call javascript or modify css from wicket panel class

in my project i've faced a problem with calling javascript code from class wich renders
html in wicket.Suppose we have a class ExamplePanel with following code for wicket panel

 public final class ExamplePanel extends Panel {

      public ExamplePanel(String id) {
          super(id);
          add(new Label("someText", "hello"));
      }}

and html file 'ExamplePanel'

 <html xmlns:wicket>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
        <title>ExamplePanel</title>
        <wicket:head>
            <link href="panel.css" rel="stylesheet"/>
            <script src="jquery.min.js"></script>
            <script src="jquery-ui.min.js"></script>

        </wicket:head>
    </head>
    <body>
        <wicket:panel>
            <div id="parentContainer">
                <div id="box" wicket:id="someText"></div>
            </div>
        </wicket:panel>
    </body>
</html>

and following css

    #box{
    background: #f0f0f0;
    width: 50px;
    height: 50px;
    position: absolute;
    top: 200px;
    left: 200px;
    font-size: 1.5em;
    word-wrap: break-word; 
}

#parentContainer{
    width:500px;
    height: 500px;
     background:RGB(57,51,51);
     position:relative;
}

from this code we have box inside the parentContainer div, and i need to pass the position coordinates to box when initialize the ExamplePanel class, for example :

public ExamplePanel(String id) {
    super(id);
    add(new Label("someText", "hello"));
    // add some code for css positioning of box div
    // $('#div').css({position:'relative',top:'5px',left='29px'}) for example
}

any suggestions?

Solution

ExamplePanel must implement IHeaderContributor which provides a method renderHead(IHeaderResponse). From this method, you can call response.renderString() passing it the styles you want to apply. In your case, you are not adding styles, you are adding a JS call that adds some styles. Doing this makes the java call a little more simple because instead of needing to create the as part of the string you render, you will only need to call response.renderJavascript()...

public class ExamplePanel implements IHeaderContributor {
    public ExamplePanel(String id) {
        super(id);

        add(new Label("someText", "hello"));
    }

    @Override
    public void renderHead(IHeaderResponse response) {
        // use this if you want to add only the styles
        response.renderString("<style>#div {position:'relative'; top:'5px'; left='29px';}</style>");

        // or, use this if you still want the JS selector
        // the uniqueId should not be null if you want Wicket to check if the script has already been rendered
        response.renderJavascript("$('#div').css({position:'relative',top:'5px',left='29px'})", null);
    }
}

The IHeaderContributor interface is intended to facilitate the addition of Resources such as JavaScript and CSS.