Startup optimizations (#5090)

* Delay DitheringSelector startup
* Delay setting the drag target
* Delay & enqueue menu reloading

laf

@@ -1 +1 @@
-Subproject commit f858a8412897a4f9e95fd8aeac891466fbd06852
+Subproject commit fdc9001cb0251a40092ebb9b2bca6e61fdf9f6f7

src/app/ui/dithering_selector.cpp

@@ -180,7 +180,6 @@ DitheringSelector::DitheringSelector(Type type) : m_type(type)
   m_extChanges = extensions.DitheringMatricesChange.connect([this] { regenerate(); });
 
   setUseCustomWidget(true);
-  regenerate();
 }
 
 void DitheringSelector::onInitTheme(ui::InitThemeEvent& ev)
@@ -190,6 +189,16 @@ void DitheringSelector::onInitTheme(ui::InitThemeEvent& ev)
     setSizeHint(calcItemSizeHint(0));
 }
 
+void DitheringSelector::onVisible(bool visible)
+{
+  if (visible && !m_initialized) {
+    // Only do the expensive regeneration when we're set as visible for the first time.
+    regenerate();
+    m_initialized = true;
+  }
+  ComboBox::onVisible(visible);
+}
+
 void DitheringSelector::setSelectedItemByName(const std::string& name)
 {
   int index = findItemIndex(name);

src/app/ui/dithering_selector.h

@@ -31,6 +31,7 @@ public:
 
 protected:
   void onInitTheme(ui::InitThemeEvent& ev) override;
+  void onVisible(bool visible) override;
 
 private:
   void regenerate(int selectedItemIndex = 0);
@@ -38,6 +39,7 @@ private:
 
   Type m_type;
   obs::scoped_connection m_extChanges;
+  bool m_initialized = false;
 };
 
 } // namespace app

src/app/ui/main_menu_bar.cpp

@@ -14,6 +14,8 @@
 #include "app/app.h"
 #include "app/app_menus.h"
 #include "app/extensions.h"
+#include "ui/manager.h"
+#include "ui/message.h"
 
 namespace app {
 
@@ -26,13 +28,26 @@ MainMenuBar::MainMenuBar()
 
   // Reload the main menu if there are changes in keyboard shortcuts
   // or scripts when extensions are installed/uninstalled or
-  // enabled/disabled.
-  m_extKeys = extensions.KeysChange.connect([this] { reload(); });
-  m_extScripts = extensions.ScriptsChange.connect([this] { reload(); });
+  // enabled/disabled, enqueued to avoid multiple reloads.
+  m_extKeys = extensions.KeysChange.connect([&] { queueReload(); });
+  m_extScripts = extensions.ScriptsChange.connect([&] { queueReload(); });
+}
+
+void MainMenuBar::queueReload()
+{
+  if (m_queuedReload)
+    return;
+
+  m_queuedReload = true;
+
+  auto* msg = new CallbackMessage([this] { reload(); });
+  msg->setRecipient(this);
+  Manager::getDefault()->enqueueMessage(msg);
 }
 
 void MainMenuBar::reload()
 {
+  m_queuedReload = false;
   setMenu(nullptr);
 
   // Reload all menus.

src/app/ui/main_menu_bar.h

@@ -18,11 +18,13 @@ class MainMenuBar : public ui::MenuBar {
 public:
   MainMenuBar();
 
+  void queueReload();
   void reload();
 
 private:
   obs::scoped_connection m_extKeys;
   obs::scoped_connection m_extScripts;
+  bool m_queuedReload = false;
 };
 
 } // namespace app

src/ui/manager.cpp

@@ -197,10 +197,8 @@ Manager::Manager(const os::WindowRef& nativeWindow)
   , m_mouseButton(kButtonNone)
 {
   // The native window can be nullptr when running tests
-  if (nativeWindow) {
+  if (nativeWindow)
     nativeWindow->setUserData(&m_display);
-    nativeWindow->setDragTarget(this);
-  }
 
   ASSERT(manager_thread == std::thread::id());
   manager_thread = std::this_thread::get_id();
@@ -242,6 +240,14 @@ Manager::Manager(const os::WindowRef& nativeWindow)
 
   // TODO check if this is needed
   onNewDisplayConfiguration(&m_display);
+
+  if (nativeWindow) {
+    // Setting the drag target has a slight performance cost that we can offset by running it later.
+    auto* callbackMessage = new CallbackMessage(
+      [this, nativeWindow] { nativeWindow->setDragTarget(this); });
+    callbackMessage->setRecipient(this);
+    enqueueMessage(callbackMessage);
+  }
 }
 
 Manager::~Manager()