/*******************************************************************************
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* Copyright 2011, 2012 Chris Banes.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*******************************************************************************/
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package com.handmark.pulltorefresh.library.extras;
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import java.util.concurrent.atomic.AtomicBoolean;
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import android.content.Context;
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import android.util.AttributeSet;
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import android.webkit.WebView;
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import com.handmark.pulltorefresh.library.PullToRefreshWebView;
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/**
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* An advanced version of {@link PullToRefreshWebView} which delegates the
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* triggering of the PullToRefresh gesture to the Javascript running within the
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* WebView. This means that you should only use this class if:
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* <p/>
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* <ul>
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* <li>{@link PullToRefreshWebView} doesn't work correctly because you're using
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* <code>overflow:scroll</code> or something else which means
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* {@link WebView#getScrollY()} doesn't return correct values.</li>
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* <li>You control the web content being displayed, as you need to write some
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* Javascript callbacks.</li>
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* </ul>
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* <p/>
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* <p/>
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* The way this call works is that when a PullToRefresh gesture is in action,
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* the following Javascript methods will be called:
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* <code>isReadyForPullDown()</code> and <code>isReadyForPullUp()</code>, it is
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* your job to calculate whether the view is in a state where a PullToRefresh
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* can happen, and return the result via the callback mechanism. An example can
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* be seen below:
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* <p/>
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*
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* <pre>
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* function isReadyForPullDown() {
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* var result = ... // Probably using the .scrollTop DOM attribute
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* ptr.isReadyForPullDownResponse(result);
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* }
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*
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* function isReadyForPullUp() {
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* var result = ... // Probably using the .scrollBottom DOM attribute
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* ptr.isReadyForPullUpResponse(result);
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* }
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* </pre>
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*
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* @author Chris Banes
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*/
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public class PullToRefreshWebView2 extends PullToRefreshWebView {
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static final String JS_INTERFACE_PKG = "ptr";
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static final String DEF_JS_READY_PULL_DOWN_CALL = "javascript:isReadyForPullDown();";
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static final String DEF_JS_READY_PULL_UP_CALL = "javascript:isReadyForPullUp();";
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public PullToRefreshWebView2(Context context) {
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super(context);
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}
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public PullToRefreshWebView2(Context context, AttributeSet attrs) {
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super(context, attrs);
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}
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public PullToRefreshWebView2(Context context, Mode mode) {
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super(context, mode);
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}
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private JsValueCallback mJsCallback;
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private final AtomicBoolean mIsReadyForPullDown = new AtomicBoolean(false);
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private final AtomicBoolean mIsReadyForPullUp = new AtomicBoolean(false);
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@Override
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protected WebView createRefreshableView(Context context, AttributeSet attrs) {
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WebView webView = super.createRefreshableView(context, attrs);
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// Need to add JS Interface so we can get the response back
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mJsCallback = new JsValueCallback();
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webView.addJavascriptInterface(mJsCallback, JS_INTERFACE_PKG);
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return webView;
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}
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@Override
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protected boolean isReadyForPullStart() {
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// Call Javascript...
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getRefreshableView().loadUrl(DEF_JS_READY_PULL_DOWN_CALL);
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// Response will be given to JsValueCallback, which will update
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// mIsReadyForPullDown
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return mIsReadyForPullDown.get();
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}
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@Override
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protected boolean isReadyForPullEnd() {
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// Call Javascript...
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getRefreshableView().loadUrl(DEF_JS_READY_PULL_UP_CALL);
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// Response will be given to JsValueCallback, which will update
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// mIsReadyForPullUp
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return mIsReadyForPullUp.get();
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}
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/**
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* Used for response from Javascript
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*
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* @author Chris Banes
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*/
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final class JsValueCallback {
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public void isReadyForPullUpResponse(boolean response) {
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mIsReadyForPullUp.set(response);
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}
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public void isReadyForPullDownResponse(boolean response) {
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mIsReadyForPullDown.set(response);
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}
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}
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}
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