src/com/android/launcher3/allapps/PredictionRowView.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.launcher3.allapps;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.LinearLayout;

import com.android.launcher3.AppInfo;
import com.android.launcher3.config.FeatureFlags;
import com.android.launcher3.util.ComponentKey;
import com.android.launcher3.util.ComponentKeyMapper;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;

public class PredictionRowView extends LinearLayout {

    private static final String TAG = "PredictionRowView";

    private HashMap<ComponentKey, AppInfo> mComponentToAppMap;
    private int mNumPredictedAppsPerRow;
    // The set of predicted app component names
    private final List<ComponentKeyMapper<AppInfo>> mPredictedAppComponents = new ArrayList<>();
    // The set of predicted apps resolved from the component names and the current set of apps
    private final List<AppInfo> mPredictedApps = new ArrayList<>();

    public PredictionRowView(@NonNull Context context) {
        this(context, null);
    }

    public PredictionRowView(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        setOrientation(LinearLayout.HORIZONTAL);
    }

    public void setComponentToAppMap(HashMap<ComponentKey, AppInfo> componentToAppMap) {
        this.mComponentToAppMap = componentToAppMap;
    }

    /**
     * Sets the number of apps per row.
     */
    public void setNumAppsPerRow(int numPredictedAppsPerRow) {
        mNumPredictedAppsPerRow = numPredictedAppsPerRow;
    }

    public void onAppsUpdated() {
        // TODO
    }

    /**
     * Returns the predicted apps.
     */
    public List<AppInfo> getPredictedApps() {
        return mPredictedApps;
    }

    /**
     * Sets the current set of predicted apps.
     *
     * This can be called before we get the full set of applications, we should merge the results
     * only in onAppsUpdated() which is idempotent.
     *
     * If the number of predicted apps is the same as the previous list of predicted apps,
     * we can optimize by swapping them in place.
     */
    public void setPredictedApps(List<ComponentKeyMapper<AppInfo>> apps) {
        mPredictedAppComponents.clear();
        mPredictedAppComponents.addAll(apps);

        List<AppInfo> newPredictedApps = processPredictedAppComponents(apps);
        // We only need to do work if any of the visible predicted apps have changed.
        if (!newPredictedApps.equals(mPredictedApps)) {
            if (newPredictedApps.size() == mPredictedApps.size()) {
                swapInNewPredictedApps(newPredictedApps);
            } else {
                // We need to update the appIndex of all the items.
                onAppsUpdated();
            }
        }
    }

    private List<AppInfo> processPredictedAppComponents(
            List<ComponentKeyMapper<AppInfo>> components) {
        if (mComponentToAppMap.isEmpty()) {
            // Apps have not been bound yet.
            return Collections.emptyList();
        }

        List<AppInfo> predictedApps = new ArrayList<>();
        for (ComponentKeyMapper<AppInfo> mapper : components) {
            AppInfo info = mapper.getItem(mComponentToAppMap);
            if (info != null) {
                predictedApps.add(info);
            } else {
                if (FeatureFlags.IS_DOGFOOD_BUILD) {
                    Log.e(TAG, "Predicted app not found: " + mapper);
                }
            }
            // Stop at the number of predicted apps
            if (predictedApps.size() == mNumPredictedAppsPerRow) {
                break;
            }
        }
        return predictedApps;
    }

    /**
     * Swaps out the old predicted apps with the new predicted apps, in place. This optimization
     * allows us to skip an entire relayout that would otherwise be called by notifyDataSetChanged.
     *
     * Note: This should only be called if the # of predicted apps is the same.
     *       This method assumes that predicted apps are the first items in the adapter.
     */
    private void swapInNewPredictedApps(List<AppInfo> apps) {
        // TODO
    }

}