com.google.gwt.user.client.ui

Class CustomScrollPanel

java.lang.Object

com.google.gwt.user.client.ui.UIObject

com.google.gwt.user.client.ui.Widget

com.google.gwt.user.client.ui.Panel

com.google.gwt.user.client.ui.SimplePanel

com.google.gwt.user.client.ui.ScrollPanel

com.google.gwt.user.client.ui.CustomScrollPanel

All Implemented Interfaces:

HasScrollHandlers, HasAttachHandlers, HasHandlers, EventListener, AcceptsOneWidget, HasHorizontalScrolling, HasOneWidget, HasScrolling, HasVerticalScrolling, HasVisibility, HasWidgets, HasWidgets.ForIsWidget, IsWidget, ProvidesResize, RequiresResize, SourcesScrollEvents, Iterable<Widget>

public class CustomScrollPanel
extends ScrollPanel

A custom version of the ScrollPanel that allows user provided scrollbars.

The postion of scrollbars in a CustomScrollPanel differs from that of a native scrollable element. In a native element, scrollbars appear adjacent to the content, shrinking the content client height and width when they appear. CustomScrollPanel instead overlays scrollbars on top of the content, so the content does not change size when scrollbars appear. If the scrollbars obscures the content, you can set the padding-top and padding-bottom of the content to shift the content out from under the scrollbars.

NOTE: Unlike ScrollPanel, which implements RequiresResize but doesn't really require it, CustomScrollPanel actually does require resize and should only be added to a panel that implements ProvidesResize, such as most layout panels and ResizeLayoutPanel.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	CustomScrollPanel.Resources A ClientBundle of resources used by this widget.
static interface	CustomScrollPanel.Style Styles used by this widget.

Nested classes/interfaces inherited from class com.google.gwt.user.client.ui.UIObject

UIObject.DebugIdImpl, UIObject.DebugIdImplEnabled

Nested classes/interfaces inherited from interface com.google.gwt.user.client.ui.HasWidgets

HasWidgets.ForIsWidget

Field Summary

Fields inherited from class com.google.gwt.user.client.ui.UIObject

DEBUG_ID_PREFIX

Constructor Summary

Constructors

Constructor and Description
CustomScrollPanel() Creates an empty CustomScrollPanel.
CustomScrollPanel(CustomScrollPanel.Resources resources)
CustomScrollPanel(Widget child) Creates a CustomScrollPanel with the specified child widget.

Method Summary

Modifier and Type	Method and Description
protected void	doAttachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call Widget.onAttach() for each of its child widgets.
protected void	doDetachChildren() If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call Widget.onDetach() for each of its child widgets.
HorizontalScrollbar	getHorizontalScrollbar() Get the scrollbar used for horizontal scrolling.
VerticalScrollbar	getVerticalScrollbar() Get the scrollbar used for vertical scrolling.
protected void	onAttach() This method is called when a widget is attached to the browser's document.
void	onBrowserEvent(Event event) Fired whenever a browser event is received.
protected void	onDetach() This method is called when a widget is detached from the browser's document.
protected void	onLoad() This method is called immediately after a widget becomes attached to the browser's document.
void	onResize() This method must be called whenever the implementor's size has been modified.
boolean	remove(Widget w) Removes a child widget.
void	removeHorizontalScrollbar() Remove the HorizontalScrollbar, if one exists.
void	removeVerticalScrollbar() Remove the VerticalScrollbar, if one exists.
void	setAlwaysShowScrollBars(boolean alwaysShow) Sets whether this panel always shows its scroll bars, or only when necessary.
void	setHorizontalScrollbar(HorizontalScrollbar scrollbar, int height) Set the scrollbar used for horizontal scrolling.
void	setVerticalScrollbar(VerticalScrollbar scrollbar, int width) Set the scrollbar used for vertical scrolling.
void	setWidget(Widget w) Sets this panel's widget.

Methods inherited from class com.google.gwt.user.client.ui.ScrollPanel

addScrollHandler, addScrollListener, ensureVisible, getContainerElement, getHorizontalScrollPosition, getMaximumHorizontalScrollPosition, getMaximumVerticalScrollPosition, getMinimumHorizontalScrollPosition, getMinimumVerticalScrollPosition, getScrollableElement, getScrollPosition, getVerticalScrollPosition, isTouchScrollingDisabled, removeScrollListener, scrollToBottom, scrollToLeft, scrollToRight, scrollToTop, setHeight, setHorizontalScrollPosition, setScrollPosition, setSize, setTouchScrollingDisabled, setVerticalScrollPosition, setWidth

Methods inherited from class com.google.gwt.user.client.ui.SimplePanel

add, getWidget, iterator, setWidget

Methods inherited from class com.google.gwt.user.client.ui.Panel

add, adopt, clear, orphan, remove

Methods inherited from class com.google.gwt.user.client.ui.Widget

addAttachHandler, addBitlessDomHandler, addDomHandler, addHandler, asWidget, asWidgetOrNull, createHandlerManager, delegateEvent, fireEvent, getHandlerCount, getLayoutData, getParent, isAttached, isOrWasAttached, onUnload, removeFromParent, setLayoutData, sinkEvents, unsinkEvents

Methods inherited from class com.google.gwt.user.client.ui.UIObject

addStyleDependentName, addStyleName, ensureDebugId, ensureDebugId, ensureDebugId, getAbsoluteLeft, getAbsoluteTop, getElement, getOffsetHeight, getOffsetWidth, getStyleElement, getStyleName, getStyleName, getStylePrimaryName, getStylePrimaryName, getTitle, isVisible, isVisible, onEnsureDebugId, removeStyleDependentName, removeStyleName, resolvePotentialElement, setElement, setElement, setPixelSize, setStyleDependentName, setStyleName, setStyleName, setStyleName, setStyleName, setStylePrimaryName, setStylePrimaryName, setTitle, setVisible, setVisible, sinkBitlessEvent, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode

Methods inherited from interface com.google.gwt.event.shared.HasHandlers

fireEvent

Methods inherited from interface com.google.gwt.user.client.ui.IsWidget

asWidget

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

CustomScrollPanel

public CustomScrollPanel()

Creates an empty CustomScrollPanel.

CustomScrollPanel

public CustomScrollPanel(CustomScrollPanel.Resources resources)

CustomScrollPanel

public CustomScrollPanel(Widget child)

Creates a CustomScrollPanel with the specified child widget.

Parameters:

child - the widget to be wrapped by the scroll panel

Method Detail

getHorizontalScrollbar

public HorizontalScrollbar getHorizontalScrollbar()

Get the scrollbar used for horizontal scrolling.

Returns:

the horizontal scrollbar, or null if none specified

getVerticalScrollbar

public VerticalScrollbar getVerticalScrollbar()

Get the scrollbar used for vertical scrolling.

Returns:

the vertical scrollbar, or null if none specified

onBrowserEvent

public void onBrowserEvent(Event event)

Description copied from interface: EventListener

Fired whenever a browser event is received.

Specified by:

onBrowserEvent in interface EventListener

Overrides:

onBrowserEvent in class Widget

Parameters:

event - the event received

onResize

public void onResize()

Description copied from interface: RequiresResize

This method must be called whenever the implementor's size has been modified.

Specified by:

onResize in interface RequiresResize

Overrides:

onResize in class ScrollPanel

remove

public boolean remove(Widget w)

Description copied from class: Panel

Removes a child widget.

How to Override this Method

There are several important things that must take place in the correct order to properly remove a Widget from a Panel. Not all of these steps will be relevant to every Panel, but all of the steps must be considered.

1. Validate: Make sure this Panel is actually the parent of the child Widget; return false if it is not.
2. Orphan: Call Panel.orphan(Widget) first while the child Widget is still attached.
3. Physical Detach: Adjust the DOM to account for the removal of the child Widget. The Widget's Element must be physically removed from the DOM.
4. Logical Detach: Update the Panel's state variables to reflect the removal of the child Widget. Example: the Widget is removed from the Panel's WidgetCollection.

Specified by:

remove in interface HasWidgets

Overrides:

remove in class SimplePanel

Parameters:

w - the widget to be removed

Returns:

true if the child was present

removeHorizontalScrollbar

public void removeHorizontalScrollbar()

Remove the HorizontalScrollbar, if one exists.

removeVerticalScrollbar

public void removeVerticalScrollbar()

Remove the VerticalScrollbar, if one exists.

setAlwaysShowScrollBars

public void setAlwaysShowScrollBars(boolean alwaysShow)

Description copied from class: ScrollPanel

Sets whether this panel always shows its scroll bars, or only when necessary.

Overrides:

setAlwaysShowScrollBars in class ScrollPanel

Parameters:

alwaysShow - true to show scroll bars at all times

setHorizontalScrollbar

public void setHorizontalScrollbar(HorizontalScrollbar scrollbar,
                                   int height)

Set the scrollbar used for horizontal scrolling.

Parameters:

scrollbar - the scrollbar, or null to clear it

height - the height of the scrollbar in pixels

setVerticalScrollbar

public void setVerticalScrollbar(VerticalScrollbar scrollbar,
                                 int width)

Set the scrollbar used for vertical scrolling.

Parameters:

scrollbar - the scrollbar, or null to clear it

width - the width of the scrollbar in pixels

setWidget

public void setWidget(Widget w)

Description copied from class: SimplePanel

Sets this panel's widget. Any existing child widget will be removed.

Specified by:

setWidget in interface HasOneWidget

Overrides:

setWidget in class SimplePanel

Parameters:

w - the panel's new widget, or null to clear the panel

doAttachChildren

protected void doAttachChildren()

Description copied from class: Widget

If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call Widget.onAttach() for each of its child widgets.

Overrides:

doAttachChildren in class Panel

See Also:

Widget.onAttach()

doDetachChildren

protected void doDetachChildren()

Description copied from class: Widget

If a widget contains one or more child widgets that are not in the logical widget hierarchy (the child is physically connected only on the DOM level), it must override this method and call Widget.onDetach() for each of its child widgets.

Overrides:

doDetachChildren in class Panel

See Also:

Widget.onDetach()

onAttach

protected void onAttach()

Description copied from class: Widget

This method is called when a widget is attached to the browser's document. To receive notification after a Widget has been added to the document, override the Widget.onLoad() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).

It is strongly recommended that you override Widget.onLoad() or Widget.doAttachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

Subclasses that override this method must call super.onAttach() to ensure that the Widget has been attached to its underlying Element.

Overrides:

onAttach in class ScrollPanel

See Also:

Widget.onLoad(), Widget.doAttachChildren()

onDetach

protected void onDetach()

Description copied from class: Widget

This method is called when a widget is detached from the browser's document. To receive notification before a Widget is removed from the document, override the Widget.onUnload() method or use Widget.addAttachHandler(com.google.gwt.event.logical.shared.AttachEvent.Handler).

It is strongly recommended that you override Widget.onUnload() or Widget.doDetachChildren() instead of this method to avoid inconsistencies between logical and physical attachment states.

Subclasses that override this method must call super.onDetach() to ensure that the Widget has been detached from the underlying Element. Failure to do so will result in application memory leaks due to circular references between DOM Elements and JavaScript objects.

Overrides:

onDetach in class ScrollPanel

See Also:

Widget.onUnload(), Widget.doDetachChildren()

onLoad

protected void onLoad()

Description copied from class: Widget

This method is called immediately after a widget becomes attached to the browser's document.

Overrides:

onLoad in class Widget