Add API to Retrieve Detailed SignalStrength Info

This commit adds an API to retrieve detailed
CellSignalStrength from a SignalStrength instance,
which permits granular attribution of signal strength
details and avoids proliferating duplicate code up to
the SignalStrength class (which ideally never needs to
changed again except when adding a new technology or
if we add CarrierAggregation support).

Bug: 118166143
Test: wip
Change-Id: I6bbd86ec460c3cff84f1a22348381b15c66c1065

2 files changed, 32 insertions, 0 deletions

diff --git a/api/current.txt b/api/current.txt
index 65c988fb046e..1ccb77587321 100755
--- a/api/current.txt
+++ b/api/current.txt
@@ -42719,6 +42719,7 @@ package android.telephony {
     method public int describeContents();
     method public int getCdmaDbm();
     method public int getCdmaEcio();
+    method public java.util.List<android.telephony.CellSignalStrength> getCellSignalStrengths();
     method public int getEvdoDbm();
     method public int getEvdoEcio();
     method public int getEvdoSnr();
diff --git a/telephony/java/android/telephony/SignalStrength.java b/telephony/java/android/telephony/SignalStrength.java
index ef185c5eeaf1..72e6e00c6085 100644
--- a/telephony/java/android/telephony/SignalStrength.java
+++ b/telephony/java/android/telephony/SignalStrength.java
@@ -24,6 +24,8 @@ import android.os.Parcel;
 import android.os.Parcelable;
 import android.os.PersistableBundle;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Objects;
 
 /**
@@ -178,6 +180,35 @@ public class SignalStrength implements Parcelable {
         return mLte;
     }
 
+    /**
+     * Returns a List of CellSignalStrength Components of this SignalStrength Report.
+     *
+     * Use this API to access underlying
+     * {@link android.telephony#CellSignalStrength CellSignalStrength} objects that provide more
+     * granular information about the SignalStrength report. Only valid (non-empty)
+     * CellSignalStrengths will be returned. The order of any returned elements is not guaranteed,
+     * and the list may contain more than one instance of a CellSignalStrength type.
+     *
+     * @return a List of CellSignalStrength or an empty List if there are no valid measurements.
+     *
+     * @see android.telephony#CellSignalStrength
+     * @see android.telephony#CellSignalStrengthNr
+     * @see android.telephony#CellSignalStrengthLte
+     * @see android.telephony#CellSignalStrengthTdscdma
+     * @see android.telephony#CellSignalStrengthWcdma
+     * @see android.telephony#CellSignalStrengthCdma
+     * @see android.telephony#CellSignalStrengthGsm
+     */
+    public @NonNull List<CellSignalStrength> getCellSignalStrengths() {
+        List<CellSignalStrength> cssList = new ArrayList<>(2); // Usually have 2 or fewer elems
+        if (mLte.isValid()) cssList.add(mLte);
+        if (mCdma.isValid()) cssList.add(mCdma);
+        if (mTdscdma.isValid()) cssList.add(mTdscdma);
+        if (mWcdma.isValid()) cssList.add(mWcdma);
+        if (mGsm.isValid()) cssList.add(mGsm);
+        return cssList;
+    }
+
     /** @hide */
     public void updateLevel(PersistableBundle cc, ServiceState ss) {
         mLteRsrpBoost = ss.getLteEarfcnRsrpBoost();