Fix macOS pixel ratio detection

src/citra_qt/bootmanager.cpp

@@ -144,8 +144,8 @@ QByteArray GRenderWindow::saveGeometry() {
 }
 
 qreal GRenderWindow::windowPixelRatio() const {
-    // windowHandle() might not be accessible until the window is displayed to screen.
-    return windowHandle() ? windowHandle()->screen()->devicePixelRatio() : 1.0f;
+    // QOpenGLWidget isn't backed by a native window, so we need to use the top level window instead
+    return QApplication::activeWindow()->devicePixelRatio();
 }
 
 std::pair<u32, u32> GRenderWindow::ScaleTouch(const QPointF pos) const {

src/citra_qt/main.cpp

@@ -2062,6 +2062,7 @@ int main(int argc, char* argv[]) {
     std::string bin_path = FileUtil::GetBundleDirectory() + DIR_SEP + "..";
     chdir(bin_path.c_str());
 #endif
+    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
     QCoreApplication::setAttribute(Qt::AA_DontCheckOpenGLContextThreadAffinity);
     QCoreApplication::setAttribute(Qt::AA_ShareOpenGLContexts);
     QApplication app(argc, argv);