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/*
* 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 android.support.car.drawer;
import android.content.Context;
import android.graphics.PorterDuff;
import android.graphics.drawable.Drawable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.car.R;
import android.support.car.widget.PagedListView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* Base adapter for displaying items in the car navigation drawer, which uses a
* {@link PagedListView}.
*
* <p>Subclasses must 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()}.
*/
public abstract class CarDrawerAdapter extends RecyclerView.Adapter<DrawerItemViewHolder>
implements PagedListView.ItemCap, DrawerItemClickListener {
private final boolean mShowDisabledListOnEmpty;
private final Drawable mEmptyListDrawable;
private int mMaxItems = PagedListView.ItemCap.UNLIMITED;
private CharSequence mTitle;
private TitleChangeListener mTitleChangeListener;
/**
* 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(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);
}
/** 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(@NonNull CharSequence title) {
if (title == null) {
throw new IllegalArgumentException("setTitle() cannot be passed a null 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)
? R.layout.car_drawer_list_item_small
: R.layout.car_drawer_list_item_normal;
}
/**
* 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) {
if (shouldShowDisabledListItem()) {
holder.getTitle().setText(null);
holder.getIcon().setImageDrawable(mEmptyListDrawable);
holder.setItemClickListener(null);
} else {
holder.setItemClickListener(this);
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() {}
}
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