;
-        hbFont->userData = this;
-
-        font_ = (void *)hbFont;
-        font_destroy_func = free;
-    }
-
     glyphFormat = -1;
     m_subPixelPositionCount = 0;
 
@@ -262,8 +251,12 @@ QFixed QFontEngine::underlinePosition() const
 
 void *QFontEngine::harfbuzzFont() const
 {
-    HB_FontRec *hbFont = (HB_FontRec *)font_;
-    if (!hbFont->x_ppem) {
+    if (!font_) {
+        HB_FontRec *hbFont = (HB_FontRec *) malloc(sizeof(HB_FontRec));
+        Q_CHECK_PTR(hbFont);
+        hbFont->klass = &hb_fontClass;
+        hbFont->userData = const_cast<QFontEngine *>(this);
+
         qint64 emSquare = emSquareSize().truncate();
         Q_ASSERT(emSquare == emSquareSize().toInt()); // ensure no truncation
         if (emSquare == 0)
@@ -273,6 +266,9 @@ void *QFontEngine::harfbuzzFont() const
         // same as QFixed(x)/QFixed(emSquare) but without int32 overflow for x
         hbFont->x_scale = (((qint64)hbFont->x_ppem << 6) * 0x10000L + (emSquare >> 1)) / emSquare;
         hbFont->y_scale = (((qint64)hbFont->y_ppem << 6) * 0x10000L + (emSquare >> 1)) / emSquare;
+
+        font_ = (void *)hbFont;
+        font_destroy_func = free;
     }
     return font_;
 }
diff --git a/src/gui/text/qfontengine_ft.cpp b/src/gui/text/qfontengine_ft.cpp
index 7b4925a9c8..cad9b02f41 100644
--- a/src/gui/text/qfontengine_ft.cpp
+++ b/src/gui/text/qfontengine_ft.cpp
@@ -46,8 +46,6 @@
 #include "qfontengine_ft_p.h"
 #include "private/qimage_p.h"
 
-#include <private/qharfbuzz_p.h>
-
 #ifndef QT_NO_FREETYPE
 
 #include "qfile.h"
@@ -118,24 +116,6 @@ QT_BEGIN_NAMESPACE
 #define TRUNC(x)    ((x) >> 6)
 #define ROUND(x)    (((x)+32) & -64)
 
-static HB_Error hb_getSFntTable(void *font, HB_Tag tableTag, HB_Byte *buffer, HB_UInt *length)
-{
-#if (FREETYPE_MAJOR*10000 + FREETYPE_MINOR*100 + FREETYPE_PATCH) > 20103
-    FT_Face face = (FT_Face)font;
-    FT_ULong ftlen = *length;
-    FT_Error error = 0;
-
-    if ( !FT_IS_SFNT(face) )
-        return HB_Err_Invalid_Argument;
-
-    error = FT_Load_Sfnt_Table(face, tableTag, 0, buffer, &ftlen);
-    *length = ftlen;
-    return (HB_Error)error;
-#else
-    return HB_Err_Invalid_Argument;
-#endif
-}
-
 // -------------------------- Freetype support ------------------------------
 
 class QtFreetypeData
@@ -191,19 +171,19 @@ int QFreetypeFace::getPointInOutline(glyph_t glyph, int flags, quint32 point, QF
         return error;
 
     if (face->glyph->format != FT_GLYPH_FORMAT_OUTLINE)
-        return HB_Err_Invalid_SubTable;
+        return Err_Invalid_SubTable;
 
     *nPoints = face->glyph->outline.n_points;
     if (!(*nPoints))
-        return HB_Err_Ok;
+        return Err_Ok;
 
     if (point > *nPoints)
-        return HB_Err_Invalid_SubTable;
+        return Err_Invalid_SubTable;
 
     *xpos = QFixed::fromFixed(face->glyph->outline.points[point].x);
     *ypos = QFixed::fromFixed(face->glyph->outline.points[point].y);
 
-    return HB_Err_Ok;
+    return Err_Ok;
 }
 
 extern QByteArray qt_fontdata_from_index(int);
@@ -260,11 +240,8 @@ QFreetypeFace *QFreetypeFace::getFace(const QFontEngine::FaceId &face_id,
         }
         newFreetype->face = face;
 
-        HB_Face hbFace = qHBNewFace(face, hb_getSFntTable);
-        Q_CHECK_PTR(hbFace);
-        if (hbFace->font_for_init != 0)
-            hbFace = qHBLoadFace(hbFace);
-        newFreetype->hbFace = (void *)hbFace;
+        newFreetype->hbFace = 0;
+        newFreetype->hbFace_destroy_func = 0;
 
         newFreetype->ref.store(1);
         newFreetype->xsize = 0;
@@ -319,7 +296,10 @@ void QFreetypeFace::release(const QFontEngine::FaceId &face_id)
 {
     QtFreetypeData *freetypeData = qt_getFreetypeData();
     if (!ref.deref()) {
-        qHBFreeFace((HB_Face)hbFace);
+        if (hbFace && hbFace_destroy_func) {
+            hbFace_destroy_func(hbFace);
+            hbFace = 0;
+        }
         FT_Done_Face(face);
         if(freetypeData->faces.contains(face_id))
             freetypeData->faces.take(face_id);
@@ -695,8 +675,6 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
     if (FT_Get_PS_Font_Info(freetype->face, &psrec) == FT_Err_Ok) {
         symbol = bool(fontDef.family.contains(QLatin1String("symbol"), Qt::CaseInsensitive));
     }
-    // #####
-    ((HB_Face)freetype->hbFace)->isSymbolFont = symbol;
 
     lbearing = rbearing = SHRT_MIN;
     freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing);
@@ -734,18 +712,6 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
     if (line_thickness < 1)
         line_thickness = 1;
 
-    HB_FontRec *hbFont = (HB_FontRec *)font_;
-    hbFont->x_ppem  = face->size->metrics.x_ppem;
-    hbFont->y_ppem  = face->size->metrics.y_ppem;
-    hbFont->x_scale = face->size->metrics.x_scale;
-    hbFont->y_scale = face->size->metrics.y_scale;
-
-    // ###
-    if (face_ && face_destroy_func)
-        face_destroy_func(face_);
-    face_ = freetype->hbFace;
-    face_destroy_func = 0; // we share the face in QFreeTypeFace, don't let ~QFontEngine delete it
-
     metrics = face->size->metrics;
 
     /*
@@ -773,6 +739,15 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
 
     fontDef.styleName = QString::fromUtf8(face->style_name);
 
+    if (!freetype->hbFace) {
+        freetype->hbFace = harfbuzzFace();
+        freetype->hbFace_destroy_func = face_destroy_func;
+    } else {
+        Q_ASSERT(!face_);
+        face_ = freetype->hbFace;
+    }
+    face_destroy_func = 0; // we share the HB face in QFreeTypeFace, so do not let ~QFontEngine() destroy it
+
     unlockFace();
 
     fsType = freetype->fsType();
diff --git a/src/gui/text/qfontengine_ft_p.h b/src/gui/text/qfontengine_ft_p.h
index bd4c855b91..e2e99893c8 100644
--- a/src/gui/text/qfontengine_ft_p.h
+++ b/src/gui/text/qfontengine_ft_p.h
@@ -99,7 +99,6 @@ struct QFreetypeFace
     }
 
     FT_Face face;
-    void *hbFace;
     int xsize; // 26.6
     int ysize; // 26.6
     FT_Matrix matrix;
@@ -124,6 +123,9 @@ private:
     QAtomicInt ref;
     QMutex _lock;
     QByteArray fontData;
+
+    void *hbFace;
+    qt_destroy_func_t hbFace_destroy_func;
 };
 
 // If this is exported this breaks compilation of the windows
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index 855f0099ff..4427000d03 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -75,6 +75,15 @@ struct QGlyphLayout;
     ((quint32)(ch4)) \
    )
 
+// ### this only used in getPointInOutline(), refactor it and then remove these magic numbers
+enum HB_Compat_Error {
+    Err_Ok                           = 0x0000,
+    Err_Not_Covered                  = 0xFFFF,
+    Err_Invalid_Argument             = 0x1A66,
+    Err_Invalid_SubTable_Format      = 0x157F,
+    Err_Invalid_SubTable             = 0x1570
+};
+
 typedef void (*qt_destroy_func_t) (void *user_data);
 
 class Q_GUI_EXPORT QFontEngine : public QObject
diff --git a/src/gui/text/qfontengine_qpf.cpp b/src/gui/text/qfontengine_qpf.cpp
index def671c62f..78bc3f871a 100644
--- a/src/gui/text/qfontengine_qpf.cpp
+++ b/src/gui/text/qfontengine_qpf.cpp
@@ -50,7 +50,6 @@
 #include <QtCore/qbuffer.h>
 #if !defined(QT_NO_FREETYPE)
 #include "private/qfontengine_ft_p.h"
-#include <private/qharfbuzz_p.h>
 #endif
 #include "private/qcore_unix_p.h" // overrides QT_OPEN
 
@@ -858,7 +857,7 @@ void QFontEngineQPF::doKerning(QGlyphLayout *g, QFontEngine::ShaperFlags flags)
 int QFontEngineQPF::getPointInOutline(glyph_t glyph, int flags, quint32 point, QFixed *xpos, QFixed *ypos, quint32 *nPoints)
 {
     if (!freetype)
-        return HB_Err_Not_Covered;
+        return Err_Not_Covered;
     lockFace();
     int result = freetype->getPointInOutline(glyph, flags, point, xpos, ypos, nPoints);
     unlockFace();