This component defines a subtree of the component tree as draggable for drag-and-drop operations. Within such a "drag zone," you can click the mouse button on an item and drag it to any component that supports drop operations (a "drop zone"). It encodes all the necessary JavaScript for supporting drag-and-drop operations.

Figure 6.50.  <rich:dragSupport> component

The dragSupport tag inside a component completely specifies the events and JavaScript required to use the component and it's children for dragging as part of a drag-and-drop operation. In order to work, though, dragSupport must be placed inside a wrapper component that outputs child components and that has the right events defined on it. Thus, this example won't work, because the <h:column> tag doesn't provide the necessary properties for redefining events on the client:

Example:

...

<h:column>

        <rich:dragSupport dragIndicator=":form:iii" dragType="text">

                <a4j:actionparam value="#{caps.name}" name="name"/>

        </rich:dragSupport>

        <h:outputText value="#{caps.name}"/> 

</h:column>

...

However, using a4j:outputPanel as a wrapper inside <h:column> , the following code could be used successfully:

Example:

...

<h:column>

        <a4j:outputPanel>

                <rich:dragSupport dragIndicator=":form:iii" dragType="text">

                        <a4j:actionparam value="#{caps.name}" name="name"/>

                </rich:dragSupport>

                <h:outputText value="#{caps.name}"/> 

        </a4j:outputPanel>

</h:column>

...

This code makes all rows of this column draggable.

One of the main attributes for dragSupport is "dragType" , which associates a name with the drag zone. Only drop zones with this name as an acceptable type can be used in drag-and-drop operations. Here is an example:

Example:

...

<h:panelGrid id="drag1">

        <rich:dragSupport dragType="singleItems" .../>

        <!--Some content to be dragged-->

</h:panelGrid>      

...

<h:panelGrid id="drag2">

        <rich:dragSupport dragType="groups" .../>

        <!--Some content to be dragged-->

</h:panelGrid>      

...

<h:panelGrid id="drop1">

        <rich:dropSupport acceptedTypes="singleItems" .../>

        <!--Drop zone content-->

</h:panelGrid>

...

In this example, the drop1 panel grid is a drop zone that invokes drag-and-drop for drops of items from the first drag1 panel grid, but not the second drag2 panel grid. In the section about dropSupport , you will find an example that shows more detailed information about moving data between tables with drag and drop.

The dragSupport component also has a "value" attribute for passing data into the processing after a drop event.

One more important attribute for <rich:dragSupport> is the "dragIndicator" attribute that point to the component id of the <rich:dragIndicator> component to be used for dragged items from this drag zone. If it isn't defined, a default indicator for drag operations is used.

Finally, the component has the following extra attributes for event processing on the client:

You can use your own custom JavaScript functions to handle these events.

Table of <rich:dragSupport> attributes.

On the component Live Demo page you can see the example of <rich:dragSupport> usage and sources for the given example.