more JUCE GUI support implementation code.

Now it can render JUCE GUI on the remote SurfaceView.
Inputs still does not work though.

aap-modules/aap_audio_processors/juceaap_AAPWrappers.cpp

@@ -26,6 +26,8 @@ using namespace juce;
 extern juce::AudioProcessor *
 createPluginFilter(); // it is defined in each Audio plugin project (by Projucer).
 
+extern "C" void juce_juceEventsAndroidStartApp();
+
 extern "C" { int juce_aap_wrapper_last_error_code{0}; }
 
 #define JUCEAAP_SUCCESS 0
@@ -213,6 +215,7 @@ class JuceAAPWrapper : juce::AudioPlayHead, juce::AudioProcessorListener {
     void addAndroidView(void* parentLinearLayout) {
         auto creator = [&] {
             auto editor = juce_processor->createEditorIfNeeded();
+            editor->setVisible(true);
             editor->addToDesktop(0, parentLinearLayout);
         };
         if (juce::MessageManager::getInstance()->isThisTheMessageThread())
@@ -936,7 +939,7 @@ struct AndroidAudioPluginFactory juceaap_factory{
         nullptr
 };
 
-extern "C" AndroidAudioPluginFactory *GetJuceAAPFactory() {
+JNIEXPORT extern "C" AndroidAudioPluginFactory *GetJuceAAPFactory() {
     return &juceaap_factory;
 }
 
@@ -945,6 +948,7 @@ JNIEXPORT void JNICALL
 Java_org_androidaudioplugin_juce_JuceAudioProcessorEditorView_addAndroidComponentPeerViewTo(
         JNIEnv *env, jclass clazz, jlong pluginServiceNative, jstring plugin_id, jint instanceId,
         jobject parentLinearLayout) {
+    juce_juceEventsAndroidStartApp();
     auto service = (aap::PluginService *) pluginServiceNative;
     auto instance = service->getLocalInstance(instanceId);
     auto plugin = instance->getPlugin();

java/org/androidaudioplugin/juce/JuceAudioPluginViewFactory.kt

@@ -6,7 +6,6 @@ import android.view.ViewGroup
 import android.widget.LinearLayout
 import org.androidaudioplugin.AudioPluginServiceHelper
 import org.androidaudioplugin.AudioPluginViewFactory
-import org.androidaudioplugin.NativePluginService
 
 class JuceAudioPluginViewFactory : AudioPluginViewFactory() {
     override fun createView(context: Context, pluginId: String, instanceId: Int): View =
@@ -19,15 +18,15 @@ internal class JuceAudioProcessorEditorView(
     private val instanceId: Int) : LinearLayout(context) {
 
     companion object {
+        // note: adding the view might be asynchronously done (depending on whether it is main thread or not).
         @JvmStatic
         private external fun addAndroidComponentPeerViewTo(serviceInstance: Long, pluginId: String, instanceId: Int, juceAudioProcessorEditorView: JuceAudioProcessorEditorView)
     }
 
     constructor(context: Context) : this(context, "", 0)
 
     init {
-        layoutParams = ViewGroup.LayoutParams(width, height)
-        // adding the view is synchronously done.
+        layoutParams = ViewGroup.LayoutParams(200, 200) // stub values
         addAndroidComponentPeerViewTo(AudioPluginServiceHelper.getServiceInstance(pluginId), pluginId, instanceId, this)
     }
 }

juce-patches/7.0.6/support-plugin-ui.patch

@@ -0,0 +1,37 @@
+diff --git a/modules/juce_core/native/juce_Threads_android.cpp b/modules/juce_core/native/juce_Threads_android.cpp
+index efbf3a9f6..099e67fb5 100644
+--- a/modules/juce_core/native/juce_Threads_android.cpp
++++ b/modules/juce_core/native/juce_Threads_android.cpp
+@@ -269,7 +269,7 @@ private:
+
+ //==============================================================================
+ #if JUCE_MODULE_AVAILABLE_juce_events && JUCE_ANDROID
+-void juce_juceEventsAndroidStartApp();
++extern "C" void juce_juceEventsAndroidStartApp();
+ #endif
+
+ void Thread::initialiseJUCE (void* jniEnv, void* context)
+@@ -303,7 +303,7 @@ void Thread::initialiseJUCE (void* jniEnv, void* context)
+         JuceActivityWatcher::getInstance();
+
+        #if JUCE_MODULE_AVAILABLE_juce_events && JUCE_ANDROID
+-        juce_juceEventsAndroidStartApp();
++        //juce_juceEventsAndroidStartApp();
+        #endif
+     }
+ }
+diff --git a/modules/juce_events/native/juce_Messaging_android.cpp b/modules/juce_events/native/juce_Messaging_android.cpp
+index 8062840f2..84f1c7679 100644
+--- a/modules/juce_events/native/juce_Messaging_android.cpp
++++ b/modules/juce_events/native/juce_Messaging_android.cpp
+@@ -288,8 +288,8 @@ private:
+ //==============================================================================
+ File juce_getExecutableFile();
+
+-void juce_juceEventsAndroidStartApp();
+-void juce_juceEventsAndroidStartApp()
++extern "C" void juce_juceEventsAndroidStartApp();
++extern "C" void juce_juceEventsAndroidStartApp()
+ {
+     auto dllPath = juce_getExecutableFile().getFullPathName();
+     auto addr = reinterpret_cast<juce::JUCEApplicationBase*(*)()> (DynamicLibrary (dllPath)