Fixed detection of alsa channels capabilities. This resolves bug 2994

and issue #16.
The code is partially based on previous work from TCH <tch@protonmail.com>.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

kmix/mixer_alsa9.cpp

@@ -199,9 +199,10 @@ Mixer_ALSA::open()
 	sid = (snd_mixer_selem_id_t*)malloc(snd_mixer_selem_id_sizeof());  // I believe *we* must malloc it for ourself
 	snd_mixer_selem_get_id( elem, sid );
 
-	bool canRecord = false;
-	bool canMute = false;
+	bool canPlay = false;
 	bool canCapture = false;
+	bool hasPlaySwitch = false;
+	bool hasCaptureSwitch = false;
 	long maxVolumePlay= 0, minVolumePlay= 0;
 	long maxVolumeRec = 0, minVolumeRec = 0;
 	validDevice = true;
@@ -261,6 +262,7 @@ Mixer_ALSA::open()
 				? Volume::MLEFT : (Volume::ChannelMask)(Volume::MLEFT | Volume::MRIGHT);
 			chn = (Volume::ChannelMask) (chn | chnTmp);
 			cc = MixDevice::SLIDER;
+			canPlay = true;
 			volPlay = new Volume( chn, maxVolumePlay, minVolumePlay );
 		} else {
 			volPlay = new Volume();
@@ -283,72 +285,83 @@ Mixer_ALSA::open()
 		mixer_sid_list.append( sid );
 
 		if ( snd_mixer_selem_has_playback_switch ( elem ) ) {
-			//kdDebug(67100) << "has_playback_switch()" << endl;
-			canMute = true;
+		    //kdDebug(67100) << "has_playback_switch()" << endl;
+		    hasPlaySwitch = true;
 		}
 		if ( snd_mixer_selem_has_capture_switch ( elem ) )	{
-			//kdDebug(67100) << "has_capture_switch()" << endl;
-			canRecord = true;
+		    //kdDebug(67100) << "has_capture_switch()" << endl;
+		    hasCaptureSwitch = true;
 		}
 		if ( snd_mixer_selem_has_common_switch ( elem ) ) {
-			//kdDebug(67100) << "has_common_switch()" << endl;
-			canMute = true;
-			canRecord = true;
+		    //kdDebug(67100) << "has_common_switch()" << endl;
+		    hasPlaySwitch = true;
+		    hasCaptureSwitch = true;
 		}
 
-		if ( /*snd_mixer_selem_has_common_switch ( elem ) || */
-                     cc == MixDevice::UNDEFINED )
+		if (cc == MixDevice::UNDEFINED )
 		{
 		    // Everything unknown is handled as switch
 		    cc = MixDevice::SWITCH;
 		}
 	    } // is ordinary mixer element (NOT an enum)
 
+	    if (canPlay || cc == MixDevice::SWITCH || cc == MixDevice::ENUM)
+	    {
 		MixDevice* md = new MixDevice( mixerIdx,
-				   canCapture ? *volCapture : *volPlay,
-				   canCapture ? true : canRecord,
-				   canMute,
-				   snd_mixer_selem_id_get_name( sid ),
-				   ct,
-				   cc );
-
-			m_mixDevices.append( md );
-
+					   *volPlay,
+					   false,
+					   hasPlaySwitch,
+					   snd_mixer_selem_id_get_name( sid ),
+					   ct,
+					   cc );
+		m_mixDevices.append( md );
 
 		if (!masterChosen && ct==MixDevice::VOLUME) {
-		// Determine a nicer MasterVolume
-		m_recommendedMaster = md;
-		masterChosen = true;
+		    // Determine a nicer MasterVolume
+		    m_recommendedMaster = md;
+		    masterChosen = true;
 		}
 
 		if ( enumList.count() > 0 ) {
-		  int maxEnumId= enumList.count();
-		  TQPtrList<TQString>& enumValuesRef = md->enumValues(); // retrieve a ref
-		  for (int i=0; i<maxEnumId; i++ ) {
-		    // we have an enum. Lets set the names of the enum items in the MixDevice
-		    // the enum names are assumed to be static!
-		    enumValuesRef.append(enumList.at(i) );
-		  }
+		    int maxEnumId= enumList.count();
+		    TQPtrList<TQString>& enumValuesRef = md->enumValues(); // retrieve a ref
+		    for (int i=0; i<maxEnumId; i++ ) {
+			// we have an enum. Lets set the names of the enum items in the MixDevice
+			// the enum names are assumed to be static!
+			enumValuesRef.append(enumList.at(i) );
+		    }
 		}
-		//kdDebug(67100) << "ALSA create MDW, vol= " << *vol << endl;
-		delete volPlay;
-		delete volCapture;
-	    } // virginOpen
-	    else
+	    }
+	    if (canCapture)
 	    {
-			MixDevice* md;
-			bool found = false;
-    		for ( md = m_mixDevices.first(); md != 0; md = m_mixDevices.next() ) {
-				if ( md->num() == mixerIdx ) {
-					found = true;
-					writeVolumeToHW( mixerIdx, md->getVolume() );
-				}
-			}
-			if( !found )
-			{
-				return Mixer::ERR_INCOMPATIBLESET;
-			}
-	    } // !virginOpen
+		MixDevice* md = new MixDevice( mixerIdx,
+					   *volCapture,
+					   true,
+					   hasCaptureSwitch,
+					   snd_mixer_selem_id_get_name( sid ),
+					   ct,
+					   cc );
+		m_mixDevices.append( md );
+	    }
+	    //kdDebug(67100) << "ALSA create MDW, vol= " << *vol << endl;
+	    delete volPlay;
+	    delete volCapture;
+	} // virginOpen
+	else
+	{
+	    MixDevice* md;
+	    bool found = false;
+	    for ( md = m_mixDevices.first(); md != 0; md = m_mixDevices.next() ) {
+		if ( md->num() == mixerIdx ) {
+		    found = true;
+		    writeVolumeToHW( mixerIdx, md->getVolume() );
+		}
+	    }
+	    if( !found )
+	    {
+		return Mixer::ERR_INCOMPATIBLESET;
+	    }
+	} // !virginOpen
     } // for all elems
 
     /**************************************************************************************