com/android/setupwizardlib/template/RecyclerMixin.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 com.android.setupwizardlib.template;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.os.Build.VERSION_CODES;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.RecyclerView.Adapter;
import androidx.recyclerview.widget.RecyclerView.ViewHolder;
import android.util.AttributeSet;
import android.view.View;
import com.android.setupwizardlib.DividerItemDecoration;
import com.android.setupwizardlib.R;
import com.android.setupwizardlib.TemplateLayout;
import com.android.setupwizardlib.items.ItemHierarchy;
import com.android.setupwizardlib.items.ItemInflater;
import com.android.setupwizardlib.items.RecyclerItemAdapter;
import com.android.setupwizardlib.util.DrawableLayoutDirectionHelper;
import com.android.setupwizardlib.view.HeaderRecyclerView;
import com.android.setupwizardlib.view.HeaderRecyclerView.HeaderAdapter;

/**
 * A {@link Mixin} for interacting with templates with recycler views. This mixin constructor takes
 * the instance of the recycler view to allow it to be instantiated dynamically, as in the case for
 * preference fragments.
 *
 * <p>Unlike typical mixins, this mixin is designed to be created in onTemplateInflated, which is
 * called by the super constructor, and then parse the XML attributes later in the constructor.
 */
public class RecyclerMixin implements Mixin {

  private final TemplateLayout templateLayout;

  @NonNull private final RecyclerView recyclerView;

  @Nullable private View header;

  @NonNull private DividerItemDecoration dividerDecoration;

  private Drawable defaultDivider;
  private Drawable divider;

  private int dividerInsetStart;
  private int dividerInsetEnd;

  /**
   * Creates the RecyclerMixin. Unlike typical mixins which are created in the constructor, this
   * mixin should be called in {@link TemplateLayout#onTemplateInflated()}, which is called by the
   * super constructor, because the recycler view and the header needs to be made available before
   * other mixins from the super class.
   *
   * @param layout The layout this mixin belongs to.
   */
  public RecyclerMixin(@NonNull TemplateLayout layout, @NonNull RecyclerView recyclerView) {
    templateLayout = layout;

    dividerDecoration = new DividerItemDecoration(templateLayout.getContext());

    // The recycler view needs to be available
    this.recyclerView = recyclerView;
    this.recyclerView.setLayoutManager(new LinearLayoutManager(templateLayout.getContext()));

    if (recyclerView instanceof HeaderRecyclerView) {
      header = ((HeaderRecyclerView) recyclerView).getHeader();
    }

    this.recyclerView.addItemDecoration(dividerDecoration);
  }

  /**
   * Parse XML attributes and configures this mixin and the recycler view accordingly. This should
   * be called from the constructor of the layout.
   *
   * @param attrs The {@link AttributeSet} as passed into the constructor. Can be null if the layout
   *     was not created from XML.
   * @param defStyleAttr The default style attribute as passed into the layout constructor. Can be 0
   *     if it is not needed.
   */
  public void parseAttributes(@Nullable AttributeSet attrs, int defStyleAttr) {
    final Context context = templateLayout.getContext();
    final TypedArray a =
        context.obtainStyledAttributes(attrs, R.styleable.SuwRecyclerMixin, defStyleAttr, 0);

    final int entries = a.getResourceId(R.styleable.SuwRecyclerMixin_android_entries, 0);
    if (entries != 0) {
      final ItemHierarchy inflated = new ItemInflater(context).inflate(entries);
      final RecyclerItemAdapter adapter = new RecyclerItemAdapter(inflated);
      adapter.setHasStableIds(a.getBoolean(R.styleable.SuwRecyclerMixin_suwHasStableIds, false));
      setAdapter(adapter);
    }
    int dividerInset = a.getDimensionPixelSize(R.styleable.SuwRecyclerMixin_suwDividerInset, -1);
    if (dividerInset != -1) {
      setDividerInset(dividerInset);
    } else {
      int dividerInsetStart =
          a.getDimensionPixelSize(R.styleable.SuwRecyclerMixin_suwDividerInsetStart, 0);
      int dividerInsetEnd =
          a.getDimensionPixelSize(R.styleable.SuwRecyclerMixin_suwDividerInsetEnd, 0);
      setDividerInsets(dividerInsetStart, dividerInsetEnd);
    }

    a.recycle();
  }

  /**
   * @return The recycler view contained in the layout, as marked by {@code @id/suw_recycler_view}.
   *     This will return {@code null} if the recycler view doesn't exist in the layout.
   */
  @SuppressWarnings("NullableProblems") // If clients guarantee that the template has a recycler
  // view, and call this after the template is inflated,
  // this will not return null.
  public RecyclerView getRecyclerView() {
    return recyclerView;
  }

  /**
   * Gets the header view of the recycler layout. This is useful for other mixins if they need to
   * access views within the header, usually via {@link TemplateLayout#findManagedViewById(int)}.
   */
  @SuppressWarnings("NullableProblems") // If clients guarantee that the template has a header,
  // this call will not return null.
  public View getHeader() {
    return header;
  }

  /**
   * Recycler mixin needs to update the dividers if the layout direction has changed. This method
   * should be called when {@link View#onLayout(boolean, int, int, int, int)} of the template is
   * called.
   */
  public void onLayout() {
    if (divider == null) {
      // Update divider in case layout direction has just been resolved
      updateDivider();
    }
  }

  /**
   * Gets the adapter of the recycler view in this layout. If the adapter includes a header, this
   * method will unwrap it and return the underlying adapter.
   *
   * @return The adapter, or {@code null} if the recycler view has no adapter.
   */
  public Adapter<? extends ViewHolder> getAdapter() {
    @SuppressWarnings("unchecked") // RecyclerView.getAdapter returns raw type :(
    final RecyclerView.Adapter<? extends ViewHolder> adapter = recyclerView.getAdapter();
    if (adapter instanceof HeaderAdapter) {
      return ((HeaderAdapter<? extends ViewHolder>) adapter).getWrappedAdapter();
    }
    return adapter;
  }

  /** Sets the adapter on the recycler view in this layout. */
  public void setAdapter(Adapter<? extends ViewHolder> adapter) {
    recyclerView.setAdapter(adapter);
  }

  /** @deprecated Use {@link #setDividerInsets(int, int)} instead. */
  @Deprecated
  public void setDividerInset(int inset) {
    setDividerInsets(inset, 0);
  }

  /**
   * Sets the start inset of the divider. This will use the default divider drawable set in the
   * theme and apply insets to it.
   *
   * @param start The number of pixels to inset on the "start" side of the list divider. Typically
   *     this will be either {@code @dimen/suw_items_glif_icon_divider_inset} or
   *     {@code @dimen/suw_items_glif_text_divider_inset}.
   * @param end The number of pixels to inset on the "end" side of the list divider.
   */
  public void setDividerInsets(int start, int end) {
    dividerInsetStart = start;
    dividerInsetEnd = end;
    updateDivider();
  }

  /**
   * @return The number of pixels inset on the start side of the divider.
   * @deprecated This is the same as {@link #getDividerInsetStart()}. Use that instead.
   */
  @Deprecated
  public int getDividerInset() {
    return getDividerInsetStart();
  }

  /** @return The number of pixels inset on the start side of the divider. */
  public int getDividerInsetStart() {
    return dividerInsetStart;
  }

  /** @return The number of pixels inset on the end side of the divider. */
  public int getDividerInsetEnd() {
    return dividerInsetEnd;
  }

  private void updateDivider() {
    boolean shouldUpdate = true;
    if (Build.VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
      shouldUpdate = templateLayout.isLayoutDirectionResolved();
    }
    if (shouldUpdate) {
      if (defaultDivider == null) {
        defaultDivider = dividerDecoration.getDivider();
      }
      divider =
          DrawableLayoutDirectionHelper.createRelativeInsetDrawable(
              defaultDivider,
              dividerInsetStart /* start */,
              0 /* top */,
              dividerInsetEnd /* end */,
              0 /* bottom */,
              templateLayout);
      dividerDecoration.setDivider(divider);
    }
  }

  /** @return The drawable used as the divider. */
  public Drawable getDivider() {
    return divider;
  }

  /**
   * Sets the divider item decoration directly. This is a low level method which should be used only
   * if custom divider behavior is needed, for example if the divider should be shown / hidden in
   * some specific cases for view holders that cannot implement {@link
   * com.android.setupwizardlib.DividerItemDecoration.DividedViewHolder}.
   */
  public void setDividerItemDecoration(@NonNull DividerItemDecoration decoration) {
    recyclerView.removeItemDecoration(dividerDecoration);
    dividerDecoration = decoration;
    recyclerView.addItemDecoration(dividerDecoration);
    updateDivider();
  }
}