LayoutInflaterBuilder helper in systemui util

/*

 * Copyright (C) 2016 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.systemui.util;

import android.annotation.NonNull;

import android.content.Context;

import android.util.ArrayMap;

import android.util.ArraySet;

import android.util.AttributeSet;

import android.util.Log;

import android.view.LayoutInflater;

import android.view.View;

import java.util.Map;

import java.util.Set;

/**

 * Builder class to create a {@link LayoutInflater} with various properties.

 *

 * Call any desired configuration methods on the Builder and then use

 * {@link Builder#build} to create the LayoutInflater. This is an alternative to directly using

 * {@link LayoutInflater#setFilter} and {@link LayoutInflater#setFactory}.

 * @hide for use by framework

 */

public class LayoutInflaterBuilder {

    private static final String TAG = "LayoutInflaterBuilder";

    private Context mFromContext;

    private Context mTargetContext;

    private Map<String, String> mReplaceMap;

    private Set<Class> mDisallowedClasses;

    private LayoutInflater mBuiltInflater;

    /**

     * Creates a new Builder which will construct a LayoutInflater.

     *

     * @param fromContext This context's LayoutInflater will be cloned by the Builder using

     * {@link LayoutInflater#cloneInContext}. By default, the new LayoutInflater will point at

     * this same Context.

     */

    public LayoutInflaterBuilder(@NonNull Context fromContext) {

        mFromContext = fromContext;

        mTargetContext = fromContext;

        mReplaceMap = null;

        mDisallowedClasses = null;

        mBuiltInflater = null;

    }

    /**

     * Instructs the Builder to point the LayoutInflater at a different Context.

     *

     * @param targetContext Context to be provided to

     * {@link LayoutInflater#cloneInContext(Context)}.

     * @return Builder object post-modification.

     */

    public LayoutInflaterBuilder target(@NonNull Context targetContext) {

        assertIfAlreadyBuilt();

        mTargetContext = targetContext;

        return this;

    }

    /**

     * Instructs the Builder to configure the LayoutInflater such that all instances

     * of one {@link View} will be replaced with instances of another during inflation.

     *

     * @param from Instances of this class will be replaced during inflation.

     * @param to Instances of this class will be inflated as replacements.

     * @return Builder object post-modification.

     */

    public LayoutInflaterBuilder replace(@NonNull Class from, @NonNull Class to) {

        assertIfAlreadyBuilt();

        if (mReplaceMap == null) {

            mReplaceMap = new ArrayMap<String, String>();

        }

        mReplaceMap.put(from.getName(), to.getName());

        return this;

    }

    /**

     * Instructs the Builder to configure the LayoutInflater such that any attempt to inflate

     * a {@link View} of a given type will throw a {@link InflateException}.

     *

     * @param disallowedClass The Class type that will be disallowed.

     * @return Builder object post-modification.

     */

    public LayoutInflaterBuilder disallow(@NonNull Class disallowedClass) {

        assertIfAlreadyBuilt();

        if (mDisallowedClasses == null) {

            mDisallowedClasses = new ArraySet<Class>();

        }

        mDisallowedClasses.add(disallowedClass);

        return this;

    }

    /**

     * Builds and returns the LayoutInflater.  Afterwards, this Builder can no longer can be

     * used, all future calls on the Builder will throw {@link AssertionError}.

     */

    public LayoutInflater build() {

        assertIfAlreadyBuilt();

        mBuiltInflater =

                LayoutInflater.from(mFromContext).cloneInContext(mTargetContext);

        setFactoryIfNeeded(mBuiltInflater);

        setFilterIfNeeded(mBuiltInflater);

        return mBuiltInflater;

    }

    private void assertIfAlreadyBuilt() {

        if (mBuiltInflater != null) {

            throw new AssertionError("Cannot use this Builder after build() has been called.");

        }

    }

    private void setFactoryIfNeeded(LayoutInflater inflater) {

        if (mReplaceMap == null) {

            return;

        }

        inflater.setFactory(

                new LayoutInflater.Factory() {

                    @Override

                    public View onCreateView(String name, Context context, AttributeSet attrs) {

                        String replacingClassName = mReplaceMap.get(name);

                        if (replacingClassName != null) {

                            try {

                                return inflater.createView(replacingClassName, null, attrs);

                            } catch (ClassNotFoundException e) {

                                Log.e(TAG, "Could not replace " + name

                                        + " with " + replacingClassName

                                        + ", Exception: ", e);

                            }

                        }

                        return null;

                    }

                });

    }

    private void setFilterIfNeeded(LayoutInflater inflater) {

        if (mDisallowedClasses == null) {

            return;

        }

        inflater.setFilter(

                new LayoutInflater.Filter() {

                    @Override

                    public boolean onLoadClass(Class clazz) {

                        return !mDisallowedClasses.contains(clazz);

                    }

                });

    }

}