/*
* ScrollUtil.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.core.client;
import org.rstudio.core.client.widget.RStudioFrame;
import org.rstudio.studio.client.workbench.views.viewer.ViewerPane;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.core.client.Scheduler.RepeatingCommand;
import com.google.gwt.dom.client.Document;
public class ScrollUtil
{
public static void setScrollPositionOnLoad(final RStudioFrame frame,
final int scrollPosition)
{
Scheduler.get().scheduleFixedDelay(new RepeatingCommand() {
@Override
public boolean execute()
{
// don't wait indefinitely for the document to load
retries_++;
if (retries_ > MAX_SCROLL_RETRIES)
return false;
// wait for a document to become available in the frame
if (frame.getIFrame() == null)
return true;
if (frame.getIFrame().getContentDocument() == null)
return true;
// wait for the document to finish loading
Document doc = frame.getIFrame().getContentDocument();
String readyState = getDocumentReadyState(doc);
if (readyState == null)
return true;
if (!readyState.equals("complete"))
return true;
// wait for a real document to load (about:blank may be intermediate)
if (doc.getScrollTop() > 0)
return true;
if (doc.getURL().equals(ViewerPane.ABOUT_BLANK))
return true;
// restore scroll position
if (scrollPosition > 0)
doc.setScrollTop(scrollPosition);
return false;
}
private int retries_ = 0;
}, SCROLL_RETRY_MS);
}
private final native static String getDocumentReadyState(Document doc) /*-{
return doc.readyState || null;
}-*/;
private final static int SCROLL_RETRY_MS = 50;
private final static int MAX_SCROLL_RETRIES = 200; // 10s
}