Upstream JellyBean Accessibility Support

content/public/android/java/src/org/chromium/content/browser/accessibility/JellyBeanAccessibilityInjector.java

Index: content/public/android/java/src/org/chromium/content/browser/accessibility/JellyBeanAccessibilityInjector.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/accessibility/JellyBeanAccessibilityInjector.java b/content/public/android/java/src/org/chromium/content/browser/accessibility/JellyBeanAccessibilityInjector.java
new file mode 100644
index 0000000000000000000000000000000000000000..2f0ad61b03943dfa342b4a1fbb8dc09a70522458
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/accessibility/JellyBeanAccessibilityInjector.java
@@ -0,0 +1,253 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.content.browser.accessibility;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.os.SystemClock;
+import android.view.View;
+import android.view.accessibility.AccessibilityNodeInfo;
+
+import org.chromium.content.browser.ContentViewCore;
+import org.chromium.content.browser.JavascriptInterface;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicInteger;
+
+/**
+ * Handles injecting accessibility Javascript and related Javascript -> Java APIs for JB and newer
+ * devices.
+ */
+class JellyBeanAccessibilityInjector extends AccessibilityInjector {
+    private CallbackHandler mCallback;
+    private JSONObject mAccessibilityJSONObject;
+
+    private static final String ALIAS_TRAVERSAL_JS_INTERFACE = "accessibilityTraversal";
+
+    // Template for JavaScript that performs AndroidVox actions.
+    private static final String ACCESSIBILITY_ANDROIDVOX_TEMPLATE =
+            "cvox.AndroidVox.performAction('%1s')";
+
+    /**
+     * Constructs an instance of the JellyBeanAccessibilityInjector.
+     * @param view The ContentViewCore that this AccessibilityInjector manages.
+     */
+    protected JellyBeanAccessibilityInjector(ContentViewCore view) {
+        super(view);
+    }
+
+    @Override
+    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);
+    }
+
+    @Override
+    public boolean supportsAccessibilityAction(int action) {
+        if (action == AccessibilityNodeInfo.ACTION_NEXT_AT_MOVEMENT_GRANULARITY ||
+                action == AccessibilityNodeInfo.ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY ||
+                action == AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT ||
+                action == AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT ||
+                action == AccessibilityNodeInfo.ACTION_CLICK) {
+            return true;
+        }
+
+        return false;
+    }
+
+    @Override
+    public boolean performAccessibilityAction(int action, Bundle arguments) {
+        if (!accessibilityIsAvailable() || !mContentViewCore.isAlive() ||
+                !mInjectedScriptEnabled || !mScriptInjected) {
+            return false;
+        }
+
+        return sendActionToAndroidVox(action, arguments);
+    }
+
+    @Override
+    protected void addAccessibilityApis() {
+        super.addAccessibilityApis();
+
+        Context context = mContentViewCore.getContext();
+        if (context != null && mCallback == null) {
+            mCallback = new CallbackHandler(ALIAS_TRAVERSAL_JS_INTERFACE);
+            mContentViewCore.addJavascriptInterface(
+                    mCallback, ALIAS_TRAVERSAL_JS_INTERFACE, true);
+        }
+    }
+
+    @Override
+    protected void removeAccessibilityApis() {
+        super.removeAccessibilityApis();
+
+        if (mCallback != null) {
+            mContentViewCore.removeJavascriptInterface(ALIAS_TRAVERSAL_JS_INTERFACE);
+            mCallback = null;
+        }
+    }
+
+    /**
+     * 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 (mCallback == null) return false;
+        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);
+            if (arguments != null) {
+                if (action == AccessibilityNodeInfo.ACTION_NEXT_AT_MOVEMENT_GRANULARITY ||
+                        action == AccessibilityNodeInfo.ACTION_PREVIOUS_AT_MOVEMENT_GRANULARITY) {
+                    final int granularity = arguments.getInt(AccessibilityNodeInfo.
+                            ACTION_ARGUMENT_MOVEMENT_GRANULARITY_INT);
+                    mAccessibilityJSONObject.accumulate("granularity", granularity);
+                } else if (action == AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT ||
+                        action == AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT) {
+                    final String element = arguments.getString(
+                            AccessibilityNodeInfo.ACTION_ARGUMENT_HTML_ELEMENT_STRING);
+                    mAccessibilityJSONObject.accumulate("element", element);
+                }
+            }
+        } catch (JSONException ex) {
+            return false;
+        }
+
+        final String jsonString = mAccessibilityJSONObject.toString();
+        final String jsCode = String.format(ACCESSIBILITY_ANDROIDVOX_TEMPLATE, jsonString);
+        return mCallback.performAction(mContentViewCore, jsCode);
+    }
+
+    private static class CallbackHandler {
+        private static final String JAVASCRIPT_ACTION_TEMPLATE =
+                "(function() { %s.onResult(%d, %s); })()";
+
+        // Time in milliseconds to wait for a result before failing.
+        private static final long RESULT_TIMEOUT = 5000;
+
+        private final AtomicInteger mResultIdCounter = new AtomicInteger();
+        private final Object mResultLock = new Object();
+        private final String mInterfaceName;
+
+        private boolean mResult = false;
+        private long mResultId = -1;
+
+        private CallbackHandler(String interfaceName) {
+            mInterfaceName = interfaceName;
+        }
+
+        /**
+         * Performs an action and attempts to wait for a result.
+         *
+         * @param contentView The ContentViewCore to perform the action on.
+         * @param code Javascript code that evaluates to a result.
+         * @return The result of the action.
+         */
+        private boolean performAction(ContentViewCore contentView, String code) {
+            final int resultId = mResultIdCounter.getAndIncrement();
+            final String js = String.format(JAVASCRIPT_ACTION_TEMPLATE, mInterfaceName, resultId,
+                    code);
+            contentView.evaluateJavaScript(js);
+
+            return getResultAndClear(resultId);
+        }
+
+        /**
+         * Gets the result of a request to perform an accessibility action.
+         *
+         * @param resultId The result id to match the result with the request.
+         * @return The result of the request.
+         */
+        private boolean getResultAndClear(int resultId) {
+            synchronized (mResultLock) {
+                final boolean success = waitForResultTimedLocked(resultId);
+                final boolean result = success ? mResult : false;
+                clearResultLocked();
+                return result;
+            }
+        }
+
+        /**
+         * Clears the result state.
+         */
+        private void clearResultLocked() {
+            mResultId = -1;
+            mResult = false;
+        }
+
+        /**
+         * 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 o fa request as a {@link String}.
+         */
+        @JavascriptInterface
+        @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 = Boolean.parseBoolean(result);
+                    mResultId = resultId;
+                }
+                mResultLock.notifyAll();
+            }
+        }
+    }
+}