Class UIObject

The superclass for all user-interface objects. It simply wraps a DOM element, and cannot receive events. Most interesting user-interface classes derive from Widget.

Styling With CSS

All UIObject objects can be styled using CSS. Style names that are specified programmatically in Java source are implicitly associated with CSS style rules. In terms of HTML and CSS, a GWT style name is the element's CSS "class". By convention, GWT style names are of the form [project]-[widget].

For example, the Button widget has the style name gwt-Button, meaning that within the Button constructor, the following call occurs:

 setStyleName("gwt-Button");

A corresponding CSS style rule can then be written as follows:

 // Example of how you might choose to style a Button widget 
 .gwt-Button {
   background-color: yellow;
   color: black;
   font-size: 24pt;
 }

Note the dot prefix in the CSS style rule. This syntax is called a CSS class selector.

Style Name Specifics

Every UIObject has a primary style name that identifies the key CSS style rule that should always be applied to it. Use setStylePrimaryName(String) to specify an object's primary style name. In most cases, the primary style name is set in a widget's constructor and never changes again during execution. In the case that no primary style name is specified, it defaults to the first style name that is added.

More complex styling behavior can be achieved by manipulating an object's secondary style names. Secondary style names can be added and removed using addStyleName(String) and removeStyleName(String). The purpose of secondary style names is to associate a variety of CSS style rules over time as an object progresses through different visual states.

There is an important special formulation of secondary style names called dependent style names. A dependent style name is a secondary style name prefixed with the primary style name of the widget itself. See addStyleName(String) for details.

Methods

addStyleDependentName(String)	Adds a dependent style name by specifying the style name's suffix.
addStyleName(String)	Adds a secondary or dependent style name to this object.
getAbsoluteLeft()	Gets the object's absolute left position in pixels, as measured from the browser window's client area.
getAbsoluteTop()	Gets the object's absolute top position in pixels, as measured from the browser window's client area.
getElement()	Gets a handle to the object's underlying DOM element.
getOffsetHeight()	Gets the object's offset height in pixels.
getOffsetWidth()	Gets the object's offset width in pixels.
getStyleElement()	Template method that returns the element to which style names will be applied.
getStyleName(Element)	Gets all of the element's style names, as a space-separated list.
getStyleName()	Gets all of the object's style names, as a space-separated list.
getStylePrimaryName(Element)	Gets the element's primary style name.
getStylePrimaryName()	Gets the primary style name associated with the object.
getTitle()	Gets the title associated with this object.
isVisible(Element)
isVisible()	Determines whether or not this object is visible.
removeStyleDependentName(String)	Removes a dependent style name by specifying the style name's suffix.
removeStyleName(String)	Removes a style name.
setElement(Element)	Sets this object's browser element.
setHeight(String)	Sets the object's height.
setPixelSize(int, int)	Sets the object's size, in pixels, not including decorations such as border, margin, and padding.
setSize(String, String)	Sets the object's size.
setStyleName(Element, String)	Clears all of the element's style names and sets it to the given style.
setStyleName(Element, String, boolean)	This convenience method adds or removes a style name for a given element.
setStyleName(String)	Clears all of the object's style names and sets it to the given style.
setStylePrimaryName(Element, String)	Sets the element's primary style name and updates all dependent style names.
setStylePrimaryName(String)	Sets the object's primary style name and updates all dependent style names.
setTitle(String)	Sets the title associated with this object.
setVisible(Element, boolean)
setVisible(boolean)	Sets whether this object is visible.
setWidth(String)	Sets the object's width.
sinkEvents(int)	Adds a set of events to be sunk by this object.
toString()	This method is overridden so that any object can be viewed in the debugger as an HTML snippet.
unsinkEvents(int)	Removes a set of events from this object's event list.

Method Detail

addStyleDependentName

Adds a dependent style name by specifying the style name's suffix. The actual form of the style name that is added is:

 getStylePrimaryName() + '-' + styleSuffix
 

Parameters

styleSuffix

the suffix of the dependent style to be added.

See Also

setStylePrimaryName(String), removeStyleDependentName(String), addStyleName(String)

---

addStyleName

Adds a secondary or dependent style name to this object. A secondary style name is an additional style name that is, in HTML/CSS terms, included as a space-separated token in the value of the CSS class attribute for this object's root element.

The most important use for this method is to add a special kind of secondary style name called a dependent style name. To add a dependent style name, use addStyleDependentName(String), which will prefix the 'style' argument with the result of getStylePrimaryName() (followed by a '-'). For example, suppose the primary style name is gwt-TextBox. If the following method is called as obj.setReadOnly(true):

 public void setReadOnly(boolean readOnly) {
   isReadOnlyMode = readOnly;
   
   // Create a dependent style name.
   String readOnlyStyle = "readonly";
    
   if (readOnly) {
     addStyleDependentName(readOnlyStyle);
   } else {
     removeStyleDependentName(readOnlyStyle);
   }
 }

then both of the CSS style rules below will be applied:

 // This rule is based on the primary style name and is always active.
 .gwt-TextBox {
   font-size: 12pt;
 }
 
 // This rule is based on a dependent style name that is only active
 // when the widget has called addStyleName(getStylePrimaryName() +
 // "-readonly").
 .gwt-TextBox-readonly {
   background-color: lightgrey;
   border: none;
 }

Dependent style names are powerful because they are automatically updated whenever the primary style name changes. Continuing with the example above, if the primary style name changed due to the following call:

setStylePrimaryName("my-TextThingy");

then the object would be re-associated with following style rules, removing those that were shown above.

 .my-TextThingy {
   font-size: 20pt;
 }
 
 .my-TextThingy-readonly {
   background-color: red;
   border: 2px solid yellow;
 }

Secondary style names that are not dependent style names are not automatically updated when the primary style name changes.

Parameters

style

the secondary style name to be added

See Also

UIObject, removeStyleName(String)

---

getAbsoluteLeft

Gets the object's absolute left position in pixels, as measured from the browser window's client area.

Return Value

the object's absolute left position

---

getAbsoluteTop

Gets the object's absolute top position in pixels, as measured from the browser window's client area.

Return Value

the object's absolute top position

---

getElement

Gets a handle to the object's underlying DOM element.

Return Value

the object's browser element

---

getOffsetHeight

Gets the object's offset height in pixels. This is the total height of the object, including decorations such as border, margin, and padding.

Return Value

the object's offset height

---

getOffsetWidth

Gets the object's offset width in pixels. This is the total width of the object, including decorations such as border, margin, and padding.

Return Value

the object's offset width

---

getStyleElement

Template method that returns the element to which style names will be applied. By default it returns the root element, but this method may be overridden to apply styles to a child element.

Return Value

the element to which style names will be applied

---

getStyleName

Gets all of the element's style names, as a space-separated list.

Parameters

elem

the element whose style is to be retrieved

Return Value

the objects's space-separated style names

---

getStyleName

Gets all of the object's style names, as a space-separated list. If you wish to retrieve only the primary style name, call getStylePrimaryName().

Return Value

the objects's space-separated style names

See Also

getStylePrimaryName()

---

getStylePrimaryName

Gets the element's primary style name.

Parameters

elem

the element whose primary style name is to be retrieved

Return Value

the element's primary style name

---

getStylePrimaryName

Gets the primary style name associated with the object.

Return Value

the object's primary style name

See Also

setStyleName(String), addStyleName(String), removeStyleName(String)

---

getTitle

Gets the title associated with this object. The title is the 'tool-tip' displayed to users when they hover over the object.

Return Value

the object's title

---

isVisible

Parameters

elem

---

isVisible

Determines whether or not this object is visible.

Return Value

true if the object is visible

---

removeStyleDependentName

Removes a dependent style name by specifying the style name's suffix.

Parameters

styleSuffix

the suffix of the dependent style to be removed

See Also

setStylePrimaryName(Element, String), addStyleDependentName(String), addStyleName(String)

---

removeStyleName

Removes a style name. This method is typically used to remove secondary style names, but it can be used to remove primary stylenames as well. That use is not recommended.

Parameters

style

the secondary style name to be removed

See Also

addStyleName(String)

---

setElement

Sets this object's browser element. UIObject subclasses must call this method before attempting to call any other methods. If the browser element has already been set, then the current element's position is located in the DOM and removed. The new element is added into the previous element's position.

Parameters

elem

the object's new element

---

setHeight

Sets the object's height. This height does not include decorations such as border, margin, and padding.

Parameters

height

the object's new height, in CSS units (e.g. "10px", "1em")

---

setPixelSize

Sets the object's size, in pixels, not including decorations such as border, margin, and padding.

Parameters

width

the object's new width, in pixels

height

the object's new height, in pixels

---

setSize

Sets the object's size. This size does not include decorations such as border, margin, and padding.

Parameters

width

the object's new width, in CSS units (e.g. "10px", "1em")

height

the object's new height, in CSS units (e.g. "10px", "1em")

---

setStyleName

Clears all of the element's style names and sets it to the given style.

Parameters

elem

the element whose style is to be modified

styleName

the new style name

---

setStyleName

This convenience method adds or removes a style name for a given element. This method is typically used to add and remove secondary style names, but it can be used to remove primary stylenames as well, but that is not recommended. See setStyleName(String) for a description of how primary and secondary style names are used.

Parameters

elem

the element whose style is to be modified

style

the secondary style name to be added or removed

add

true to add the given style, false to remove it

---

setStyleName

Clears all of the object's style names and sets it to the given style. You should normally use setStylePrimaryName(String) unless you wish to explicitly remove all existing styles.

Parameters

style

the new style name

See Also

setStylePrimaryName(String)

---

setStylePrimaryName

Sets the element's primary style name and updates all dependent style names.

Parameters

elem

the element whose style is to be reset

style

the new primary style name

See Also

setStyleName(Element, String, boolean)

---

setStylePrimaryName

Sets the object's primary style name and updates all dependent style names.

Parameters

style

the new primary style name

See Also

addStyleName(String), removeStyleName(String)

---

setTitle

Sets the title associated with this object. The title is the 'tool-tip' displayed to users when they hover over the object.

Parameters

title

the object's new title

---

setVisible

Parameters

elem

visible

---

setVisible

Sets whether this object is visible.

Parameters

visible

true to show the object, false to hide it

---

setWidth

Sets the object's width. This width does not include decorations such as border, margin, and padding.

Parameters

width

the object's new width, in CSS units (e.g. "10px", "1em")

---

sinkEvents

Adds a set of events to be sunk by this object. Note that only widgets may actually receive events, but can receive events from all objects contained within them.

Parameters

eventBitsToAdd

a bitfield representing the set of events to be added to this element's event set

See Also

Event

---

toString

This method is overridden so that any object can be viewed in the debugger as an HTML snippet.

Return Value

a string representation of the object

---

unsinkEvents

Removes a set of events from this object's event list.

Parameters

eventBitsToRemove

a bitfield representing the set of events to be removed from this element's event set

See Also

sinkEvents, Event

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