Fix calling canRequestParameterValueChanges() during constructor

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

distrho/src/DistrhoPlugin.cpp

@@ -23,6 +23,7 @@ START_NAMESPACE_DISTRHO
 
 uint32_t d_lastBufferSize = 0;
 double   d_lastSampleRate = 0.0;
+bool     d_lastCanRequestParameterValueChanges = false;
 
 /* ------------------------------------------------------------------------------------------------------------
  * Static fallback data, see DistrhoPluginInternal.hpp */
@@ -112,7 +113,7 @@ bool Plugin::writeMidiEvent(const MidiEvent& midiEvent) noexcept
 #if DISTRHO_PLUGIN_WANT_PARAMETER_VALUE_CHANGE_REQUEST
 bool Plugin::canRequestParameterValueChanges() const noexcept
 {
-    return pData->requestParameterValueChangeCallbackFunc != nullptr;
+    return pData->canRequestParameterValueChanges;
 }
 
 bool Plugin::requestParameterValueChange(const uint32_t index, const float value) noexcept

distrho/src/DistrhoPluginInternal.hpp

@@ -31,6 +31,7 @@ static const uint32_t kMaxMidiEvents = 512;
 
 extern uint32_t d_lastBufferSize;
 extern double   d_lastSampleRate;
+extern bool     d_lastCanRequestParameterValueChanges;
 
 // -----------------------------------------------------------------------
 // DSP callbacks
@@ -78,6 +79,7 @@ struct Plugin::PrivateData {
 
     uint32_t bufferSize;
     double   sampleRate;
+    bool     canRequestParameterValueChanges;
 
     PrivateData() noexcept
         : isProcessing(false),
@@ -103,7 +105,8 @@ struct Plugin::PrivateData {
           writeMidiCallbackFunc(nullptr),
           requestParameterValueChangeCallbackFunc(nullptr),
           bufferSize(d_lastBufferSize),
-          sampleRate(d_lastSampleRate)
+          sampleRate(d_lastSampleRate),
+          canRequestParameterValueChanges(d_lastCanRequestParameterValueChanges)
     {
         DISTRHO_SAFE_ASSERT(bufferSize != 0);
         DISTRHO_SAFE_ASSERT(d_isNotZero(sampleRate));

distrho/src/DistrhoPluginLV2.cpp

@@ -1367,6 +1367,7 @@ static LV2_Handle lv2_instantiate(const LV2_Descriptor*, double sampleRate, cons
     }
 
     d_lastSampleRate = sampleRate;
+    d_lastCanRequestParameterValueChanges = ctrlInPortChangeReq != nullptr;
 
     return new PluginLv2(sampleRate, uridMap, worker, ctrlInPortChangeReq, usingNominal);
 }

distrho/src/DistrhoPluginVST.cpp

@@ -1286,6 +1286,7 @@ static intptr_t vst_dispatcherCallback(AEffect* effect, int32_t opcode, int32_t
         // set valid but dummy values
         d_lastBufferSize = 512;
         d_lastSampleRate = 44100.0;
+        d_lastCanRequestParameterValueChanges = true;
     }
 
     // Create dummy plugin to get data from
@@ -1296,6 +1297,7 @@ static intptr_t vst_dispatcherCallback(AEffect* effect, int32_t opcode, int32_t
         // unset
         d_lastBufferSize = 0;
         d_lastSampleRate = 0.0;
+        d_lastCanRequestParameterValueChanges = false;
 
         *(PluginExporter**)ptr = &plugin;
         return 0;
@@ -1317,6 +1319,7 @@ static intptr_t vst_dispatcherCallback(AEffect* effect, int32_t opcode, int32_t
 
             d_lastBufferSize = audioMaster(effect, audioMasterGetBlockSize, 0, 0, nullptr, 0.0f);
             d_lastSampleRate = audioMaster(effect, audioMasterGetSampleRate, 0, 0, nullptr, 0.0f);
+            d_lastCanRequestParameterValueChanges = true;
 
             // some hosts are not ready at this point or return 0 buffersize/samplerate
             if (d_lastBufferSize == 0)