fix zoom detection issue in old OSX versions

PanoPainter-OSX/main.cpp

@@ -467,7 +467,9 @@
     view = [[View alloc] initWithFrame:r];
     controller = [[Controller alloc] initWithWindow:window];
     App::I->osx_view = view;
-    App::I->zoom = Settings::value_or<Serializer::Float>("ui-scale", (float)view.layer.contentsScale);
+    
+    float z = (float)window.backingScaleFactor;
+    App::I->zoom = Settings::value_or<Serializer::Float>("ui-scale", (z > 0.f) ? z : 1.f);
 
     auto style = NSTitledWindowMask|NSMiniaturizableWindowMask|NSResizableWindowMask|NSClosableWindowMask;
     window = [[Window alloc] initWithContentRect:r styleMask:style backing:NSBackingStoreBuffered defer:NO];

src/app_events.cpp

@@ -41,6 +41,13 @@ bool App::clipboard_set_text(const std::string& s)
 #endif
 }
 
+void App::stacktrace()
+{
+#if __OSX__
+    NSString* callstack = [[NSThread callStackSymbols] componentsJoinedByString:@"\n"];
+    LOG("callstack:\n%s", [callstack cStringUsingEncoding:NSUTF8StringEncoding]);
+#endif
+}
 
 void App::crash_test()
 {

src/app_layout.cpp

@@ -1248,7 +1248,7 @@ void App::initLayout()
     };
 
     layout.on_loaded = [&] (bool reloaded) {
-        LOG("initializing layout updating after load");
+        LOG("initializing layout updating after load %d x %d zoom %f", (int)width, (int)height, zoom);
         layout[main_id]->update(width, height, zoom);
 
         LOG("initializing layout components");

src/node_canvas.cpp

@@ -621,6 +621,7 @@ void NodeCanvas::reset_camera()
 void NodeCanvas::create_buffers()
 {
     auto new_size = GetSize() * m_density;
+    LOG("NodeCanvas::create_buffers size: %d x %d density %f", (int)new_size.x, (int)new_size.y, m_density);
     m_canvas->m_mixer.create((int)new_size.x * m_canvas->m_mixer_scale,
         (int)new_size.y * m_canvas->m_mixer_scale, -1, GL_RGBA8);
     m_blender_rtt.create((int)new_size.x, (int)new_size.y, -1, GL_RGBA8);