lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/TitleDetector.java

/*
 * Copyright (C) 2012 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.tools.lint.checks;

import static com.android.SdkConstants.ANDROID_URI;
import static com.android.SdkConstants.ATTR_TITLE;
import static com.android.SdkConstants.ATTR_VISIBLE;
import static com.android.SdkConstants.TAG_ITEM;
import static com.android.SdkConstants.VALUE_FALSE;
import static com.android.tools.lint.detector.api.LintFix.TODO;

import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.resources.ResourceFolderType;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.LintFix;
import com.android.tools.lint.detector.api.ResourceXmlDetector;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.XmlContext;
import java.util.Collection;
import java.util.Collections;
import org.w3c.dom.Element;

/** Check which makes sure menu items specify a title */
public class TitleDetector extends ResourceXmlDetector {
    /** The main issue discovered by this detector */
    public static final Issue ISSUE =
            Issue.create(
                            "MenuTitle",
                            "Missing menu title",
                            "From the action bar documentation:\n"
                                    +
                                    // u2014: em dash
                                    "\"It's important that you always define android:title for each menu item \u2014 "
                                    + "even if you don't declare that the title appear with the action item \u2014 for "
                                    + "three reasons:\n"
                                    + "\n"
                                    + "* If there's not enough room in the action bar for the action item, the menu "
                                    + "item appears in the overflow menu and only the title appears.\n"
                                    + "* Screen readers for sight-impaired users read the menu item's title.\n"
                                    + "* If the action item appears with only the icon, a user can long-press the item "
                                    + "to reveal a tool-tip that displays the action item's title.\n"
                                    + "The android:icon is always optional, but recommended.",
                            Category.USABILITY,
                            5,
                            Severity.ERROR,
                            new Implementation(TitleDetector.class, Scope.RESOURCE_FILE_SCOPE))
                    .addMoreInfo("https://developer.android.com/training/appbar");

    /** Constructs a new {@link TitleDetector} */
    public TitleDetector() {}

    @Override
    public boolean appliesTo(@NonNull ResourceFolderType folderType) {
        return folderType == ResourceFolderType.MENU;
    }

    @Override
    @Nullable
    public Collection<String> getApplicableElements() {
        return Collections.singletonList(TAG_ITEM);
    }

    @Override
    public void visitElement(@NonNull XmlContext context, @NonNull Element element) {
        if (element.hasAttributeNS(ANDROID_URI, ATTR_TITLE)
                || TODO.equals(element.getAttributeNS(ANDROID_URI, ATTR_TITLE))) {
            return;
        }

        // TODO: Find out if this is necessary on older versions too.
        // I swear I saw it mentioned.
        if (context.getMainProject().getTargetSdk() < 11) {
            return;
        }

        if (VALUE_FALSE.equals(element.getAttributeNS(ANDROID_URI, ATTR_VISIBLE))) {
            return;
        }

        LintFix fix = fix().set().todo(ANDROID_URI, ATTR_TITLE).build();
        String message = "Menu items should specify a `title`";
        context.report(ISSUE, element, context.getNameLocation(element), message, fix);
    }
}