Implement file callback, used in audio and midi-file plugs

source/backend/engine/CarlaEngine.cpp

@@ -1632,7 +1632,7 @@ void CarlaEngine::setCallback(const EngineCallbackFunc func, void* const ptr) no
 const char* CarlaEngine::runFileCallback(const FileCallbackOpcode action, const bool isDir, const char* const title, const char* const filter) noexcept
 {
     CARLA_SAFE_ASSERT_RETURN(title != nullptr && title[0] != '\0', nullptr);
-    CARLA_SAFE_ASSERT_RETURN(filter != nullptr && filter[0] != '\0', nullptr);
+    CARLA_SAFE_ASSERT_RETURN(filter != nullptr, nullptr);
     carla_debug("CarlaEngine::runFileCallback(%i:%s, %s, \"%s\", \"%s\")", action, FileCallbackOpcode2Str(action), bool2str(isDir), title, filter);
     CARLA_ENGINE_THREAD_SAFE_SECTION
 

source/carla_backend.py

@@ -29,9 +29,10 @@ from sys import platform, maxsize
 kIs64bit = bool(architecture()[0] == "64bit" and maxsize > 2**32)
 
 # ------------------------------------------------------------------------------------------------------------
-# Define enum type (integer)
+# Define custom types
 
 c_enum = c_int
+c_uintptr = c_uint64 if kIs64bit else c_uint32
 
 # ------------------------------------------------------------------------------------------------------------
 # Set Platform

source/carla_host.py

@@ -163,6 +163,8 @@ class HostWindow(QMainWindow):
         if Carla.host is not None:
             Carla.host.set_engine_callback(engineCallback)
 
+        Carla.host.set_file_callback(fileCallback)
+
         # -------------------------------------------------------------
         # Internal stuff
 
@@ -1218,3 +1220,26 @@ def engineCallback(ptr, action, pluginId, value1, value2, value3, valueStr):
         Carla.gui.ErrorCallback.emit(valueStr)
     elif action == ENGINE_CALLBACK_QUIT:
         Carla.gui.QuitCallback.emit()
+
+# ------------------------------------------------------------------------------------------------------------
+# File callback
+
+def fileCallback(ptr, action, isDir, title, filter):
+    if Carla.gui is None:
+        return None
+
+    ret = ""
+
+    if action == FILE_CALLBACK_DEBUG:
+        pass
+    elif action == FILE_CALLBACK_OPEN:
+        ret = QFileDialog.getOpenFileName(Carla.gui, charPtrToString(title), "", charPtrToString(filter) ) #, QFileDialog.ShowDirsOnly if isDir else 0x0)
+    elif action == FILE_CALLBACK_SAVE:
+        ret = QFileDialog.getSaveFileName(Carla.gui, charPtrToString(title), "", charPtrToString(filter), QFileDialog.ShowDirsOnly if isDir else 0x0)
+
+    if not ret:
+        return None
+
+    Carla.gui._fileRet = c_char_p(ret.encode("utf-8"))
+    retval = cast(byref(Carla.gui._fileRet), POINTER(c_uintptr))
+    return retval.contents.value