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Merge "Add movement actions to JS accessibility." into jb-dev

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This commit is contained in:
Charles Chen
2012-05-17 16:55:20 -07:00
committed by Android (Google) Code Review
parent 3d6f7eadb2 448902d757
commit 9a9a041cb7
4 changed files with 354 additions and 5 deletions
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291
core/java/android/webkit/AccessibilityInjector.java
View File

@@ -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();
}
}
}
}

9
core/java/android/webkit/WebView.java
View File

@@ -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,

57
core/java/android/webkit/WebViewClassic.java
View File

@@ -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

2
core/java/android/webkit/WebViewProvider.java
View File

@@ -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);