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      1 /*
      2  * libjingle
      3  * Copyright 2004--2010, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef TALK_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
     29 #define TALK_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
     30 
     31 #include "talk/base/common.h"
     32 #include "talk/base/logging.h"
     33 #include "talk/base/scoped_ptr.h"
     34 #include "talk/sound/soundsysteminterface.h"
     35 #include "talk/sound/soundsystemproxy.h"
     36 
     37 namespace cricket {
     38 
     39 // A function type that creates an instance of a sound system implementation.
     40 typedef SoundSystemInterface *(*SoundSystemCreator)();
     41 
     42 // An AutomaticallyChosenSoundSystem is a sound system proxy that defers to
     43 // an instance of the first sound system implementation in a list that
     44 // successfully initializes.
     45 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     46 class AutomaticallyChosenSoundSystem : public SoundSystemProxy {
     47  public:
     48   // Chooses and initializes the underlying sound system.
     49   virtual bool Init();
     50   // Terminates the underlying sound system implementation, but caches it for
     51   // future re-use.
     52   virtual void Terminate();
     53 
     54   virtual const char *GetName() const;
     55 
     56  private:
     57   talk_base::scoped_ptr<SoundSystemInterface> sound_systems_[kNumSoundSystems];
     58 };
     59 
     60 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     61 bool AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     62                                     kNumSoundSystems>::Init() {
     63   if (wrapped_) {
     64     return true;
     65   }
     66   for (int i = 0; i < kNumSoundSystems; ++i) {
     67     if (!sound_systems_[i].get()) {
     68       sound_systems_[i].reset((*kSoundSystemCreators[i])());
     69     }
     70     if (sound_systems_[i]->Init()) {
     71       // This is the first sound system in the list to successfully
     72       // initialize, so we're done.
     73       wrapped_ = sound_systems_[i].get();
     74       break;
     75     }
     76     // Else it failed to initialize, so try the remaining ones.
     77   }
     78   if (!wrapped_) {
     79     LOG(LS_ERROR) << "Failed to find a usable sound system";
     80     return false;
     81   }
     82   LOG(LS_INFO) << "Selected " << wrapped_->GetName() << " sound system";
     83   return true;
     84 }
     85 
     86 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     87 void AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     88                                     kNumSoundSystems>::Terminate() {
     89   if (!wrapped_) {
     90     return;
     91   }
     92   wrapped_->Terminate();
     93   wrapped_ = NULL;
     94   // We do not free the scoped_ptrs because we may be re-init'ed soon.
     95 }
     96 
     97 template <const SoundSystemCreator kSoundSystemCreators[], int kNumSoundSystems>
     98 const char *AutomaticallyChosenSoundSystem<kSoundSystemCreators,
     99                                            kNumSoundSystems>::GetName() const {
    100   return wrapped_ ? wrapped_->GetName() : "automatic";
    101 }
    102 
    103 }  // namespace cricket
    104 
    105 #endif  // TALK_SOUND_AUTOMATICALLYCHOSENSOUNDSYSTEM_H_
    106