android/setupwizardlib/TemplateLayout.java

/*
 * Copyright (C) 2015 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;

import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Build.VERSION_CODES;
import androidx.annotation.Keep;
import androidx.annotation.LayoutRes;
import androidx.annotation.StyleRes;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.widget.FrameLayout;
import com.android.setupwizardlib.template.Mixin;
import com.android.setupwizardlib.util.FallbackThemeWrapper;
import java.util.HashMap;
import java.util.Map;

/**
 * A generic template class that inflates a template, provided in the constructor or in {@code
 * android:layout} through XML, and adds its children to a "container" in the template. When
 * inflating this layout from XML, the {@code android:layout} and {@code suwContainer} attributes
 * are required.
 */
public class TemplateLayout extends FrameLayout {

  /**
   * The container of the actual content. This will be a view in the template, which child views
   * will be added to when {@link #addView(View)} is called.
   */
  private ViewGroup container;

  private final Map<Class<? extends Mixin>, Mixin> mixins = new HashMap<>();

  public TemplateLayout(Context context, int template, int containerId) {
    super(context);
    init(template, containerId, null, R.attr.suwLayoutTheme);
  }

  public TemplateLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(0, 0, attrs, R.attr.suwLayoutTheme);
  }

  @TargetApi(VERSION_CODES.HONEYCOMB)
  public TemplateLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(0, 0, attrs, defStyleAttr);
  }

  // All the constructors delegate to this init method. The 3-argument constructor is not
  // available in LinearLayout before v11, so call super with the exact same arguments.
  private void init(int template, int containerId, AttributeSet attrs, int defStyleAttr) {
    final TypedArray a =
        getContext().obtainStyledAttributes(attrs, R.styleable.SuwTemplateLayout, defStyleAttr, 0);
    if (template == 0) {
      template = a.getResourceId(R.styleable.SuwTemplateLayout_android_layout, 0);
    }
    if (containerId == 0) {
      containerId = a.getResourceId(R.styleable.SuwTemplateLayout_suwContainer, 0);
    }
    inflateTemplate(template, containerId);

    a.recycle();
  }

  /**
   * Registers a mixin with a given class. This method should be called in the constructor.
   *
   * @param cls The class to register the mixin. In most cases, {@code cls} is the same as {@code
   *     mixin.getClass()}, but {@code cls} can also be a super class of that. In the latter case
   *     the mixin must be retrieved using {@code cls} in {@link #getMixin(Class)}, not the
   *     subclass.
   * @param mixin The mixin to be registered.
   * @param <M> The class of the mixin to register. This is the same as {@code cls}
   */
  protected <M extends Mixin> void registerMixin(Class<M> cls, M mixin) {
    mixins.put(cls, mixin);
  }

  /**
   * Same as {@link android.view.View#findViewById(int)}, but may include views that are managed by
   * this view but not currently added to the view hierarchy. e.g. recycler view or list view
   * headers that are not currently shown.
   */
  // Returning generic type is the common pattern used for findViewBy* methods
  @SuppressWarnings("TypeParameterUnusedInFormals")
  public <T extends View> T findManagedViewById(int id) {
    return findViewById(id);
  }

  /**
   * Get a {@link Mixin} from this template registered earlier in {@link #registerMixin(Class,
   * Mixin)}.
   *
   * @param cls The class marker of Mixin being requested. The actual Mixin returned may be a
   *     subclass of this marker. Note that this must be the same class as registered in {@link
   *     #registerMixin(Class, Mixin)}, which is not necessarily the same as the concrete class of
   *     the instance returned by this method.
   * @param <M> The type of the class marker.
   * @return The mixin marked by {@code cls}, or null if the template does not have a matching
   *     mixin.
   */
  @SuppressWarnings("unchecked")
  public <M extends Mixin> M getMixin(Class<M> cls) {
    return (M) mixins.get(cls);
  }

  @Override
  public void addView(View child, int index, ViewGroup.LayoutParams params) {
    container.addView(child, index, params);
  }

  private void addViewInternal(View child) {
    super.addView(child, -1, generateDefaultLayoutParams());
  }

  private void inflateTemplate(int templateResource, int containerId) {
    final LayoutInflater inflater = LayoutInflater.from(getContext());
    final View templateRoot = onInflateTemplate(inflater, templateResource);
    addViewInternal(templateRoot);

    container = findContainer(containerId);
    if (container == null) {
      throw new IllegalArgumentException("Container cannot be null in TemplateLayout");
    }
    onTemplateInflated();
  }

  /**
   * Inflate the template using the given inflater and theme. The fallback theme will be applied to
   * the theme without overriding the values already defined in the theme, but simply providing
   * default values for values which have not been defined. This allows templates to add additional
   * required theme attributes without breaking existing clients.
   *
   * <p>In general, clients should still set the activity theme to the corresponding theme in setup
   * wizard lib, so that the content area gets the correct styles as well.
   *
   * @param inflater A LayoutInflater to inflate the template.
   * @param fallbackTheme A fallback theme to apply to the template. If the values defined in the
   *     fallback theme is already defined in the original theme, the value in the original theme
   *     takes precedence.
   * @param template The layout template to be inflated.
   * @return Root of the inflated layout.
   * @see FallbackThemeWrapper
   */
  protected final View inflateTemplate(
      LayoutInflater inflater, @StyleRes int fallbackTheme, @LayoutRes int template) {
    if (template == 0) {
      throw new IllegalArgumentException("android:layout not specified for TemplateLayout");
    }
    if (fallbackTheme != 0) {
      inflater =
          LayoutInflater.from(new FallbackThemeWrapper(inflater.getContext(), fallbackTheme));
    }
    return inflater.inflate(template, this, false);
  }

  /**
   * This method inflates the template. Subclasses can override this method to customize the
   * template inflation, or change to a different default template. The root of the inflated layout
   * should be returned, and not added to the view hierarchy.
   *
   * @param inflater A LayoutInflater to inflate the template.
   * @param template The resource ID of the template to be inflated, or 0 if no template is
   *     specified.
   * @return Root of the inflated layout.
   */
  protected View onInflateTemplate(LayoutInflater inflater, @LayoutRes int template) {
    return inflateTemplate(inflater, 0, template);
  }

  protected ViewGroup findContainer(int containerId) {
    if (containerId == 0) {
      // Maintain compatibility with the deprecated way of specifying container ID.
      containerId = getContainerId();
    }
    return (ViewGroup) findViewById(containerId);
  }

  /**
   * This is called after the template has been inflated and added to the view hierarchy. Subclasses
   * can implement this method to modify the template as necessary, such as caching views retrieved
   * from findViewById, or other view operations that need to be done in code. You can think of this
   * as {@link View#onFinishInflate()} but for inflation of the template instead of for child views.
   */
  protected void onTemplateInflated() {}

  /**
   * @return ID of the default container for this layout. This will be used to find the container
   *     ViewGroup, which all children views of this layout will be placed in.
   * @deprecated Override {@link #findContainer(int)} instead.
   */
  @Deprecated
  protected int getContainerId() {
    return 0;
  }

  /* Animator support */

  private float xFraction;
  private ViewTreeObserver.OnPreDrawListener preDrawListener;

  /**
   * Set the X translation as a fraction of the width of this view. Make sure this method is not
   * stripped out by proguard when using this with {@link android.animation.ObjectAnimator}. You may
   * need to add <code>
   *     -keep @androidx.annotation.Keep class *
   * </code> to your proguard configuration if you are seeing mysterious {@link NoSuchMethodError}
   * at runtime.
   */
  @Keep
  @TargetApi(VERSION_CODES.HONEYCOMB)
  public void setXFraction(float fraction) {
    xFraction = fraction;
    final int width = getWidth();
    if (width != 0) {
      setTranslationX(width * fraction);
    } else {
      // If we haven't done a layout pass yet, wait for one and then set the fraction before
      // the draw occurs using an OnPreDrawListener. Don't call translationX until we know
      // getWidth() has a reliable, non-zero value or else we will see the fragment flicker on
      // screen.
      if (preDrawListener == null) {
        preDrawListener =
            new ViewTreeObserver.OnPreDrawListener() {
              @Override
              public boolean onPreDraw() {
                getViewTreeObserver().removeOnPreDrawListener(preDrawListener);
                setXFraction(xFraction);
                return true;
              }
            };
        getViewTreeObserver().addOnPreDrawListener(preDrawListener);
      }
    }
  }

  /**
   * Return the X translation as a fraction of the width, as previously set in {@link
   * #setXFraction(float)}.
   *
   * @see #setXFraction(float)
   */
  @Keep
  @TargetApi(VERSION_CODES.HONEYCOMB)
  public float getXFraction() {
    return xFraction;
  }
}