MessageTemplate.java
/*
* Copyright 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 androidx.car.app.model;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_BODY_WITH_PRIMARY_ACTION;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_HEADER;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_SIMPLE;
import static java.util.Objects.hash;
import static java.util.Objects.requireNonNull;
import android.util.Log;
import androidx.annotation.Keep;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.car.app.annotations.CarProtocol;
import androidx.car.app.annotations.RequiresCarApi;
import androidx.car.app.model.constraints.CarIconConstraints;
import androidx.car.app.model.constraints.CarTextConstraints;
import androidx.car.app.utils.CollectionUtils;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;
/**
* A template for displaying a message and associated actions.
*
* <h4>Template Restrictions</h4>
*
* In regards to template refreshes, as described in
* {@link androidx.car.app.Screen#onGetTemplate()}, this template is
* considered a refresh of a previous one if the title and messages have not changed.
*/
@CarProtocol
public final class MessageTemplate implements Template {
@Keep
private final boolean mIsLoading;
@Keep
@Nullable
private final CarText mTitle;
@Keep
@Nullable
private final CarText mMessage;
@Keep
@Nullable
private final CarText mDebugMessage;
@Keep
@Nullable
private final CarIcon mIcon;
@Keep
@Nullable
private final Action mHeaderAction;
@Keep
private final List<Action> mActionList;
@Keep
@Nullable
private final ActionStrip mActionStrip;
/**
* Returns whether the template is loading.
*
* @see Builder#setLoading(boolean)
*/
@RequiresCarApi(2)
public boolean isLoading() {
return mIsLoading;
}
/**
* Returns the title of the template or {@code null} if not set.
*
* @see Builder#setTitle(CharSequence)
*/
@Nullable
public CarText getTitle() {
return mTitle;
}
/**
* Returns the {@link Action} that is set to be displayed in the header of the template, or
* {@code null} if not set.
*
* @see Builder#setHeaderAction(Action)
*/
@Nullable
public Action getHeaderAction() {
return mHeaderAction;
}
/**
* Returns the {@link ActionStrip} for this template or {@code null} if not set.
*
* @see Builder#setActionStrip(ActionStrip)
*/
@RequiresCarApi(2)
@Nullable
public ActionStrip getActionStrip() {
return mActionStrip;
}
/**
* Returns the message to display in the template.
*
* @see Builder#Builder(CharSequence)
*/
@NonNull
public CarText getMessage() {
return requireNonNull(mMessage);
}
/**
* Returns a debug message to display in the template or {@code null} if not set.
*
* @see Builder#setDebugMessage(Throwable)
* @see Builder#setDebugMessage(String)
*/
@Nullable
public CarText getDebugMessage() {
return mDebugMessage;
}
/**
* Returns the icon to display in the template or {@code null} if not set.
*
* @see Builder#setIcon(CarIcon)
*/
@Nullable
public CarIcon getIcon() {
return mIcon;
}
/**
* Returns the list of actions to display in the template.
*
* @see Builder#addAction(Action)
*/
@NonNull
public List<Action> getActions() {
return CollectionUtils.emptyIfNull(mActionList);
}
@NonNull
@Override
public String toString() {
return "MessageTemplate";
}
@Override
public int hashCode() {
return hash(mIsLoading, mTitle, mMessage, mDebugMessage, mHeaderAction, mActionList, mIcon,
mActionStrip);
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (!(other instanceof MessageTemplate)) {
return false;
}
MessageTemplate otherTemplate = (MessageTemplate) other;
return mIsLoading == otherTemplate.mIsLoading
&& Objects.equals(mTitle, otherTemplate.mTitle)
&& Objects.equals(mMessage, otherTemplate.mMessage)
&& Objects.equals(mDebugMessage, otherTemplate.mDebugMessage)
&& Objects.equals(mHeaderAction, otherTemplate.mHeaderAction)
&& Objects.equals(mActionList, otherTemplate.mActionList)
&& Objects.equals(mIcon, otherTemplate.mIcon)
&& Objects.equals(mActionStrip, otherTemplate.mActionStrip);
}
MessageTemplate(Builder builder) {
mIsLoading = builder.mIsLoading;
mTitle = builder.mTitle;
mMessage = builder.mMessage;
mDebugMessage = builder.mDebugMessage;
mIcon = builder.mIcon;
mHeaderAction = builder.mHeaderAction;
mActionStrip = builder.mActionStrip;
mActionList = CollectionUtils.unmodifiableCopy(builder.mActionList);
}
/** Constructs an empty instance, used by serialization code. */
private MessageTemplate() {
mIsLoading = false;
mTitle = null;
mMessage = null;
mDebugMessage = null;
mIcon = null;
mHeaderAction = null;
mActionStrip = null;
mActionList = Collections.emptyList();
}
/** A builder of {@link MessageTemplate}. */
public static final class Builder {
boolean mIsLoading;
@Nullable
CarText mTitle;
CarText mMessage;
@Nullable
CarText mDebugMessage;
@Nullable
CarIcon mIcon;
@Nullable
Action mHeaderAction;
@Nullable
ActionStrip mActionStrip;
List<Action> mActionList = new ArrayList<>();
@Nullable
Throwable mDebugCause;
@Nullable
String mDebugString;
/**
* Sets whether the template is in a loading state.
*
* <p>If set to {@code true}, the UI shows a loading indicator where the icon
* would be otherwise. The caller is expected to call
* {@link androidx.car.app.Screen#invalidate()} and send the new template content to the
* host once the data is ready.
*/
@RequiresCarApi(2)
@NonNull
public Builder setLoading(boolean isLoading) {
mIsLoading = isLoading;
return this;
}
/**
* Sets the title of the template.
*
* <p>Unless set with this method, the template will not have a title.
*
* <p>Only {@link DistanceSpan}s and {@link DurationSpan}s are supported in the input
* string.
*
* @throws NullPointerException if {@code title} is {@code null}
* @throws IllegalArgumentException if {@code title} contains unsupported spans
* @see CarText
*/
@NonNull
public Builder setTitle(@NonNull CharSequence title) {
mTitle = CarText.create(requireNonNull(title));
CarTextConstraints.TEXT_ONLY.validateOrThrow(mTitle);
return this;
}
/**
* Sets a {@link Throwable} for debugging purposes.
*
* <p>The cause will be displayed along with the message set in
* {@link #setDebugMessage(String)}.
*
* <p>The host may choose to not display this debugging information if it doesn't deem it
* appropriate, for example, when running on a production environment rather than in a
* simulator such as the Desktop Head Unit.
*
* @throws NullPointerException if {@code icon} is {@code null}
*/
@NonNull
public Builder setDebugMessage(@NonNull Throwable cause) {
mDebugCause = requireNonNull(cause);
return this;
}
/**
* Sets a debug message for debugging purposes.
*
* <p>The debug message will be displayed along with the cause set in
* {@link #setDebugMessage}.
*
* <p>The host may choose to not display this debugging information if it doesn't deem it
* appropriate, for example, when running on a production environment rather than in a
* simulator such as the Desktop Head Unit.
*
* @throws NullPointerException if {@code icon} is {@code null}
*/
@NonNull
public Builder setDebugMessage(@NonNull String debugMessage) {
mDebugString = requireNonNull(debugMessage);
return this;
}
/**
* Sets the icon to be displayed along with the message.
*
* <p>Unless set with this method, an icon will not be displayed.
*
* <h4>Icon Sizing Guidance</h4>
*
* To minimize scaling artifacts across a wide range of car screens, apps should provide
* icons targeting a 128 x 128 dp bounding box. If the icon exceeds this maximum size in
* either one of the dimensions, it will be scaled down to be centered inside the
* bounding box while preserving its aspect ratio.
*
* <p>See {@link CarIcon} for more details related to providing icon and image resources
* that work with different car screen pixel densities.
*
* @throws NullPointerException if {@code icon} is {@code null}
*/
@NonNull
public Builder setIcon(@NonNull CarIcon icon) {
CarIconConstraints.DEFAULT.validateOrThrow(requireNonNull(icon));
mIcon = icon;
return this;
}
/**
* Sets the {@link Action} that will be displayed in the header of the template.
*
* <p>Unless set with this method, the template will not have a header action.
*
* <h4>Requirements</h4>
*
* This template only supports either one of {@link Action#APP_ICON} and
* {@link Action#BACK} as a header {@link Action}.
*
* @throws IllegalArgumentException if {@code headerAction} does not meet the template's
* requirements
* @throws NullPointerException if {@code headerAction} is {@code null}
*/
@NonNull
public Builder setHeaderAction(@NonNull Action headerAction) {
ACTIONS_CONSTRAINTS_HEADER.validateOrThrow(
Collections.singletonList(requireNonNull(headerAction)));
mHeaderAction = headerAction;
return this;
}
/**
* Sets the {@link ActionStrip} for this template or {@code null} to not display an {@link
* ActionStrip}.
*
* <p>Unless set with this method, the template will not have an action strip.
*
* <h4>Requirements</h4>
*
* This template allows up to 2 {@link Action}s in its {@link ActionStrip}. Of the 2 allowed
* {@link Action}s, one of them can contain a title as set via
* {@link Action.Builder#setTitle}. Otherwise, only {@link Action}s with icons are allowed.
*
* @throws IllegalArgumentException if {@code actionStrip} does not meet the requirements
* @throws NullPointerException if {@code actionStrip} is {@code null}
*/
@RequiresCarApi(2)
@NonNull
public Builder setActionStrip(@NonNull ActionStrip actionStrip) {
ACTIONS_CONSTRAINTS_SIMPLE.validateOrThrow(requireNonNull(actionStrip).getActions());
mActionStrip = actionStrip;
return this;
}
/**
* Adds an {@link Action} to display along with the message.
*
* <h4>Requirements</h4>
*
* This template allows up to 2 {@link Action}s in its body. Each action's title color
* can be customized with {@link ForegroundCarColorSpan} instances. Any other span is not
* supported.
*
* @throws NullPointerException if {@code action} is {@code null}
* @throws IllegalArgumentException if {@code action} does not meet the requirements
*/
@NonNull
public Builder addAction(@NonNull Action action) {
mActionList.add(requireNonNull(action));
ACTIONS_CONSTRAINTS_BODY_WITH_PRIMARY_ACTION.validateOrThrow(mActionList);
return this;
}
/**
* Constructs the {@link MessageTemplate} defined by this builder.
*
* <h4>Requirements</h4>
*
* A non-empty message must be set on the template.
*
* <p>Either a header {@link Action} or title must be set on the template.
*
* @throws IllegalStateException if the message is empty, if the template does not have
* either a title or header {@link Action} set, or if the
* template is in loading state and an icon is specified.
*/
@NonNull
public MessageTemplate build() {
if (mIsLoading && mIcon != null) {
throw new IllegalStateException(
"Template in a loading state can not have an icon");
}
if (mMessage.isEmpty()) {
throw new IllegalStateException("Message cannot be empty");
}
String debugString = mDebugString == null ? "" : mDebugString;
if (!debugString.isEmpty() && mDebugCause != null) {
debugString += "\n";
}
debugString += Log.getStackTraceString(mDebugCause);
if (!debugString.isEmpty()) {
mDebugMessage = CarText.create(debugString);
}
if (CarText.isNullOrEmpty(mTitle) && mHeaderAction == null) {
throw new IllegalStateException("Either the title or header action must be set");
}
return new MessageTemplate(this);
}
/**
* Returns a {@link Builder} instance.
*
* @param message the text message to display in the template
* @throws NullPointerException if the {@code message} is {@code null}
*/
public Builder(@NonNull CharSequence message) {
mMessage = CarText.create(requireNonNull(message));
}
/**
* Returns a {@link Builder} instance.
*
* @param message the text message to display in the template
* @throws NullPointerException if the {@code message} is {@code null}
*/
public Builder(@NonNull CarText message) {
mMessage = requireNonNull(message);
}
}
}