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Refactor source XML tree generation
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Mykola Mokhnach committed Oct 26, 2018
1 parent f796a18 commit fca4bbe
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280 changes: 107 additions & 173 deletions app/src/main/java/io/appium/uiautomator2/core/AccessibilityNodeInfoDumper.java
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* See the License for the specific language governing permissions and
* limitations under the License.
*/

package io.appium.uiautomator2.core;

import android.graphics.Point;
import android.os.SystemClock;
import android.util.Xml;
import android.support.annotation.Nullable;
import android.util.SparseArray;
import android.view.Display;
import android.view.accessibility.AccessibilityNodeInfo;

import org.xmlpull.v1.XmlSerializer;
import org.w3c.dom.Document;
import org.w3c.dom.Element;

import java.lang.reflect.Field;

import java.io.IOException;
import java.io.StringWriter;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import io.appium.uiautomator2.common.exceptions.UiAutomator2Exception;
import io.appium.uiautomator2.model.NotificationListener;
import io.appium.uiautomator2.model.UiAutomationElement;
import io.appium.uiautomator2.model.UiElement;
import io.appium.uiautomator2.utils.Attribute;
import io.appium.uiautomator2.utils.Logger;

import static io.appium.uiautomator2.utils.XMLHierarchy.safeCharSeqToString;

import static io.appium.uiautomator2.utils.AXWindowHelpers.currentActiveWindowRoot;
import static io.appium.uiautomator2.utils.XMLHelpers.DEFAULT_VIEW_CLASS_NAME;
import static io.appium.uiautomator2.utils.XMLHelpers.toNodeName;
import static io.appium.uiautomator2.utils.XMLHelpers.toSafeXmlString;

/**
* The AccessibilityNodeInfoDumper in Android Open Source Project contains a lot of bugs which will
* stay in old android versions forever. By coping the code of the latest version it is ensured that
* all patches become available on old android versions. <p/> down ported bugs are e.g. { @link
* https://code.google.com/p/android/issues/detail?id=62906 } { @link
* https://code.google.com/p/android/issues/detail?id=58733 }
*/
public class AccessibilityNodeInfoDumper {
private static final String[] NAF_EXCLUDED_CLASSES = new String[]{
android.widget.GridView.class.getName(),
android.widget.GridLayout.class.getName(),
android.widget.ListView.class.getName(),
android.widget.TableLayout.class.getName()};
// https://github.com/appium/appium/issues/10204
private static final int MAX_DEPTH = 70;
private static final String UI_ELEMENT_INDEX = "uiElementIndex";

/**
* Using {@link AccessibilityNodeInfo} this method will walk the layout hierarchy and return
* String object of xml hierarchy
*
* @param root The root accessibility node.
*/
public static String getWindowXMLHierarchy(AccessibilityNodeInfo root) {
final long startTime = SystemClock.uptimeMillis();
StringWriter xmlDump = new StringWriter();
private static void setNodeLocalName(Element element, String className) {
try {
XmlSerializer serializer = Xml.newSerializer();
serializer.setOutput(xmlDump);
serializer.startDocument("UTF-8", true);
serializer.startTag("", "hierarchy");

if (root != null) {
Display display = UiAutomatorBridge.getInstance().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
final int width = size.x;
final int height = size.y;

serializer.attribute("", "rotation", Integer.toString(display.getRotation()));

dumpNodeRec(root, serializer, 0, width, height, 0);
}

serializer.endTag("", "hierarchy");
serializer.endDocument();

/*FileWriter writer = new FileWriter(dumpFile);
writer.write(stringWriter.toString());
writer.close();*/
} catch (IOException e) {
throw new UiAutomator2Exception("Cannot dump views hierarchy to XML format", e);
Field localName = element.getClass().getDeclaredField("localName");
localName.setAccessible(true);
localName.set(element, tag(className));
} catch (Exception e) {
Logger.error(String.format("Unable to set field's localName to '%s'", className), e);
}
final long endTime = SystemClock.uptimeMillis();
Logger.info("Fetch time: " + (endTime - startTime) + "ms");
return xmlDump.toString();
}

private static void dumpNodeRec(AccessibilityNodeInfo node, XmlSerializer serializer,
int index, int width, int height, final int depth)
throws IOException {
// Some views might have unlimited number of children:
// https://bugs.chromium.org/p/chromium/issues/detail?id=805014
if (depth >= MAX_DEPTH) {
Logger.error(String.format("The xml tree dump has reached its maximum depth of %s at " +
"%s. The recursion is stopped to avoid StackOverflowError", MAX_DEPTH,
node.toString()));
return;

private static Element toDOMElement(UiElement<?, ?> uiElement, final Document document,
final SparseArray<UiElement<?, ?>> uiElementsMapping,
final int depth) {
String className = uiElement.getClassName();
if (className == null) {
className = DEFAULT_VIEW_CLASS_NAME;
}
Element element = document.createElement(toNodeName(className));
final int uiElementIndex = uiElementsMapping.size();
uiElementsMapping.put(uiElementIndex, uiElement);

/*
* Setting the Element's className field.
* Reason for setting className field in Element object explicitly,
* className property might contain special characters like '$' if it is a Inner class and
* just not possible to create Element object with special characters.
* But Appium should consider Inner classes i.e special characters should be included.
*/
setNodeLocalName(element, className);

for (Attribute attr : Attribute.values()) {
setAttribute(element, attr, toSafeXmlString(uiElement.get(attr), "?"));
}
element.setAttribute(UI_ELEMENT_INDEX, Integer.toString(uiElementIndex));

serializer.startTag("", "node");
if (!isOfNafExcludedClass(node) && !isAccessibilityFriendly(node))
serializer.attribute("", "NAF", Boolean.toString(true));
serializer.attribute("", "index", Integer.toString(index));
final String text;
if (node.getRangeInfo() == null) {
text = safeCharSeqToString(node.getText());
if (depth >= MAX_DEPTH) {
Logger.error(String.format("The xml tree dump has reached its maximum depth of %s at " +
"'%s'. The recursion is stopped to avoid StackOverflowError", MAX_DEPTH, className));
} else {
text = Float.toString(node.getRangeInfo().getCurrent());
}
serializer.attribute("", "text", text);
serializer.attribute("", "class", safeCharSeqToString(node.getClassName()));
serializer.attribute("", "package", safeCharSeqToString(node.getPackageName()));
serializer.attribute("", "content-desc", safeCharSeqToString(node.getContentDescription()));
serializer.attribute("", "checkable", Boolean.toString(node.isCheckable()));
serializer.attribute("", "checked", Boolean.toString(node.isChecked()));
serializer.attribute("", "clickable", Boolean.toString(node.isClickable()));
serializer.attribute("", "enabled", Boolean.toString(node.isEnabled()));
serializer.attribute("", "focusable", Boolean.toString(node.isFocusable()));
serializer.attribute("", "focused", Boolean.toString(node.isFocused()));
serializer.attribute("", "scrollable", Boolean.toString(node.isScrollable()));
serializer.attribute("", "long-clickable", Boolean.toString(node.isLongClickable()));
serializer.attribute("", "password", Boolean.toString(node.isPassword()));
serializer.attribute("", "selected", Boolean.toString(node.isSelected()));
serializer.attribute("", "bounds",
AccessibilityNodeInfoHelper.getVisibleBoundsInScreen(node, width, height).toShortString());
serializer.attribute("", "resource-id", safeCharSeqToString(node.getViewIdResourceName()));

int count = node.getChildCount();
for (int i = 0; i < count; i++) {
AccessibilityNodeInfo child = node.getChild(i);
if (child != null) {
if (child.isVisibleToUser()) {
dumpNodeRec(child, serializer, i, width, height, depth + 1);
child.recycle();
} else {
Logger.info(String.format("Skipping invisible child: %s", child.toString()));
}
} else {
Logger.info(String.format("Null child %s/%s, parent: %s", i, count, node.toString()));
for (UiElement<?, ?> child : uiElement.getChildren()) {
element.appendChild(toDOMElement(child, document, uiElementsMapping, depth + 1));
}
}
serializer.endTag("", "node");
return element;
}

/**
* The list of classes to exclude may not be complete. We're attempting to only reduce noise from
* standard layout classes that may be falsely configured to accept clicks and are also
* enabled.
*
* @return true if node is excluded.
*/
private static boolean isOfNafExcludedClass(AccessibilityNodeInfo node) {
String className = safeCharSeqToString(node.getClassName());
for (String excludedClassName : NAF_EXCLUDED_CLASSES) {
if (className.endsWith(excludedClassName)) {
return true;
}
private static void setAttribute(Element element, Attribute attr, Object value) {
if (value != null) {
element.setAttribute(attr.getName(), String.valueOf(value));
}
return false;
}

/**
* We're looking for UI controls that are enabled, clickable but have no text nor
* content-description. Such controls configuration indicate an interactive control is present
* in the UI and is most likely not accessibility friendly. We refer to such controls here as
* NAF controls (Not Accessibility Friendly)
*
* @return false if a node fails the check, true if all is OK
*/
private static boolean isAccessibilityFriendly(AccessibilityNodeInfo node) {
boolean isNaf = node.isClickable() && node.isEnabled() &&
safeCharSeqToString(node.getContentDescription()).isEmpty() &&
safeCharSeqToString(node.getText()).isEmpty();
if (!isNaf) {
return true;
}
// check children since sometimes the containing element is clickable
// and NAF but a child's text or description is available. Will assume
// such layout as fine.
return isAnyDescendantAccessibilityFriendly(node, 0);
public static Document asXmlDocument() {
return asXmlDocument(null, null);
}

/**
* This should be used when it's already determined that the node is NAF and a further check of
* its children is in order. A node maybe a container such as LinerLayout and may be set to be
* clickable but have no text or content description but it is counting on one of its children
* to fulfill the requirement for being accessibility friendly by having one or more of its
* children fill the text or content-description. Such a combination is considered by this
* dumper as acceptable for accessibility.
*
* @return false if node fails the check.
*/
private static boolean isAnyDescendantAccessibilityFriendly(AccessibilityNodeInfo node,
final int depth) {
// Some views might have unlimited number of children:
// https://bugs.chromium.org/p/chromium/issues/detail?id=805014
if (depth >= MAX_DEPTH) {
Logger.error(String.format("The NAF verification has reached its maximum depth of %s at " +
"%s. The recursion is stopped to avoid StackOverflowError", MAX_DEPTH,
node.toString()));
return false;
public static Document asXmlDocument(@Nullable Object root,
@Nullable SparseArray<UiElement<?, ?>> uiElementsMapping) {
final long startTime = SystemClock.uptimeMillis();
final Document document;
try {
document = DocumentBuilderFactory.newInstance()
.newDocumentBuilder()
.newDocument();
} catch (ParserConfigurationException e) {
throw new UiAutomator2Exception(e);
}
if (uiElementsMapping == null) {
uiElementsMapping = new SparseArray<>();
}

int childCount = node.getChildCount();
for (int x = 0; x < childCount; x++) {
AccessibilityNodeInfo childNode = node.getChild(x);
if (childNode == null) {
Logger.info(String.format("Null child %s/%s, parent: %s", x, childCount, node.toString()));
continue;
}
if (!safeCharSeqToString(childNode.getContentDescription()).isEmpty()
|| !safeCharSeqToString(childNode.getText()).isEmpty()) {
return true;
}
if (isAnyDescendantAccessibilityFriendly(childNode, depth + 1)) {
return true;
}
final UiElement<?, ?> xpathRoot;
if (root instanceof UiElement) {
xpathRoot = (UiElement<?, ?>) root;
} else if (root instanceof AccessibilityNodeInfo) {
xpathRoot = UiAutomationElement.rebuildForNewRoot((AccessibilityNodeInfo) root, null);
} else {
xpathRoot = UiAutomationElement.rebuildForNewRoot(currentActiveWindowRoot(),
NotificationListener.getInstance().getToastMessage());
}
return false;
final Element domNode = toDOMElement(xpathRoot, document, uiElementsMapping, 0);
document.appendChild(domNode);
alterDisplayInfo(domNode);
Logger.info(String.format("XML tree fetch time: %sms", SystemClock.uptimeMillis() - startTime));
return document;
}

private static void alterDisplayInfo(Element node) {
Display display = UiAutomatorBridge.getInstance().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
node.setAttribute("rotation", Integer.toString(display.getRotation()));
node.setAttribute("width", Integer.toString(size.x));
node.setAttribute("height", Integer.toString(size.y));
}

/**
* @param clsName the original class name
* @return The tag name used to build UiElement DOM. It is preferable to use
* this to build XPath instead of String literals.
*/
private static String tag(String clsName) {
// the nth anonymous class has a class name ending in "Outer$n"
// and local inner classes have names ending in "Outer.$1Inner"
return clsName
.replaceAll("\\?+", "_")
.replaceAll("\\$[0-9]+", "\\$");
}
}
6 changes: 3 additions & 3 deletions app/src/main/java/io/appium/uiautomator2/handler/FindElement.java
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import static io.appium.uiautomator2.utils.AXWindowHelpers.refreshRootAXNode;
import static io.appium.uiautomator2.utils.Device.getAndroidElement;
import static io.appium.uiautomator2.utils.LocationHelpers.getXPathNodeMatch;
import static io.appium.uiautomator2.utils.LocationHelpers.rewriteIdLocator;
import static io.appium.uiautomator2.utils.LocationHelpers.toSelector;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.getXPathNodeMatch;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.rewriteIdLocator;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.toSelector;

public class FindElement extends SafeRequestHandler {

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6 changes: 3 additions & 3 deletions app/src/main/java/io/appium/uiautomator2/handler/FindElements.java
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import static io.appium.uiautomator2.utils.Device.getAndroidElement;
import static io.appium.uiautomator2.utils.Device.getUiDevice;
import static io.appium.uiautomator2.utils.LocationHelpers.getXPathNodeMatch;
import static io.appium.uiautomator2.utils.LocationHelpers.rewriteIdLocator;
import static io.appium.uiautomator2.utils.LocationHelpers.toSelectors;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.getXPathNodeMatch;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.rewriteIdLocator;
import static io.appium.uiautomator2.utils.ElementLocationHelpers.toSelectors;

public class FindElements extends SafeRequestHandler {

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