Merge pull request #28 from Leo-Neat/master

[Infra] Adding a button to snapshot the current Media Browse Tree

Author: Leo Neat

mediacontroller/build.gradle

@@ -49,4 +49,5 @@ dependencies {
     implementation "androidx.leanback:leanback:$leanback_version"
     implementation 'com.android.support:design:28.0.0'
     implementation "com.google.android.material:material:$material_version"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0"
 }

mediacontroller/src/main/java/com/example/android/mediacontroller/MediaAppControllerActivity.java

@@ -18,6 +18,7 @@
 import static androidx.media.MediaBrowserServiceCompat.BrowserRoot.EXTRA_SUGGESTED;
 import static java.util.Arrays.asList;
 
+import android.Manifest;
 import android.app.Activity;
 import android.app.PendingIntent;
 import android.content.Context;
@@ -61,6 +62,7 @@
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.Toolbar;
+import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
 import androidx.core.content.res.ResourcesCompat;
 import androidx.core.graphics.drawable.DrawableCompat;
@@ -73,6 +75,8 @@
 
 import com.google.android.material.tabs.TabLayout;
 
+import java.io.FileNotFoundException;
+import java.io.OutputStream;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
@@ -111,12 +115,16 @@ public class MediaAppControllerActivity extends AppCompatActivity {
     // Key name for Intent extras.
     private static final String APP_DETAILS_EXTRA =
             "com.example.android.mediacontroller.APP_DETAILS_EXTRA";
+    private static final String DEFAULT_BROWSE_TREE_FILE_NAME = "_BrowseTreeContent.txt";
 
     // Index values for spinner.
     private static final int SEARCH_INDEX = 0;
     private static final int MEDIA_ID_INDEX = 1;
     private static final int URI_INDEX = 2;
 
+    // Used for user storage permission request
+    private static final int CREATE_DOCUMENT_REQUEST_FOR_SNAPSHOT = 1;
+
     private MediaAppDetails mMediaAppDetails;
     private MediaControllerCompat mController;
     private MediaBrowserCompat mBrowser;
@@ -143,6 +151,8 @@ public class MediaAppControllerActivity extends AppCompatActivity {
 
     private ViewGroup mRatingViewGroup;
 
+    private MediaBrowseTreeSnapshot mMediaBrowseTreeSnapshot;
+
     private final SparseArray<ImageButton> mActionButtonMap = new SparseArray<>();
 
     /**
@@ -248,20 +258,20 @@ public Object instantiateItem(@NonNull ViewGroup container, int position) {
         browseTreeList.setHasFixedSize(true);
         browseTreeList.setAdapter(mBrowseMediaItemsAdapter);
         mBrowseMediaItemsAdapter.init(findViewById(R.id.media_browse_tree_top),
-                findViewById(R.id.media_browse_tree_up));
+                findViewById(R.id.media_browse_tree_up), findViewById(R.id.media_browse_tree_save));
 
         final RecyclerView browseTreeListExtraSuggested = findViewById(R.id.media_items_list_extra_suggested);
         browseTreeListExtraSuggested.setLayoutManager(new LinearLayoutManager(this));
         browseTreeListExtraSuggested.setHasFixedSize(true);
         browseTreeListExtraSuggested.setAdapter(mBrowseMediaItemsExtraSuggestedAdapter);
         mBrowseMediaItemsExtraSuggestedAdapter.init(findViewById(R.id.media_browse_tree_top_extra_suggested),
-                findViewById(R.id.media_browse_tree_up_extra_suggested));
+                findViewById(R.id.media_browse_tree_up_extra_suggested), findViewById(R.id.media_browse_tree_save));
 
         final RecyclerView searchItemsList = findViewById(R.id.search_items_list);
         searchItemsList.setLayoutManager(new LinearLayoutManager(this));
         searchItemsList.setHasFixedSize(true);
         searchItemsList.setAdapter(mSearchMediaItemsAdapter);
-        mSearchMediaItemsAdapter.init(null, null);
+        mSearchMediaItemsAdapter.init(null, null, null);
 
         findViewById(R.id.search_button).setOnClickListener(v -> {
             CharSequence queryText = ((TextView) findViewById(R.id.search_query)).getText();
@@ -271,6 +281,28 @@ public Object instantiateItem(@NonNull ViewGroup container, int position) {
         });
     }
 
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
+        super.onActivityResult(requestCode, resultCode, data);
+        if (requestCode == CREATE_DOCUMENT_REQUEST_FOR_SNAPSHOT) {
+            if (resultCode == RESULT_OK && mMediaBrowseTreeSnapshot != null) {
+                Uri uri = data.getData();
+                OutputStream outputStream = null;
+                try {
+                    outputStream = getContentResolver().openOutputStream(uri);
+                } catch (FileNotFoundException e) {
+                    e.printStackTrace();
+                }
+                mMediaBrowseTreeSnapshot.takeBrowserSnapshot(outputStream);
+                Toast.makeText(this, "Output file location: " + uri.getPath(), Toast.LENGTH_SHORT).show();
+            } else {
+                Toast.makeText(this, "File could not be saved.", Toast.LENGTH_SHORT).show();
+            }
+
+
+        }
+    }
+
     @Override
     protected void onDestroy() {
         if (mController != null) {
@@ -1102,7 +1134,7 @@ private class BrowseMediaItemsAdapter extends
             RecyclerView.Adapter<BrowseMediaItemsAdapter.ViewHolder> {
 
         private List<MediaBrowserCompat.MediaItem> mItems;
-        private Stack<String> mNodes = new Stack<>();
+        private final Stack<String> mNodes = new Stack<>();
 
         MediaBrowserCompat.SubscriptionCallback callback =
                 new MediaBrowserCompat.SubscriptionCallback() {
@@ -1206,7 +1238,7 @@ void updateItems(List<MediaBrowserCompat.MediaItem> items) {
          * Assigns click handlers to the buttons if provided for moving to the top of the tree or
          * for moving up one level in the tree.
          */
-        void init(View topButtonView, View upButtonView) {
+        void init(View topButtonView, View upButtonView, View saveButtonView) {
             if (topButtonView != null) {
                 topButtonView.setOnClickListener(v -> {
                     if (mNodes.size() > 1) {
@@ -1228,6 +1260,38 @@ void init(View topButtonView, View upButtonView) {
                     }
                 });
             }
+            if (saveButtonView != null) {
+                saveButtonView.setOnClickListener(v -> {
+                    takeMediaBrowseTreeSnapshot();
+                });
+            }
+
+        }
+
+        private void takeMediaBrowseTreeSnapshot(){
+            if(mBrowser != null) {
+                if(mMediaBrowseTreeSnapshot == null) {
+                    mMediaBrowseTreeSnapshot = new MediaBrowseTreeSnapshot(
+                            MediaAppControllerActivity.this, mBrowser);
+                }
+                Intent saveTextFileIntent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
+                saveTextFileIntent.addCategory(Intent.CATEGORY_OPENABLE);
+                saveTextFileIntent.setType("text/plain");
+                saveTextFileIntent.putExtra(
+                        Intent.EXTRA_TITLE, DEFAULT_BROWSE_TREE_FILE_NAME);
+                MediaAppControllerActivity.this.startActivityForResult(saveTextFileIntent,
+                        CREATE_DOCUMENT_REQUEST_FOR_SNAPSHOT);
+
+            }else{
+                Log.e(TAG, "Media browser is null");
+                runOnUiThread(new Runnable() {
+                    @Override
+                    public void run() {
+                        Toast.makeText(getApplicationContext(),"No media browser to snapshot",
+                                Toast.LENGTH_SHORT).show();
+                    }
+                });
+            }
         }
 
         protected void subscribe() {
@@ -1284,7 +1348,8 @@ private class SearchMediaItemsAdapter extends BrowseMediaItemsAdapter {
         @Override
         protected void subscribe() {
             if (treeDepth() == 1) {
-                mBrowser.search(getCurrentNode(), null, new MediaBrowserCompat.SearchCallback() {
+                mBrowser.search(getCurrentNode(), null,
+                        new MediaBrowserCompat.SearchCallback() {
                     @Override
                     public void onSearchResult(@NonNull String query, Bundle extras,
                             @NonNull List<MediaBrowserCompat.MediaItem> items) {

mediacontroller/src/main/java/com/example/android/mediacontroller/MediaBrowseTreeSnapshot.kt

@@ -0,0 +1,126 @@
+package com.example.android.mediacontroller
+
+import android.content.Context
+import android.os.Handler
+import android.os.Looper
+import android.support.v4.media.MediaBrowserCompat
+import android.support.v4.media.MediaBrowserCompat.SubscriptionCallback
+import android.util.Log
+import android.widget.Toast
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.launch
+import java.io.OutputStream
+import java.io.PrintWriter
+import kotlin.coroutines.resume
+import kotlin.coroutines.suspendCoroutine
+
+
+class MediaBrowseTreeSnapshot(private val context: Context, private val browser: MediaBrowserCompat):ViewModel() {
+    private val TAG = "MediaBrowseTreeSnapshot"
+
+
+    /**
+     * Loads the browsers top level children and runs a DFS on them printing out
+     * each media item's contentes as it is visited.
+     */
+    fun takeBrowserSnapshot(outputStream: OutputStream) {
+
+        viewModelScope.launch {
+            val mediaItems: MutableList<MediaBrowserCompat.MediaItem> = getChildNodes(browser.root)
+            if (mediaItems.isNotEmpty()) {
+                runDFSOnBrowseTree(mediaItems, outputStream)
+                for (item in mediaItems) {
+                    Log.i(TAG, item.toString())
+                }
+            } else {
+                notifyUser("No media items found, could not save tree.")
+            }
+        }
+    }
+
+    private suspend fun getChildNodes(rootItemMid: String): MutableList<MediaBrowserCompat.MediaItem> =
+            suspendCoroutine {
+                val mediaItems: MutableList<MediaBrowserCompat.MediaItem> = ArrayList()
+                browser.subscribe(rootItemMid, object : SubscriptionCallback() {
+                    override fun onChildrenLoaded(parentId: String,
+                                                  children: List<MediaBrowserCompat.MediaItem>) {
+                        // Notify the main thread that all of the children have loaded
+                        mediaItems.addAll(children)
+                        super.onChildrenLoaded(parentId, children)
+                        it.resume(mediaItems)
+                    }
+                })
+            }
+
+    /**
+     * Kicks off the browse tree depth first search by visiting all of the top level media
+     * item nodes.
+     */
+    private suspend fun runDFSOnBrowseTree(mediaItems: MutableList<MediaBrowserCompat.MediaItem>, outputStream: OutputStream) {
+        val printWriter = PrintWriter(outputStream)
+        printWriter.println("Root:")
+        for (item in mediaItems) {
+            visitMediaItemNode(item, printWriter, 1)
+        }
+        printWriter.flush()
+        printWriter.close()
+        outputStream.close()
+        notifyUser("MediaItems saved to specified location.")
+    }
+
+    /**
+     * Visits a media item node by printing out its contents and then visiting all of its children.
+     */
+    private suspend fun visitMediaItemNode(mediaItem: MediaBrowserCompat.MediaItem?, printWriter: PrintWriter, depth: Int) {
+        if (mediaItem != null) {
+            printMediaItemDescription(printWriter, mediaItem, depth)
+            val mid = if (mediaItem.mediaId != null) mediaItem.mediaId!! else ""
+
+            // If a media item is not a leaf continue DFS on it
+            if (mediaItem.isBrowsable && mid != "") {
+
+                val mediaChildren: MutableList<MediaBrowserCompat.MediaItem> = getChildNodes(mid)
+
+                // Run visit on all of the nodes children
+                for (mediaItemChild in mediaChildren) {
+                    visitMediaItemNode(mediaItemChild, printWriter, depth + 1)
+                    Log.i(TAG, "Visiting:" + mediaItemChild.toString())
+                }
+            }
+        }
+    }
+
+    /**
+     * Prints the contents of a media item using a print writer.
+     */
+    private fun printMediaItemDescription(printWriter: PrintWriter, mediaItem: MediaBrowserCompat.MediaItem, depth: Int) {
+        val descriptionCompat = mediaItem.description
+        // Tab the media item to the respective depth
+        val tabStr = String(CharArray(depth)).replace("\u0000",
+                "\t")
+        val titleStr = if (descriptionCompat.title != null) descriptionCompat.title.toString() else "NAN"
+        val subTitleStr = if (descriptionCompat.subtitle != null) descriptionCompat.subtitle.toString() else "NAN"
+        val mIDStr = if (descriptionCompat.mediaId != null) descriptionCompat.mediaId else "NAN"
+        val uriStr = if (descriptionCompat.mediaUri != null) descriptionCompat.mediaUri.toString() else "NAN"
+        val desStr = if (descriptionCompat.description != null) descriptionCompat.description.toString() else "NAN"
+        val infoStr = String.format(
+                "%sTitle:%s,Subtitle:%s,MediaId:%s,URI:%s,Description:%s",
+                tabStr, titleStr, subTitleStr, mIDStr, uriStr, desStr)
+        printWriter.println(infoStr)
+    }
+
+    /**
+     * Display formatted toast to user.
+     */
+    private fun notifyUser(textToNotify: String) {
+        Handler(Looper.getMainLooper()).post {
+            val toast = Toast.makeText(
+                    context,
+                    textToNotify,
+                    Toast.LENGTH_LONG)
+            toast.setMargin(50f, 50f)
+            toast.show()
+        }
+    }
+}

mediacontroller/src/main/res/layout/media_browse_tree.xml

@@ -44,6 +44,11 @@
             android:layout_height="wrap_content"
             android:text="@string/media_browse_tree_up" />
 
+        <Button android:id="@+id/media_browse_tree_save"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/media_browse_tree_save"/>
+
     </LinearLayout>
 
     <TextView

mediacontroller/src/main/res/values/strings.xml

@@ -119,6 +119,7 @@
     <string name="media_no_browser">No Browser</string>
     <string name="media_browse_tree_loading">Loading…</string>
     <string name="media_browse_tree_empty">Empty.</string>
+    <string name="media_browse_tree_save">Save to file</string>
     <string name="search_media">Search</string>
 
     <string name="rating_thumb_up">Thumb Up</string>