From d0615041f084021887e069a3edca8113b90e1996 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Thu, 2 Sep 2021 16:43:13 +0100
Subject: [PATCH] Plugin clients:  Avoid notifying listeners when parameters
 have not changed

---
 .../AU/juce_AU_Wrapper.mm                     |  9 ++---
 .../VST/juce_VST_Wrapper.cpp                  | 23 ++++++------
 .../VST3/juce_VST3_Wrapper.cpp                | 35 +++++++------------
 3 files changed, 28 insertions(+), 39 deletions(-)

diff --git a/modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm b/modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm
index 37f0486712..c35d55a07a 100644
--- a/modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm
+++ b/modules/juce_audio_plugin_client/AU/juce_AU_Wrapper.mm
@@ -1029,10 +1029,11 @@ public:
             {
                 auto value = inValue / getMaximumParameterValue (param);
 
-                param->setValue (value);
-
-                inParameterChangedCallback = true;
-                param->sendValueChangedMessageToListeners (value);
+                if (value != param->getValue())
+                {
+                    inParameterChangedCallback = true;
+                    param->setValueNotifyingHost (value);
+                }
 
                 return noErr;
             }
diff --git a/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp b/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
index 84df483a05..d0b42aed28 100644
--- a/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
+++ b/modules/juce_audio_plugin_client/VST/juce_VST_Wrapper.cpp
@@ -703,12 +703,7 @@ public:
     void setParameter (int32 index, float value)
     {
         if (auto* param = juceParameters.getParamForIndex (index))
-        {
-            param->setValue (value);
-
-            inParameterChangedCallback = true;
-            param->sendValueChangedMessageToListeners (value);
-        }
+            setValueAndNotifyIfChanged (*param, value);
     }
 
     static void setParameterCB (Vst2::AEffect* vstInterface, int32 index, float value)
@@ -1433,6 +1428,15 @@ private:
     static void checkWhetherMessageThreadIsCorrect() {}
    #endif
 
+    void setValueAndNotifyIfChanged (AudioProcessorParameter& param, float newValue)
+    {
+        if (param.getValue() == newValue)
+            return;
+
+        inParameterChangedCallback = true;
+        param.setValueNotifyingHost (newValue);
+    }
+
     //==============================================================================
     template <typename FloatType>
     void deleteTempChannels (VstTempBuffers<FloatType>& tmpBuffers)
@@ -1716,12 +1720,7 @@ private:
         {
             if (! LegacyAudioParameter::isLegacy (param))
             {
-                auto value = param->getValueForText (String::fromUTF8 ((char*) args.ptr));
-                param->setValue (value);
-
-                inParameterChangedCallback = true;
-                param->sendValueChangedMessageToListeners (value);
-
+                setValueAndNotifyIfChanged (*param, param->getValueForText (String::fromUTF8 ((char*) args.ptr)));
                 return 1;
             }
         }
diff --git a/modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp b/modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp
index f654ba54f4..33f3adafd0 100644
--- a/modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp
+++ b/modules/juce_audio_plugin_client/VST3/juce_VST3_Wrapper.cpp
@@ -622,6 +622,15 @@ class JuceVST3Component;
 
 static thread_local bool inParameterChangedCallback = false;
 
+static void setValueAndNotifyIfChanged (AudioProcessorParameter& param, float newValue)
+{
+    if (param.getValue() == newValue)
+        return;
+
+    const InParameterChangedCallbackSetter scopedSetter { inParameterChangedCallback };
+    param.setValueNotifyingHost (newValue);
+}
+
 //==============================================================================
 class JuceVST3EditController : public Vst::EditController,
                                public Vst::IMidiMapping,
@@ -745,14 +754,7 @@ public:
                 // otherwise we get parallel streams of parameter value updates
                 // during playback
                 if (! owner.vst3IsPlaying)
-                {
-                    auto value = static_cast<float> (v);
-
-                    param.setValue (value);
-
-                    const InParameterChangedCallbackSetter scopedSetter { inParameterChangedCallback };
-                    param.sendValueChangedMessageToListeners (value);
-                }
+                    setValueAndNotifyIfChanged (param, (float) v);
 
                 changed();
                 return true;
@@ -2363,13 +2365,7 @@ public:
     void setBypassed (bool shouldBeBypassed)
     {
         if (auto* bypassParam = comPluginInstance->getBypassParameter())
-        {
-            auto floatValue = (shouldBeBypassed ? 1.0f : 0.0f);
-            bypassParam->setValue (floatValue);
-
-            const InParameterChangedCallbackSetter scopedSetter { inParameterChangedCallback };
-            bypassParam->sendValueChangedMessageToListeners (floatValue);
-        }
+            setValueAndNotifyIfChanged (*bypassParam, shouldBeBypassed ? 1.0f : 0.0f);
     }
 
     //==============================================================================
@@ -3109,15 +3105,8 @@ public:
                     else
                    #endif
                     {
-                        auto floatValue = static_cast<float> (value);
-
                         if (auto* param = comPluginInstance->getParamForVSTParamID (vstParamID))
-                        {
-                            param->setValue (floatValue);
-
-                            const InParameterChangedCallbackSetter scopedSetter { inParameterChangedCallback };
-                            param->sendValueChangedMessageToListeners (floatValue);
-                        }
+                            setValueAndNotifyIfChanged (*param, (float) value);
                     }
                 }
             }