better way to solve yesterday font problem, small visual avatar rendering fix

shared/global.cpp

@@ -17,6 +17,7 @@
  */
 
 #include "global.h"
+#include <QFontDatabase>
 
 #include "enums.h"
 #include "ui/models/roster.h"
@@ -26,6 +27,25 @@ constexpr bool OMEMO_SUPPORT = true;
 constexpr bool OMEMO_SUPPORT = false
 #endif
 
+QFont getFont (QFontDatabase::SystemFont type, bool bold = false, bool italic = false, qreal factor = 1.0) {
+    QFont font = QFontDatabase::systemFont(type);
+    if (bold)
+        font.setBold(true);
+    if (italic)
+        font.setItalic(true);
+
+    if (factor != 1.0) {
+        float ps = font.pointSizeF();
+        if (ps != -1) {
+            font.setPointSizeF(ps * factor);
+        } else {
+            font.setPointSize(font.pointSize() * factor);
+        }
+    }
+
+    return font;
+}
+
 Shared::Global* Shared::Global::instance = 0;
 const std::set<QString> Shared::Global::supportedImagesExts = {"png", "jpg", "webp", "jpeg", "gif", "svg"};
 
@@ -102,6 +122,14 @@ Shared::Global::Global():
     defaultSystemStyle(QApplication::style()->objectName()),
     defaultSystemPalette(QApplication::palette()),
     omemoSupport(OMEMO_SUPPORT),
+    defaultFont(QFontDatabase::systemFont(QFontDatabase::GeneralFont)),
+    smallFont(getFont(QFontDatabase::SmallestReadableFont, false, true)),
+    headerFont(getFont(QFontDatabase::TitleFont, true, false, 1.1)),
+    titleFont(getFont(QFontDatabase::TitleFont, true, false, 1.3)),
+    defaultFontMetrics(defaultFont),
+    smallFontMetrics(smallFont),
+    headerFontMetrics(headerFont),
+    titleFontMetrics(titleFont),
     pluginSupport({
         {"KWallet", false},
         {"openFileManagerWindowJob", false},

shared/global.h

@@ -42,6 +42,8 @@
 #include <QProcess>
 #include <QDesktopServices>
 #include <QRegularExpression>
+#include <QFont>
+#include <QFontMetrics>
 
 namespace Shared {
     
@@ -100,6 +102,14 @@ namespace Shared {
         static void setTheme(const QString& path);
         static void setStyle(const QString& style);
         const bool omemoSupport;
+        QFont defaultFont;
+        QFont smallFont;
+        QFont headerFont;
+        QFont titleFont;
+        QFontMetrics defaultFontMetrics;
+        QFontMetrics smallFontMetrics;
+        QFontMetrics headerFontMetrics;
+        QFontMetrics titleFontMetrics;
         
         template<typename T>
         static T fromInt(int src);