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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.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.Nullable;
import androidx.core.util.Preconditions;
import com.android.car.ui.utils.DirectManipulationHelper;
/**
* A {@link View.OnKeyListener} and {@link View.OnGenericMotionListener} that adds a
* "Direct Manipulation" mode to any {@link View} that uses it.
* <p>
* Direct Manipulation mode in the Rotary context is a mode in which the user can use the
* Rotary controls to manipulate and change the UI elements they are interacting with rather
* than navigate through the entire UI.
* <p>
* Treats {@link KeyEvent#KEYCODE_DPAD_CENTER} as the signal to enter Direct Manipulation
* mode, and {@link KeyEvent#KEYCODE_BACK} as the signal to exit, and keeps track of which
* mode the {@link View} using it is currently in.
* <p>
* When in Direct Manipulation mode, it delegates to {@code mDirectionalDelegate}
* for handling nudge behavior and {@code mMotionDelegate} for rotation behavior. Generally
* it is expected that in Direct Manipulation mode, nudges are used for navigation and
* rotation is used for "manipulating" the value of the selected {@link View}.
* <p>
* To reduce boilerplate, this class provides "no op" nudge and rotation behavior if
* no {@link View.OnKeyListener} or {@link View.OnGenericMotionListener} are provided as
* delegates for tackling the relevant events.
* <p>
* Allows {@link View}s that are within a {@link ViewGroup} to provide a link to their
* ancestor {@link ViewGroup} from which Direct Manipulation mode was first enabled. That way
* when the user finally exits Direct Manipulation mode, both objects are restored to their
* original state.
*/
public class DirectManipulationHandler implements View.OnKeyListener,
View.OnGenericMotionListener {
/** 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;
private final DirectManipulationState mDirectManipulationMode;
private final View.OnKeyListener mNudgeDelegate;
private final View.OnGenericMotionListener mRotationDelegate;
/**
* A builder for {@link DirectManipulationHandler}.
*/
public static class Builder {
private final DirectManipulationState mDmState;
private View.OnKeyListener mNudgeDelegate;
private View.OnGenericMotionListener mRotationDelegate;
public Builder(DirectManipulationState dmState) {
Preconditions.checkNotNull(dmState);
this.mDmState = dmState;
}
public Builder setNudgeHandler(View.OnKeyListener directionalDelegate) {
Preconditions.checkNotNull(directionalDelegate);
this.mNudgeDelegate = directionalDelegate;
return this;
}
public Builder setRotationHandler(View.OnGenericMotionListener motionDelegate) {
Preconditions.checkNotNull(motionDelegate);
this.mRotationDelegate = motionDelegate;
return this;
}
public DirectManipulationHandler build() {
if (mNudgeDelegate == null && mRotationDelegate == null) {
throw new IllegalStateException("At least one delegate must be provided.");
}
return new DirectManipulationHandler(mDmState, mNudgeDelegate, mRotationDelegate);
}
}
private DirectManipulationHandler(DirectManipulationState dmState,
@Nullable View.OnKeyListener nudgeDelegate,
@Nullable View.OnGenericMotionListener rotationDelegate) {
Preconditions.checkNotNull(dmState);
mDirectManipulationMode = dmState;
mNudgeDelegate = nudgeDelegate;
mRotationDelegate = rotationDelegate;
}
@Override
public boolean onKey(View view, int keyCode, KeyEvent keyEvent) {
boolean isActionUp = keyEvent.getAction() == KeyEvent.ACTION_UP;
Log.d("RotaryPlayGround", "View: " + view + "\n is handling " + keyCode
+ " and action " + keyEvent.getAction()
+ " having entered direct manipulation mode from "
+ mDirectManipulationMode.getStartingView());
switch (keyCode) {
case KeyEvent.KEYCODE_DPAD_CENTER:
// If not yet in Direct Manipulation mode, switch to that mode.
// We generally want to give some kind of visual indication that this change
// has happened. In this example we change the background color.
if (!mDirectManipulationMode.isActive() && isActionUp) {
mDirectManipulationMode.setStartingView(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, true);
}
return true;
case KeyEvent.KEYCODE_BACK:
// If in Direct Manipulation mode, exit, and clean up state.
if (mDirectManipulationMode.isActive() && isActionUp) {
// This may or may not be the same as argument v. It is possible
// for us to enter Direct Manipulation mode from view A and exit from
// view B. dmStartingView represents A and v represents B.
View dmStartingView = mDirectManipulationMode.getStartingView();
// 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 (dmStartingView instanceof ViewGroup) {
ViewGroup viewGroup = (ViewGroup) dmStartingView;
viewGroup.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
}
// Restore any visual indicators that the view was in Direct Manipulation.
dmStartingView.setBackgroundColor(
BACKGROUND_COLOR_NOT_IN_DIRECT_MANIPULATION_MODE);
// Actually go ahead and disable Direct Manipulation mode for the view.
DirectManipulationHelper.enableDirectManipulationMode(dmStartingView, false);
// Update mode.
mDirectManipulationMode.setStartingView(null);
}
return true;
default:
// This handler is only responsible for behavior during Direct Manipulation
// mode. When the mode is disabled, ignore events.
if (!mDirectManipulationMode.isActive()) {
return false;
}
// If no delegate present, ignore events.
if (mNudgeDelegate == null) {
return false;
}
return mNudgeDelegate.onKey(view, keyCode, keyEvent);
}
}
@Override
public boolean onGenericMotion(View v, MotionEvent event) {
// This handler is only responsible for behavior during Direct Manipulation
// mode. When the mode is disabled, ignore events.
if (!mDirectManipulationMode.isActive()) {
return false;
}
// If no delegate present, ignore events.
if (mRotationDelegate == null) {
return false;
}
return mRotationDelegate.onGenericMotion(v, event);
}
}
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