src/com/android/launcher3/widget/NavigableAppWidgetHostView.java

/*
 * Copyright (C) 2018 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.widget;

import android.appwidget.AppWidgetHostView;
import android.content.Context;
import android.graphics.Rect;
import android.view.KeyEvent;
import android.view.View;
import android.view.ViewDebug;
import android.view.ViewGroup;

import java.util.ArrayList;

/**
 * Extension of AppWidgetHostView with support for controlled keyboard navigation.
 */
public abstract class NavigableAppWidgetHostView extends AppWidgetHostView {

    @ViewDebug.ExportedProperty(category = "launcher")
    private boolean mChildrenFocused;

    public NavigableAppWidgetHostView(Context context) {
        super(context);
    }

    @Override
    public int getDescendantFocusability() {
        return mChildrenFocused ? ViewGroup.FOCUS_BEFORE_DESCENDANTS
                : ViewGroup.FOCUS_BLOCK_DESCENDANTS;
    }

    @Override
    public boolean dispatchKeyEvent(KeyEvent event) {
        if (mChildrenFocused && event.getKeyCode() == KeyEvent.KEYCODE_ESCAPE
                && event.getAction() == KeyEvent.ACTION_UP) {
            mChildrenFocused = false;
            requestFocus();
            return true;
        }
        return super.dispatchKeyEvent(event);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (!mChildrenFocused && keyCode == KeyEvent.KEYCODE_ENTER) {
            event.startTracking();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if (event.isTracking()) {
            if (!mChildrenFocused && keyCode == KeyEvent.KEYCODE_ENTER) {
                mChildrenFocused = true;
                ArrayList<View> focusableChildren = getFocusables(FOCUS_FORWARD);
                focusableChildren.remove(this);
                int childrenCount = focusableChildren.size();
                switch (childrenCount) {
                    case 0:
                        mChildrenFocused = false;
                        break;
                    case 1: {
                        if (shouldAllowDirectClick()) {
                            focusableChildren.get(0).performClick();
                            mChildrenFocused = false;
                            return true;
                        }
                        // continue;
                    }
                    default:
                        focusableChildren.get(0).requestFocus();
                        return true;
                }
            }
        }
        return super.onKeyUp(keyCode, event);
    }

    /**
     * For a widget with only a single interactive element, return true if whole widget should act
     * as a single interactive element, and clicking 'enter' should activate the child element
     * directly. Otherwise clicking 'enter' will only move the focus inside the widget.
     */
    protected abstract boolean shouldAllowDirectClick();

    @Override
    protected void onFocusChanged(boolean gainFocus, int direction, Rect previouslyFocusedRect) {
        if (gainFocus) {
            mChildrenFocused = false;
            dispatchChildFocus(false);
        }
        super.onFocusChanged(gainFocus, direction, previouslyFocusedRect);
    }

    @Override
    public void requestChildFocus(View child, View focused) {
        super.requestChildFocus(child, focused);
        dispatchChildFocus(mChildrenFocused && focused != null);
        if (focused != null) {
            focused.setFocusableInTouchMode(false);
        }
    }

    @Override
    public void clearChildFocus(View child) {
        super.clearChildFocus(child);
        dispatchChildFocus(false);
    }

    @Override
    public boolean dispatchUnhandledMove(View focused, int direction) {
        return mChildrenFocused;
    }

    private void dispatchChildFocus(boolean childIsFocused) {
        // The host view's background changes when selected, to indicate the focus is inside.
        setSelected(childIsFocused);
    }
}