(Resubmit) Move dream metadata parsing to framework.

Bug: 214117287
Test: atest com.android.server.dreams.DreamServiceTest
Test: manually on device by opening Screensaver settings because it
calls into the metadata parsing from DreamBackend

Change-Id: I252f634dd10297ba7dcd91fae6289a85a2904e3d

1 files changed, 115 insertions, 2 deletions

diff --git a/core/java/android/service/dreams/DreamService.java b/core/java/android/service/dreams/DreamService.java
index bb1f393b99bc..45ddbe4b0a18 100644
--- a/core/java/android/service/dreams/DreamService.java
+++ b/core/java/android/service/dreams/DreamService.java
@@ -31,6 +31,11 @@ import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
+import android.content.pm.PackageManager;
+import android.content.pm.ServiceInfo;
+import android.content.res.TypedArray;
+import android.content.res.XmlResourceParser;
+import android.graphics.drawable.Drawable;
 import android.os.Build;
 import android.os.Handler;
 import android.os.IBinder;
@@ -39,9 +44,11 @@ import android.os.Looper;
 import android.os.PowerManager;
 import android.os.RemoteException;
 import android.os.ServiceManager;
+import android.util.AttributeSet;
 import android.util.Log;
 import android.util.MathUtils;
 import android.util.Slog;
+import android.util.Xml;
 import android.view.ActionMode;
 import android.view.Display;
 import android.view.KeyEvent;
@@ -59,7 +66,11 @@ import android.view.accessibility.AccessibilityEvent;
 
 import com.android.internal.util.DumpUtils;
 
+import org.xmlpull.v1.XmlPullParser;
+import org.xmlpull.v1.XmlPullParserException;
+
 import java.io.FileDescriptor;
+import java.io.IOException;
 import java.io.PrintWriter;
 import java.util.ArrayDeque;
 import java.util.function.Consumer;
@@ -159,8 +170,9 @@ import java.util.function.Consumer;
  * </pre>
  */
 public class DreamService extends Service implements Window.Callback {
-    private final String mTag =
-            DreamService.class.getSimpleName() + "[" + getClass().getSimpleName() + "]";
+    private static final String TAG = DreamService.class.getSimpleName();
+    private final String mTag = TAG + "[" + getClass().getSimpleName() + "]";
+    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
 
     /**
      * The name of the dream manager service.
@@ -191,6 +203,11 @@ public class DreamService extends Service implements Window.Callback {
     public static final String DREAM_META_DATA = "android.service.dream";
 
     /**
+     * Name of the root tag under which a Dream defines its metadata in an XML file.
+     */
+    private static final String DREAM_META_DATA_ROOT_TAG = "dream";
+
+    /**
      * Extra containing a boolean for whether to show complications on the overlay.
      * @hide
      */
@@ -1081,6 +1098,84 @@ public class DreamService extends Service implements Window.Callback {
     // end public api
 
     /**
+     * Parses and returns metadata of the dream service indicated by the service info. Returns null
+     * if metadata cannot be found.
+     *
+     * Note that {@link ServiceInfo} must be fetched with {@link PackageManager#GET_META_DATA} flag.
+     *
+     * @hide
+     */
+    @Nullable
+    public static DreamMetadata getDreamMetadata(Context context, ServiceInfo serviceInfo) {
+        final PackageManager pm = context.getPackageManager();
+
+        final TypedArray rawMetadata = readMetadata(pm, serviceInfo);
+        if (rawMetadata == null) return null;
+
+        final DreamMetadata metadata = new DreamMetadata(
+                convertToComponentName(rawMetadata.getString(
+                        com.android.internal.R.styleable.Dream_settingsActivity), serviceInfo),
+                rawMetadata.getDrawable(
+                        com.android.internal.R.styleable.Dream_previewImage));
+        rawMetadata.recycle();
+        return metadata;
+    }
+
+    /**
+     * Returns the raw XML metadata fetched from the {@link ServiceInfo}.
+     *
+     * Returns <code>null</code> if the {@link ServiceInfo} doesn't contain valid dream metadata.
+     */
+    @Nullable
+    private static TypedArray readMetadata(PackageManager pm, ServiceInfo serviceInfo) {
+        if (serviceInfo == null || serviceInfo.metaData == null) {
+            return null;
+        }
+
+        try (XmlResourceParser parser =
+                     serviceInfo.loadXmlMetaData(pm, DreamService.DREAM_META_DATA)) {
+            if (parser == null) {
+                if (DEBUG) Log.w(TAG, "No " + DreamService.DREAM_META_DATA + " metadata");
+                return null;
+            }
+
+            final AttributeSet attrs = Xml.asAttributeSet(parser);
+            while (true) {
+                final int type = parser.next();
+                if (type == XmlPullParser.END_DOCUMENT || type == XmlPullParser.START_TAG) {
+                    break;
+                }
+            }
+
+            if (!parser.getName().equals(DREAM_META_DATA_ROOT_TAG)) {
+                if (DEBUG) {
+                    Log.w(TAG, "Metadata does not start with " + DREAM_META_DATA_ROOT_TAG + " tag");
+                }
+                return null;
+            }
+
+            return pm.getResourcesForApplication(serviceInfo.applicationInfo).obtainAttributes(
+                    attrs, com.android.internal.R.styleable.Dream);
+        } catch (PackageManager.NameNotFoundException | IOException | XmlPullParserException e) {
+            if (DEBUG) Log.e(TAG, "Error parsing: " + serviceInfo.packageName, e);
+            return null;
+        }
+    }
+
+    private static ComponentName convertToComponentName(String flattenedString,
+            ServiceInfo serviceInfo) {
+        if (flattenedString == null) {
+            return null;
+        }
+
+        if (!flattenedString.contains("/")) {
+            return new ComponentName(serviceInfo.packageName, flattenedString);
+        }
+
+        return ComponentName.unflattenFromString(flattenedString);
+    }
+
+    /**
      * Called by DreamController.stopDream() when the Dream is about to be unbound and destroyed.
      *
      * Must run on mHandler.
@@ -1302,4 +1397,22 @@ public class DreamService extends Service implements Window.Callback {
             onWindowCreated(a.getWindow());
         }
     }
+
+    /**
+     * Represents metadata defined in {@link android.R.styleable#Dream &lt;dream&gt;}.
+     *
+     * @hide
+     */
+    public static final class DreamMetadata {
+        @Nullable
+        public final ComponentName settingsActivity;
+
+        @Nullable
+        public final Drawable previewImage;
+
+        DreamMetadata(ComponentName settingsActivity, Drawable previewImage) {
+            this.settingsActivity = settingsActivity;
+            this.previewImage = previewImage;
+        }
+    }
 }