WinRT: Use registerFontFamily to reduce font registration overhead

Adopt to the new lazy font loading strategy in order to reduce memory
and startup time associated with populating the entire font database.

Change-Id: I0134cc123f73cb8485fe85c4a6b8e3b3a3a2cab0
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>

src/plugins/platforms/winrt/qwinrtfontdatabase.cpp

@@ -63,7 +63,7 @@ QString QWinRTFontDatabase::fontDir() const
         fontDirectory = applicationDirPath + QLatin1String("/fonts");
         if (!QFile::exists(fontDirectory)) {
 #ifndef Q_OS_WINPHONE
-            if (m_fonts.isEmpty())
+            if (m_fontFamilies.isEmpty())
 #endif
                 qWarning("No fonts directory found in application package.");
             fontDirectory = applicationDirPath;
@@ -78,6 +78,9 @@ QWinRTFontDatabase::~QWinRTFontDatabase()
 {
     foreach (IDWriteFontFile *fontFile, m_fonts.keys())
         fontFile->Release();
+
+    foreach (IDWriteFontFamily *fontFamily, m_fontFamilies)
+        fontFamily->Release();
 }
 
 QFont QWinRTFontDatabase::defaultFont() const
@@ -132,15 +135,36 @@ void QWinRTFontDatabase::populateFontDatabase()
         }
         QString familyName = QString::fromWCharArray(familyBuffer.data(), familyNameLength);
 
-        int fontCount = fontFamily->GetFontCount();
+        m_fontFamilies.insert(familyName, fontFamily.Detach());
+
+        registerFontFamily(familyName);
+    }
+
+    QBasicFontDatabase::populateFontDatabase();
+}
+
+void QWinRTFontDatabase::populateFamily(const QString &familyName)
+{
+    IDWriteFontFamily *fontFamily = m_fontFamilies.value(familyName);
+    if (!fontFamily) {
+        qWarning("The font family %s was not found.", qPrintable(familyName));
+        return;
+    }
+
+    bool fontRegistered = false;
+    const int fontCount = fontFamily->GetFontCount();
     for (int j = 0; j < fontCount; ++j) {
         ComPtr<IDWriteFont> font;
-            hr = fontFamily->GetFont(j, &font);
+        HRESULT hr = fontFamily->GetFont(j, &font);
         if (FAILED(hr)) {
-                qWarning("Unable to get base font: %s", qPrintable(qt_error_string(hr)));
+            qWarning("Unable to get font: %s", qPrintable(qt_error_string(hr)));
             continue;
         }
 
+        // Skip simulated faces
+        if (font->GetSimulations() != DWRITE_FONT_SIMULATIONS_NONE)
+            continue;
+
         ComPtr<IDWriteFontFace> baseFontFace;
         hr = font->CreateFontFace(&baseFontFace);
         if (FAILED(hr)) {
@@ -154,13 +178,6 @@ void QWinRTFontDatabase::populateFontDatabase()
             continue;
         }
 
-            // Only try to load true-type fonts
-            DWRITE_FONT_FACE_TYPE type = fontFace->GetType();
-            if (!(type == DWRITE_FONT_FACE_TYPE_TRUETYPE
-                  || type == DWRITE_FONT_FACE_TYPE_TRUETYPE_COLLECTION)) {
-                continue;
-            }
-
         // We can't deal with multi-file fonts
         quint32 fileCount;
         hr = fontFace->GetFiles(&fileCount, NULL);
@@ -168,7 +185,7 @@ void QWinRTFontDatabase::populateFontDatabase()
             qWarning("Unable to get font file count: %s", qPrintable(qt_error_string(hr)));
             continue;
         }
-            if (fileCount != 1) // Should not happen as we only look at TT fonts
+        if (fileCount != 1)
             continue;
 
         ComPtr<IDWriteLocalizedStrings> informationalStrings;
@@ -293,14 +310,21 @@ void QWinRTFontDatabase::populateFontDatabase()
         m_fonts.insert(fontFile, description);
         registerFont(familyName, QString(), foundryName, weight, style, stretch,
                      true, true, 0, fixedPitch, writingSystems, fontFile);
-        }
+        fontRegistered = true;
     }
 
-    QBasicFontDatabase::populateFontDatabase();
+    // Always populate something to avoid an assert
+    if (!fontRegistered) {
+        registerFont(familyName, QString(), QString(), QFont::Normal, QFont::StyleNormal,
+                     QFont::Unstretched, false, false, 0, false, QSupportedWritingSystems(), 0);
+    }
 }
 
 QFontEngine *QWinRTFontDatabase::fontEngine(const QFontDef &fontDef, void *handle)
 {
+    if (!handle) // Happens if a font family population failed
+        return 0;
+
     IDWriteFontFile *fontFile = reinterpret_cast<IDWriteFontFile *>(handle);
     if (!m_fonts.contains(fontFile))
         return QBasicFontDatabase::fontEngine(fontDef, handle);
@@ -361,6 +385,9 @@ QFontEngine *QWinRTFontDatabase::fontEngine(const QFontDef &fontDef, void *handl
 
 void QWinRTFontDatabase::releaseHandle(void *handle)
 {
+    if (!handle)
+        return;
+
     IDWriteFontFile *fontFile = reinterpret_cast<IDWriteFontFile *>(handle);
     if (m_fonts.contains(fontFile)) {
         m_fonts.remove(fontFile);

src/plugins/platforms/winrt/qwinrtfontdatabase.h

@@ -48,6 +48,7 @@ QT_BEGIN_NAMESPACE
 
 #ifndef Q_OS_WINPHONE
 struct IDWriteFontFile;
+struct IDWriteFontFamily;
 
 struct FontDescription
 {
@@ -64,10 +65,12 @@ public:
     ~QWinRTFontDatabase();
     QFont defaultFont() const Q_DECL_OVERRIDE;
     void populateFontDatabase() Q_DECL_OVERRIDE;
+    void populateFamily(const QString &familyName) Q_DECL_OVERRIDE;
     QFontEngine *fontEngine(const QFontDef &fontDef, void *handle) Q_DECL_OVERRIDE;
     void releaseHandle(void *handle) Q_DECL_OVERRIDE;
 private:
     QHash<IDWriteFontFile *, FontDescription> m_fonts;
+    QHash<QString, IDWriteFontFamily *> m_fontFamilies;
 #endif // !Q_OS_WINPHONE
 };