AUDIO: Add per sound type mute flag setting to Mixer(Impl).

This also adapts our default implementation MixerImpl to handle the newly
added flags properly.

Now we do not need to set the sound volume for all types to 0, in case we want
to mute them, but instead just set the mute flag for all types to true. This
allows engines to be a bit more agonstic about mute support, when it comes to
volume options etc. since they can just setup any volume they like, but are
still muted (and thus will not break muting anymore).

MIDI sound is of course not affected by this.

3 files changed, 50 insertions, 10 deletions

diff --git a/audio/mixer.cpp b/audio/mixer.cpp
index dc0287e3fb..547d2d5f55 100644
--- a/audio/mixer.cpp
+++ b/audio/mixer.cpp
@@ -168,6 +168,9 @@ MixerImpl::MixerImpl(OSystem *system, uint sampleRate)
 
 	int i;
 
+	for (i = 0; i < ARRAYSIZE(_mute); ++i)
+		_mute[i] = false;
+
 	for (i = 0; i < ARRAYSIZE(_volumeForSoundType); i++)
 		_volumeForSoundType[i] = kMaxMixerVolume;
 
@@ -322,6 +325,21 @@ void MixerImpl::stopHandle(SoundHandle handle) {
 	_channels[index] = 0;
 }
 
+void MixerImpl::setMuteForSoundType(SoundType type, bool mute) {
+	assert(0 <= type && type < ARRAYSIZE(_mute));
+	_mute[type] = mute;
+
+	for (int i = 0; i != NUM_CHANNELS; ++i) {
+		if (_channels[i] && _channels[i]->getType() == type)
+			_channels[i]->notifyGlobalVolChange();
+	}
+}
+
+bool MixerImpl::getMuteForSoundType(SoundType type) const {
+	assert(0 <= type && type < ARRAYSIZE(_mute));
+	return _mute[type];
+}
+
 void MixerImpl::setChannelVolume(SoundHandle handle, byte volume) {
 	Common::StackLock lock(_mutex);
 
@@ -486,17 +504,21 @@ void Channel::updateChannelVolumes() {
 	// volume is in the range 0 - kMaxMixerVolume.
 	// Hence, the vol_l/vol_r values will be in that range, too
 
-	int vol = _mixer->getVolumeForSoundType(_type) * _volume;
-
-	if (_balance == 0) {
-		_volL = vol / Mixer::kMaxChannelVolume;
-		_volR = vol / Mixer::kMaxChannelVolume;
-	} else if (_balance < 0) {
-		_volL = vol / Mixer::kMaxChannelVolume;
-		_volR = ((127 + _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
+	if (!_mixer->getMuteForSoundType(_type)) {
+		int vol = _mixer->getVolumeForSoundType(_type) * _volume;
+
+		if (_balance == 0) {
+			_volL = vol / Mixer::kMaxChannelVolume;
+			_volR = vol / Mixer::kMaxChannelVolume;
+		} else if (_balance < 0) {
+			_volL = vol / Mixer::kMaxChannelVolume;
+			_volR = ((127 + _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
+		} else {
+			_volL = ((127 - _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
+			_volR = vol / Mixer::kMaxChannelVolume;
+		}
 	} else {
-		_volL = ((127 - _balance) * vol) / (Mixer::kMaxChannelVolume * 127);
-		_volR = vol / Mixer::kMaxChannelVolume;
+		_volL = _volR = 0;
 	}
 }
 
diff --git a/audio/mixer.h b/audio/mixer.h
index a048124ca3..fe24b85613 100644
--- a/audio/mixer.h
+++ b/audio/mixer.h
@@ -197,6 +197,20 @@ public:
 	virtual bool isSoundHandleActive(SoundHandle handle) = 0;
 
 
+	/**
+	 * Set the mute state for a given sound type.
+	 *
+	 * @param mute Whether to mute (= true) or not (= false).
+	 * @param type the sound type
+	 */
+	virtual void setMuteForSoundType(SoundType type, bool mute) = 0;
+
+	/**
+	 * Query the mute state for a given sound type.
+	 *
+	 * @param type the sound type
+	 */
+	virtual bool getMuteForSoundType(SoundType type) const = 0;
 
 	/**
 	 * Set the channel volume for the given handle.
diff --git a/audio/mixer_intern.h b/audio/mixer_intern.h
index dd2746e9ea..c42436b9a4 100644
--- a/audio/mixer_intern.h
+++ b/audio/mixer_intern.h
@@ -64,6 +64,7 @@ private:
 	bool _mixerReady;
 	uint32 _handleSeed;
 
+	bool _mute[4];
 	int _volumeForSoundType[4];
 	Channel *_channels[NUM_CHANNELS];
 
@@ -97,6 +98,9 @@ public:
 
 	virtual bool isSoundHandleActive(SoundHandle handle);
 
+	virtual void setMuteForSoundType(SoundType type, bool mute);
+	virtual bool getMuteForSoundType(SoundType type) const;
+
 	virtual void setChannelVolume(SoundHandle handle, byte volume);
 	virtual void setChannelBalance(SoundHandle handle, int8 balance);