Avoid using HB types in QFontEngine API

This affects HB_Font and HB_Face.

As of now, the Hurfbuzz API usage is concentrated in qfontengine(|_ft).cpp
and qtextengine.cpp, thus it is a lot easier to switch to Hurfbuzz-NG.

Change-Id: Ie06959efd5d6080fe44c407d9f5de0a07dd1c210
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Josh Faust <jfaust@suitabletech.com>

src/gui/text/qfontengine.cpp

@@ -165,19 +165,33 @@ static HB_Error hb_getSFntTable(void *font, HB_Tag tableTag, HB_Byte *buffer, HB
     return HB_Err_Ok;
 }
 
+static void hb_freeFace(void *face)
+{
+    qHBFreeFace((HB_Face)face);
+}
+
 // QFontEngine
 
 QFontEngine::QFontEngine()
-    : QObject(), ref(0)
+    : QObject(), ref(0),
+      font_(0), font_destroy_func(0),
+      face_(0), face_destroy_func(0)
 {
     cache_count = 0;
     fsType = 0;
     symbol = false;
-    memset(&hbFont, 0, sizeof(hbFont));
-    hbFont.klass = &hb_fontClass;
-    hbFont.userData = this;
 
-    hbFace = 0;
+    {
+        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;
 }
@@ -185,7 +199,15 @@ QFontEngine::QFontEngine()
 QFontEngine::~QFontEngine()
 {
     m_glyphCaches.clear();
-    qHBFreeFace(hbFace);
+
+    if (font_ && font_destroy_func) {
+        font_destroy_func(font_);
+        font_ = 0;
+    }
+    if (face_ && face_destroy_func) {
+        face_destroy_func(face_);
+        face_ = 0;
+    }
 }
 
 QFixed QFontEngine::lineThickness() const
@@ -206,39 +228,37 @@ QFixed QFontEngine::underlinePosition() const
     return ((lineThickness() * 2) + 3) / 6;
 }
 
-HB_Font QFontEngine::harfbuzzFont() const
+void *QFontEngine::harfbuzzFont() const
 {
-    if (!hbFont.x_ppem) {
+    HB_FontRec *hbFont = (HB_FontRec *)font_;
+    if (!hbFont->x_ppem) {
         QFixed emSquare = emSquareSize();
-        hbFont.x_ppem = fontDef.pixelSize;
-        hbFont.y_ppem = fontDef.pixelSize * fontDef.stretch / 100;
-        hbFont.x_scale = (QFixed(hbFont.x_ppem * (1 << 16)) / emSquare).value();
-        hbFont.y_scale = (QFixed(hbFont.y_ppem * (1 << 16)) / emSquare).value();
+        hbFont->x_ppem = fontDef.pixelSize;
+        hbFont->y_ppem = fontDef.pixelSize * fontDef.stretch / 100;
+        hbFont->x_scale = (QFixed(hbFont->x_ppem * (1 << 16)) / emSquare).value();
+        hbFont->y_scale = (QFixed(hbFont->y_ppem * (1 << 16)) / emSquare).value();
     }
-    return &hbFont;
+    return font_;
 }
 
-HB_Face QFontEngine::harfbuzzFace() const
+void *QFontEngine::harfbuzzFace() const
 {
-    if (!hbFace) {
-        hbFace = qHBNewFace(const_cast<QFontEngine *>(this), hb_getSFntTable);
+    if (!face_) {
+        HB_Face hbFace = qHBNewFace(const_cast<QFontEngine *>(this), hb_getSFntTable);
         Q_CHECK_PTR(hbFace);
-    }
-    return hbFace;
-}
+        if (hbFace->font_for_init != 0)
+            hbFace = qHBLoadFace(hbFace);
 
-HB_Face QFontEngine::initializedHarfbuzzFace() const
-{
-    HB_Face face = harfbuzzFace();
-    if (face != 0 && face->font_for_init != 0)
-        face = qHBLoadFace(face);
-
-    return face;
+        face_ = (void *)hbFace;
+        face_destroy_func = hb_freeFace;
+    }
+    return face_;
 }
 
 bool QFontEngine::supportsScript(QChar::Script script) const
 {
-    return initializedHarfbuzzFace()->supported_scripts[script_to_hbscript(script)];
+    HB_Face hbFace = (HB_Face)harfbuzzFace();
+    return hbFace->supported_scripts[script_to_hbscript(script)];
 }
 
 glyph_metrics_t QFontEngine::boundingBox(glyph_t glyph, const QTransform &matrix)

src/gui/text/qfontengine_ft.cpp

@@ -46,6 +46,8 @@
 #include "qfontengine_ft_p.h"
 #include "private/qimage_p.h"
 
+#include <private/qharfbuzz_p.h>
+
 #ifndef QT_NO_FREETYPE
 
 #include "qfile.h"
@@ -258,8 +260,12 @@ QFreetypeFace *QFreetypeFace::getFace(const QFontEngine::FaceId &face_id,
         }
         newFreetype->face = face;
 
-        newFreetype->hbFace = qHBNewFace(face, hb_getSFntTable);
-        Q_CHECK_PTR(newFreetype->hbFace);
+        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->ref.store(1);
         newFreetype->xsize = 0;
         newFreetype->ysize = 0;
@@ -313,7 +319,7 @@ void QFreetypeFace::release(const QFontEngine::FaceId &face_id)
 {
     QtFreetypeData *freetypeData = qt_getFreetypeData();
     if (!ref.deref()) {
-        qHBFreeFace(hbFace);
+        qHBFreeFace((HB_Face)hbFace);
         FT_Done_Face(face);
         if(freetypeData->faces.contains(face_id))
             freetypeData->faces.take(face_id);
@@ -654,7 +660,6 @@ QFontEngineFT::~QFontEngineFT()
 {
     if (freetype)
         freetype->release(face_id);
-    hbFace = 0; // we share the face in QFreeTypeFace, don't let ~QFontEngine delete it
 }
 
 bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
@@ -691,7 +696,7 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
         symbol = bool(fontDef.family.contains(QLatin1String("symbol"), Qt::CaseInsensitive));
     }
     // #####
-    freetype->hbFace->isSymbolFont = symbol;
+    ((HB_Face)freetype->hbFace)->isSymbolFont = symbol;
 
     lbearing = rbearing = SHRT_MIN;
     freetype->computeSize(fontDef, &xsize, &ysize, &defaultGlyphSet.outline_drawing);
@@ -729,12 +734,17 @@ bool QFontEngineFT::init(FaceId faceId, bool antialias, GlyphFormat format,
     if (line_thickness < 1)
         line_thickness = 1;
 
-    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;
+    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;
 
-    hbFace = freetype->hbFace;
+    // ###
+    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;
 

src/gui/text/qfontengine_ft_p.h

@@ -69,8 +69,6 @@
 
 #include <qmutex.h>
 
-#include "private/qharfbuzz_copy_p.h"
-
 QT_BEGIN_NAMESPACE
 
 class QFontEngineFTRawFont;
@@ -101,7 +99,7 @@ struct QFreetypeFace
     }
 
     FT_Face face;
-    HB_Face hbFace;
+    void *hbFace;
     int xsize; // 26.6
     int ysize; // 26.6
     FT_Matrix matrix;

src/gui/text/qfontengine_p.h

@@ -60,8 +60,6 @@
 #include "private/qtextengine_p.h"
 #include "private/qfont_p.h"
 
-#include "private/qharfbuzz_copy_p.h"
-
 #include <private/qfontengineglyphcache_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -77,6 +75,7 @@ struct QGlyphLayout;
     ((quint32)(ch4)) \
    )
 
+typedef void (*qt_destroy_func_t) (void *user_data);
 
 class Q_GUI_EXPORT QFontEngine : public QObject
 {
@@ -162,11 +161,6 @@ public:
 
     /* returns 0 as glyph index for non existent glyphs */
     virtual bool stringToCMap(const QChar *str, int len, QGlyphLayout *glyphs, int *nglyphs, ShaperFlags flags) const = 0;
-
-    /**
-     * This is a callback from harfbuzz. The font engine uses the font-system in use to find out the
-     * advances of each glyph and set it on the layout.
-     */
     virtual void recalcAdvances(QGlyphLayout *, ShaperFlags) const {}
     virtual void doKerning(QGlyphLayout *, ShaperFlags) const;
 
@@ -248,9 +242,8 @@ public:
 
     virtual QFontEngine *cloneWithSize(qreal /*pixelSize*/) const { return 0; }
 
-    HB_Font harfbuzzFont() const;
-    HB_Face harfbuzzFace() const;
-    HB_Face initializedHarfbuzzFace() const;
+    void *harfbuzzFont() const;
+    void *harfbuzzFace() const;
     bool supportsScript(QChar::Script script) const;
 
     virtual int getPointInOutline(glyph_t glyph, int flags, quint32 point, QFixed *xpos, QFixed *ypos, quint32 *nPoints);
@@ -273,12 +266,16 @@ public:
 
     QAtomicInt ref;
     QFontDef fontDef;
+
+    mutable void *font_;
+    mutable qt_destroy_func_t font_destroy_func;
+    mutable void *face_;
+    mutable qt_destroy_func_t face_destroy_func;
+
     uint cache_cost; // amount of mem used in kb by the font
     int cache_count;
     uint fsType : 16;
     bool symbol;
-    mutable HB_FontRec hbFont;
-    mutable HB_Face hbFace;
     struct KernPair {
         uint left_right;
         QFixed adjust;

src/gui/text/qfontengine_qpf.cpp

@@ -50,6 +50,7 @@
 #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
 

src/gui/text/qtextengine.cpp

@@ -1111,8 +1111,8 @@ void QTextEngine::shapeTextWithHarfbuzz(int item) const
         si.descent = qMax(actualFontEngine->descent(), si.descent);
         si.leading = qMax(actualFontEngine->leading(), si.leading);
 
-        shaper_item.font = actualFontEngine->harfbuzzFont();
-        shaper_item.face = actualFontEngine->initializedHarfbuzzFace();
+        shaper_item.font = (HB_Font)actualFontEngine->harfbuzzFont();
+        shaper_item.face = (HB_Face)actualFontEngine->harfbuzzFace();
 
         shaper_item.glyphIndicesPresent = true;