Show all folders for an account.

This is just the start. Needs a lot more passes, and will
want to make this a fragment instead of an activity.

Change-Id: I107390ee6c2e3af044c977c160b8d9a52477d569

21 files changed, 496 insertions, 6 deletions

diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index cd78cc20d..450a3079b 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -44,6 +44,7 @@
         <activity android:name=".compose.ComposeActivity" />
         <activity android:name=".browse.ConversationListActivity" />
         <activity android:name=".browse.ConversationViewActivity" />
+        <activity android:name=".browse.FoldersListActivity" />
         <activity android:name=".browse.FolderItem" />
         <activity
            android:name=".ui.ActionbarActivity"
diff --git a/res/color/text_color_unread_invertible.xml b/res/color/text_color_unread_invertible.xml
new file mode 100644
index 000000000..6043e910e
--- /dev/null
+++ b/res/color/text_color_unread_invertible.xml
@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2012 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_enabled="false"
+        android:color="#ff999999"/>
+    <item android:state_activated="true"
+        android:color="@android:color/white" />
+    <item
+        android:color="#bcbcbc" />
+</selector>
\ No newline at end of file
diff --git a/res/drawable/folder_drag_target.xml b/res/drawable/folder_drag_target.xml
new file mode 100644
index 000000000..c1fea431d
--- /dev/null
+++ b/res/drawable/folder_drag_target.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2011 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- If this selector has more than one state, LabelItemView will need to be changed
+    to change the reference there to not be static -->
+    <item android:drawable="@drawable/list_pressed_holo" />
+</selector>
diff --git a/res/drawable/folder_item.xml b/res/drawable/folder_item.xml
new file mode 100644
index 000000000..cc362eda0
--- /dev/null
+++ b/res/drawable/folder_item.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2011 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_pressed="true" android:drawable="@drawable/list_selected_holo" />
+    <item android:drawable="@android:color/transparent" />
+</selector>
diff --git a/res/drawable/folder_no_hover.xml b/res/drawable/folder_no_hover.xml
new file mode 100644
index 000000000..99c85349d
--- /dev/null
+++ b/res/drawable/folder_no_hover.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2011 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <!-- If this selector has more than one state, LabelItemView will need to be changed
+    to change the reference there to not be static -->
+    <item android:drawable="@android:color/transparent" />
+</selector>
diff --git a/res/layout/folder_item.xml b/res/layout/folder_item.xml
new file mode 100644
index 000000000..9be38fa12
--- /dev/null
+++ b/res/layout/folder_item.xml
@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2012 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<com.android.mail.ui.FolderItemView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_height="wrap_content"
+    android:layout_width="match_parent"
+    android:minHeight="@dimen/folder_list_minimum_height"
+    android:background="@drawable/folder_item">
+
+    <ImageView
+        android:id="@+id/label_box"
+        style="@style/FolderItemIcon"
+        android:layout_alignParentLeft="true"
+        android:layout_alignParentTop="true" />
+
+    <TextView
+        android:id="@+id/unread"
+        style="@style/UnreadCount"
+        android:layout_marginRight="@dimen/folder_list_item_right_margin"
+        android:layout_alignParentRight="true"
+        android:textColor="@color/text_color_unread_invertible" />
+
+    <RelativeLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_centerVertical="true"
+        android:layout_toLeftOf="@id/unread"
+        android:layout_marginLeft="@dimen/folder_list_item_left_margin"
+        android:layout_marginTop="@dimen/folder_swatch_height"
+        android:layout_marginBottom="@dimen/folder_swatch_height">
+
+        <TextView
+            android:id="@+id/name"
+            android:layout_height="wrap_content"
+            android:layout_width="match_parent"
+            android:maxLines="2"
+            android:ellipsize="end"
+            android:textColor="@color/text_color_primary_invertible"
+            android:textAppearance="?android:attr/textAppearanceMedium" />
+
+        <TextView
+            android:id="@+id/description"
+            android:layout_height="wrap_content"
+            android:layout_width="match_parent"
+            android:layout_below="@id/name"
+            android:textColor="@color/text_color_primary_invertible"
+            android:textAppearance="?android:attr/textAppearanceSmall"
+            android:visibility="gone" />
+
+    </RelativeLayout>
+
+</com.android.mail.ui.FolderItemView>
\ No newline at end of file
diff --git a/res/layout/folders_activity.xml b/res/layout/folders_activity.xml
new file mode 100644
index 000000000..82875fd89
--- /dev/null
+++ b/res/layout/folders_activity.xml
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2012 Google Inc.
+     Licensed to The Android Open Source Project.
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical" >
+
+    <ListView
+        android:id="@+id/folders_list"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:cacheColorHint="@android:color/transparent"
+        android:drawSelectorOnTop="false"
+        android:fadingEdge="none" />
+
+    <TextView android:id="@+id/empty_view"
+        android:visibility="gone"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/folders_activity_instructions"/>
+
+</LinearLayout>
diff --git a/res/menu/conversation_list_menu.xml b/res/menu/conversation_list_menu.xml
index ce6dda08d..44221ab98 100644
--- a/res/menu/conversation_list_menu.xml
+++ b/res/menu/conversation_list_menu.xml
@@ -30,8 +30,8 @@
         android:icon="@drawable/ic_menu_search_holo_light"
         android:actionLayout="@layout/mail_actionbar_searchview" />
 
-    <item android:id="@+id/show_all_labels"
-        android:title="@string/show_all_labels"
+    <item android:id="@+id/show_all_folders"
+        android:title="@string/show_all_folders"
         android:showAsAction="ifRoom"
         android:icon="@drawable/ic_menu_labels_holo_light" />
 
diff --git a/res/menu/conversation_list_search_results_actions.xml b/res/menu/conversation_list_search_results_actions.xml
index c358204cd..7edfa7622 100644
--- a/res/menu/conversation_list_search_results_actions.xml
+++ b/res/menu/conversation_list_search_results_actions.xml
@@ -30,8 +30,8 @@
         android:icon="@drawable/ic_menu_search_holo_light"
         android:actionLayout="@layout/mail_actionbar_searchview" />
 
-    <item android:id="@+id/show_all_labels"
-        android:title="@string/show_all_labels"
+    <item android:id="@+id/show_all_folders"
+        android:title="@string/show_all_folders"
         android:showAsAction="ifRoom"
         android:icon="@drawable/ic_menu_labels_holo_light" />
 
diff --git a/res/mipmap-hdpi/ic_launcher_mail.png b/res/mipmap-hdpi/ic_launcher_mail.png
new file mode 100644
index 000000000..4620e7101
--- /dev/null
+++ b/res/mipmap-hdpi/ic_launcher_mail.png
diff --git a/res/mipmap-hdpi/ic_launcher_shortcut_folder.png b/res/mipmap-hdpi/ic_launcher_shortcut_folder.png
new file mode 100644
index 000000000..96eddb33a
--- /dev/null
+++ b/res/mipmap-hdpi/ic_launcher_shortcut_folder.png
diff --git a/res/mipmap-mdpi/ic_launcher_mail.png b/res/mipmap-mdpi/ic_launcher_mail.png
new file mode 100644
index 000000000..2c43d0d83
--- /dev/null
+++ b/res/mipmap-mdpi/ic_launcher_mail.png
diff --git a/res/mipmap-mdpi/ic_launcher_shortcut_folder.png b/res/mipmap-mdpi/ic_launcher_shortcut_folder.png
new file mode 100644
index 000000000..eb8653d5d
--- /dev/null
+++ b/res/mipmap-mdpi/ic_launcher_shortcut_folder.png
diff --git a/res/mipmap-xhdpi/ic_launcher_shortcut_folder.png b/res/mipmap-xhdpi/ic_launcher_shortcut_folder.png
new file mode 100644
index 000000000..00ed48d39
--- /dev/null
+++ b/res/mipmap-xhdpi/ic_launcher_shortcut_folder.png
diff --git a/res/values/colors.xml b/res/values/colors.xml
index 6e53af243..3be280cd9 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -45,4 +45,7 @@
     <!-- Conversation message header colors -->
     <color name="conv_subject_border">#c0c0c0</color>
     <color name="conv_header_text_light">#777777</color>
+
+    <!-- Folder colors -->
+    <color name="folder_disabled_drop_target_text_color">#999999</color>
 </resources>
diff --git a/res/values/dimen.xml b/res/values/dimen.xml
index bc6c4970d..9f350a3c8 100644
--- a/res/values/dimen.xml
+++ b/res/values/dimen.xml
@@ -60,4 +60,11 @@
     <dimen name="message_header_inner_side_padding">8dip</dimen>
     <dimen name="attachment_toast_yoffset">-100dip</dimen>
     <dimen name="spinner_frame_width">168dip</dimen>
+    <dimen name="folder_list_heading_padding_side">8dp</dimen>
+    <dimen name="folder_list_item_left_margin">24dp</dimen>
+    <dimen name="folder_list_item_right_margin">16dp</dimen>
+    <dimen name="folder_swatch_height">8dip</dimen>
+    <dimen name="folder_list_popup_width">200dip</dimen>
+    <dimen name="folder_list_folder_color_width">36dip</dimen>
+    <dimen name="folder_list_minimum_height">48dip</dimen>
 </resources>
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 9ae89ead9..eeb776f9e 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -263,8 +263,8 @@
     <!-- Strings used to show myself in a To/Cc list. [CHAR LIMIT=15] -->
     <string name="me">me</string>
     <string name="labels">Labels</string>
-    <!-- List item to open label view in account dropdown [CHAR LIMIT=50] -->
-    <string name="show_all_labels">Show all labels</string>
+    <!-- List item to open fodlers view in account dropdown [CHAR LIMIT=50] -->
+    <string name="show_all_folders">Show all folders</string>
 
     <!-- Undo bar strings -->
     <!-- Displayed in the middle of the screen when the inbox is empty [CHAR LIMIT 100]-->
@@ -469,4 +469,8 @@
     <string name="done">Done</string>
     <string name="cancel">Cancel</string>
     <string name="close">Close</string>
+
+    <!-- Folders -->
+    <!-- Displayed in the middle of the Folders screen when no folders have been defined -->
+    <string name="folders_activity_instructions">No folders have been set for this account.</string>
 </resources>
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 8e8c200a9..290dbb7ad 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -307,4 +307,10 @@
         <item name="android:contentDescription">@string/collapse_recipient_details</item>
     </style>
     <!-- End conversation view message header styles -->
+
+    <!-- Folder styles -->
+    <style name="FolderItemIcon">
+        <item name="android:layout_height">@dimen/folder_swatch_height</item>
+        <item name="android:layout_width">@dimen/folder_list_folder_color_width</item>
+    </style>
 </resources>
diff --git a/src/com/android/mail/browse/ConversationListActivity.java b/src/com/android/mail/browse/ConversationListActivity.java
index 72ce5b628..fee0a105b 100644
--- a/src/com/android/mail/browse/ConversationListActivity.java
+++ b/src/com/android/mail/browse/ConversationListActivity.java
@@ -117,6 +117,9 @@ public class ConversationListActivity extends Activity implements OnItemSelected
             case R.id.compose:
                 ComposeActivity.compose(this, mSelectedAccount);
                 break;
+            case R.id.show_all_folders:
+                showAllFolders();
+                break;
             default:
                 handled = false;
                 break;
@@ -124,6 +127,10 @@ public class ConversationListActivity extends Activity implements OnItemSelected
         return handled;
     }
 
+    private void showAllFolders() {
+        FoldersListActivity.launch(this, mSelectedAccount);
+    }
+
     @Override
     public Loader<Cursor> onCreateLoader(int id, Bundle args) {
         // Currently this activity only creates a single loader (Account List)
diff --git a/src/com/android/mail/browse/FoldersListActivity.java b/src/com/android/mail/browse/FoldersListActivity.java
new file mode 100644
index 000000000..33909ff8d
--- /dev/null
+++ b/src/com/android/mail/browse/FoldersListActivity.java
@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) 2012, Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.mail.browse;
+
+import com.android.mail.R;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ListView;
+import android.widget.SimpleCursorAdapter;
+
+import com.android.mail.providers.Account;
+import com.android.mail.providers.Folder;
+import com.android.mail.providers.Message;
+import com.android.mail.providers.UIProvider;
+import com.android.mail.ui.FolderItemView;
+import com.android.mail.ui.FolderItemView.DropHandler;
+import com.android.mail.utils.Utils;
+
+public class FoldersListActivity extends Activity {
+    private ListView mListView;
+    private Account mAccount;
+    private Cursor mFoldersCursor;
+
+    public static void launch(Context launcher, Account account) {
+        Intent intent = new Intent(launcher, FoldersListActivity.class);
+        intent.putExtra(Utils.EXTRA_ACCOUNT, account);
+        launcher.startActivity(intent);
+    }
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.folders_activity);
+        mListView = (ListView) findViewById(R.id.folders_list);
+        mAccount = (Account) getIntent().getParcelableExtra(Utils.EXTRA_ACCOUNT);
+        mFoldersCursor = getContentResolver().query(Uri.parse(mAccount.folderListUri),
+                UIProvider.FOLDERS_PROJECTION, null, null, null);
+        mListView.setAdapter(new FolderListAdapter(this, R.layout.folder_item, mFoldersCursor,
+                null, null));
+    }
+
+    private class FolderListAdapter extends SimpleCursorAdapter {
+
+        public FolderListAdapter(Context context, int layout, Cursor c, String[] from, int[] to) {
+            super(context, layout, c, new String[0], new int[0], 0);
+        }
+
+        @Override
+        public View getView(int position, View convertView, ViewGroup parent) {
+            FolderItemView folderItemView;
+            if (convertView != null) {
+                folderItemView = (FolderItemView) convertView;
+            } else {
+                folderItemView = (FolderItemView) LayoutInflater.from(FoldersListActivity.this)
+                        .inflate(R.layout.folder_item, null);
+            }
+            mFoldersCursor.moveToPosition(position);
+            folderItemView.bind(new Folder(mFoldersCursor), null);
+            return folderItemView;
+        }
+    }
+}
diff --git a/src/com/android/mail/ui/FolderItemView.java b/src/com/android/mail/ui/FolderItemView.java
new file mode 100644
index 000000000..d24f5da7e
--- /dev/null
+++ b/src/com/android/mail/ui/FolderItemView.java
@@ -0,0 +1,178 @@
+/**
+ * Copyright (c) 2012, Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.mail.ui;
+
+import com.android.mail.R;
+
+import android.widget.TextView;
+
+import com.android.mail.providers.Folder;
+import android.content.Context;
+import android.content.res.ColorStateList;
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
+import android.view.DragEvent;
+import android.widget.RelativeLayout;
+
+/**
+ * The view for each label in the label list.
+ */
+public class FolderItemView extends RelativeLayout {
+    // Static colors
+    private static int NON_DROPPABLE_TARGET_TEXT_COLOR;
+
+    // Static bitmap
+    private static Bitmap SHORTCUT_ICON;
+
+    // These are fine to be static, as these Drawables only have one state
+    private static Drawable DROPPABLE_HOVER_BACKGROUND;
+    private static Drawable DRAG_STEADY_STATE_BACKGROUND;
+
+    private Drawable mBackground;
+    private ColorStateList mInitialLabelTextColor;
+    private ColorStateList mInitialUnreadCountTextColor;
+
+    private Folder mFolder;
+    private TextView mFolderTextView;
+    private TextView mUnreadCountTextView;
+    private DropHandler mDropHandler;
+
+
+    /**
+     * A delegate for a handler to handle a drop of an item.
+     */
+    public interface DropHandler {
+        /**
+         * Return whether or not the drag event is supported by the drop handler. The
+         *     {@code FolderItemView} will present appropriate visual affordances if the drag is
+         *     supported.
+         */
+        boolean supportsDrag(DragEvent event, Folder folder);
+
+        /**
+         * Handles a drop event, applying the appropriate logic.
+         */
+        void handleDrop(DragEvent event, Folder folder);
+    }
+
+    public FolderItemView(Context context) {
+        super(context);
+    }
+
+    public FolderItemView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public FolderItemView(Context context, AttributeSet attrs, int defStyle) {
+        super(context, attrs, defStyle);
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+        if (SHORTCUT_ICON == null) {
+            final Resources res = getResources();
+            SHORTCUT_ICON = BitmapFactory.decodeResource(
+                    res, R.mipmap.ic_launcher_shortcut_folder);
+            DROPPABLE_HOVER_BACKGROUND =
+                    res.getDrawable(R.drawable.folder_drag_target);
+            DRAG_STEADY_STATE_BACKGROUND =
+                    res.getDrawable(R.drawable.folder_no_hover);
+            NON_DROPPABLE_TARGET_TEXT_COLOR =
+                    res.getColor(R.color.folder_disabled_drop_target_text_color);
+        }
+        mFolderTextView = (TextView)findViewById(R.id.name);
+        mUnreadCountTextView = (TextView)findViewById(R.id.unread);
+        mBackground = getBackground();
+        mInitialLabelTextColor = mFolderTextView.getTextColors();
+        mInitialUnreadCountTextColor = mUnreadCountTextView.getTextColors();
+    }
+
+    public void bind(Folder folder, DropHandler dropHandler) {
+        mFolder = folder;
+        mDropHandler = dropHandler;
+        mFolderTextView.setText(folder.name);
+    }
+
+    private boolean isDroppableTarget(DragEvent event) {
+        return (mDropHandler != null && mDropHandler.supportsDrag(event, mFolder));
+    }
+
+    /**
+     * Handles the drag event.
+     *
+     * @param event the drag event to be handled
+     */
+    @Override
+    public boolean onDragEvent(DragEvent event) {
+        switch (event.getAction()) {
+            case DragEvent.ACTION_DRAG_STARTED:
+                // If this label is not a drop target, dim the text.
+                if (!isDroppableTarget(event)) {
+                    // Make sure we update this at the time we drop on the target.
+                    mInitialLabelTextColor = mFolderTextView.getTextColors();
+                    mInitialUnreadCountTextColor = mUnreadCountTextView.getTextColors();
+                    mFolderTextView.setTextColor(NON_DROPPABLE_TARGET_TEXT_COLOR);
+                    mUnreadCountTextView.setTextColor(NON_DROPPABLE_TARGET_TEXT_COLOR);
+                }
+                // Set the background to a steady state background.
+                setBackgroundDrawable(DRAG_STEADY_STATE_BACKGROUND);
+                return true;
+
+            case DragEvent.ACTION_DRAG_ENTERED:
+                // Change background color to indicate this label is the drop target.
+                if (isDroppableTarget(event)) {
+                    setBackgroundDrawable(DROPPABLE_HOVER_BACKGROUND);
+                    return true;
+                }
+                break;
+
+            case DragEvent.ACTION_DRAG_EXITED:
+                // If this is a droppable target, make sure that it is set back to steady state,
+                // when the drag leaves the view.
+                if (isDroppableTarget(event)) {
+                    setBackgroundDrawable(DRAG_STEADY_STATE_BACKGROUND);
+                    return true;
+                }
+                break;
+
+            case DragEvent.ACTION_DRAG_ENDED:
+                // Reset the text of the non draggable views back to the color it had been..
+                if (!isDroppableTarget(event)) {
+                    mFolderTextView.setTextColor(mInitialLabelTextColor);
+                    mUnreadCountTextView.setTextColor(mInitialUnreadCountTextColor);
+                }
+                // Restore the background of the view.
+                setBackgroundDrawable(mBackground);
+                return true;
+
+            case DragEvent.ACTION_DRAG_LOCATION:
+                return true;
+
+            case DragEvent.ACTION_DROP:
+                if (mDropHandler == null) {
+                    return false;
+                }
+
+                mDropHandler.handleDrop(event, mFolder);
+                return true;
+        }
+        return false;
+    }
+}