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      1 /*
      2  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
     12 #define WEBRTC_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
     13 
     14 #include "webrtc/sound/soundsysteminterface.h"
     15 #include "webrtc/sound/soundsystemproxy.h"
     16 #include "webrtc/base/common.h"
     17 #include "webrtc/base/logging.h"
     18 #include "webrtc/base/scoped_ptr.h"
     19 
     20 namespace rtc {
     21 
     22 // A function type that creates an instance of a sound system implementation.
     23 typedef SoundSystemInterface *(*SoundSystemCreator)();
     24 
     25 // An AutomaticallyChosenSoundSystem is a sound system proxy that defers to
     26 // an instance of the first sound system implementation in a list that
     27 // successfully initializes.
     28 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     29 class AutomaticallyChosenSoundSystem : public SoundSystemProxy {
     30  public:
     31   // Chooses and initializes the underlying sound system.
     32   virtual bool Init();
     33   // Terminates the underlying sound system implementation, but caches it for
     34   // future re-use.
     35   virtual void Terminate();
     36 
     37   virtual const char *GetName() const;
     38 
     39  private:
     40   rtc::scoped_ptr<SoundSystemInterface> sound_systems_[kNumSoundSystems];
     41 };
     42 
     43 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     44 bool AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     45                                     kNumSoundSystems>::Init() {
     46   if (wrapped_) {
     47     return true;
     48   }
     49   for (int i = 0; i < kNumSoundSystems; ++i) {
     50     if (!sound_systems_[i].get()) {
     51       sound_systems_[i].reset((*kSoundSystemCreators[i])());
     52     }
     53     if (sound_systems_[i]->Init()) {
     54       // This is the first sound system in the list to successfully
     55       // initialize, so we're done.
     56       wrapped_ = sound_systems_[i].get();
     57       break;
     58     }
     59     // Else it failed to initialize, so try the remaining ones.
     60   }
     61   if (!wrapped_) {
     62     LOG(LS_ERROR) << "Failed to find a usable sound system";
     63     return false;
     64   }
     65   LOG(LS_INFO) << "Selected " << wrapped_->GetName() << " sound system";
     66   return true;
     67 }
     68 
     69 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     70 void AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     71                                     kNumSoundSystems>::Terminate() {
     72   if (!wrapped_) {
     73     return;
     74   }
     75   wrapped_->Terminate();
     76   wrapped_ = NULL;
     77   // We do not free the scoped_ptrs because we may be re-init'ed soon.
     78 }
     79 
     80 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     81 const char *AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     82                                            kNumSoundSystems>::GetName() const {
     83   return wrapped_ ? wrapped_->GetName() : "automatic";
     84 }
     85 
     86 }  // namespace rtc
     87 
     88 #endif  // WEBRTC_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
     89