AudioService: Define minimum levels for volume streams.

 - Set a floor of 1 for voice call + bluetooth sco, otherwise 0.
 - All api calls validated to ensure a floor of the min level.
 - Volume UI updated to shift the seekbar by the min value.
 - Remove duplicate static max method in AudioService.
 - Ensure streams with a min level > 0 are not considered muteable.

Bug: 19260237
Change-Id: I213180c9c277f51bd3897b7f777e5f88ed1db125

2 files changed, 20 insertions, 0 deletions

diff --git a/media/java/android/media/AudioManager.java b/media/java/android/media/AudioManager.java
index 4fdcfa4..8c1ba05 100644
--- a/media/java/android/media/AudioManager.java
+++ b/media/java/android/media/AudioManager.java
@@ -866,6 +866,24 @@ public class AudioManager {
     }
 
     /**
+     * Returns the minimum volume index for a particular stream.
+     *
+     * @param streamType The stream type whose minimum volume index is returned.
+     * @return The minimum valid volume index for the stream.
+     * @see #getStreamVolume(int)
+     * @hide
+     */
+    public int getStreamMinVolume(int streamType) {
+        IAudioService service = getService();
+        try {
+            return service.getStreamMinVolume(streamType);
+        } catch (RemoteException e) {
+            Log.e(TAG, "Dead object in getStreamMinVolume", e);
+            return 0;
+        }
+    }
+
+    /**
      * Returns the current volume index for a particular stream.
      *
      * @param streamType The stream type whose volume index is returned.
diff --git a/media/java/android/media/IAudioService.aidl b/media/java/android/media/IAudioService.aidl
index 827cb13..8e96218 100644
--- a/media/java/android/media/IAudioService.aidl
+++ b/media/java/android/media/IAudioService.aidl
@@ -59,6 +59,8 @@ interface IAudioService {
 
     int getStreamVolume(int streamType);
 
+    int getStreamMinVolume(int streamType);
+
     int getStreamMaxVolume(int streamType);
 
     int getLastAudibleStreamVolume(int streamType);