bindings
This section is tested and adjusted for the current Firefox implementation. Please edit only if an actual behavior differs from the described one. Please do not edit only on the basis of another XBL specification.
<!ELEMENT bindings ( binding* ) > Hierarchy: root element May contain: <binding>
The bindings element is the root element of any XBL document. It should usually declare XBL as the default namespace (unless an XBL namespace prefix is used) and it may additionally declare other namespace prefixes used in your binding.
bindings contains zero or more binding elements as children. Each binding child element defines a unique binding that can be attached to elements in other documents.
An element can have only one binding attached (explicitly or inherited) at one moment. From several bindings only the last in the sequence will be used (like with any CSS rule).
helloworld.html:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
<title>Hello world!</title>
<style type="text/css">
p {
-moz-binding: url(hello.xml#default);
}
#p03 {
-moz-binding: url(hello.xml#hello2);
}
</style>
</head>
<body>
<p>Default content</p>
<p>Default content</p>
<p id="p03">Default content</p>
</body>
</html>
hello.xml:
<?xml version="1.0"?>
<bindings xmlns="http://www.mozilla.org/xbl"
xmlns:html="http://www.w3.org/1999/xhtml">
<binding id="default">
<content><html:b>Hello world! </html:b><children/></content>
</binding>
<binding id="hello2">
<content><html:b>Hello from my binding! </html:b><children/></content>
</binding>
</bindings>
You can view the result by opening helloworld.html in Firefox. hello.xml should reside in the same directory which contains helloworld.html.
Next: <big>bindings > binding</big> element.
Notes
- In the current stable releases of Mozilla products (e.g. Firefox 2) it is impossible to attach bindings to table sub-elements (rows, cells etc.) You can attach binding only to the table element itself. This has been fixed for future versions of Mozilla products. See bug 83830 for more information and for workarounds.
- Default encoding in XML documents (including XBL files) is UTF-8. An explicit encoding declarations may be present to override the default, for example
<?xml version="1.0" encoding="ISO-8859-1"?> - URI in namespace declarations is an opaque string used to uniquely identify the namespace. It doesn't have to (and often it doesn't) point to some actual schema or a namespace-related resource. Namespaces in XML
- Besides the default namespace, you can declare any amount of additional namespaces to handle your content. The most useful namespaces could be HTML/XHTML, XUL (XML User Interface Language), SVG (Scalable Vector Graphics) and XLink. This way a more-or-less universal namespace declaration in your
bindingscould be like:
<bindings xmlns="http://www.mozilla.org/xbl" xmlns:html = "http://www.w3.org/1999/xhtml" xmlns:xul = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" xmlns:svg = "http://www.w3.org/2000/svg" xmlns:xlink= "http://www.w3.org/1999/xlink">
binding
<!ENTITY % binding-content "(resources?,content?,implementation?,handlers?)"> <!ELEMENT binding %binding-content;> <!ATTLIST binding id ID #REQUIRED extends CDATA #IMPLIED display CDATA #IMPLIED inheritstyle true #IMPLIED >
The binding element describes a single XBL binding. A XBL binding can add anonymous content, fields, properties, methods, and event handlers to HTML/XML elements.
A single XBL binding can be attached to an element by using style sheets or by scripting. (See bug 83830 for <table> specifics).
CSS:
div {
-moz-binding: url(myBinding.xml#default);
}
DOM:
elementReference.style.MozBinding = "url(myBinding.xml#default)";
In both cases above we are using binding with id="default" contained in file myBinding.xml
Starting with Firefox 3, you can also use a data: URL to embed the binding inline:
div {
-moz-binding: url(data:text/xml;charset=utf-8,%3C%3Fxml%20version%3D%221.0%22%3F%3E%0A%3Cbindings%20id%3D%22xbltestBindings%22%20xmlns%3D%22http%3A//www.mozilla.org/xbl%22%3E%0A%20%20%3Cbinding%20id%3D%22xbltest%22%3E%3Ccontent%3EPASS%3C/content%3E%3C/binding%3E%0A%3C/bindings%3E%0A);
}
Since data: URLs don't support fragment identifiers, the first binding found in the embedded XML is used instead. Keep in mind that the binding is still required to have an ID even though you're not referencing it. In addition, data: URLs are only supported from chrome code (in other words, from the application or an extension).
For clarity's sake, here's what the embedded XML in the previous example looks like:
<?xml version="1.0"?> <bindings id="xbltestBindings" xmlns="http://www.mozilla.org/xbl"> <binding id="xbltest"><content>PASS</content></binding> </bindings>
Only CSS declarations provide an easy way to attach bindings to any set of elements. It also makes your binding partially functional if scripting is disabled. In the latter case all methods and handlers will be blocked, but the anonymous content and styling will be still used. Given that the CSS declarations should be always used - unless you need to add bindings at runtime to individual elements.
A binding element may contain a resources tag, a content tag, a implementation tag and a handlers tag.
id- Theidattribute is a document-unique identifier. For thebindingelement, this attribute is required, since it is used to attach bindings.extends- Theextendsattribute is used to specify the URL of a binding that this binding inherits from (see Inheritance of Implementations). The URL specifies a particular binding document. The # notation must be used to point to a specific bindingidwithin a binding document. Note that content cannot be inherited, only behavior.display- This attribute specifies how the tag is displayed. By setting this attribute, you can have an element have the layout and display characteristics of an existing element. For example, use the value 'xul:button' to create an element that is displayed like a button. The part before the colon is a namespace prefix so you must declare the XUL namespace as well. Not all tags have a unique display type. The following XUL display types may be used: browser, button, checkbox, description, editor, grippy, iframe, image, label, menu, menuitem, menubar, progressmeter, radio, resizer, scrollbar, scrollbox, spacer, splitter, titlebar, treechildren and treecol. You may also use a number of HTML, MathML and SVG tags. The 'display' attribute does not work unless theextendsattribute is set, see bug bug 119389. In that case, put the value of thedisplayattribute into theextendsattribute.inheritstyle- Theinheritstyleattribute indicates whether style rules from the document will affect anonymous content generated by the XBL binding. If this attribute is true, styles from the document will also be applied to the XBL generated anonymous content.
content
<!ELEMENT content ANY> <!ATTLIST content id ID #IMPLIED >
A binding can specify new content that is placed inside the bound element. Although you can see this content on screen as if it was directly in the file, this content is anonymous and is hidden from the normal DOM. To access anonymous nodes on an XBL bound element, you can use the getAnonymousElementByAttribute and getAnonymousNodes functions. The only XBL element that can appear inside the content tag is the children tag. Attributes on the <content> element in the binding are set on the bound element.
id- The id attribute is a document-unique identifier.
children
<!ELEMENT children EMPTY> <!ATTLIST children id ID #IMPLIED includes CDATA #IMPLIED >
Specifies the location where any child elements of the bound element are placed in the generated content.
Normally, if the element bound to has its own content, the anonymous content is not generated. However, with a children element, you can merge the content from the HTML/XML element and the XBL content.
If the children tag contains content itself, that content will become the default content. If the element the binding is attached to contains content, the default content will be ignored. If the element does not contain content, the default content will be added.
id- Theidattribute is a document-unique identifier.includes- Theincludesattribute can be used to indicate that only certain content should be placed at the insertion point specified by thechildrenelement. Its value can be a tag name or multiple tag names separated by the pipe character ("|"). A child can only be placed within the insertion point if it is matched by the value in theincludesattribute. Only immediate children are matched against the selector. For example, an XML fragment<customElement><foobar><hoge/></foobar></customElement>with an binding definition<binding id="customElement"><content><xul:box><children includes="hoge"/></xul:box></content></binding>for thecustomElementelement,<xul:box/>becomes empty because the selectorincludes="hoge"doesn't match for the immediate childfoobarelement.
implementation
<!ENTITY % implementation-content "(method|property)*"> <!ELEMENT implementation %implementation-content;> <!ATTLIST implementation id ID #IMPLIED name CDATA #IMPLIED implements CDATA #IMPLIED >
The implementation element describes the set of methods and properties that are attached to the bound element. Once the binding is attached, these methods and properties can be invoked directly from the bound element.
id- Theidattribute is a document-unique identifier.name- Thenameattribute can be used to provide a specific name for an implementation. This name can then be used to reference the implementation. For example, in JavaScript the value of this attribute represents the name of the corresponding class that is constructed for the implementation. If no name attribute is specified then the binding's document URI and id are used to uniquely reference the binding's implementation.implements- Theimplementsattribute can be used to describe the set of interfaces that are implemented by the binding. Its value is a comma-separated list of named interfaces. If supported, in strongly typed languages the bound element can be referenced not only as any of the interfaces that the element might already support (e.g., HTMLElement) but also as any of the interfaces described by this attribute. Support of this capability is optional.
constructor
The code inside the constructor is called when a binding has just been attached to an element. So full access to anonymous nodes generated by the binding is already possible. The constructor tag must be placed inside the implementation tag.
id- Theidattribute is a document-unique identifier.
destructor
The code inside the destructor is called when a binding is being removed from an element. You can use this to unload resources to free memory. However the destructor is often not called when it should, see bug 230086. The destructor tag must be placed inside the implementation tag.
id- Theidattribute is a document-unique identifier.
method
<!ENTITY % method-content "(parameter*,body?)"> <!ELEMENT method %method-content;> <!ATTLIST method id ID #IMPLIED name CDATA #REQUIRED type CDATA #IMPLIED >
The method element is used to describe a single method of a binding implementation.
id- Theidattribute is a document-unique identifier.name- Thenameattribute's value is the name given to the method when it is attached to the bound element. The method can be invoked directly from the bound element using this value.
Example
<method name="scrollTo">
<parameter name="index"/>
<body>
this.setAttribute("scrollpos", index);
</body>
</method>
parameter
<!ELEMENT parameter EMPTY> <!ATTLIST parameter id ID #IMPLIED name CDATA #REQUIRED >
The parameter element is used inside a method element. It represents a single parameter of a method.
id- Theidattribute is a document-unique identifier.name- The value of thenameattribute is used by script within a method'sbodyelement to reference this parameter.
body
<!ELEMENT body CDATA> <!ATTLIST body id ID #IMPLIED >
The body element represents the implementation of its corresponding method. Its contents are the script that is executed when the method is invoked.
id- Theidattribute is a document-unique identifier.
field
<!ELEMENT field EMPTY> <!ATTLIST field id ID #IMPLIED name CDATA #REQUIRED readonly (true|false) #IMPLIED >
A field is similar to a property, except that it should not have a getter or setter. It is useful as a simple holder for a value. The field element must have content which is code that determines the initial value of the field. The field tag must be inside the implementation tag.
id- Theidattribute is a document-unique identifier.name- The name of the field. This is the name used to refer to the field on the bound element.readonly- If true, this field is read-only. If this attribute is omitted, the field will be readable and writable.
readonly attribute did not work correctly on XBL fields until Gecko 2.0.Here are some examples of cases in which the behavior of your code may change due to this change in Firefox 3:
- If you have two fields, one named
Aand one namedB, and fieldAsets.B, the value of.Bwill depend on whether or not.Ahas already been accessed. - If a proto is inserted into the proto chain after binding instantiation, doing so may affect field values (this wasn't the case in prior versions of Firefox).
- At binding attachment time,
<field name="parentNode">this.parentNode</field>is undefined instead of the value ofparentNode. - A field no longer changes the value of a property set on the object itself (rather than a proto) before binding attachment.
property
<!ENTITY % property-content "(getter?,setter?)"> <!ELEMENT property %property-content;> <!ATTLIST property id ID #IMPLIED name CDATA #REQUIRED readonly (true|false) #IMPLIED onget CDATA #IMPLIED onset CDATA #IMPLIED >
The property element represents a single property of an implementation. A property consists of a pair of getter/setter functions that can be defined using onget/onset attributes or getter/setter elements underneath the property element. Like methods, once the binding is attached, the property can be obtained directly from the bound element. The property tag must be inside the implementation tag.
id- Theidattribute is a document-unique identifier.name- The name of the property. This is the name used to refer to the property on the bound element.readonly- Thereadonlyattribute is used to designate a property as read-only. If set totrue, the value of the property cannot be altered. If this attribute is omitted, the property will be readable and writable.onget- Theongetattribute's value is a script that executes when the value of the property is requested. If this attribute is set, any initial value contained underneath the element will be ignored. The return value of the script represents the value of the property that will be returned to the requestor. A property getter can also be specified as a child of thepropertyelement using thegettertag.onset- Theonsetattribute's value is a script that executes when the value of the property is being altered. If this attribute is set, any initial value contained underneath the element will be ignored. Within the script, the parametervalrepresents the new value being assigned. A property setter can also be specified as a child of thepropertyelement using asettertag.
getter
<!ELEMENT getter PCDATA> <!ATTLIST getter id ID #IMPLIED >
The getter element contains script that gets executed when a specific property gets called. The getter tag must be inside the property tag.
id- Theidattribute is a document-unique identifier.
setter
<!ELEMENT setter PCDATA> <!ATTLIST setter id ID #IMPLIED >
The setter element contains script that gets executed when a specific property is being set. The setter tag must be inside the property tag.
id- Theidattribute is a document-unique identifier.
handlers
<!ENTITY % handlers-content "handler*"> <!ELEMENT handlers %handlers-content;> <!ATTLIST handlers id ID #IMPLIED >
The handlers element contains event handlers that can be attached to elements within the bound document. These handlers are installed when the binding is attached and removed when the binding is detached. The handlers tag must be inside the binding tag.
id- Theidattribute is a document-unique identifier.
handler
<!ENTITY % handler-content "PCDATA"> <!ELEMENT handler %handler-content;> <!ATTLIST handler id ID #IMPLIED event NMREF #REQUIRED action CDATA #IMPLIED phase (capturing|bubbling|target) #IMPLIED button (1|2|3) #IMPLIED modifiers CDATA #IMPLIED keycode CDATA #IMPLIED key CDATA #IMPLIED charcode CDATA #IMPLIED clickcount (1|2|3) #IMPLIED command ID #IMPLIED preventdefault false|true #IMPLIED >
The handler element describes a single event handler. This handler is attached to its target at the time the binding is attached and unhooked when the binding is detached from the bound element. The script inside the handler is executed when the event handler is matched. The handler tag must be inside the handlers tag.
id- Theidattribute is a document-unique identifier.event- Theeventattribute describes the specific event that this handler is listening for. Its value can be any legal DOM event name (including custom events created using the DocumentEvent interface of the DOM).action- Theactionattribute contains script that is invoked when the handler fires. Thetypeattribute on the enclosinghandlerselement determines the language of the script. The handler script can also be specified as a child of thehandlerelement.phase- This attribute specifies the phase of the event flow that this handler should monitor. The possible values arecapturing,bubbling, andtarget. If a phase is specified, the handler will only be invoked during that phase of the event handling process. If no phase is specified, a default ofbubblingis assumed.button- Thebuttonattribute imposes a filter on the handler. It is used with mouse handlers to specify a particular button. The event handler will only be matched if the value of thebuttonfield in the DOM mouse event object matches the value of the attribute.modifiers- Themodifiersattribute imposes a filter on key and mouse handlers. Its value is a whitespace- or comma-separated list of modifier keys. If present in the list, then the modifier key must be set in the DOM event object in order for the handler to be matched. If themodifiersis not empty and the modifier is not present in the list, then the modifier key must not be set in the DOM event object in order for the handler to be matched.
Supported modifiers are:shiftaltcontrolmetaaccel- the platform's primary accelerator key. It is left up to the user agent to decide which modifier key represents the primary key. (It's the Control key on Windows and Meta on Mac.)accesskey- the platform's primary shortcut mnemonic key should be used (the Alt key on Windows and Linux, has no effect on Mac).any- This causes the filter to ignore the state of any modifiers that occur before theanykeword. For example:key="x" modifiers="control shift any"- the handler will match whether or not the control and/or shift keys are pressed. This will match control-x, shift-x, control-shift-x, and x with no modifiers. It will not match any other combinations, such as alt-x or control-altx.key="x" modifiers="control any shift"- the handler will match if the shift key is pressed, whether or not the control key is pressed. This will match shift-x or control-shift-x, but no other combinations.
keycode- Thekeycodeattribute imposes a filter on key handlers. Its value is a key identifier for a specific keycode, e.g.,vk_enter.
[Editor's Note: A forthcoming DOM events specification will presumably outline the list of valid keycode strings.]
If this attribute is present, then its value must match the keyCode field of the DOM key event object in order for the handler to fire.charcode- Thecharcodeattribute imposes a filter on key handlers. Its value is a single character, e.g., "z". If this attribute is present, then its value must match the charCode field of the DOM key event object in order for the handler to fire.
[Editor's note: As DOM Events mature more attributes may be added. For example, mutation events define several new fields such as relatedTarget that could be supported in the filtering syntax.]key- Thekeyattribute has the same meaning ascharcode.clickcount- Theclickcountattribute imposes a filter on the handler. It is used with mouse handlers to specify how many times a button has been clicked. The event handler will only be matched if the value of theclickcountfield in the DOM mouse event object matches the value of the attribute.command- The id of a command to invoke when the event occurs. If used in a non-chrome document, the entire handler will be ignored.preventdefault- If set to true, the default action of the event is not performed. See also preventDefault method of the Event object.
resources
<!ENTITY % resources-content "(image?,stylesheet?)"> <!ELEMENT resources %resources-content;> <!ATTLIST property id ID #IMPLIED >
Used for inclusion of image elements, to cache them for later use, and for inclusion of stylesheet elements. The resources tag must be used directly inside the binding tag.
id- Theidattribute is a document-unique identifier.
stylesheet
<!ELEMENT stylesheet EMPTY> <!ATTLIST stylesheet id ID #IMPLIED src URI #REQUIRED >
The stylesheet element declares a style sheet used by the binding. The style rules in the style sheet will only be applied to the binding, not to other elements in the document. The stylesheet tag must be inside the resources tag.
id- Theidattribute is a document-unique identifier.src- The URL of the style sheet to apply to the binding content.
image
<!ELEMENT image EMPTY> <!ATTLIST image id ID #IMPLIED src URI #REQUIRED >
Declares an image resource used by the binding. The image is loaded as soon as the binding is used. You can use this to preload a number of images for later use. The image tag must be inside the resources tag.
id- Theidattribute is a document-unique identifier.src- The URL of the image to load.