QWindowsFontDatabase: replace a QPair with a dedicated struct

Pairs are easy to use, but they have no semantics attached: Two
QPair<QString, QString> compare equal, e.g., even though one is used
as a FontAndStyle and the other as, say, a type/subtype. It also
carries no information for the reader of the code.

So, write a minimal struct with equality and qHash() instead.

Change-Id: I9514c9b7d6c2cc6a4831f9ca83ca2ee466d91553
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

3 files changed, 20 insertions, 5 deletions

diff --git a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
index 060e3fb618..2beb35eb03 100644
--- a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
+++ b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase.cpp
@@ -496,7 +496,7 @@ namespace {
         {}
 
         QString populatedFontFamily;
-        QSet<QPair<QString,QString> > foundFontAndStyles;
+        QSet<FontAndStyle> foundFontAndStyles;
         QWindowsFontDatabase *windowsFontDatabase;
     };
 }
@@ -637,7 +637,7 @@ static int QT_WIN_CALLBACK storeFont(const LOGFONT *logFont, const TEXTMETRIC *t
         signature = &reinterpret_cast<const NEWTEXTMETRICEX *>(textmetric)->ntmFontSig;
         // We get a callback for each script-type supported, but we register them all
         // at once using the signature, so we only need one call to addFontToDatabase().
-        QPair<QString,QString> fontAndStyle(familyName, styleName);
+        FontAndStyle fontAndStyle = {familyName, styleName};
         if (sfp->foundFontAndStyles.contains(fontAndStyle))
             return 1;
         sfp->foundFontAndStyles.insert(fontAndStyle);
diff --git a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_ft.cpp b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_ft.cpp
index 3543f22c61..cde20eebc2 100644
--- a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_ft.cpp
+++ b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_ft.cpp
@@ -318,8 +318,8 @@ static int QT_WIN_CALLBACK storeFont(const LOGFONT *logFont, const TEXTMETRIC *t
         signature = &reinterpret_cast<const NEWTEXTMETRICEX *>(textmetric)->ntmFontSig;
         // We get a callback for each script-type supported, but we register them all
         // at once using the signature, so we only need one call to addFontToDatabase().
-        QSet<QPair<QString,QString>> *foundFontAndStyles = reinterpret_cast<QSet<QPair<QString,QString>> *>(lparam);
-        QPair<QString,QString> fontAndStyle(faceName, styleName);
+        QSet<FontAndStyle> *foundFontAndStyles = reinterpret_cast<QSet<FontAndStyle> *>(lparam);
+        FontAndStyle fontAndStyle = {faceName, styleName};
         if (foundFontAndStyles->contains(fontAndStyle))
             return 1;
         foundFontAndStyles->insert(fontAndStyle);
@@ -352,7 +352,7 @@ void QWindowsFontDatabaseFT::populateFamily(const QString &familyName)
     lf.lfFaceName[familyName.size()] = 0;
     lf.lfCharSet = DEFAULT_CHARSET;
     lf.lfPitchAndFamily = 0;
-    QSet<QPair<QString,QString>> foundFontAndStyles;
+    QSet<FontAndStyle> foundFontAndStyles;
     EnumFontFamiliesEx(dummy, &lf, storeFont, reinterpret_cast<intptr_t>(&foundFontAndStyles), 0);
     ReleaseDC(0, dummy);
 }
diff --git a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_p.h b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_p.h
index 38ddb178bd..0652685fc5 100644
--- a/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_p.h
+++ b/src/platformsupport/fontdatabases/windows/qwindowsfontdatabase_p.h
@@ -56,6 +56,7 @@
 #include <qpa/qplatformfontdatabase.h>
 #include <QtCore/QSharedPointer>
 #include <QtCore/QLoggingCategory>
+#include <QtCore/qhashfunctions.h>
 #include <QtCore/qt_windows.h>
 
 QT_BEGIN_NAMESPACE
@@ -154,6 +155,20 @@ bool qt_localizedName(const QString &name);
 QString qt_getEnglishName(const QString &familyName, bool includeStyle = false);
 QFontNames qt_getCanonicalFontNames(const LOGFONT &lf);
 
+struct FontAndStyle {
+    QString font;
+    QString style;
+
+    friend inline bool operator==(const FontAndStyle &lhs, const FontAndStyle &rhs) noexcept
+    { return lhs.font == rhs.font && lhs.style == rhs.style; }
+    friend inline bool operator!=(const FontAndStyle &lhs, const FontAndStyle &rhs) noexcept
+    { return !operator==(lhs, rhs); }
+};
+inline size_t qHash(const FontAndStyle &key, size_t seed) noexcept
+{
+    return qHashMulti(seed, key.font, key.style);
+}
+
 QT_END_NAMESPACE
 
 #endif // QWINDOWSFONTDATABASE_H