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/*
* Copyright 2008 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.user.client.ui;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Style.Overflow;
import com.google.gwt.dom.client.Style.Position;
import com.google.gwt.event.dom.client.ScrollEvent;
import com.google.gwt.event.dom.client.ScrollHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.touch.client.TouchScroller;
import com.google.gwt.user.client.Element;
import com.google.gwt.user.client.Event;
/**
* A simple panel that wraps its contents in a scrollable area.
*/
@SuppressWarnings("deprecation")
public class ScrollPanel extends SimplePanel implements SourcesScrollEvents,
RequiresResize, ProvidesResize, HasScrolling {
private final Element containerElem;
private final Element scrollableElem;
/**
* The scroller used to support touch events.
*/
private TouchScroller touchScroller;
/**
* Creates an empty scroll panel.
*/
public ScrollPanel() {
this.scrollableElem = getElement();
this.containerElem = Document.get().createDivElement().cast();
scrollableElem.appendChild(containerElem);
initialize();
}
/**
* Creates a new scroll panel with the given child widget.
*
* @param child the widget to be wrapped by the scroll panel
*/
public ScrollPanel(Widget child) {
this();
setWidget(child);
}
/**
* Creates an empty scroll panel using the specified root, scrollable, and
* container elements.
*
* @param root the root element of the Widget
* @param scrollable the scrollable element, which can be the same as the root
* element
* @param container the container element that holds the child
*/
protected ScrollPanel(Element root, Element scrollable, Element container) {
super(root);
this.scrollableElem = scrollable;
this.containerElem = container;
initialize();
}
public HandlerRegistration addScrollHandler(ScrollHandler handler) {
/*
* Sink the event on the scrollable element, which may not be the root
* element.
*/
Event.sinkEvents(getScrollableElement(), Event.ONSCROLL);
return addHandler(handler, ScrollEvent.getType());
}
/**
* @deprecated Use {@link #addScrollHandler} instead
*/
@Deprecated
public void addScrollListener(ScrollListener listener) {
ListenerWrapper.WrappedScrollListener.add(this, listener);
}
/**
* Ensures that the specified item is visible, by adjusting the panel's scroll
* position.
*
* @param item the item whose visibility is to be ensured
*/
public void ensureVisible(UIObject item) {
Element scroll = getScrollableElement();
Element element = item.getElement();
ensureVisibleImpl(scroll, element);
}
/**
* Gets the horizontal scroll position.
*
* @return the horizontal scroll position, in pixels
*/
public int getHorizontalScrollPosition() {
return getScrollableElement().getScrollLeft();
}
public int getMaximumHorizontalScrollPosition() {
return ScrollImpl.get().getMaximumHorizontalScrollPosition(getScrollableElement());
}
public int getMaximumVerticalScrollPosition() {
return getScrollableElement().getScrollHeight() - getScrollableElement().getClientHeight();
}
public int getMinimumHorizontalScrollPosition() {
return ScrollImpl.get().getMinimumHorizontalScrollPosition(getScrollableElement());
}
public int getMinimumVerticalScrollPosition() {
return 0;
}
/**
* Gets the vertical scroll position.
*
* @return the vertical scroll position, in pixels
* @deprecated as of GWT 2.3, replaced by {@link #getVerticalScrollPosition()}
*/
@Deprecated
public int getScrollPosition() {
return getScrollableElement().getScrollTop();
}
public int getVerticalScrollPosition() {
return getScrollPosition();
}
/**
* Check whether or not touch based scrolling is disabled. This method always
* returns false on devices that do not support touch scrolling.
*
* @return true if disabled, false if enabled
*/
public boolean isTouchScrollingDisabled() {
return touchScroller == null;
}
public void onResize() {
Widget child = getWidget();
if ((child != null) && (child instanceof RequiresResize)) {
((RequiresResize) child).onResize();
}
}
/**
* @deprecated Use the {@link HandlerRegistration#removeHandler}
* method on the object returned by {@link #addScrollHandler} instead
*/
@Deprecated
public void removeScrollListener(ScrollListener listener) {
ListenerWrapper.WrappedScrollListener.remove(this, listener);
}
/**
* Scroll to the bottom of this panel.
*/
public void scrollToBottom() {
setVerticalScrollPosition(getMaximumVerticalScrollPosition());
}
/**
* Scroll to the far left of this panel.
*/
public void scrollToLeft() {
setHorizontalScrollPosition(getMinimumHorizontalScrollPosition());
}
/**
* Scroll to the far right of this panel.
*/
public void scrollToRight() {
setHorizontalScrollPosition(getMaximumHorizontalScrollPosition());
}
/**
* Scroll to the top of this panel.
*/
public void scrollToTop() {
setVerticalScrollPosition(getMinimumVerticalScrollPosition());
}
/**
* Sets whether this panel always shows its scroll bars, or only when
* necessary.
*
* @param alwaysShow true to show scroll bars at all times
*/
public void setAlwaysShowScrollBars(boolean alwaysShow) {
getScrollableElement().getStyle().setOverflow(alwaysShow ? Overflow.SCROLL : Overflow.AUTO);
}
/**
* Sets the object's height. This height does not include decorations such as
* border, margin, and padding.
*
* @param height the object's new height, in absolute CSS units (e.g. "10px",
* "1em" but not "50%")
*/
@Override
public void setHeight(String height) {
super.setHeight(height);
}
/**
* Sets the horizontal scroll position.
*
* @param position the new horizontal scroll position, in pixels
*/
public void setHorizontalScrollPosition(int position) {
getScrollableElement().setScrollLeft(position);
}
/**
* Sets the vertical scroll position.
*
* @param position the new vertical scroll position, in pixels
* @deprecated as of GWT 2.3, replaced by
* {@link #setVerticalScrollPosition(int)}
*/
@Deprecated
public void setScrollPosition(int position) {
getScrollableElement().setScrollTop(position);
}
/**
* Sets the object's size. This size does not include decorations such as
* border, margin, and padding.
*
* @param width the object's new width, in absolute CSS units (e.g. "10px",
* "1em", but not "50%")
* @param height the object's new height, in absolute CSS units (e.g. "10px",
* "1em", but not "50%")
*/
@Override
public void setSize(String width, String height) {
super.setSize(width, height);
}
/**
* Set whether or not touch scrolling is disabled. By default, touch scrolling
* is enabled on devices that support touch events.
*
* @param isDisabled true to disable, false to enable
* @return true if touch scrolling is enabled and supported, false if disabled
* or not supported
*/
public boolean setTouchScrollingDisabled(boolean isDisabled) {
if (isDisabled == isTouchScrollingDisabled()) {
return isDisabled;
}
if (isDisabled) {
// Detach the touch scroller.
touchScroller.setTargetWidget(null);
touchScroller = null;
} else {
// Attach a new touch scroller.
touchScroller = TouchScroller.createIfSupported(this);
}
return isTouchScrollingDisabled();
}
public void setVerticalScrollPosition(int position) {
setScrollPosition(position);
}
/**
* Sets the object's width. This width does not include decorations such as
* border, margin, and padding.
*
* @param width the object's new width, in absolute CSS units (e.g. "10px",
* "1em", but not "50%")
*/
@Override
public void setWidth(String width) {
super.setWidth(width);
}
@Override
protected Element getContainerElement() {
return containerElem;
}
/**
* Get the scrollable element. That is the element with its overflow set to
* 'auto' or 'scroll'.
*
* @return the scrollable element
*/
protected Element getScrollableElement() {
return scrollableElem;
}
@Override
protected void onAttach() {
super.onAttach();
/*
* Attach the event listener in onAttach instead of onLoad so users cannot
* accidentally override it. If the scrollable element is the same as the
* root element, then we set the event listener twice (once in
* super.onAttach() and once here), which is fine.
*/
Event.setEventListener(getScrollableElement(), this);
}
@Override
protected void onDetach() {
/*
* Detach the event listener in onDetach instead of onUnload so users cannot
* accidentally override it.
*/
Event.setEventListener(getScrollableElement(), null);
super.onDetach();
}
private native void ensureVisibleImpl(Element scroll, Element e) /*-{
if (!e)
return;
var item = e;
var realOffset = 0;
while (item && (item != scroll)) {
realOffset += item.offsetTop;
item = item.offsetParent;
}
scroll.scrollTop = realOffset - scroll.offsetHeight / 2;
}-*/;
/**
* Initialize the widget.
*/
private void initialize() {
setAlwaysShowScrollBars(false);
// Prevent IE standard mode bug when a AbsolutePanel is contained.
scrollableElem.getStyle().setPosition(Position.RELATIVE);
containerElem.getStyle().setPosition(Position.RELATIVE);
// Hack to account for the IE6/7 scrolling bug described here:
// http://stackoverflow.com/questions/139000/div-with-overflowauto-and-a-100-wide-table-problem
scrollableElem.getStyle().setProperty("zoom", "1");
containerElem.getStyle().setProperty("zoom", "1");
// Enable touch scrolling.
setTouchScrollingDisabled(false);
// Initialize the scrollable element.
ScrollImpl.get().initialize(scrollableElem, containerElem);
}
}
