Use System::appName() to specify the window class on Windows and X11

os/common/system.h

@@ -29,7 +29,8 @@ class CommonSystem : public System {
   CommonSystem();
   ~CommonSystem();
 
-  void setAppName(const std::string& appName) override { }
+  const std::string& appName() const override { return m_appName; }
+  void setAppName(const std::string& appName) override { m_appName = appName; }
   void setAppMode(AppMode appMode) override { }
 
   void markCliFileAsProcessed(const std::string& fn) override { }
@@ -79,6 +80,7 @@ class CommonSystem : public System {
   void destroyInstance();
 
 private:
+  std::string m_appName;
   Ref<NativeDialogs> m_nativeDialogs;
 #ifdef LAF_FREETYPE
   std::unique_ptr<ft::Lib> m_ft;

os/none/os.cpp

@@ -20,7 +20,6 @@ namespace os {
 
 class NoneSystem : public System {
 public:
-  void setAppName(const std::string& appName) override { }
   void setAppMode(AppMode appMode) override { }
 
   void markCliFileAsProcessed(const std::string& fn) override { }

os/system.h

@@ -58,11 +58,15 @@ namespace os {
     virtual ~System() { }
   public:
 
-    // Windows-specific: The app name at the moment is used to receive
-    // DDE messages (WM_DDE_INITIATE) and convert WM_DDE_EXECUTE
-    // messages into Event::DropFiles. This allows to the user
-    // double-click files in the File Explorer and open the file in a
-    // running instance of your app.
+    // The app name is used in several places.
+    //
+    // For X11 it's used for the WM_CLASS name of the main window.
+    //
+    // For Windows it's used for 1) the main window class name, and
+    // 2) to receive DDE messages (WM_DDE_INITIATE) and convert
+    // WM_DDE_EXECUTE messages into Event::DropFiles. This allows to
+    // the user double-click files in the File Explorer and open the
+    // file in a running instance of your app.
     //
     // To receive DDE messages you have to configure the registry in
     // this way (HKCR=HKEY_CLASSES_ROOT):
@@ -76,6 +80,7 @@ namespace os {
     //
     // The default value of "HKCR\AppFile\shell\open\ddeexec\application"
     // must match the "appName" given in this function.
+    virtual const std::string& appName() const = 0;
     virtual void setAppName(const std::string& appName) = 0;
 
     // We can use this function to create an application that can run

os/win/system.cpp

@@ -175,11 +175,6 @@ void SystemWin::setAppMode(AppMode appMode)
   }
 }
 
-void SystemWin::setAppName(const std::string& appName)
-{
-  m_appName = appName;
-}
-
 void SystemWin::setTabletOptions(const TabletOptions& options)
 {
   m_tabletOptions = options;

os/win/system.h

@@ -25,9 +25,6 @@ class SystemWin : public CommonSystem {
   WinAPI& winApi() { return m_winApi; }
   WintabAPI& wintabApi() { return m_wintabApi; }
 
-  void setAppName(const std::string& appName) override;
-  std::string appName() const { return m_appName; }
-
   void setTabletOptions(const TabletOptions& options) override;
   TabletOptions tabletOptions() const override { return m_tabletOptions; }
 
@@ -56,7 +53,6 @@ class SystemWin : public CommonSystem {
   void _setInternalMousePosition(const Event& ev);
 
 private:
-  std::string m_appName;
   TabletOptions m_tabletOptions;
   WinAPI m_winApi;
   WintabAPI m_wintabApi;

os/win/window.cpp

@@ -44,10 +44,6 @@
 
 #include <algorithm>
 
-// TODO the window name should be customized from the CMakeLists.txt
-//      properties (see LAF_X11_WM_CLASS too)
-#define OS_WND_CLASS_NAME L"Aseprite.Window"
-
 #define KEY_TRACE(...)
 #define MOUSE_TRACE(...)
 #define TOUCH_TRACE(...)
@@ -137,6 +133,17 @@ static BOOL CALLBACK log_monitor_info(HMONITOR monitor,
   return TRUE;
 }
 
+std::wstring get_wnd_class_name()
+{
+  if (auto sys = instance()) {
+    if (!sys->appName().empty())
+      return base::from_utf8(sys->appName());
+  }
+  // On Windows the class name cannot be empty, if we use an empty
+  // class the window class registration will fail.
+  return std::wstring(L"laf");
+}
+
 // Keys used to detect if the Windows 11 dark mode is selected.
 static constexpr const char* kPersonalizeKey = "Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize";
 static constexpr const char* kAppsUseLightThemeValue = "AppsUseLightTheme";
@@ -2501,9 +2508,10 @@ TabletAPI WindowWin::tabletAPI() const
 void WindowWin::registerClass()
 {
   HMODULE instance = GetModuleHandle(nullptr);
+  const auto className = get_wnd_class_name();
 
   WNDCLASSEX wcex;
-  if (GetClassInfoEx(instance, OS_WND_CLASS_NAME, &wcex))
+  if (GetClassInfoEx(instance, className.c_str(), &wcex))
     return;                 // Already registered
 
   wcex.cbSize        = sizeof(WNDCLASSEX);
@@ -2516,7 +2524,7 @@ void WindowWin::registerClass()
   wcex.hCursor       = NULL;
   wcex.hbrBackground = (HBRUSH)(COLOR_WINDOWFRAME+1);
   wcex.lpszMenuName  = nullptr;
-  wcex.lpszClassName = OS_WND_CLASS_NAME;
+  wcex.lpszClassName = className.c_str();
   wcex.hIconSm       = nullptr;
 
   if (RegisterClassEx(&wcex) == 0)
@@ -2593,9 +2601,10 @@ HWND WindowWin::createHwnd(WindowWin* self, const WindowSpec& spec)
     rc.h = CW_USEDEFAULT;
   }
 
+  const auto className = get_wnd_class_name();
   HWND hwnd = CreateWindowEx(
     exStyle,
-    OS_WND_CLASS_NAME,
+    className.c_str(),
     L"",
     style,
     rc.x, rc.y, rc.w, rc.h,

os/win/wintab.cpp

@@ -87,7 +87,7 @@ class HandleSigSegv {
 
 private:
   static std::string getFilename() {
-    std::string appName = ((SystemWin*)os::instance())->appName();
+    std::string appName = os::instance()->appName();
     return base::join_path(base::get_temp_path(),
                            appName + "-wintab32.crash");
   }

os/x11/window.cpp

@@ -41,10 +41,6 @@
 
 #define LAF_X11_DOUBLE_CLICK_TIMEOUT 250
 
-// TODO the window name should be customized from the CMakeLists.txt
-//      properties (see OS_WND_CLASS_NAME too)
-#define LAF_X11_WM_CLASS "Aseprite"
-
 const int _NET_WM_STATE_REMOVE = 0;
 const int _NET_WM_STATE_ADD    = 1;
 
@@ -166,6 +162,14 @@ std::string decode_url(const std::string& in)
   return out;
 }
 
+std::string get_x11_wm_class_name()
+{
+  if (auto sys = instance())
+    return sys->appName();
+  // On X11 the class name can be empty.
+  return std::string();
+}
+
 } // anonymous namespace
 
 // static
@@ -294,7 +298,7 @@ WindowX11::WindowX11(::Display* display, const WindowSpec& spec)
   if (!m_window)
     throw std::runtime_error("Cannot create X11 window");
 
-  setWMClass(LAF_X11_WM_CLASS);
+  setWMClass(get_x11_wm_class_name());
 
   // Special frame for this window
   if (spec.floating()) {