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/*
* Copyright (C) 2011 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_CONTENT_DESCRIPTION;
import static com.android.SdkConstants.ATTR_IMPORTANT_FOR_ACCESSIBILITY;
import static com.android.SdkConstants.IMAGE_BUTTON;
import static com.android.SdkConstants.IMAGE_VIEW;
import static com.android.SdkConstants.VALUE_NO;
import com.android.annotations.NonNull;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.LayoutDetector;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.android.tools.lint.detector.api.Speed;
import com.android.tools.lint.detector.api.XmlContext;
import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import java.util.Arrays;
import java.util.Collection;
/**
* Check which looks for accessibility problems like missing content descriptions
* <p>
* TODO: Resolve styles and don't warn where styles are defining the content description
* (though this seems unusual; content descriptions are not typically generic enough to
* put in styles)
*/
public class AccessibilityDetector extends LayoutDetector {
/** The main issue discovered by this detector */
public static final Issue ISSUE = Issue.create(
"ContentDescription", //$NON-NLS-1$
"Ensures that image widgets provide a contentDescription",
"Non-textual widgets like ImageViews and ImageButtons should use the " +
"`contentDescription` attribute to specify a textual description of " +
"the widget such that screen readers and other accessibility tools " +
"can adequately describe the user interface.",
Category.A11Y,
3,
Severity.WARNING,
AccessibilityDetector.class,
Scope.RESOURCE_FILE_SCOPE);
/** Constructs a new {@link AccessibilityDetector} */
public AccessibilityDetector() {
}
@Override
public @NonNull Speed getSpeed() {
return Speed.FAST;
}
@Override
public Collection<String> getApplicableElements() {
return Arrays.asList(
IMAGE_BUTTON,
IMAGE_VIEW
);
}
@Override
public void visitElement(@NonNull XmlContext context, @NonNull Element element) {
if (!element.hasAttributeNS(ANDROID_URI, ATTR_CONTENT_DESCRIPTION)) {
// Ignore views that are explicitly not important for accessibility
if (VALUE_NO.equals(element.getAttributeNS(ANDROID_URI,
ATTR_IMPORTANT_FOR_ACCESSIBILITY))) {
return;
}
context.report(ISSUE, element, context.getLocation(element),
"[Accessibility] Missing contentDescription attribute on image", null);
} else {
Attr attributeNode = element.getAttributeNodeNS(ANDROID_URI, ATTR_CONTENT_DESCRIPTION);
String attribute = attributeNode.getValue();
if (attribute.length() == 0 || attribute.equals("TODO")) { //$NON-NLS-1$
context.report(ISSUE, attributeNode, context.getLocation(attributeNode),
"[Accessibility] Empty contentDescription attribute on image", null);
}
}
}
}
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