Re-add tracktion vst fix. Use CARLA_TRACKTION_WORKAROUND env var

source/backend/engine/CarlaEngineNative.cpp

@@ -63,7 +63,8 @@ class CarlaEngineNativeUI : public CarlaExternalUI
 {
 public:
     CarlaEngineNativeUI(CarlaEngine* const engine)
-        : fEngine(engine)
+        : fEngine(engine),
+          fIsReady(false)
     {
         carla_debug("CarlaEngineNativeUI::CarlaEngineNativeUI(%p)", engine);
     }
@@ -73,6 +74,11 @@ public:
         carla_debug("CarlaEngineNativeUI::~CarlaEngineNativeUI()");
     }
 
+    bool isReady() const noexcept
+    {
+        return fIsReady;
+    }
+
 protected:
     bool msgReceived(const char* const msg) noexcept override
     {
@@ -536,6 +542,10 @@ protected:
             if (CarlaPlugin* const plugin = fEngine->getPlugin(pluginId))
                 plugin->showCustomUI(yesNo);
         }
+        else if (std::strcmp(msg, "ready") == 0)
+        {
+            fIsReady = true;
+        }
         else
         {
             carla_stderr("CarlaEngineNativeUI::msgReceived : %s", msg);
@@ -555,6 +565,7 @@ protected:
 
 private:
     CarlaEngine* const fEngine;
+    bool               fIsReady;
 
     void _updateParamValues(CarlaPlugin* const plugin, const uint32_t pluginId) const noexcept
     {
@@ -577,7 +588,8 @@ public:
           fIsActive(false),
           fIsRunning(false),
           fUiServer(this),
-          fOptionsForced(false)
+          fOptionsForced(false),
+          fWaitForReadyMsg(false)
     {
         carla_debug("CarlaEngineNative::CarlaEngineNative()");
 
@@ -1498,6 +1510,16 @@ protected:
 
             if (kIsPatchbay)
                 patchbayRefresh(false);
+
+            if (fWaitForReadyMsg)
+            {
+                carla_stdout("Using Carla plugin embedded in Tracktion, waiting for it to be ready...");
+
+                for (; fUiServer.isPipeRunning() && ! fUiServer.isReady();)
+                    fUiServer.idlePipe();
+
+                carla_stdout("Done!");
+            }
         }
         else
         {
@@ -1751,6 +1773,8 @@ public:
         switch(opcode)
         {
         case NATIVE_PLUGIN_OPCODE_NULL:
+            if (static_cast<uint32_t>(index) == 0xDEADF00D && value == 0xC0C0B00B)
+                handlePtr->fWaitForReadyMsg = true;
             return 0;
         case NATIVE_PLUGIN_OPCODE_BUFFER_SIZE_CHANGED:
             CARLA_SAFE_ASSERT_RETURN(value > 0, 0);
@@ -1794,6 +1818,7 @@ private:
     CarlaEngineNativeUI fUiServer;
 
     bool fOptionsForced;
+    bool fWaitForReadyMsg;
     char fTmpBuf[STR_MAX+1];
 
     CarlaPlugin* _getFirstPlugin() const noexcept

source/native-plugins/resources/carla-plugin

@@ -485,6 +485,8 @@ class CarlaEmbedW(QEmbedWidget):
         self.addWidget(self.gui.centralWidget())
         self.finalSetup(self.gui, winId)
 
+        self.gui.send(["ready"])
+
     def addShortcutActions(self, actions):
         for action in actions:
             if not action.shortcut().isEmpty():

source/plugin/carla-vst.cpp

@@ -275,12 +275,39 @@ public:
                 // set CARLA_PLUGIN_EMBED_WINID for external process
                 carla_setenv("CARLA_PLUGIN_EMBED_WINID", strBuf);
 
+                // check if vst host is an old version of tracktion
+                bool oldTracktionWorkaround = false;
+
+                // tracktion doesn't export its version properly, use env var instead
+                if (std::getenv("CARLA_TRACKTION_WORKAROUND") != nullptr)
+                {
+                    carla_zeroChars(strBuf, 0xff+1);
+                    hostCallback(audioMasterGetProductString, 0, 0, strBuf, 0.0f);
+                    oldTracktionWorkaround = (std::strcmp(strBuf, "Tracktion") == 0);
+
+                    // if vst host is old tracktion, delay UI appearance for a bit (part 1)
+                    if (oldTracktionWorkaround)
+                        fDescriptor->dispatcher(fHandle, NATIVE_PLUGIN_OPCODE_NULL, (int32_t)0xDEADF00D, 0xC0C0B00B, nullptr, 0.0f);
+                }
+
                 // show UI now
                 fDescriptor->ui_show(fHandle, true);
 
                 // reset CARLA_PLUGIN_EMBED_WINID just in case
                 carla_setenv("CARLA_PLUGIN_EMBED_WINID", "0");
 
+                // if vst host is old tracktion, delay UI appearance for a bit (part 2)
+                if (oldTracktionWorkaround)
+                {
+                    carla_stdout("Old Tracktion detected, delaying UI appearance so it works properly...");
+
+                    for (int x=10; --x>=0;)
+                    {
+                        hostCallback(audioMasterIdle);
+                        carla_msleep(25);
+                    }
+                }
+
                 ret = 1;
             }
             break;