Change fallback fonts.

app/main.cpp

@@ -109,6 +109,7 @@ int main(int argc, char *argv[])
 
     engine.rootContext()->setContextProperty("workdir", getNamedArgument(args, "--workdir", "$HOME"));
     engine.rootContext()->setContextProperty("fileIO", &fileIO);
+    engine.rootContext()->setContextProperty("monospaceFontManager", &monospaceFontManager);
     engine.rootContext()->setContextProperty("monospaceSystemFonts", monospaceFontManager.retrieveMonospaceFonts());
 
     engine.rootContext()->setContextProperty("devicePixelRatio", app.devicePixelRatio());

app/monospacefontmanager.cpp

@@ -1,6 +1,7 @@
 #include "monospacefontmanager.h"
 
 #include <QDebug>
+#include <QFont>
 
 MonospaceFontManager::MonospaceFontManager(QObject *parent) : QObject(parent)
 {
@@ -23,3 +24,25 @@ QStringList MonospaceFontManager::retrieveMonospaceFonts() {
 
     return result;
 }
+
+void MonospaceFontManager::setFontSubstitution(const QString &family, const QString &substitute)
+{
+    if (family.isEmpty() || substitute.isEmpty()) {
+        return;
+    }
+
+    QFont::removeSubstitutions(family);
+    QFont::insertSubstitution(family, substitute);
+
+    qDebug() << "Font substitution set:" << family << "->" << substitute;
+}
+
+void MonospaceFontManager::removeFontSubstitution(const QString &family)
+{
+    if (family.isEmpty()) {
+        return;
+    }
+
+    QFont::removeSubstitutions(family);
+    qDebug() << "Font substitution removed for:" << family;
+}

app/monospacefontmanager.h

@@ -10,6 +10,10 @@ class MonospaceFontManager : public QObject
 public:
     explicit MonospaceFontManager(QObject *parent = nullptr);
     Q_INVOKABLE QStringList retrieveMonospaceFonts();
+
+public slots:
+    void setFontSubstitution(const QString &family, const QString &substitute);
+    void removeFontSubstitution(const QString &family);
 };
 
 #endif // MONOSPACEFONTMANAGER_H

app/qml/PreprocessedTerminal.qml

@@ -155,6 +155,10 @@ Item{
             scaleTexture = Math.max(1.0, Math.floor(screenScaling * appSettings.windowScaling));
 
             kterminal.lineSpacing = lineSpacing;
+
+            // Set up font fallback based on platform
+            var fallbackFont = appSettings.isMacOS ? "Menlo" : "monospace";
+            monospaceFontManager.setFontSubstitution(fontFamily, fallbackFont);
         }
 
         function startSession() {