1 /* 2 * Copyright (C) 2020 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.car.rotaryplayground; 18 19 import android.graphics.Color; 20 import android.view.View; 21 import android.view.ViewGroup; 22 23 import androidx.annotation.NonNull; 24 import androidx.annotation.Nullable; 25 26 import com.android.car.ui.utils.DirectManipulationHelper; 27 28 /** 29 * Keeps track of the state of "direct manipulation" Rotary mode for this application window by 30 * tracking a reference to the {@link View} from which the user first enters into "direct 31 * manipulation" mode. 32 * 33 * <p>See {@link DirectManipulationHandler} for a definition of "direct manipulation". 34 */ 35 public class DirectManipulationState { 36 37 38 /** Background color of a view when it's in direct manipulation mode. */ 39 private static final int BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE = Color.BLUE; 40 41 /** Background color of a view when it's not in direct manipulation mode. */ 42 private static final int BACKGROUND_COLOR_NOT_IN_DIRECT_MANIPULATION_MODE = Color.TRANSPARENT; 43 44 /** The view that is in direct manipulation mode, or null if none. */ 45 @Nullable private View mViewInDirectManipulationMode; 46 setStartingView(@ullable View view)47 private void setStartingView(@Nullable View view) { 48 mViewInDirectManipulationMode = view; 49 } 50 51 /** 52 * Returns true if Direct Manipulation mode is active, false otherwise. 53 */ isActive()54 public boolean isActive() { 55 return mViewInDirectManipulationMode != null; 56 } 57 58 /** 59 * Enables Direct Manipulation mode, and keeps track of {@code view} as the starting point 60 * of this transition. 61 * <p> 62 * We generally want to give some kind of visual indication that this change has happened. In 63 * this example we change the background color of {@code view}. 64 * 65 * @param view - the {@link View} from which we entered into Direct Manipulation mode. 66 */ enable(@onNull View view)67 public void enable(@NonNull View view) { 68 /* 69 * A more robust approach would be to fetch the current background color from 70 * the view object and store it back onto the View itself using the {@link 71 * View#setTag(int, java.lang.Object)} API. This could then be fetched back 72 * and used to restore the background color without needing to keep a constant 73 * reference to the color here which could fall out of sync with the xml files. 74 */ 75 view.setBackgroundColor(BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE); 76 DirectManipulationHelper.enableDirectManipulationMode(view, /* enable= */ true); 77 setStartingView(view); 78 } 79 80 /** 81 * Disables Direct Manipulation mode and restores any visual indicators for the {@link View} 82 * from which we entered into Direct Manipulation mode. 83 */ disable()84 public void disable() { 85 mViewInDirectManipulationMode.setBackgroundColor( 86 BACKGROUND_COLOR_NOT_IN_DIRECT_MANIPULATION_MODE); 87 DirectManipulationHelper.enableDirectManipulationMode( 88 mViewInDirectManipulationMode, /* enable= */ false); 89 // For ViewGroup objects, restore descendant focusability to FOCUS_BLOCK_DESCENDANTS so 90 // during non-Direct Manipulation mode, aka, general rotary navigation, we don't go 91 // through the individual inner UI elements. 92 if (mViewInDirectManipulationMode instanceof ViewGroup) { 93 ViewGroup viewGroup = (ViewGroup) mViewInDirectManipulationMode; 94 viewGroup.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS); 95 } 96 setStartingView(null); 97 } 98 } 99