Widget Customization"
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=Override Widget's Default Behavior= | =Override Widget's Default Behavior= | ||
− | There are many ways to override the default behavior of widgets or even ZK Client Engine. JavaScript is a dynamic language and you could override almost any | + | There are many ways to override the default behavior of widgets or even ZK Client Engine. JavaScript is a dynamic language and you could override almost any methods you want. |
==Override a Widget Method== | ==Override a Widget Method== | ||
− | + | This way overrides a particular widget. So, it only overrides the widget's methods you specified and does not affect other widgets on the same page. | |
− | For example, suppose | + | For example, suppose you want to change a label's CSS style when its value is changed, then you can write the code as follows: |
<source lang="xml"> | <source lang="xml"> | ||
− | < | + | <zk xmlns:w="http://www.zkoss.org/2005/zk/client"> |
<label> | <label> | ||
<attribute w:name="setValue"> | <attribute w:name="setValue"> | ||
Line 22: | Line 22: | ||
</attribute> | </attribute> | ||
</label> | </label> | ||
− | </ | + | </zk> |
</source> | </source> | ||
where | where | ||
− | * We specify [[ZUML Reference/ZUML/Namespaces/Client|client namespace]] to the <code>setValue</code> attribute to indicate | + | * We specify [[ZUML Reference/ZUML/Namespaces/Client|client namespace]] to the <code>setValue</code> attribute to indicate the method to override |
* The content of the attribute is a complete function definition of the method, including <code>function ()</code> | * The content of the attribute is a complete function definition of the method, including <code>function ()</code> | ||
* You can access the widget by <code>this</code> in the function | * You can access the widget by <code>this</code> in the function | ||
* You can access the original method by <code>this.$xxx</code>, where xxx is the method name being overridden. If the method doesn't exist, it is null. | * You can access the original method by <code>this.$xxx</code>, where xxx is the method name being overridden. If the method doesn't exist, it is null. | ||
* To retrieve another widget, use <code>this.$f('anotherWidgetId')</code> or other methods as described in the previous section | * To retrieve another widget, use <code>this.$f('anotherWidgetId')</code> or other methods as described in the previous section | ||
− | * You can specify EL expressions | + | * {{versionSince| 5.0.2}} You can specify EL expressions in the content of the attribute, such as |
− | <source lang=" | + | <source lang="xml"> |
− | w:setValue='function (value) { this.$setValue(value + "${whatever}")}' | + | <label w:setValue='function (value) { this.$setValue(value + "${whatever}")}' /> |
</source> | </source> | ||
− | Notice EL expressions are evaluated at the server before | + | Notice that EL expressions are evaluated at the server-side before sending back to the client. Thus, you can use any Java class or variables in EL expressions. |
− | + | == Override a Widget in Java == | |
− | |||
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− | + | In addition to ZUML, you can override a Widget's '''method''' or '''field''' by the use of <javadoc method="setWidgetOverride(java.lang.String, java.lang.String)" type="interface">org.zkoss.zk.ui.Component</javadoc> at the server. For example, | |
− | In previous section, we showed how to override method of a particular widget | + | <source lang="java"> |
+ | myLabel.setWidgetOverride("setValue", | ||
+ | "function (value) {this.$setValue('overloaded setValue');}"); | ||
+ | </source> | ||
+ | |||
+ | ==Override a Default Widget Method in zul== | ||
+ | |||
+ | In the previous section, we showed you how to override the method of a particular widget. If you want to modify the behavior of all instances of a widget class, you have to override the method in <code>prototype</code> (For more information about JavaScript's prototype, please refer to [http://www.packtpub.com/article/using-prototype-property-in-javascript Using Prototype Property in JavaScript] and [http://www.w3schools.com/jsref/jsref_prototype_math.asp JavaScript prototype Property]). | ||
For example, | For example, | ||
− | <source lang="xml" | + | <source lang="xml" highlight="5"> |
<window xmlns:w="http://www.zkoss.org/2005/zk/client"> | <window xmlns:w="http://www.zkoss.org/2005/zk/client"> | ||
<label id="labelone" value="label one"/> | <label id="labelone" value="label one"/> | ||
Line 67: | Line 71: | ||
</source> | </source> | ||
− | + | Where we assign a new method to <code>zul.wgt.Label.prototype.setValue</code>. Since it is <code>prototype</code>, the <code>setValue()</code> of all instances are overriden. | |
+ | |||
+ | == Override a Default Widget Method in JavaScript File == | ||
+ | It's easy to include an overridden js in multiple zul files. Here is a sample: | ||
+ | <source lang='js'> | ||
+ | zk.afterLoad('zul.inp', function() { //specify zk widget package name | ||
+ | var exWidget = {}; | ||
+ | zk.override(zul.inp.ComboWidget.prototype, exWidget, { //specify zk full widget name | ||
+ | doClick_: function(e){ | ||
+ | exWidget.doClick_.apply(this, arguments); //call the original widget's overridden function | ||
+ | //implement your custom logic | ||
+ | }, | ||
+ | }); | ||
+ | |||
+ | }); | ||
+ | </source> | ||
+ | * Line 1: this line will run <code>zk.override()</code> after the <code>zul.inp</code> widgets are loaded, so you don't need to take care this overridden script's loading order. You can include such JavaScript in any place of a zul. | ||
+ | |||
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− | |||
==Override a Widget Field== | ==Override a Widget Field== | ||
− | You can override a method or a field no matter it exists or not. For example, | + | You can override a method or a field no matter it exists or not. For example, you can use this feature to pass an application-specific data to a widget, such as |
− | <source lang=" | + | <source lang="xml"> |
− | <label value="hello" w: | + | <label value="hello" w:myOption="'${param.enabled}'"/> |
</source> | </source> | ||
Notice that the content of the attribute must be a valid JavaScript snippet. To specify a string (as shown above), you have to enclose it with ' or " if you want to pass a string. It also means you can pass anything, such as <code>new Date()</code>. | Notice that the content of the attribute must be a valid JavaScript snippet. To specify a string (as shown above), you have to enclose it with ' or " if you want to pass a string. It also means you can pass anything, such as <code>new Date()</code>. | ||
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=Specify Your Own Widget Class= | =Specify Your Own Widget Class= | ||
Line 107: | Line 115: | ||
<source lang="javascript"> | <source lang="javascript"> | ||
+ | zk.$package("foo"); | ||
zk.afterLoad("zul.wgt", function () { | zk.afterLoad("zul.wgt", function () { | ||
− | + | foo.MyButton = zk.$extends(zul.wgt.Button, { | |
setLabel: function (label) { | setLabel: function (label) { | ||
this.$supers("setLabel", arguments); | this.$supers("setLabel", arguments); | ||
Line 119: | Line 128: | ||
Notice that <javadoc directory="jsdoc" method="afterLoad(_global_.String, _global_.Function)">_global_.zk</javadoc> is used to defer the declaration of <code>foo.MyButton</code> until <code>zul.wgt</code> has been loaded. | Notice that <javadoc directory="jsdoc" method="afterLoad(_global_.String, _global_.Function)">_global_.zk</javadoc> is used to defer the declaration of <code>foo.MyButton</code> until <code>zul.wgt</code> has been loaded. | ||
− | + | =Load JavaScript Files for Overriding Widgets= | |
+ | |||
+ | If you put your overridden js code in a separate file, you need to include it to take effect on widgets. | ||
− | + | == Page Scope== | |
+ | If you just want to override widgets on some pages, you can use one of the following: | ||
+ | * [[ZK_Component_Reference/Essential_Components/Script|<script> component]] | ||
+ | * HTML <code><script></code> | ||
+ | * [[ZUML Reference/ZUML/Processing Instructions/script|<?script ?> directive]] | ||
+ | |||
+ | == Application Scope == | ||
+ | To override all widgets in the whole application, you need to include the js file in every page with: | ||
+ | * [[ZK%20Configuration%20Reference/zk.xml/The%20device-config%20Element/The%20embed%20Element | <embed> in zk.xml]] | ||
+ | * [[ZK_Client-side_Reference/Language_Definition/javascript]] | ||
= The Client-Attribute Namespace = | = The Client-Attribute Namespace = | ||
− | + | {{versionSince| 5.0.3}} | |
− | + | You can specify additional '''DOM attributes''' that are not generated by ZK widgets with [[ZUML Reference/ZUML/Namespaces/Client Attribute|client-attribute namespace]] (<code>http://www.zkoss.org/2005/zk/client/attribute</code>. shortcut, <code>client/attribute</code>). In other words, whatever attributes you specify with the client-attribute namespace will be generated directly to the browser's DOM tree. Whether it is meaningful, it is really up to the browser -- ZK does not handle or filter it at all. | |
− | For example, you want to listen to the <code>onload</code> event, and then you can do as follows | + | For example, you want to listen to the <code>onload</code> event, and then you can do as follows. Fore more information, please refer to [[ZK Component Reference/Essential Components/Iframe#onload|ZK Component Reference: iframe]]. |
<source lang="xml"> | <source lang="xml"> | ||
Line 136: | Line 156: | ||
</source> | </source> | ||
− | If the attribute contains colon or other special characters, you can use the <code>attribute</code> element as follows | + | <syntaxhighlight lang='xml'> |
+ | <zk xmlns:ca="client/attribute"> | ||
+ | HTML 5 spell check enabled: | ||
+ | <textbox ca:spellcheck="true"/> | ||
+ | </zk> | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | If the attribute contains colon or other special characters, you can use the <code>attribute</code> element as follows: | ||
<source lang="xml"> | <source lang="xml"> | ||
Line 147: | Line 174: | ||
The other use of the client-attribute namespace is to specify attributes that are available only to certain browsers, such as accessibility and [http://www.section508.gov/index.cfm?FuseAction=Content&ID=12#Web Section 508]. | The other use of the client-attribute namespace is to specify attributes that are available only to certain browsers, such as accessibility and [http://www.section508.gov/index.cfm?FuseAction=Content&ID=12#Web Section 508]. | ||
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=Version History= | =Version History= |
Latest revision as of 06:51, 13 April 2022
Override Widget's Default Behavior
There are many ways to override the default behavior of widgets or even ZK Client Engine. JavaScript is a dynamic language and you could override almost any methods you want.
Override a Widget Method
This way overrides a particular widget. So, it only overrides the widget's methods you specified and does not affect other widgets on the same page. For example, suppose you want to change a label's CSS style when its value is changed, then you can write the code as follows:
<zk xmlns:w="http://www.zkoss.org/2005/zk/client">
<label>
<attribute w:name="setValue">
function (value) {
this.$setValue(value); //call the original method
if (this.desktop) {
this._flag = !this._flag;
this.setStyle('background:'+(this._flag ? 'red':'green'));
}
}
</attribute>
</label>
</zk>
where
- We specify client namespace to the
setValue
attribute to indicate the method to override - The content of the attribute is a complete function definition of the method, including
function ()
- You can access the widget by
this
in the function - You can access the original method by
this.$xxx
, where xxx is the method name being overridden. If the method doesn't exist, it is null. - To retrieve another widget, use
this.$f('anotherWidgetId')
or other methods as described in the previous section - Since 5.0.2 You can specify EL expressions in the content of the attribute, such as
<label w:setValue='function (value) { this.$setValue(value + "${whatever}")}' />
Notice that EL expressions are evaluated at the server-side before sending back to the client. Thus, you can use any Java class or variables in EL expressions.
Override a Widget in Java
In addition to ZUML, you can override a Widget's method or field by the use of Component.setWidgetOverride(String, String) at the server. For example,
myLabel.setWidgetOverride("setValue",
"function (value) {this.$setValue('overloaded setValue');}");
Override a Default Widget Method in zul
In the previous section, we showed you how to override the method of a particular widget. If you want to modify the behavior of all instances of a widget class, you have to override the method in prototype
(For more information about JavaScript's prototype, please refer to Using Prototype Property in JavaScript and JavaScript prototype Property).
For example,
<window xmlns:w="http://www.zkoss.org/2005/zk/client">
<label id="labelone" value="label one"/>
<label id="labeltwo" value="label two"/>
<script defer="true">
var oldSV = zul.wgt.Label.prototype.setValue;
zul.wgt.Label.prototype.setValue = function (){
arguments[0]="modified prototype"+arguments[0];
oldSV.apply(this, arguments);
}
</script>
<button label="change" onClick="labelone.setValue((new Date()).toString());
labeltwo.setValue((new Date()).toString());"/>
</window>
Where we assign a new method to zul.wgt.Label.prototype.setValue
. Since it is prototype
, the setValue()
of all instances are overriden.
Override a Default Widget Method in JavaScript File
It's easy to include an overridden js in multiple zul files. Here is a sample:
zk.afterLoad('zul.inp', function() { //specify zk widget package name
var exWidget = {};
zk.override(zul.inp.ComboWidget.prototype, exWidget, { //specify zk full widget name
doClick_: function(e){
exWidget.doClick_.apply(this, arguments); //call the original widget's overridden function
//implement your custom logic
},
});
});
- Line 1: this line will run
zk.override()
after thezul.inp
widgets are loaded, so you don't need to take care this overridden script's loading order. You can include such JavaScript in any place of a zul.
Override a Widget Field
You can override a method or a field no matter it exists or not. For example, you can use this feature to pass an application-specific data to a widget, such as
<label value="hello" w:myOption="'${param.enabled}'"/>
Notice that the content of the attribute must be a valid JavaScript snippet. To specify a string (as shown above), you have to enclose it with ' or " if you want to pass a string. It also means you can pass anything, such as new Date()
.
Specify Your Own Widget Class
You could specify your own implementation instead of the default widget class (at the client) as follows.
<zk xmlns:w="http://www.zkoss.org/2005/zk/client">
...
<button w:use="foo.MyButton"/>
</zk>
where foo.MyButton
is a widget you implement. For example,
zk.$package("foo");
zk.afterLoad("zul.wgt", function () {
foo.MyButton = zk.$extends(zul.wgt.Button, {
setLabel: function (label) {
this.$supers("setLabel", arguments);
//do whatever you want
}
});
});
Notice that zk.afterLoad(String, Function) is used to defer the declaration of foo.MyButton
until zul.wgt
has been loaded.
Load JavaScript Files for Overriding Widgets
If you put your overridden js code in a separate file, you need to include it to take effect on widgets.
Page Scope
If you just want to override widgets on some pages, you can use one of the following:
- <script> component
- HTML
<script>
- <?script ?> directive
Application Scope
To override all widgets in the whole application, you need to include the js file in every page with:
The Client-Attribute Namespace
Since 5.0.3
You can specify additional DOM attributes that are not generated by ZK widgets with client-attribute namespace (http://www.zkoss.org/2005/zk/client/attribute
. shortcut, client/attribute
). In other words, whatever attributes you specify with the client-attribute namespace will be generated directly to the browser's DOM tree. Whether it is meaningful, it is really up to the browser -- ZK does not handle or filter it at all.
For example, you want to listen to the onload
event, and then you can do as follows. Fore more information, please refer to ZK Component Reference: iframe.
<iframe src="http://www.google.com" width="100%" height="300px"
xmlns:ca="client/attribute" ca:onload="do_whater_you_want()"/>
<zk xmlns:ca="client/attribute">
HTML 5 spell check enabled:
<textbox ca:spellcheck="true"/>
</zk>
If the attribute contains colon or other special characters, you can use the attribute
element as follows:
<div xmlns:ca="client/attribute">
<attribute ca:name="ns:whatever">
whatever_value_you_want
</attribute>
</div>
The other use of the client-attribute namespace is to specify attributes that are available only to certain browsers, such as accessibility and Section 508.
Version History
Version | Date | Content |
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