Fix crash when app font is added

Loading app fonts will clear the application font cache, but
QFontPrivate::engineWithScript will try to load the font again,
in Mac the font engine used here must be the one used for shaping,
because subsequent sub font engines may be added to it during the
shaping process (QCoreTextFontEngineMulti::stringToCMap). That is
why we need to fetch the font engine directly from QTextEngine's
fontEngine cache instead of QFontCache.

Task-number: QTBUG-20250
Reviewed-by: Eskil

3 files changed, 28 insertions, 19 deletions

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 8ddf3eb..c900918 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -3051,6 +3051,22 @@ QTextItemInt::QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFo
     : justified(false), underlineStyle(QTextCharFormat::NoUnderline), charFormat(format),
       num_chars(0), chars(0), logClusters(0), f(0), fontEngine(0)
 {
+    f = font;
+    fontEngine = f->d->engineForScript(si.analysis.script);
+    Q_ASSERT(fontEngine);
+
+    initWithScriptItem(si);
+}
+
+QTextItemInt::QTextItemInt(const QGlyphLayout &g, QFont *font, const QChar *chars_, int numChars, QFontEngine *fe, const QTextCharFormat &format)
+    : flags(0), justified(false), underlineStyle(QTextCharFormat::NoUnderline), charFormat(format),
+      num_chars(numChars), chars(chars_), logClusters(0), f(font),  glyphs(g), fontEngine(fe)
+{
+}
+
+// Fix up flags and underlineStyle with given info
+void QTextItemInt::initWithScriptItem(const QScriptItem &si)
+{
     // explicitly initialize flags so that initFontAttributes can be called
     // multiple times on the same TextItem
     flags = 0;
@@ -3058,13 +3074,10 @@ QTextItemInt::QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFo
         flags |= QTextItem::RightToLeft;
     ascent = si.ascent;
     descent = si.descent;
-    f = font;
-    fontEngine = f->d->engineForScript(si.analysis.script);
-    Q_ASSERT(fontEngine);
 
-    if (format.hasProperty(QTextFormat::TextUnderlineStyle)) {
-        underlineStyle = format.underlineStyle();
-    } else if (format.boolProperty(QTextFormat::FontUnderline)
+    if (charFormat.hasProperty(QTextFormat::TextUnderlineStyle)) {
+        underlineStyle = charFormat.underlineStyle();
+    } else if (charFormat.boolProperty(QTextFormat::FontUnderline)
                || f->d->underline) {
         underlineStyle = QTextCharFormat::SingleUnderline;
     }
@@ -3073,18 +3086,12 @@ QTextItemInt::QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFo
     if (underlineStyle == QTextCharFormat::SingleUnderline)
         flags |= QTextItem::Underline;
 
-    if (f->d->overline || format.fontOverline())
+    if (f->d->overline || charFormat.fontOverline())
         flags |= QTextItem::Overline;
-    if (f->d->strikeOut || format.fontStrikeOut())
+    if (f->d->strikeOut || charFormat.fontStrikeOut())
         flags |= QTextItem::StrikeOut;
 }
 
-QTextItemInt::QTextItemInt(const QGlyphLayout &g, QFont *font, const QChar *chars_, int numChars, QFontEngine *fe)
-    : flags(0), justified(false), underlineStyle(QTextCharFormat::NoUnderline),
-      num_chars(numChars), chars(chars_), logClusters(0), f(font),  glyphs(g), fontEngine(fe)
-{
-}
-
 QTextItemInt QTextItemInt::midItem(QFontEngine *fontEngine, int firstGlyphIndex, int numGlyphs) const
 {
     QTextItemInt ti = *this;
diff --git a/src/gui/text/qtextengine_p.h b/src/gui/text/qtextengine_p.h
index 055974a..b1bd0c3 100644
--- a/src/gui/text/qtextengine_p.h
+++ b/src/gui/text/qtextengine_p.h
@@ -312,11 +312,13 @@ public:
           logClusters(0), f(0), fontEngine(0)
     {}
     QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFormat &format = QTextCharFormat());
-    QTextItemInt(const QGlyphLayout &g, QFont *font, const QChar *chars, int numChars, QFontEngine *fe);
+    QTextItemInt(const QGlyphLayout &g, QFont *font, const QChar *chars, int numChars, QFontEngine *fe,
+                 const QTextCharFormat &format = QTextCharFormat());
 
     /// copy the structure items, adjusting the glyphs arrays to the right subarrays.
     /// the width of the returned QTextItemInt is not adjusted, for speed reasons
     QTextItemInt midItem(QFontEngine *fontEngine, int firstGlyphIndex, int numGlyphs) const;
+    void initWithScriptItem(const QScriptItem &si);
 
     QFixed descent;
     QFixed ascent;
diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index c1bc846..2d5b453 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -2381,13 +2381,13 @@ void QTextLine::draw(QPainter *p, const QPointF &pos, const QTextLayout::FormatR
         unsigned short *logClusters = eng->logClusters(&si);
         QGlyphLayout glyphs = eng->shapedGlyphs(&si);
 
-        QTextItemInt gf(si, &f, format);
-        gf.glyphs = glyphs.mid(iterator.glyphsStart, iterator.glyphsEnd - iterator.glyphsStart);
-        gf.chars = eng->layoutData->string.unicode() + iterator.itemStart;
+        QTextItemInt gf(glyphs.mid(iterator.glyphsStart, iterator.glyphsEnd - iterator.glyphsStart),
+                        &f, eng->layoutData->string.unicode() + iterator.itemStart,
+                        iterator.itemEnd - iterator.itemStart, eng->fontEngine(si), format);
         gf.logClusters = logClusters + iterator.itemStart - si.position;
-        gf.num_chars = iterator.itemEnd - iterator.itemStart;
         gf.width = iterator.itemWidth;
         gf.justified = line.justified;
+        gf.initWithScriptItem(si);
 
         Q_ASSERT(gf.fontEngine);