Merge "Add movement actions to JS accessibility." into jb-dev (9a9a041c) · Commits · e / os / android_frameworks_base

core/java/android/webkit/AccessibilityInjector.java

+286 −5

Original line number	Diff line number	Diff line
		@@ -17,25 +17,37 @@
		package android.webkit;

		import android.content.Context;
		import android.os.Vibrator;
		import android.os.Bundle;
		import android.os.SystemClock;
		import android.provider.Settings;
		import android.speech.tts.TextToSpeech;
		import android.view.KeyEvent;
		import android.view.View;
		import android.view.accessibility.AccessibilityManager;
		import android.view.accessibility.AccessibilityNodeInfo;
		import android.webkit.WebViewCore.EventHub;

		import org.apache.http.NameValuePair;
		import org.apache.http.client.utils.URLEncodedUtils;
		import org.json.JSONException;
		import org.json.JSONObject;

		import java.net.URI;
		import java.net.URISyntaxException;
		import java.util.Iterator;
		import java.util.List;
		import java.util.concurrent.atomic.AtomicInteger;

		/**
		* Handles injecting accessibility JavaScript and related JavaScript -> Java
		* APIs.
		*/
		class AccessibilityInjector {
		// Default result returned from AndroidVox. Using true here means if the
		// script fails, an accessibility service will always think that traversal
		// has succeeded.
		private static final String DEFAULT_ANDROIDVOX_RESULT = "true";

		// The WebViewClassic this injector is responsible for managing.
		private final WebViewClassic mWebViewClassic;

		@@ -47,10 +59,12 @@ class AccessibilityInjector {

		// The Java objects that are exposed to JavaScript.
		private TextToSpeech mTextToSpeech;
		private CallbackHandler mCallback;

		// Lazily loaded helper objects.
		private AccessibilityManager mAccessibilityManager;
		private AccessibilityInjectorFallback mAccessibilityInjector;
		private JSONObject mAccessibilityJSONObject;

		// Whether the accessibility script has been injected into the current page.
		private boolean mAccessibilityScriptInjected;
		@@ -61,8 +75,11 @@ class AccessibilityInjector {
		@SuppressWarnings("unused")
		private static final int ACCESSIBILITY_SCRIPT_INJECTION_PROVIDED = 1;

		// Aliases for Java objects exposed to JavaScript.
		private static final String ALIAS_ACCESSIBILITY_JS_INTERFACE = "accessibility";
		// Alias for TTS API exposed to JavaScript.
		private static final String ALIAS_TTS_JS_INTERFACE = "accessibility";

		// Alias for traversal callback exposed to JavaScript.
		private static final String ALIAS_TRAVERSAL_JS_INTERFACE = "accessibilityTraversal";

		// Template for JavaScript that injects a screen-reader.
		private static final String ACCESSIBILITY_SCREEN_READER_JAVASCRIPT_TEMPLATE =
		@@ -73,6 +90,10 @@ class AccessibilityInjector {
		" document.getElementsByTagName('head')[0].appendChild(chooser);" +
		" })();";

		// Template for JavaScript that performs AndroidVox actions.
		private static final String ACCESSIBILITY_ANDROIDVOX_TEMPLATE =
		"cvox.AndroidVox.performAction('%1s')";

		/**
		* Creates an instance of the AccessibilityInjector based on
		* {@code webViewClassic}.
		@@ -99,6 +120,7 @@ class AccessibilityInjector {
		}

		addTtsApis();
		addCallbackApis();
		}

		/**
		@@ -109,6 +131,82 @@ class AccessibilityInjector {
		*/
		public void removeAccessibilityApisIfNecessary() {
		removeTtsApis();
		removeCallbackApis();
		}

		/**
		* Initializes an {@link AccessibilityNodeInfo} with the actions and
		* movement granularity levels supported by this
		* {@link AccessibilityInjector}.
		* <p>
		* If an action identifier is added in this method, this
		* {@link AccessibilityInjector} should also return {@code true} from
		* {@link #supportsAccessibilityAction(int)}.
		* </p>
		*
		* @param info The info to initialize.
		* @see View#onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo)
		*/
		public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
		info.setMovementGranularities(AccessibilityNodeInfo.MOVEMENT_GRANULARITY_CHARACTER
		\| AccessibilityNodeInfo.MOVEMENT_GRANULARITY_WORD
		\| AccessibilityNodeInfo.MOVEMENT_GRANULARITY_LINE
		\| AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PARAGRAPH
		\| AccessibilityNodeInfo.MOVEMENT_GRANULARITY_PAGE);
		info.addAction(AccessibilityNodeInfo.ACTION_NEXT_AT_MOVEMENT_GRANULARITY);
		info.addAction(AccessibilityNodeInfo.ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY);
		info.addAction(AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT);
		info.addAction(AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT);
		info.addAction(AccessibilityNodeInfo.ACTION_CLICK);
		info.setClickable(true);
		}

		/**
		* Returns {@code true} if this {@link AccessibilityInjector} should handle
		* the specified action.
		*
		* @param action An accessibility action identifier.
		* @return {@code true} if this {@link AccessibilityInjector} should handle
		* the specified action.
		*/
		public boolean supportsAccessibilityAction(int action) {
		switch (action) {
		case AccessibilityNodeInfo.ACTION_NEXT_AT_MOVEMENT_GRANULARITY:
		case AccessibilityNodeInfo.ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY:
		case AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT:
		case AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT:
		case AccessibilityNodeInfo.ACTION_CLICK:
		return true;
		default:
		return false;
		}
		}

		/**
		* Performs the specified accessibility action.
		*
		* @param action The identifier of the action to perform.
		* @param arguments The action arguments, or {@code null} if no arguments.
		* @return {@code true} if the action was successful.
		* @see View#performAccessibilityAction(int, Bundle)
		*/
		public boolean performAccessibilityAction(int action, Bundle arguments) {
		if (!isAccessibilityEnabled()) {
		mAccessibilityScriptInjected = false;
		toggleFallbackAccessibilityInjector(false);
		return false;
		}

		if (mAccessibilityScriptInjected) {
		return sendActionToAndroidVox(action, arguments);
		}

		if (mAccessibilityInjector != null) {
		// TODO: Implement actions for non-JS handler.
		return false;
		}

		return false;
		}

		/**
		@@ -261,7 +359,7 @@ class AccessibilityInjector {
		final String pkgName = mContext.getPackageName();

		mTextToSpeech = new TextToSpeech(mContext, null, null, pkgName + ".webview", true);
		mWebView.addJavascriptInterface(mTextToSpeech, ALIAS_ACCESSIBILITY_JS_INTERFACE);
		mWebView.addJavascriptInterface(mTextToSpeech, ALIAS_TTS_JS_INTERFACE);
		}

		/**
		@@ -273,12 +371,30 @@ class AccessibilityInjector {
		return;
		}

		mWebView.removeJavascriptInterface(ALIAS_ACCESSIBILITY_JS_INTERFACE);
		mWebView.removeJavascriptInterface(ALIAS_TTS_JS_INTERFACE);
		mTextToSpeech.stop();
		mTextToSpeech.shutdown();
		mTextToSpeech = null;
		}

		private void addCallbackApis() {
		if (mCallback != null) {
		return;
		}

		mCallback = new CallbackHandler(ALIAS_TRAVERSAL_JS_INTERFACE);
		mWebView.addJavascriptInterface(mCallback, ALIAS_TRAVERSAL_JS_INTERFACE);
		}

		private void removeCallbackApis() {
		if (mCallback == null) {
		return;
		}

		mWebView.removeJavascriptInterface(ALIAS_TRAVERSAL_JS_INTERFACE);
		mCallback = null;
		}

		/**
		* Returns the script injection preference requested by the URL, or
		* {@link #ACCESSIBILITY_SCRIPT_INJECTION_UNDEFINED} if the page has no
		@@ -347,4 +463,169 @@ class AccessibilityInjector {
		private boolean isAccessibilityEnabled() {
		return mAccessibilityManager.isEnabled();
		}

		/**
		* Packs an accessibility action into a JSON object and sends it to AndroidVox.
		*
		* @param action The action identifier.
		* @param arguments The action arguments, if applicable.
		* @return The result of the action.
		*/
		private boolean sendActionToAndroidVox(int action, Bundle arguments) {
		if (mAccessibilityJSONObject == null) {
		mAccessibilityJSONObject = new JSONObject();
		} else {
		// Remove all keys from the object.
		final Iterator<?> keys = mAccessibilityJSONObject.keys();
		while (keys.hasNext()) {
		keys.next();
		keys.remove();
		}
		}

		try {
		mAccessibilityJSONObject.accumulate("action", action);

		switch (action) {
		case AccessibilityNodeInfo.ACTION_NEXT_AT_MOVEMENT_GRANULARITY:
		case AccessibilityNodeInfo.ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY:
		final int granularity = arguments.getInt(
		AccessibilityNodeInfo.ACTION_ARGUMENT_MOVEMENT_GRANULARITY_INT);
		mAccessibilityJSONObject.accumulate("granularity", granularity);
		break;
		case AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT:
		case AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT:
		final String element = arguments.getString(
		AccessibilityNodeInfo.ACTION_ARGUMENT_HTML_ELEMENT_STRING);
		mAccessibilityJSONObject.accumulate("element", element);
		break;
		}
		} catch (JSONException e) {
		return false;
		}

		final String jsonString = mAccessibilityJSONObject.toString();
		final String jsCode = String.format(ACCESSIBILITY_ANDROIDVOX_TEMPLATE, jsonString);
		final String result = mCallback.performAction(mWebView, jsCode, DEFAULT_ANDROIDVOX_RESULT);

		return ("true".equalsIgnoreCase(result));
		}

		/**
		* Exposes result interface to JavaScript.
		*/
		private static class CallbackHandler {
		private static final String JAVASCRIPT_ACTION_TEMPLATE =
		"javascript:(function() { %s.onResult(%d, %s); })();";

		// Time in milliseconds to wait for a result before failing.
		private static final long RESULT_TIMEOUT = 200;

		private final AtomicInteger mResultIdCounter = new AtomicInteger();
		private final Object mResultLock = new Object();
		private final String mInterfaceName;

		private String mResult = null;
		private long mResultId = -1;

		private CallbackHandler(String interfaceName) {
		mInterfaceName = interfaceName;
		}

		/**
		* Performs an action and attempts to wait for a result.
		*
		* @param webView The WebView to perform the action on.
		* @param code JavaScript code that evaluates to a result.
		* @param defaultResult The result to return if the action times out.
		* @return The result of the action, or false if it timed out.
		*/
		private String performAction(WebView webView, String code, String defaultResult) {
		final int resultId = mResultIdCounter.getAndIncrement();
		final String url = String.format(
		JAVASCRIPT_ACTION_TEMPLATE, mInterfaceName, resultId, code);
		webView.loadUrl(url);

		return getResultAndClear(resultId, defaultResult);
		}

		/**
		* Gets the result of a request to perform an accessibility action.
		*
		* @param resultId The result id to match the result with the request.
		* @param defaultResult The default result to return on timeout.
		* @return The result of the request.
		*/
		private String getResultAndClear(int resultId, String defaultResult) {
		synchronized (mResultLock) {
		final boolean success = waitForResultTimedLocked(resultId);
		final String result = success ? mResult : defaultResult;
		clearResultLocked();
		return result;
		}
		}

		/**
		* Clears the result state.
		*/
		private void clearResultLocked() {
		mResultId = -1;
		mResult = null;
		}

		/**
		* Waits up to a given bound for a result of a request and returns it.
		*
		* @param resultId The result id to match the result with the request.
		* @return Whether the result was received.
		*/
		private boolean waitForResultTimedLocked(int resultId) {
		long waitTimeMillis = RESULT_TIMEOUT;
		final long startTimeMillis = SystemClock.uptimeMillis();
		while (true) {
		try {
		if (mResultId == resultId) {
		return true;
		}
		if (mResultId > resultId) {
		return false;
		}
		final long elapsedTimeMillis = SystemClock.uptimeMillis() - startTimeMillis;
		waitTimeMillis = RESULT_TIMEOUT - elapsedTimeMillis;
		if (waitTimeMillis <= 0) {
		return false;
		}
		mResultLock.wait(waitTimeMillis);
		} catch (InterruptedException ie) {
		/* ignore */
		}
		}
		}

		/**
		* Callback exposed to JavaScript. Handles returning the result of a
		* request to a waiting (or potentially timed out) thread.
		*
		* @param id The result id of the request as a {@link String}.
		* @param result The result of the request as a {@link String}.
		*/
		@SuppressWarnings("unused")
		public void onResult(String id, String result) {
		final long resultId;

		try {
		resultId = Long.parseLong(id);
		} catch (NumberFormatException e) {
		return;
		}

		synchronized (mResultLock) {
		if (resultId > mResultId) {
		mResult = result;
		mResultId = resultId;
		}
		mResultLock.notifyAll();
		}
		}
		}
		}

core/java/android/webkit/WebView.java

+9 −0

Original line number	Diff line number	Diff line
		@@ -1686,6 +1686,10 @@ public class WebView extends AbsoluteLayout
		WebView.super.computeScroll();
		}

		public boolean super_performAccessibilityAction(int action, Bundle arguments) {
		return WebView.super.performAccessibilityAction(action, arguments);
		}

		public boolean super_performLongClick() {
		return WebView.super.performLongClick();
		}
		@@ -1938,6 +1942,11 @@ public class WebView extends AbsoluteLayout
		mProvider.getViewDelegate().onInitializeAccessibilityEvent(event);
		}

		@Override
		public boolean performAccessibilityAction(int action, Bundle arguments) {
		return mProvider.getViewDelegate().performAccessibilityAction(action, arguments);
		}

		/** @hide */
		@Override
		protected void onDrawVerticalScrollBar(Canvas canvas, Drawable scrollBar,

core/java/android/webkit/WebViewClassic.java

+57 −0

Original line number	Diff line number	Diff line
		@@ -1663,9 +1663,66 @@ public final class WebViewClassic implements WebViewProvider, WebViewProvider.Sc
		return true;
		}

		@Override
		public boolean performAccessibilityAction(int action, Bundle arguments) {
		if (!mWebView.isEnabled()) {
		// Only default actions are supported while disabled.
		return mWebViewPrivate.super_performAccessibilityAction(action, arguments);
		}

		if (mAccessibilityInjector.supportsAccessibilityAction(action)) {
		return mAccessibilityInjector.performAccessibilityAction(action, arguments);
		}

		switch (action) {
		case AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD:
		case AccessibilityNodeInfo.ACTION_SCROLL_FORWARD: {
		final int convertedContentHeight = contentToViewY(getContentHeight());
		final int adjustedViewHeight = getHeight() - mWebView.getPaddingTop()
		- mWebView.getPaddingBottom();
		final int maxScrollY = Math.max(convertedContentHeight - adjustedViewHeight, 0);
		final boolean canScrollBackward = (getScrollY() > 0);
		final boolean canScrollForward = ((getScrollY() - maxScrollY) > 0);
		if ((action == AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD) && canScrollBackward) {
		mWebView.scrollBy(0, adjustedViewHeight);
		return true;
		}
		if ((action == AccessibilityNodeInfo.ACTION_SCROLL_FORWARD) && canScrollForward) {
		mWebView.scrollBy(0, -adjustedViewHeight);
		return true;
		}
		return false;
		}
		}

		return mWebViewPrivate.super_performAccessibilityAction(action, arguments);
		}

		@Override
		public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
		if (!mWebView.isEnabled()) {
		// Only default actions are supported while disabled.
		return;
		}

		info.setScrollable(isScrollableForAccessibility());

		final int convertedContentHeight = contentToViewY(getContentHeight());
		final int adjustedViewHeight = getHeight() - mWebView.getPaddingTop()
		- mWebView.getPaddingBottom();
		final int maxScrollY = Math.max(convertedContentHeight - adjustedViewHeight, 0);
		final boolean canScrollBackward = (getScrollY() > 0);
		final boolean canScrollForward = ((getScrollY() - maxScrollY) > 0);

		if (canScrollForward) {
		info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_FORWARD);
		}

		if (canScrollForward) {
		info.addAction(AccessibilityNodeInfo.ACTION_SCROLL_BACKWARD);
		}

		mAccessibilityInjector.onInitializeAccessibilityNodeInfo(info);
		}

		@Override

core/java/android/webkit/WebViewProvider.java

+2 −0

Original line number	Diff line number	Diff line
		@@ -276,6 +276,8 @@ public interface WebViewProvider {

		public void onInitializeAccessibilityEvent(AccessibilityEvent event);

		public boolean performAccessibilityAction(int action, Bundle arguments);

		public void setOverScrollMode(int mode);

		public void setScrollBarStyle(int style);