Support alternate AUv2 Stream Dictionary Construction Strategies

The AUv2 protocol uses a CFDictionary to constrct its stream.
The default wrapper approach uses code from the AUSDK example and
is a common approach, but not the only one. This allows you to
set other strategies. Right now JUCE is the only other strategy
supported.

This means that we can make AUv2 wrappers compatible with streams
from other toolkits and allow mgiration to the wrapper for projects.

cmake/wrap_auv2.cmake

@@ -13,6 +13,17 @@ function(target_add_auv2_wrapper)
 
             CLAP_TARGET_FOR_CONFIG
 
+            # AUV2 uses a CFDictionary to store state so
+            # we need to choose what keys to populate it with.
+            # The wrapper by default uses the key choices from
+            # the AUSDK example, but for compatability with people
+            # moving from other frameworks we do support other schema.
+            #
+            # SUpported schema today are
+            # - WRAPPER (the default)
+            # - JUCE (use the JUCE AUV2 default)
+            DICTIONARY_STREAM_FORMAT
+
             MACOS_EMBEDDED_CLAP_LOCATION
             )
     cmake_parse_arguments(AUV2 "" "${oneValueArgs}" "" ${ARGN})
@@ -149,6 +160,14 @@ function(target_add_auv2_wrapper)
 
 	    ${bhtgoutdir}/generated_entrypoints.hxx)
     target_compile_options(${AUV2_TARGET} PRIVATE -fno-char8_t)
+    if (DEFINED AUV2_DICTIONARY_STREAM_FORMAT)
+        # valud options check
+        set (sf ${AUV2_DICTIONARY_STREAM_FORMAT})
+        if (NOT ((${sf} STREQUAL "JUCE") OR (${sf} STREQUAL "WRAPPER")))
+            message(FATAL_ERROR "Unrecognized DICTIONARY_STREAM_FORMAT in AUV2: ${sf}")
+        endif()
+        target_compile_definitions(${AUV2_TARGET} PRIVATE DICTIONARY_STREAM_FORMAT_${AUV2_DICTIONARY_STREAM_FORMAT}=1)
+    endif()
 
     if (NOT TARGET ${AUV2_TARGET}-clap-wrapper-auv2-lib)
         # For now make this an interface

src/wrapasauv2.cpp

@@ -1114,6 +1114,17 @@ OSStatus WrapAsAUV2::SaveState(CFPropertyListRef* ptPList)
     Clap::StateMemento chunk;
     _plugin->_ext._state->save(_plugin->_plugin, chunk);
 
+#if DICTIONARY_STREAM_FORMAT_JUCE
+    auto err = ausdk::AUBase::SaveState(ptPList);
+    if (err != noErr) return err;
+
+    CFDataRef tData = CFDataCreate(0, (UInt8*)chunk.data(), chunk.size());
+    CFMutableDictionaryRef dict = (CFMutableDictionaryRef)*ptPList;
+
+    CFDictionarySetValue(dict, CFSTR("jucePluginState"), tData);
+    CFRelease(tData);
+    chunk.clear();
+#else
     CFDataRef tData = CFDataCreate(0, (UInt8*)chunk.data(), chunk.size());
     const AudioComponentDescription desc = GetComponentDescription();
 
@@ -1148,10 +1159,12 @@ OSStatus WrapAsAUV2::SaveState(CFPropertyListRef* ptPList)
     CFDictionarySetValue(*dict, CFSTR(kAUPresetNameKey), _current_program_name);
 
     *ptPList = static_cast<CFPropertyListRef>(dict.release());  // transfer ownership
+#endif
   }
 
   return noErr;
 }
+
 OSStatus WrapAsAUV2::RestoreState(CFPropertyListRef plist)
 {
   if (!plist) return kAudioUnitErr_InvalidParameter;
@@ -1162,7 +1175,39 @@ OSStatus WrapAsAUV2::RestoreState(CFPropertyListRef plist)
 
   // Find 'data' key
   const void* pData = CFDictionaryGetValue(tDict, CFSTR(kAUPresetDataKey));
-  if (CFGetTypeID(CFTypeRef(pData)) != CFDataGetTypeID()) return -1;
+  if (!pData || CFGetTypeID(CFTypeRef(pData)) != CFDataGetTypeID()) return -1;
+
+    /*
+   * In the read side I fall through to default, whereas in the write
+   * side I use an 'else' on the set of stream formats. This means
+   * you at least try in case saved with an older wrapper version
+   */
+#if DICTIONARY_STREAM_FORMAT_JUCE
+  /*
+   * In the case when migrating from a JUCE AUv2 to a
+   * clap-wrapper one, if you want to preserve state
+   * you want to read the juce key from the dictionary.
+   */
+  CFDataRef juceData{nullptr};
+  CFStringRef juceKey(
+      CFStringCreateWithCString(kCFAllocatorDefault, "jucePluginState", kCFStringEncodingUTF8));
+  bool valuePresent = CFDictionaryGetValueIfPresent(tDict, juceKey, (const void**)&juceData);
+  CFRelease(juceKey);
+  if (valuePresent && juceData)
+  {
+    LOGINFO("[clap-wrapper] Restoring from JUCE block");
+    const int numBytes = (int)CFDataGetLength(juceData);
+    if (numBytes > 0)
+    {
+      Clap::StateMemento chunk;
+      UInt8* streamData = (UInt8*)(CFDataGetBytePtr(juceData));
+
+      chunk.setData(streamData, numBytes);
+      _plugin->_ext._state->load(_plugin->_plugin, chunk);
+    }
+    return noErr;
+  }
+#endif
 
   const void* pName = CFDictionaryGetValue(tDict, CFSTR(kAUPresetNameKey));
   if (pName)
@@ -1355,7 +1400,6 @@ UInt32 WrapAsAUV2::GetAudioChannelLayout(AudioUnitScope scope, AudioUnitElement
                                          AudioChannelLayout* outLayoutPtr, bool& outWritable)
 {
   // TODO: This is never called so the layout is never found
-  LOGINFO("[clap-wrapper] GetAudioChannelLayout");
   return Base::GetAudioChannelLayout(scope, element, outLayoutPtr, outWritable);
 }