| page.title=Creating Lists |
| |
| @jd:body |
| |
| <div id="tb-wrapper"> |
| <div id="tb"> |
| <h2>This lesson teaches you to</h2> |
| <ol> |
| <li><a href="#add-list">Add a List View</a></li> |
| <li><a href="#layout-impl">Create a Layout Implementation for List Items</a></li> |
| <li><a href="#layout-def">Create a Layout Definition for Items</a></li> |
| <li><a href="#adapter">Create an Adapter to Populate the List</a></li> |
| <li><a href="#adapter-listener">Associate the Adapter and Set a Click Listener</a></li> |
| </ol> |
| <h2>You should also read</h2> |
| <ul> |
| <li><a href="{@docRoot}design/wear/index.html">Android Wear Design Principles</a></li> |
| </ul> |
| </div> |
| </div> |
| |
| |
| <p>Lists let users select an item from a set of choices easily on wearable devices. This lesson |
| shows you how to create lists in your Android Wear apps.</p> |
| |
| <p>The Wearable UI Library includes the <code>WearableListView</code> class, which is a list |
| implementation optimized for wearable devices..</p> |
| |
| <p class="note"><strong>Note:</strong> The <em>Notifications</em> sample in the Android SDK |
| demonstrates how to use <code>WearableListView</code> in your apps. This sample is located in |
| the <code>android-sdk/samples/android-20/wearable/Notifications</code> directory.</p> |
| |
| <p>To create a list in your Android Wear apps:</p> |
| |
| <ol> |
| <li>Add a <code>WearableListView</code> element to your activity's layout definition.</li> |
| <li>Create a custom layout implementation for your list items.</li> |
| <li>Use this implementation to create a layout definition file for your list items.</li> |
| <div style="float:right;margin-left:25px;width:215px;margin-top:-20px"> |
| <img src="{@docRoot}wear/images/06_uilib.png" width="200" height="200" alt=""/> |
| <p class="img-caption" style="text-align:center"><strong>Figure 3:</strong> |
| A list view on Android Wear.</p> |
| </div> |
| <li>Create an adapter to populate the list.</li> |
| <li>Assign the adapter to the <code>WearableListView</code> element.</li> |
| </ol> |
| |
| <p>These steps are described in detail in the following sections.</p> |
| |
| |
| <h2 id="add-list">Add a List View</h2> |
| |
| <p>The following layout adds a list view to an activity using a <code>BoxInsetLayout</code>, so |
| the list is displayed properly on both round and square devices:</p> |
| |
| <pre> |
| <android.support.wearable.view.BoxInsetLayout |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| xmlns:app="http://schemas.android.com/apk/res-auto" |
| android:background="@drawable/robot_background" |
| android:layout_height="match_parent" |
| android:layout_width="match_parent"> |
| |
| <FrameLayout |
| android:id="@+id/frame_layout" |
| android:layout_height="match_parent" |
| android:layout_width="match_parent" |
| app:layout_box="left|bottom|right"> |
| |
| <<strong>android.support.wearable.view.WearableListView</strong> |
| android:id="@+id/wearable_list" |
| android:layout_height="match_parent" |
| android:layout_width="match_parent"> |
| </android.support.wearable.view.WearableListView> |
| </FrameLayout> |
| </android.support.wearable.view.BoxInsetLayout> |
| </pre> |
| |
| |
| <h2 id="layout-impl">Create a Layout Implementation for List Items</h2> |
| |
| <p>In many cases, each list item consists of an icon and a description. The |
| <em>Notifications</em> sample from the Android SDK implements a custom layout that extends |
| {@link android.widget.LinearLayout} to incorporate these two elements inside each list item. |
| This layout also implements the methods in the <code>WearableListView.Item</code> interface |
| to animate the item's icon and fade the text in response to events from |
| <code>WearableListView</code> as the user scrolls through the list.</p> |
| |
| <pre> |
| public class WearableListItemLayout extends LinearLayout |
| implements WearableListView.Item { |
| |
| private final float mFadedTextAlpha; |
| private final int mFadedCircleColor; |
| private final int mChosenCircleColor; |
| private ImageView mCircle; |
| private float mScale; |
| private TextView mName; |
| |
| public WearableListItemLayout(Context context) { |
| this(context, null); |
| } |
| |
| public WearableListItemLayout(Context context, AttributeSet attrs) { |
| this(context, attrs, 0); |
| } |
| |
| public WearableListItemLayout(Context context, AttributeSet attrs, |
| int defStyle) { |
| super(context, attrs, defStyle); |
| mFadedTextAlpha = getResources() |
| .getInteger(R.integer.action_text_faded_alpha) / 100f; |
| mFadedCircleColor = getResources().getColor(R.color.grey); |
| mChosenCircleColor = getResources().getColor(R.color.blue); |
| } |
| |
| // Get references to the icon and text in the item layout definition |
| @Override |
| protected void onFinishInflate() { |
| super.onFinishInflate(); |
| // These are defined in the layout file for list items |
| // (see next section) |
| mCircle = (ImageView) findViewById(R.id.circle); |
| mName = (TextView) findViewById(R.id.name); |
| } |
| |
| // Provide scaling values for WearableListView animations |
| @Override |
| public float getProximityMinValue() { |
| return 1f; |
| } |
| |
| @Override |
| public float getProximityMaxValue() { |
| return 1.6f; |
| } |
| |
| @Override |
| public float getCurrentProximityValue() { |
| return mScale; |
| } |
| |
| // Scale the icon for WearableListView animations |
| @Override |
| public void setScalingAnimatorValue(float scale) { |
| mScale = scale; |
| mCircle.setScaleX(scale); |
| mCircle.setScaleY(scale); |
| } |
| |
| // Change color of the icon, remove fading from the text |
| @Override |
| public void onScaleUpStart() { |
| mName.setAlpha(1f); |
| ((GradientDrawable) mCircle.getDrawable()).setColor(mChosenCircleColor); |
| } |
| |
| // Change the color of the icon, fade the text |
| @Override |
| public void onScaleDownStart() { |
| ((GradientDrawable) mCircle.getDrawable()).setColor(mFadedCircleColor); |
| mName.setAlpha(mFadedTextAlpha); |
| } |
| } |
| </pre> |
| |
| |
| <h2 id="layout-def">Create a Layout Definition for Items</h2> |
| |
| <p>After you implement a custom layout for list items, you provide a layout definition file that |
| specifies the layout parameters of each of the components inside a list item. The following layout |
| definition uses the custom layout implementation from the previous section and defines an icon |
| and a text view whose IDs match those in the layout implementation class:</p> |
| |
| <p class="code-caption">res/layout/list_item.xml</p> |
| |
| <pre> |
| <com.example.android.support.wearable.notifications.WearableListItemLayout |
| xmlns:android="http://schemas.android.com/apk/res/android" |
| android:gravity="center_vertical" |
| android:layout_width="match_parent" |
| android:layout_height="80dp"> |
| <ImageView |
| android:id="@+id/circle" |
| android:layout_height="20dp" |
| android:layout_margin="16dp" |
| android:layout_width="20dp" |
| android:src="@drawable/wl_circle"/> |
| <TextView |
| android:id="@+id/name" |
| android:gravity="center_vertical|left" |
| android:layout_width="wrap_content" |
| android:layout_marginRight="16dp" |
| android:layout_height="match_parent" |
| android:fontFamily="sans-serif-condensed-light" |
| android:lineSpacingExtra="-4sp" |
| android:textColor="@color/text_color" |
| android:textSize="16sp"/> |
| </com.example.android.support.wearable.notifications.WearableListItemLayout> |
| </pre> |
| |
| |
| <h2 id="adapter">Create an Adapter to Populate the List</h2> |
| |
| <p>The adapter populates the <code>WearableListView</code> with content. The following simple |
| adapter populates the list with elements based on an array of strings:</p> |
| |
| <pre> |
| private static final class Adapter extends WearableListView.Adapter { |
| private String[] mDataset; |
| private final Context mContext; |
| private final LayoutInflater mInflater; |
| |
| // Provide a suitable constructor (depends on the kind of dataset) |
| public Adapter(Context context, String[] dataset) { |
| mContext = context; |
| mInflater = LayoutInflater.from(context); |
| mDataset = dataset; |
| } |
| |
| // Provide a reference to the type of views you're using |
| public static class ItemViewHolder extends WearableListView.ViewHolder { |
| private TextView textView; |
| public ItemViewHolder(View itemView) { |
| super(itemView); |
| // find the text view within the custom item's layout |
| textView = (TextView) itemView.findViewById(R.id.name); |
| } |
| } |
| |
| // Create new views for list items |
| // (invoked by the WearableListView's layout manager) |
| @Override |
| public WearableListView.ViewHolder onCreateViewHolder(ViewGroup parent, |
| int viewType) { |
| // Inflate our custom layout for list items |
| return new ItemViewHolder(mInflater.inflate(R.layout.list_item, null)); |
| } |
| |
| // Replace the contents of a list item |
| // Instead of creating new views, the list tries to recycle existing ones |
| // (invoked by the WearableListView's layout manager) |
| @Override |
| public void onBindViewHolder(WearableListView.ViewHolder holder, |
| int position) { |
| // retrieve the text view |
| ItemViewHolder itemHolder = (ItemViewHolder) holder; |
| TextView view = itemHolder.textView; |
| // replace text contents |
| view.setText(mDataset[position]); |
| // replace list item's metadata |
| holder.itemView.setTag(position); |
| } |
| |
| // Return the size of your dataset |
| // (invoked by the WearableListView's layout manager) |
| @Override |
| public int getItemCount() { |
| return mDataset.length; |
| } |
| } |
| </pre> |
| |
| |
| <h2 id="adapter-listener">Associate the Adapter and Set a Click Listener</h2> |
| |
| <p>In your activity, obtain a reference to the <code>WearableListView</code> element from |
| your layout, assign an instance of the adapter to populate the list, and set a click listener |
| to complete an action when the user selects a particular list item.</p> |
| |
| <pre> |
| public class WearActivity extends Activity |
| implements WearableListView.ClickListener { |
| |
| // Sample dataset for the list |
| String[] elements = { "List Item 1", "List Item 2", ... }; |
| |
| @Override |
| protected void onCreate(Bundle savedInstanceState) { |
| super.onCreate(savedInstanceState); |
| setContentView(R.layout.my_list_activity); |
| |
| // Get the list component from the layout of the activity |
| WearableListView listView = |
| (WearableListView) findViewById(R.id.wearable_list); |
| |
| // Assign an adapter to the list |
| listView.setAdapter(new Adapter(this, elements)); |
| |
| // Set a click listener |
| listView.setClickListener(this); |
| } |
| |
| // WearableListView click listener |
| @Override |
| public void onClick(WearableListView.ViewHolder v) { |
| Integer tag = (Integer) v.itemView.getTag(); |
| // use this data to complete some action ... |
| } |
| |
| @Override |
| public void onTopEmptyRegionClick() { |
| } |
| } |
| </pre> |