org.rstudio.studio.client.shiny.ShinyFrameHelper.java Source code

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Here is the source code for org.rstudio.studio.client.shiny.ShinyFrameHelper.java

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/*
 * ShinyFrameHelper.java
 *
 * Copyright (C) 2009-14 by RStudio, Inc.
 *
 * Unless you have received this program directly from RStudio pursuant
 * to the terms of a commercial license agreement with RStudio, then
 * this program is licensed to you under the terms of version 3 of the
 * GNU Affero General Public License. This program is distributed WITHOUT
 * ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING THOSE OF NON-INFRINGEMENT,
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please refer to the
 * AGPL (http://www.gnu.org/licenses/agpl-3.0.txt) for more details.
 *
 */
package org.rstudio.studio.client.shiny;

import org.rstudio.core.client.dom.WindowEx;
import org.rstudio.core.client.widget.Operation;

import com.google.gwt.core.client.JavaScriptObject;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.RepeatingCommand;

public class ShinyFrameHelper {
    private static class ShinyFrameEvent extends JavaScriptObject {
        protected ShinyFrameEvent() {
        }

        public final native String getEvent() /*-{
                                              return this.data.event;
                                              }-*/;

        public final native int getIntData() /*-{
                                             return this.data.data;
                                             }-*/;

        public final native String getStringData() /*-{
                                                   return this.data.data;
                                                   }-*/;

        public final native String getOrigin() /*-{
                                               return this.origin;
                                               }-*/;

        public final native WindowEx getSource() /*-{
                                                 return this.source;
                                                 }-*/;
    }

    private static class ShinyFrameMethod extends JavaScriptObject {
        protected ShinyFrameMethod() {
        }

        public final native static ShinyFrameMethod create(String method, int arg) /*-{
                                                                                   return { method: method, arg: arg };
                                                                                   }-*/;

        public final native static ShinyFrameMethod create(String method, String arg) /*-{
                                                                                      return { method: method, arg: arg };
                                                                                      }-*/;

        public final native String getMethod() /*-{
                                               return this.method;
                                               }-*/;
    }

    public void initialize(String url, Operation onComplete) {
        // remember the URL and begin waiting for the window object to arrive
        url_ = url;
        window_ = null;
        origin_ = null;
        onInitComplete_ = onComplete;
    }

    public ShinyFrameHelper() {
        initializeEvents();
    }

    public int getScrollPosition() {
        return scrollPosition_;
    }

    public String getUrl() {
        return url_;
    }

    public void setScrollPosition(int pos) {
        sendMethod(ShinyFrameMethod.create(METHOD_SET_SCROLL, pos));
    }

    public void setHash(String hash) {
        sendMethod(ShinyFrameMethod.create(METHOD_SET_HASH, hash));
    }

    // Private methods ---------------------------------------------------------

    private native void initializeEvents() /*-{  
                                           var thiz = this;   
                                           $wnd.addEventListener(
                                           "message",
                                           $entry(function(e) {
                                           thiz.@org.rstudio.studio.client.shiny.ShinyFrameHelper::onMessage(Lcom/google/gwt/core/client/JavaScriptObject;)(e);
                                           }),
                                           true);
                                           }-*/;

    private void onMessage(JavaScriptObject data) {
        // reject messages that don't match the expected origin
        ShinyFrameEvent event = data.cast();
        if (!url_.startsWith(event.getOrigin()))
            return;

        String eventName = event.getEvent();
        if (eventName.equals(EVENT_SCROLL_CHANGE)) {
            scrollPosition_ = event.getIntData();
        } else if (eventName.equals(EVENT_HASH_CHANGE)) {
            url_ = event.getStringData();
        } else if (eventName.equals(EVENT_READY)) {
            window_ = event.getSource();
            origin_ = event.getOrigin();
            if (onInitComplete_ != null) {
                onInitComplete_.execute();
                onInitComplete_ = null;
            }
        }
    }

    private void sendMethod(final ShinyFrameMethod method) {
        // if we don't have a valid window object yet, try again until we do
        // (every 100ms, up to 5s)
        if (window_ == null) {
            windowRetries_ = 0;
            Scheduler.get().scheduleFixedPeriod(new RepeatingCommand() {
                @Override
                public boolean execute() {
                    if (window_ == null && windowRetries_ < MAX_WINDOW_RETRIES) {
                        windowRetries_++;
                        return true;
                    }
                    if (window_ != null) {
                        window_.postMessage(method, origin_);
                    }
                    return false;
                }
            }, WINDOW_RETRY_DELAY);
        } else {
            window_.postMessage(method, origin_);
        }
    }

    private WindowEx window_ = null;

    private int scrollPosition_ = 0;
    private String url_ = "";
    private String origin_ = "";
    private Operation onInitComplete_;

    // how many times and how long we're willing to wait for a window object to
    // appear to communicate with
    private int windowRetries_ = 0;
    private final static int MAX_WINDOW_RETRIES = 50;
    private final static int WINDOW_RETRY_DELAY = 100;

    // event names (must match those in rsiframe.js)
    private final static String EVENT_SCROLL_CHANGE = "doc_scroll_change";
    private final static String EVENT_HASH_CHANGE = "doc_hash_change";
    private final static String EVENT_READY = "doc_ready";
    private final static String METHOD_SET_SCROLL = "rs_set_scroll_pos";
    private final static String METHOD_SET_HASH = "rs_set_hash";
}