Add ALSA support to volume keys

chrome/browser/chromeos/audio_handler.cc

Index: chrome/browser/chromeos/audio_handler.cc
diff --git a/chrome/browser/chromeos/audio_handler.cc b/chrome/browser/chromeos/audio_handler.cc
index 2f6638fe6bcd693b241632c3f7e6c3c62846cfd9..6f1bc5422dd81088409aa0b6fd59d4b140f7b7a3 100644
--- a/chrome/browser/chromeos/audio_handler.cc
+++ b/chrome/browser/chromeos/audio_handler.cc
@@ -8,13 +8,14 @@
 
 #include "base/logging.h"
 #include "base/singleton.h"
-#include "chrome/browser/chromeos/pulse_audio_mixer.h"
+#include "chrome/browser/chromeos/audio_mixer_pulse.h"
+#include "chrome/browser/chromeos/audio_mixer_alsa.h"
+#include "chrome/browser/browser_thread.h"
 
 namespace chromeos {
 
 namespace {
 
-const double kSilenceDb = -200.0;
 const double kMinVolumeDb = -90.0;
 // Choosing 6.0dB here instead of 0dB to give user chance to amplify audio some
 // in case sounds or their setup is too quiet for them.
@@ -25,12 +26,14 @@ const double kVolumeBias = 0.5;
 // If a connection is lost, we try again this many times
 const int kMaxReconnectTries = 4;
 
-}  // namespace
+const int kUsingPulseAudio = 0;
+const int kUsingAlsa = 1;
+const int kUsingNone = 2;
 
-// This class will set volume using PulseAudio to adjust volume and mute, and
-// handles the volume level logic.
+}  // namespace
 
-// TODO(davej): Serialize volume/mute for next startup?
+// This class will set volume using PulseAudio or ALSA to adjust volume and
+// mute, and handles the volume level logic.
 
 double AudioHandler::GetVolumePercent() {
   if (!VerifyMixerConnection())
@@ -40,7 +43,7 @@ double AudioHandler::GetVolumePercent() {
 }
 
 // Set volume using our internal 0-100% range.  Notice 0% is a special case of
-// silence, so we set the mixer volume to kSilenceDb instead of kMinVolumeDb.
+// silence, so we set the mixer volume to kSilenceDb instead of min_volume_db_.
 void AudioHandler::SetVolumePercent(double volume_percent) {
   if (!VerifyMixerConnection())
     return;
@@ -96,17 +99,61 @@ void AudioHandler::SetMute(bool do_mute) {
   mixer_->SetMute(do_mute);
 }
 
+bool AudioHandler::TryToConnect(bool async) {
+  if (using_mixer_ == kUsingPulseAudio) {
+    VLOG(1) << "Trying to connect to PulseAudio";
+    mixer_.reset(new AudioMixerPulse());
+  } else if (using_mixer_ == kUsingAlsa) {
+    VLOG(1) << "Trying to connect to ALSA";
+    mixer_.reset(new AudioMixerAlsa());
+  } else {
+    VLOG(1) << "Cannot find valid volume mixer";
+    mixer_.reset();
+    return false;
+  }
+
+  if (async) {
+    if (mixer_->Init(NewCallback(this, &AudioHandler::OnMixerInitialized)))
+      return true;
+  } else {
+    if (mixer_->InitSync())
+      return true;
+    VLOG(1) << "Unable to reconnect to Mixer";
+  }
+  return false;
+}
+
 void AudioHandler::OnMixerInitialized(bool success) {
   connected_ = success;
   DVLOG(1) << "OnMixerInitialized, success = " << success;
+
+  if (connected_) {
+    mixer_->GetVolumeLimits(&min_volume_db_, &max_volume_db_);
+    if (min_volume_db_ < kMinVolumeDb)
+      min_volume_db_ = kMinVolumeDb;
+    if (max_volume_db_ > kMaxVolumeDb)
+      max_volume_db_ = kMaxVolumeDb;
+  } else {
+    ++using_mixer_;

[Daniel Erat, 2010/12/20 22:01:12]

this seems fragile; please spell out the transitions between the different
values instead

[davejcool, 2010/12/21 02:00:21]

Now logic is in UseNextMixer()

+    VLOG(1) << "Unable to connect to Mixer, trying next";
+
+    BrowserThread::PostTask(
+        BrowserThread::UI, FROM_HERE,
+        NewRunnableMethod(this, &AudioHandler::TryToConnect, true));
+  }
 }
 
 AudioHandler::AudioHandler()
     : connected_(false),
-      reconnect_tries_(0) {
-  mixer_.reset(new PulseAudioMixer());
-  if (!mixer_->Init(NewCallback(this, &AudioHandler::OnMixerInitialized))) {
-    LOG(ERROR) << "Unable to connect to PulseAudio";
+      reconnect_tries_(0),
+      max_volume_db_(0),
+      min_volume_db_(-90),
+      using_mixer_(kUsingPulseAudio) {
+  while (using_mixer_ != kUsingNone) {
+    if (TryToConnect(true)) {
+      break;
+    }
+    ++using_mixer_;
   }
 }
 
@@ -115,58 +162,62 @@ AudioHandler::~AudioHandler() {
 };
 
 bool AudioHandler::VerifyMixerConnection() {
-  PulseAudioMixer::State mixer_state = mixer_->CheckState();
-  if (mixer_state == PulseAudioMixer::READY)
+  if (mixer_ == NULL)
+    return false;
+
+  AudioMixerBase::State mixer_state = mixer_->CheckState();
+  if (mixer_state == AudioMixerBase::READY)
     return true;
   if (connected_) {
     // Something happened and the mixer is no longer valid after having been
     // initialized earlier.
     connected_ = false;
-    LOG(ERROR) << "Lost connection to PulseAudio";
+    LOG(ERROR) << "Lost connection to Mixer";

[Daniel Erat, 2010/12/20 22:01:12]

nit: make all of the "mixer"s in these comments lowercase

   } else {
     LOG(ERROR) << "Mixer not valid";
   }
 
-  if ((mixer_state == PulseAudioMixer::INITIALIZING) ||
-      (mixer_state == PulseAudioMixer::SHUTTING_DOWN))
+  if ((mixer_state == AudioMixerBase::INITIALIZING) ||
+      (mixer_state == AudioMixerBase::SHUTTING_DOWN))
     return false;
 
   if (reconnect_tries_ < kMaxReconnectTries) {
     reconnect_tries_++;
-    VLOG(1) << "Re-connecting to PulseAudio attempt " << reconnect_tries_ << "/"
+    VLOG(1) << "Re-connecting to Mixer attempt " << reconnect_tries_ << "/"
             << kMaxReconnectTries;
-    mixer_.reset(new PulseAudioMixer());
-    connected_ = mixer_->InitSync();
+
+    connected_ = TryToConnect(false);
+
     if (connected_) {
       reconnect_tries_ = 0;
       return true;
     }
-    LOG(ERROR) << "Unable to re-connect to PulseAudio";
+    LOG(ERROR) << "Unable to re-connect to Mixer";
   }
   return false;
 }
 
 // VolumeDbToPercent() and PercentToVolumeDb() conversion functions allow us
 // complete control over how the 0 to 100% range is mapped to actual loudness.
-// Volume range is from kMinVolumeDb at just above 0% to kMaxVolumeDb at 100%
-// with a special case at 0% which maps to kSilenceDb.
+// Volume range is from min_volume_db_ at just above 0% to max_volume_db_
+// at 100% with a special case at 0% which maps to kSilenceDb.
 //
 // The mapping is confined to these two functions to make it easy to adjust and
 // have everything else just work.  The range is biased to give finer resolution
 // in the higher volumes if kVolumeBias is less than 1.0.
 
 // static
-double AudioHandler::VolumeDbToPercent(double volume_db) {
-  if (volume_db < kMinVolumeDb)
+double AudioHandler::VolumeDbToPercent(double volume_db) const {
+  if (volume_db < min_volume_db_)
     return 0;
-  return 100.0 * pow((volume_db - kMinVolumeDb) /
-      (kMaxVolumeDb - kMinVolumeDb), 1/kVolumeBias);
+  return 100.0 * pow((volume_db - min_volume_db_) /
+      (max_volume_db_ - min_volume_db_), 1/kVolumeBias);
 }
 
 // static
-double AudioHandler::PercentToVolumeDb(double volume_percent) {
+double AudioHandler::PercentToVolumeDb(double volume_percent) const {
   return pow(volume_percent / 100.0, kVolumeBias) *
-      (kMaxVolumeDb - kMinVolumeDb) + kMinVolumeDb;
+      (max_volume_db_ - min_volume_db_) + min_volume_db_;
 }
 
 // static