From 8bb56fcad84129fb4f26d8adf8642fe64fdc68ce Mon Sep 17 00:00:00 2001
From: hogliux <fabian.renn@gmail.com>
Date: Tue, 13 Mar 2018 11:09:01 +0000
Subject: [PATCH] Try to re-use the current selected audio device if sharing an
 AudioDeviceManager with an AudioAppComponent

---
 .../gui/juce_AudioAppComponent.cpp            | 36 ++++++++++++++++---
 .../gui/juce_AudioAppComponent.h              |  1 +
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/modules/juce_audio_utils/gui/juce_AudioAppComponent.cpp b/modules/juce_audio_utils/gui/juce_AudioAppComponent.cpp
index 6acd0bc729..31ccc2ae80 100644
--- a/modules/juce_audio_utils/gui/juce_AudioAppComponent.cpp
+++ b/modules/juce_audio_utils/gui/juce_AudioAppComponent.cpp
@@ -28,12 +28,14 @@ namespace juce
 {
 
 AudioAppComponent::AudioAppComponent()
-    : deviceManager (defaultDeviceManager)
+    : deviceManager (defaultDeviceManager),
+      usingCustomDeviceManager (false)
 {
 }
 
 AudioAppComponent::AudioAppComponent (AudioDeviceManager& adm)
-    : deviceManager (adm)
+    : deviceManager (adm),
+      usingCustomDeviceManager (true)
 {
 }
 
@@ -46,7 +48,30 @@ AudioAppComponent::~AudioAppComponent()
 
 void AudioAppComponent::setAudioChannels (int numInputChannels, int numOutputChannels, const XmlElement* const xml)
 {
-    String audioError = deviceManager.initialise (numInputChannels, numOutputChannels, xml, true);
+    String audioError;
+
+    if (usingCustomDeviceManager && xml == nullptr)
+    {
+        AudioDeviceManager::AudioDeviceSetup setup;
+        deviceManager.getAudioDeviceSetup (setup);
+
+        if (setup.inputChannels.countNumberOfSetBits() != numInputChannels
+            || setup.outputChannels.countNumberOfSetBits() != numOutputChannels)
+        {
+            setup.inputChannels.clear();
+            setup.outputChannels.clear();
+
+            setup.inputChannels.setRange (0, numInputChannels, true);
+            setup.outputChannels.setRange (0, numOutputChannels, true);
+
+            audioError = deviceManager.setAudioDeviceSetup (setup, false);
+        }
+    }
+    else
+    {
+        audioError = deviceManager.initialise (numInputChannels, numOutputChannels, xml, true);
+    }
+
     jassert (audioError.isEmpty());
 
     deviceManager.addAudioCallback (&audioSourcePlayer);
@@ -57,7 +82,10 @@ void AudioAppComponent::shutdownAudio()
 {
     audioSourcePlayer.setSource (nullptr);
     deviceManager.removeAudioCallback (&audioSourcePlayer);
-    deviceManager.closeAudioDevice();
+
+    // other audio callbacks may still be using the device
+    if (! usingCustomDeviceManager)
+        deviceManager.closeAudioDevice();
 }
 
 } // namespace juce
diff --git a/modules/juce_audio_utils/gui/juce_AudioAppComponent.h b/modules/juce_audio_utils/gui/juce_AudioAppComponent.h
index 905428451a..238439e8a0 100644
--- a/modules/juce_audio_utils/gui/juce_AudioAppComponent.h
+++ b/modules/juce_audio_utils/gui/juce_AudioAppComponent.h
@@ -126,6 +126,7 @@ private:
     //=============================================================================
     AudioDeviceManager defaultDeviceManager;
     AudioSourcePlayer audioSourcePlayer;
+    bool usingCustomDeviceManager;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (AudioAppComponent)
 };