Modal Windows"

From Documentation
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{{ZKDevelopersGuidePageHeader}}
 
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This section describes the notes when using the Servlet thread to process the event (the default).
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=== Modal Windows with Servlet Thread ===
  
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=== Modal Windows ===
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When the event is processed in the Servlet thread (default), the execution cannot be suspended. Thus, the modal window behaves the same as the highlited window (<javadoc method="doHighlighted()">org.zkoss.zul.Window</javadoc>). At the client side, the visual effect is the same: a semi-transparent mask blocks the end user from access components other than the modal window. However, at the server side, it works just like the overlapped mode – it returns immediately without waiting for user's closing the window.
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Since the event is processed in the Servlet thread, the execution cannot be suspended. Thus, the modal window behaves the same as the highlited window. At the client side, the visual effect is the same: a semi-transparent mask blocks the end user from access components other than the modal window. However, at the server side, it works just like the overlapped mode – it returns immediately without waiting for user's closing the window.
 
  
 
<source lang="java" >
 
<source lang="java" >
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  win.doHighlighted(); //returns once the mode is changed; not suspended
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  win.doModal(); //returns once the mode is changed; not suspended
 
  System.out.println("next");
 
  System.out.println("next");
 
</source>
 
</source>
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The "next" message will be printed to the console before the end user closes the modal window.
 
The "next" message will be printed to the console before the end user closes the modal window.
  
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=== Message Boxes ===
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=== Modal Windows with Event Thread ===
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The message boxes returns immediately so it always returns <tt>Messagebox.OK</tt>. Thus, it is meaningless to show buttons other than the OK button. For example, the <tt>if</tt> clause in the following example is never true.
 
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<source lang="java" >
 
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if (Messagebox.show("Delete?", "Prompt", Messagebox.YES|Messagebox.NO,
 
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    Messagebox.QUESTION) == Messagebox.YES) {
 
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    this_never_executes();
 
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}
 
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</source>
 
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Rather, you have to provide an event listener as follows.
 
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<source lang="java" >
 
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Messagebox.show("Delete?", "Prompt", Messagebox.YES|Messagebox.NO,
 
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    Messagebox.QUESTION,
 
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    new EventListener() {
 
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        public void onEvent(Event evt) {
 
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            switch (((Integer)evt.getData()).intValue()) {
 
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            case Messagebox.YES: doYes(); break; //the Yes button is pressed
 
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            case Messagebox.NO: doNo(); break; //the No button is pressed
 
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            }
 
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        }
 
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    }
 
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);
 
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</source>
 
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The event listener you provided is invoked when the user clicks one of the buttons. Then, you can identify which button is clicked by examining the data (Event's <tt>getData</tt>). The data is an integer whose value is the button's identifier, such as <tt>Messagebox.YES</tt>.
 
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Alternatively, you can examine the event name:
 
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<source lang="java" >
 
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public void onEvent(Event evt) {
 
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    if ("onYes".equals(evt.getName())) {
 
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        doYes(); //the Yes button is pressed
 
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    } else if ("onNo".equals(evt.getName())) {
 
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        doNo(); //the No button is pressed
 
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    }
 
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}
 
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</source>
 
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'''Note''': The event name for the OK button is <tt>onOK</tt>, not <tt>onOk</tt>.
 
  
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=== File Upload ===
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If the event thread is enabled, <javdoc method="doModal">org.zkoss.zul.Window</javadoc> will suspend the current thread. Thus, the "next" message won't be shown, until the modal window is closed.
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The file upload dialog is no longer applicable. Rather, you shall use <javadoc>org.zkoss.zul.Button</javadoc> or <javadoc>org.zkoss.zul.Toolbarbutton</javadoc> with upload="true" instead. For example,
 
  
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<source lang="xml">
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When the event thread is suspended, the Servlet thread will be resumed and continue to fork another event thread to process other events, if any. Thus, the end user still have the control (such that he can close the modal window if he want).
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<zk>
 
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<zscript>
 
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void upload(Event event) {
 
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org.zkoss.util.media.Media media = event.getMedia();
 
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if (media instanceof org.zkoss.image.Image) {
 
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org.zkoss.zul.Image image = new org.zkoss.zul.Image();
 
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image.setContent(media);
 
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image.setParent(pics);
 
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} else {
 
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Messagebox.show("Not an image: "+media, "Error", Messagebox.OK, Messagebox.ERROR);
 
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break; //not to show too many errors
 
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}
 
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}
 
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</zscript>
 
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<button label="Upload" upload="true" onUpload="upload(event)"/>
 
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<toolbarbutton label="Upload" upload="true" onUpload="upload(event)"/>
 
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<vbox id="pics" />
 
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</zk>
 
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</source>
 
  
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If you prefer to use a dialog (<javadoc method="get()">org.zkoss.zul.Fileupload</javadoc>), please take a look at [[ZK_Component_Reference/Essential_Components/Fileupload | ZK Component Reference: Fileupload]] for more inormation.
 
 
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{{ZKDevelopersGuidePageFooter}}

Revision as of 04:52, 3 September 2010

DocumentationZK Developer's ReferenceUI PatternsEvent ThreadsModal Windows
Modal Windows


Stop.png This documentation is for an older version of ZK. For the latest one, please click here.


Modal Windows with Servlet Thread

When the event is processed in the Servlet thread (default), the execution cannot be suspended. Thus, the modal window behaves the same as the highlited window (Window.doHighlighted()). At the client side, the visual effect is the same: a semi-transparent mask blocks the end user from access components other than the modal window. However, at the server side, it works just like the overlapped mode – it returns immediately without waiting for user's closing the window. 

 win.doModal(); //returns once the mode is changed; not suspended
 System.out.println("next");

The "next" message will be printed to the console before the end user closes the modal window.

Modal Windows with Event Thread

If the event thread is enabled, <javdoc method="doModal">org.zkoss.zul.Window</javadoc> will suspend the current thread. Thus, the "next" message won't be shown, until the modal window is closed.

When the event thread is suspended, the Servlet thread will be resumed and continue to fork another event thread to process other events, if any. Thus, the end user still have the control (such that he can close the modal window if he want).



Last Update : 2010/09/03

Copyright © Potix Corporation. This article is licensed under GNU Free Documentation License.


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