Define kCVPortIsOptional property and use it for LV2

Signed-off-by: falkTX <falktx@falktx.com>

distrho/DistrhoPlugin.hpp

@@ -72,6 +72,12 @@ static const uint32_t kCVPortHasPositiveUnipolarRange = 0x40;
  */
 static const uint32_t kCVPortHasScaledRange = 0x80;
 
+/**
+   CV port is optional, allowing hosts that do no CV ports to load the plugin.
+   When loaded in hosts that don't support CV, the float* buffer for this port will be null.
+ */
+static const uint32_t kCVPortIsOptional = 0x100;
+
 /** @} */
 
 /* ------------------------------------------------------------------------------------------------------------

distrho/src/DistrhoPluginLV2export.cpp

@@ -532,6 +532,9 @@ void lv2_generate_ttl(const char* const basename)
                     }
                 }
 
+                if ((port.hints & (kAudioPortIsCV|kCVPortIsOptional)) == (kAudioPortIsCV|kCVPortIsOptional))
+                    pluginString += "        lv2:portProperty lv2:connectionOptional;\n";
+
                 if (i+1 == DISTRHO_PLUGIN_NUM_INPUTS)
                     pluginString += "    ] ;\n";
                 else