Implement transient windows (out of process) for win32

source/backend/plugin/CarlaPlugin.cpp

@@ -2210,8 +2210,12 @@ void CarlaPlugin::uiIdle()
     CarlaString uiTitle(pData->name);
     uiTitle += " (GUI)";
 
-    if (CarlaPluginUI::tryTransientWinIdMatch(getUiBridgeProcessId(), uiTitle, pData->engine->getOptions().frontendWinId, true))
+    if (CarlaPluginUI::tryTransientWinIdMatch(getUiBridgeProcessId(), uiTitle,
+                                              pData->engine->getOptions().frontendWinId, pData->transientFirstTry))
+    {
         pData->transientTryCounter = 0;
+        pData->transientFirstTry = false;
+    }
 }
 
 void CarlaPlugin::uiParameterChange(const uint32_t index, const float value) noexcept

source/backend/plugin/CarlaPluginInternal.cpp

@@ -592,6 +592,7 @@ CarlaPlugin::ProtectedData::ProtectedData(CarlaEngine* const eng, const uint idx
       ctrlChannel(0),
       extraHints(0x0),
       transientTryCounter(0),
+      transientFirstTry(true),
       name(nullptr),
       filename(nullptr),
       iconName(nullptr),

source/backend/plugin/CarlaPluginInternal.hpp

@@ -228,6 +228,7 @@ struct CarlaPlugin::ProtectedData {
     int8_t ctrlChannel;
     uint   extraHints;
     uint   transientTryCounter;
+    bool   transientFirstTry;
 
     // data 1
     const char* name;

source/bridges-ui/CarlaBridgeToolkitNative.cpp

@@ -68,8 +68,7 @@ public:
 
         fHostUI->setTitle(options.windowTitle.buffer());
 
-#ifdef HAVE_X11
-        // Out-of-process reparenting only possible on X11
+#if (defined(CARLA_OS_WIN) && defined(BRIDGE_HWND)) || (defined(HAVE_X11) && defined(BRIDGE_X11))
         if (options.transientWindowId != 0)
         {
             fHostUI->setTransientWinId(options.transientWindowId);

source/modules/dgl/src/Window.cpp

@@ -346,22 +346,6 @@ struct Window::PrivateData {
         fModal.enabled = true;
         fModal.parent->fModal.childFocus = this;
 
-#ifdef DISTRHO_OS_WINDOWS
-        // Center this window
-        PuglInternals* const parentImpl = fModal.parent->fView->impl;
-
-        RECT curRect;
-        RECT parentRect;
-        GetWindowRect(hwnd, &curRect);
-        GetWindowRect(parentImpl->hwnd, &parentRect);
-
-        int x = parentRect.left+(parentRect.right-curRect.right)/2;
-        int y = parentRect.top +(parentRect.bottom-curRect.bottom)/2;
-
-        SetWindowPos(hwnd, 0, x, y, 0, 0, SWP_NOACTIVATE|SWP_NOOWNERZORDER|SWP_NOSIZE|SWP_NOZORDER);
-        UpdateWindow(hwnd);
-#endif
-
         fModal.parent->setVisible(true);
         setVisible(true);
 

source/utils/CarlaPluginUI.cpp

@@ -1046,10 +1046,41 @@ bool CarlaPluginUI::tryTransientWinIdMatch(const uintptr_t pid, const char* cons
 
     XFlush(sd.display);
     return true;
-#else
+#endif
+
+#ifdef CARLA_OS_MAC
+    // TODO
+#endif
+
+#ifdef CARLA_OS_WIN
+    if (HWND const childWindow = FindWindowA(nullptr, uiTitle))
+    {
+        HWND const parentWindow = (HWND)winId;
+        SetWindowLongPtr(childWindow, GWLP_HWNDPARENT, (LONG_PTR)parentWindow);
+
+        if (centerUI)
+        {
+            RECT rectChild, rectParent;
+
+            if (GetWindowRect(childWindow, &rectChild) && GetWindowRect(parentWindow, &rectParent))
+            {
+                SetWindowPos(childWindow, parentWindow,
+                             rectParent.left + (rectChild.right-rectChild.left)/2,
+                             rectParent.top + (rectChild.bottom-rectChild.top)/2,
+                             0, 0, SWP_NOSIZE);
+            }
+        }
+
+        carla_stdout("Match found using window name");
+        return true;
+    }
+
+    return false;
+#endif
+
+    // fallback, may be unused
     return true;
     (void)pid; (void)centerUI;
-#endif
 }
 
 // -----------------------------------------------------