/*
* BottomScrollPanel.java
*
* Copyright (C) 2009-12 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.widget;
import com.google.gwt.event.dom.client.ScrollEvent;
import com.google.gwt.event.dom.client.ScrollHandler;
import com.google.gwt.user.client.ui.ScrollPanel;
import com.google.gwt.user.client.ui.Widget;
import org.rstudio.core.client.dom.DomUtils;
/**
* An implementation of ScrollPanel that defaults its scroll position to the
* bottom. If resized while the scroll position is at the bottom, the scroll
* position will stay at the bottom (even if the panel is shrinking in size).
*/
public class BottomScrollPanel extends ScrollPanel
{
public BottomScrollPanel()
{
addScrollHandler(new ScrollHandler()
{
public void onScroll(ScrollEvent event)
{
scrolledToBottom_ =
(getVerticalScrollPosition() ==
getMaximumVerticalScrollPosition() ||
((getVerticalScrollPosition() + getOffsetHeight()) ==
getElement().getScrollHeight()));
}
});
}
public BottomScrollPanel(Widget widget)
{
this();
setWidget(widget);
}
public boolean isScrolledToBottom()
{
return scrolledToBottom_;
}
@Override
protected void onLoad()
{
super.onLoad();
scrollToBottom();
}
@Override
public void onResize()
{
if (scrolledToBottom_)
scrollToBottom();
super.onResize();
}
@Override
public void scrollToBottom()
{
DomUtils.scrollToBottom(getElement());
scrolledToBottom_ = true;
}
public void onContentSizeChanged()
{
if (scrolledToBottom_)
scrollToBottom();
}
public void saveScrollPosition()
{
vScroll_ = scrolledToBottom_ ? null : getVerticalScrollPosition();
hScroll_ = getHorizontalScrollPosition();
}
public void restoreScrollPosition()
{
if (vScroll_ == null)
scrollToBottom();
else
setVerticalScrollPosition(vScroll_);
setHorizontalScrollPosition(hScroll_);
}
private boolean scrolledToBottom_;
private Integer vScroll_;
private int hScroll_;
}