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
(cherry picked from commit 1f90ae36cff8acf581d1624bf011fe3a55c623c0)

3 files changed, 28 insertions, 19 deletions

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index 9271f34..8374c62 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -2778,6 +2778,22 @@ 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;
@@ -2785,13 +2801,10 @@ 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;
     }
@@ -2800,18 +2813,12 @@ 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 09610ff..86551a4 100644
--- a/src/gui/text/qtextengine_p.h
+++ b/src/gui/text/qtextengine_p.h
@@ -311,11 +311,13 @@ 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 0fbf838..86c6f48 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -2319,13 +2319,13 @@ 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);