CarDrawerAdapter.java
/*
* Copyright (C) 2017 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.
*/
package androidx.car.drawer;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.PorterDuff;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.LayoutRes;
import androidx.annotation.Nullable;
import androidx.car.R;
import androidx.car.util.CarUxRestrictionsHelper;
import androidx.car.uxrestrictions.CarUxRestrictions;
import androidx.car.widget.PagedListView;
import androidx.recyclerview.widget.RecyclerView;
/**
* Base adapter for displaying items in the car navigation drawer, which uses a
* {@link PagedListView}.
*
* <p>Subclasses can optionally set the title that will be displayed when displaying the contents
* of the drawer via {@link #setTitle(CharSequence)}. The title can be updated at any point later
* on. The title of the root adapter will also be the main title showed in the toolbar when the
* drawer is closed. See {@link CarDrawerController#setRootAdapter(CarDrawerAdapter)} for more
* information.
*
* <p>This class also takes care of implementing the PageListView.ItemCamp contract and subclasses
* should implement {@link #getActualItemCount()}.
*
* <p>To enable support for {@link CarUxRestrictions}, call {@link #start()} in your
* {@code Activity}'s {@link android.app.Activity#onCreate(Bundle)}, and {@link #stop()} in
* {@link Activity#onStop()}.
*/
public abstract class CarDrawerAdapter extends RecyclerView.Adapter<DrawerItemViewHolder>
implements PagedListView.ItemCap {
private final boolean mShowDisabledListOnEmpty;
private final Drawable mEmptyListDrawable;
private int mMaxItems = PagedListView.ItemCap.UNLIMITED;
private CharSequence mTitle;
private TitleChangeListener mTitleChangeListener;
private final CarUxRestrictionsHelper mUxRestrictionsHelper;
private CarUxRestrictions mCurrentUxRestrictions;
@LayoutRes private final int mSmallLayoutResId;
@LayoutRes private final int mNormalLayoutResId;
/**
* Enables support for {@link CarUxRestrictions}.
*
* <p>This method can be called from {@code Activity}'s {@link Activity#onStart()}, or at the
* time of construction.
*
* <p>This method must be accompanied with a matching {@link #stop()} to avoid leak.
*/
public void start() {
mUxRestrictionsHelper.start();
}
/**
* Disables support for {@link CarUxRestrictions}, and frees up resources.
*
* <p>This method should be called from {@code Activity}'s {@link Activity#onStop()}, or at the
* time of this adapter being discarded.
*/
public void stop() {
mUxRestrictionsHelper.stop();
}
/**
* Interface for a class that will be notified a new title has been set on this adapter.
*/
interface TitleChangeListener {
/**
* Called when {@link #setTitle(CharSequence)} has been called and the title has been
* changed.
*/
void onTitleChanged(@Nullable CharSequence newTitle);
}
protected CarDrawerAdapter(Context context, boolean showDisabledListOnEmpty) {
mShowDisabledListOnEmpty = showDisabledListOnEmpty;
mEmptyListDrawable = context.getDrawable(R.drawable.ic_list_view_disable);
mEmptyListDrawable.setColorFilter(context.getColor(R.color.car_tint),
PorterDuff.Mode.SRC_IN);
TypedValue outValue = new TypedValue();
Resources.Theme theme = context.getTheme();
mSmallLayoutResId = theme.resolveAttribute(R.attr.drawerSmallLayoutId, outValue, true)
? outValue.resourceId
: R.layout.car_drawer_list_item_small;
mNormalLayoutResId = theme.resolveAttribute(R.attr.drawerNormalLayoutId, outValue, true)
? outValue.resourceId
: R.layout.car_drawer_list_item_normal;
mUxRestrictionsHelper =
new CarUxRestrictionsHelper(context, carUxRestrictions -> {
mCurrentUxRestrictions = new CarUxRestrictions(carUxRestrictions);
notifyDataSetChanged();
});
}
/** Returns the title set via {@link #setTitle(CharSequence)}. */
CharSequence getTitle() {
return mTitle;
}
/** Updates the title to display in the toolbar for this Adapter. */
public final void setTitle(@Nullable CharSequence title) {
mTitle = title;
if (mTitleChangeListener != null) {
mTitleChangeListener.onTitleChanged(mTitle);
}
}
/** Sets a listener to be notified whenever the title of this adapter has been changed. */
void setTitleChangeListener(@Nullable TitleChangeListener listener) {
mTitleChangeListener = listener;
}
@Override
public final void setMaxItems(int maxItems) {
mMaxItems = maxItems;
}
@Override
public final int getItemCount() {
if (shouldShowDisabledListItem()) {
return 1;
}
return mMaxItems >= 0 ? Math.min(mMaxItems, getActualItemCount()) : getActualItemCount();
}
/**
* Returns the absolute number of items that can be displayed in the list.
*
* <p>A class should implement this method to supply the number of items to be displayed.
* Returning 0 from this method will cause an empty list icon to be displayed in the drawer.
*
* <p>A class should override this method rather than {@link #getItemCount()} because that
* method is handling the logic of when to display the empty list icon. It will return 1 when
* {@link #getActualItemCount()} returns 0.
*
* @return The number of items to be displayed in the list.
*/
protected abstract int getActualItemCount();
@Override
public final int getItemViewType(int position) {
if (shouldShowDisabledListItem()) {
return R.layout.car_drawer_list_item_empty;
}
return usesSmallLayout(position)
? mSmallLayoutResId
: mNormalLayoutResId;
}
/**
* Used to indicate the layout used for the Drawer item at given position. Subclasses can
* override this to use normal layout which includes text element below title.
*
* <p>A small layout is presented by the layout {@code R.layout.car_drawer_list_item_small}.
* Otherwise, the layout {@code R.layout.car_drawer_list_item_normal} will be used.
*
* @param position Adapter position of item.
* @return Whether the item at this position will use a small layout (default) or normal layout.
*/
protected boolean usesSmallLayout(int position) {
return true;
}
@Override
public final DrawerItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(viewType, parent, false);
return new DrawerItemViewHolder(view);
}
@Override
public final void onBindViewHolder(DrawerItemViewHolder holder, int position) {
// Car may not be initialized thus current UXR will not be available.
if (mCurrentUxRestrictions != null) {
holder.onUxRestrictionsChanged(mCurrentUxRestrictions);
}
if (shouldShowDisabledListItem()) {
holder.getTitleView().setText(null);
holder.getIconView().setImageDrawable(mEmptyListDrawable);
} else {
populateViewHolder(holder, position);
}
}
/**
* Whether or not this adapter should be displaying an empty list icon. The icon is shown if it
* has been configured to show and there are no items to be displayed.
*/
private boolean shouldShowDisabledListItem() {
return mShowDisabledListOnEmpty && getActualItemCount() == 0;
}
/**
* Subclasses should set all elements in {@code holder} to populate the drawer-item. If some
* element is not used, it should be nulled out since these ViewHolder/View's are recycled.
*/
protected abstract void populateViewHolder(DrawerItemViewHolder holder, int position);
/**
* Called when this adapter has been popped off the stack and is no longer needed. Subclasses
* can override to do any necessary cleanup.
*/
public void cleanup() {}
}