GridTemplate.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_HEADER;
import static androidx.car.app.model.constraints.ActionsConstraints.ACTIONS_CONSTRAINTS_SIMPLE;
import static java.util.Objects.requireNonNull;
import androidx.annotation.Keep;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.car.app.annotations.CarProtocol;
import androidx.car.app.model.constraints.CarTextConstraints;
import java.util.Collections;
import java.util.Objects;
/**
* A template representing a grid of items.
*
* <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:
*
* <ul>
* <li>The previous template is in a loading state (see {@link Builder#setLoading}, or
* <li>The template title has not changed, and the number of grid items and the title of each
* grid item have not changed.
* </ul>
*/
@CarProtocol
public final class GridTemplate implements Template {
@Keep
private final boolean mIsLoading;
@Keep
@Nullable
private final CarText mTitle;
@Keep
@Nullable
private final Action mHeaderAction;
@Keep
@Nullable
private final ItemList mSingleList;
@Keep
@Nullable
private final ActionStrip mActionStrip;
/**
* 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)
*/
@Nullable
public ActionStrip getActionStrip() {
return mActionStrip;
}
/**
* Returns whether the template is loading.
*
* @see Builder#setLoading(boolean)
*/
public boolean isLoading() {
return mIsLoading;
}
/**
* Returns the {@link ItemList} instance that contains the grid items to display or {@code
* null} if not set.
*
* @see Builder#setSingleList(ItemList)
*/
@Nullable
public ItemList getSingleList() {
return mSingleList;
}
@NonNull
@Override
public String toString() {
return "GridTemplate";
}
@Override
public int hashCode() {
return Objects.hash(mIsLoading, mTitle, mHeaderAction, mSingleList, mActionStrip);
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (!(other instanceof GridTemplate)) {
return false;
}
GridTemplate otherTemplate = (GridTemplate) other;
return mIsLoading == otherTemplate.mIsLoading
&& Objects.equals(mTitle, otherTemplate.mTitle)
&& Objects.equals(mHeaderAction, otherTemplate.mHeaderAction)
&& Objects.equals(mSingleList, otherTemplate.mSingleList)
&& Objects.equals(mActionStrip, otherTemplate.mActionStrip);
}
GridTemplate(Builder builder) {
mIsLoading = builder.mIsLoading;
mTitle = builder.mTitle;
mHeaderAction = builder.mHeaderAction;
mSingleList = builder.mSingleList;
mActionStrip = builder.mActionStrip;
}
/** Constructs an empty instance, used by serialization code. */
private GridTemplate() {
mIsLoading = false;
mTitle = null;
mHeaderAction = null;
mSingleList = null;
mActionStrip = null;
}
/** A builder of {@link GridTemplate}. */
public static final class Builder {
boolean mIsLoading;
@Nullable
ItemList mSingleList;
@Nullable
CarText mTitle;
@Nullable
Action mHeaderAction;
@Nullable
ActionStrip mActionStrip;
/**
* Sets whether the template is in a loading state.
*
* <p>If set to {@code true}, the UI shows a loading indicator where the grid content
* 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. If set to {@code false}, the UI shows the
* {@link ItemList} contents added via {@link #setSingleList}.
*/
@NonNull
public Builder setLoading(boolean isLoading) {
mIsLoading = isLoading;
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(headerAction));
mHeaderAction = headerAction;
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 null
* @throws IllegalArgumentException if {@code title} contains unsupported spans
*/
@NonNull
public Builder setTitle(@NonNull CharSequence title) {
mTitle = CarText.create(requireNonNull(title));
CarTextConstraints.TEXT_ONLY.validateOrThrow(mTitle);
return this;
}
/**
* Sets a single {@link ItemList} to show in the template.
*
* @throws NullPointerException if {@code list} is null
*/
@NonNull
public Builder setSingleList(@NonNull ItemList list) {
mSingleList = requireNonNull(list);
return this;
}
/**
* Sets the {@link ActionStrip} for this template.
*
* <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}
*/
@NonNull
public Builder setActionStrip(@NonNull ActionStrip actionStrip) {
ACTIONS_CONSTRAINTS_SIMPLE.validateOrThrow(requireNonNull(actionStrip).getActions());
mActionStrip = actionStrip;
return this;
}
/**
* Constructs the template defined by this builder.
*
* <h4>Requirements</h4>
*
* The number of items in the {@link ItemList} should be smaller or equal than the limit
* provided by
* {@link androidx.car.app.constraints.ConstraintManager#CONTENT_LIMIT_TYPE_GRID}. The
* host will ignore any items over that limit.
*
* <p>Either a header {@link Action} or title must be set on the template.
*
* @throws IllegalStateException if the template is in a loading state but there are
* lists added, or vice versa, or if the template does not
* have either a title or header {@link Action} set.
* @throws IllegalArgumentException if the added {@link ItemList} does not meet the
* template's requirements.
* @see androidx.car.app.constraints.ConstraintManager#getContentLimit(int)
*/
@NonNull
public GridTemplate build() {
boolean hasList = mSingleList != null;
if (mIsLoading == hasList) {
throw new IllegalStateException(
"Template is in a loading state but lists are added, or vice versa");
}
if (mSingleList != null) {
for (Item gridItemObject : mSingleList.getItems()) {
if (!(gridItemObject instanceof GridItem)) {
throw new IllegalArgumentException(
"All the items in grid template's item list must be grid items");
}
}
}
if (CarText.isNullOrEmpty(mTitle) && mHeaderAction == null) {
throw new IllegalStateException("Either the title or header action must be set");
}
return new GridTemplate(this);
}
/** Returns an empty {@link Builder} instance. */
public Builder() {
}
}
}