Android: show drawer ("hamburger") icon on root directory

When browsing the root directory, the application home button (on the
top left corner) becomes a drawer icon. When not in the root dir, the
icon is an arrow as usual.

This will increase the visibility of the document providers feature.

Also, modified the behavior of the system back key to close the drawer
in case it is open.

Change-Id: Id0ce932907bcec4b8601029482eda0c1c1f0df35
Reviewed-on: https://gerrit.libreoffice.org/16246
Reviewed-by: Jacobo Aragunde Pérez <jaragunde@igalia.com>
Tested-by: Jacobo Aragunde Pérez <jaragunde@igalia.com>

android/source/res/values/strings.xml

@@ -46,6 +46,8 @@
     <string name="share_via">Share via</string>
 
     <!-- Document provider names -->
+    <string name="document_locations">Document locations</string>
+    <string name="close_document_locations">Close document locations</string>
     <string name="local_documents">Local documents</string>
     <string name="local_file_system">Local file system</string>
     <string name="owncloud">ownCloud</string>

android/source/src/java/org/libreoffice/ui/LibreOfficeUIActivity.java

@@ -25,6 +25,7 @@ import android.preference.PreferenceManager;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.ActionBarActivity;
+import android.support.v7.app.ActionBarDrawerToggle;
 import android.support.v7.widget.Toolbar;
 import android.util.Log;
 import android.view.ContextMenu;
@@ -93,6 +94,7 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
 
     private DrawerLayout drawerLayout;
     private ListView drawerList;
+    private ActionBarDrawerToggle drawerToggle;
     GridView gv;
     ListView lv;
 
@@ -128,6 +130,7 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
         setSupportActionBar(toolbar);
         ActionBar actionBar = getSupportActionBar();
         actionBar.setDisplayShowTitleEnabled(false); //This should show current directory if anything
+        actionBar.setDisplayHomeAsUpEnabled(true);
 
         //make the navigation spinner
         Context context = actionBar.getThemedContext();
@@ -163,6 +166,25 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
 
         drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
         drawerList = (ListView) findViewById(R.id.left_drawer);
+        drawerToggle = new ActionBarDrawerToggle(this, drawerLayout,
+                R.string.document_locations, R.string.close_document_locations) {
+
+            @Override
+            public void onDrawerOpened(View drawerView) {
+                super.onDrawerOpened(drawerView);
+                supportInvalidateOptionsMenu();
+                drawerList.requestFocus(); // Make keypad navigation easier
+            }
+
+            @Override
+            public void onDrawerClosed(View drawerView) {
+                super.onDrawerClosed(drawerView);
+                supportInvalidateOptionsMenu();
+            }
+        };
+        drawerToggle.setDrawerIndicatorEnabled(true);
+        drawerLayout.setDrawerListener(drawerToggle);
+        drawerToggle.syncState();
 
         // Set the adapter for the list view
         drawerList.setAdapter(new ArrayAdapter<String>(this,
@@ -178,12 +200,19 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
         });
     }
 
+    @Override
+    protected void onPostCreate(Bundle savedInstanceState) {
+        super.onPostCreate(savedInstanceState);
+
+        drawerToggle.syncState();
+    }
+
     private void refreshView() {
         // enable home icon as "up" if required
         if (!currentDirectory.equals(homeDirectory)) {
-            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+            drawerToggle.setDrawerIndicatorEnabled(false);
         } else {
-            getSupportActionBar().setDisplayHomeAsUpEnabled(false);
+            drawerToggle.setDrawerIndicatorEnabled(true);
         }
 
         FileUtilities.sortFiles(filePaths, sortMode);
@@ -201,7 +230,9 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
 
     @Override
     public void onBackPressed() {
-        if (!currentDirectory.equals(homeDirectory)) {
+        if (drawerLayout.isDrawerOpen(drawerList)) {
+            drawerLayout.closeDrawer(drawerList);
+        } else if (!currentDirectory.equals(homeDirectory)) {
             // navigate upwards in directory hierarchy
             openParentDirectory();
         } else {
@@ -459,7 +490,13 @@ public class LibreOfficeUIActivity extends ActionBarActivity implements ActionBa
         return true;
     }
 
+    @Override
     public boolean onOptionsItemSelected(MenuItem item) {
+        // Will close the drawer if the home button is pressed
+        if (drawerToggle.onOptionsItemSelected(item)) {
+            return true;
+        }
+
         switch (item.getItemId()) {
             case android.R.id.home:
                 if (!currentDirectory.equals(homeDirectory)){