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/*
* Copyright (C) 2020 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.car.rotaryplayground;
import android.graphics.Color;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.android.car.ui.utils.DirectManipulationHelper;
/**
* Keeps track of the state of "direct manipulation" Rotary mode for this application window by
* tracking a reference to the {@link View} from which the user first enters into "direct
* manipulation" mode.
*
* <p>See {@link DirectManipulationHandler} for a definition of "direct manipulation".
*/
public class DirectManipulationState {
/** Background color of a view when it's in direct manipulation mode. */
private static final int BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE = Color.BLUE;
/** Background color of a view when it's not in direct manipulation mode. */
private static final int BACKGROUND_COLOR_NOT_IN_DIRECT_MANIPULATION_MODE = Color.TRANSPARENT;
/** The view that is in direct manipulation mode, or null if none. */
@Nullable private View mViewInDirectManipulationMode;
private void setStartingView(@Nullable View view) {
mViewInDirectManipulationMode = view;
}
/**
* Returns true if Direct Manipulation mode is active, false otherwise.
*/
public boolean isActive() {
return mViewInDirectManipulationMode != null;
}
/**
* Enables Direct Manipulation mode, and keeps track of {@code view} as the starting point
* of this transition.
* <p>
* We generally want to give some kind of visual indication that this change has happened. In
* this example we change the background color of {@code view}.
*
* @param view - the {@link View} from which we entered into Direct Manipulation mode.
*/
public void enable(@NonNull View view) {
/*
* A more robust approach would be to fetch the current background color from
* the view object and store it back onto the View itself using the {@link
* View#setTag(int, java.lang.Object)} API. This could then be fetched back
* and used to restore the background color without needing to keep a constant
* reference to the color here which could fall out of sync with the xml files.
*/
view.setBackgroundColor(BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE);
DirectManipulationHelper.enableDirectManipulationMode(view, /* enable= */ true);
setStartingView(view);
}
/**
* Disables Direct Manipulation mode and restores any visual indicators for the {@link View}
* from which we entered into Direct Manipulation mode.
*/
public void disable() {
mViewInDirectManipulationMode.setBackgroundColor(
BACKGROUND_COLOR_NOT_IN_DIRECT_MANIPULATION_MODE);
DirectManipulationHelper.enableDirectManipulationMode(
mViewInDirectManipulationMode, /* enable= */ false);
// For ViewGroup objects, restore descendant focusability to FOCUS_BLOCK_DESCENDANTS so
// during non-Direct Manipulation mode, aka, general rotary navigation, we don't go
// through the individual inner UI elements.
if (mViewInDirectManipulationMode instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup) mViewInDirectManipulationMode;
viewGroup.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
}
setStartingView(null);
}
}
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