80 lines
2.7 KiB
Java
Executable File
80 lines
2.7 KiB
Java
Executable File
// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package org.chromium.android_webview;
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import android.os.Handler;
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import android.os.Message;
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import android.view.View;
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import android.view.accessibility.AccessibilityEvent;
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/**
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* Helper used to post the VIEW_SCROLLED accessibility event.
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*
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* TODO(mkosiba): Investigate whether this is behavior we want to share with the chrome/ layer.
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* TODO(mkosiba): We currently don't handle JS-initiated scrolling for layers other than the root
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* layer.
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*/
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class ScrollAccessibilityHelper {
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// This is copied straight out of android.view.ViewConfiguration.
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private static final long SEND_RECURRING_ACCESSIBILITY_EVENTS_INTERVAL_MILLIS = 100;
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private class HandlerCallback implements Handler.Callback {
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public static final int MSG_VIEW_SCROLLED = 1;
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private View mEventSender;
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public HandlerCallback(View eventSender) {
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mEventSender = eventSender;
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}
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@Override
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public boolean handleMessage(Message msg) {
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switch(msg.what) {
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case MSG_VIEW_SCROLLED:
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mMsgViewScrolledQueued = false;
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mEventSender.sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_SCROLLED);
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break;
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default:
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throw new IllegalStateException(
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"AccessibilityInjector: unhandled message: " + msg.what);
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}
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return true;
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}
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}
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private Handler mHandler;
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private boolean mMsgViewScrolledQueued;
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public ScrollAccessibilityHelper(View eventSender) {
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mHandler = new Handler(new HandlerCallback(eventSender));
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}
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/**
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* Post a callback to send a {@link AccessibilityEvent#TYPE_VIEW_SCROLLED} event.
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* This event is sent at most once every
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* {@link android.view.ViewConfiguration#getSendRecurringAccessibilityEventsInterval()}
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*/
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public void postViewScrolledAccessibilityEventCallback() {
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if (mMsgViewScrolledQueued)
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return;
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mMsgViewScrolledQueued = true;
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Message msg = mHandler.obtainMessage(HandlerCallback.MSG_VIEW_SCROLLED);
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mHandler.sendMessageDelayed(msg, SEND_RECURRING_ACCESSIBILITY_EVENTS_INTERVAL_MILLIS);
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}
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public void removePostedViewScrolledAccessibilityEventCallback() {
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if (!mMsgViewScrolledQueued)
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return;
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mMsgViewScrolledQueued = false;
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mHandler.removeMessages(HandlerCallback.MSG_VIEW_SCROLLED);
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}
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public void removePostedCallbacks() {
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removePostedViewScrolledAccessibilityEventCallback();
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}
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}
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