Display the busy indicator for long-running activity in a mobile application

The Spark BusyIndicator control displays a rotating spinner with 12 spokes. You use the BusyIndicator control to provide a visual indication that a long-running operation is in progress.

The following figure shows the BusyIndicator control in the control bar area of a Spark Panel container, next to the Submit button:

Make the BusyIndicator control visible while a long-running operation is in progress. When the operation is complete, hide the control.

For example, you can create an instance of the BusyIndicator control in an event handler, possibly the event handler that starts the long-running process. In the event handler, call the addElement() method to add the control to a container. When the process is complete, call removeElement() to remove the BusyIndicator control from the container.

Another option is to use the visible property of the control to show and hide it. In the following example, you add the BusyIndicator control to the control bar area of a Spark Panel container in a View container:
<?xml version="1.0" encoding="utf-8"?>
<!-- components\mobile\views\SimpleBusyIndicatorHomeView.mxml -->
<s:View xmlns:fx="http://ns.adobe.com/mxml/2009" 
    <s:Panel id="panel" title="Busy Indicator Example" 
        width="100%" height="100%">
            <s:Button label="Submit" />
            <s:BusyIndicator id="bi" 
        <s:VGroup left="10" right="10" top="10" bottom="10">
            <s:Label width="100%" color="blue"
                text="Click the Busy button to see the BusyIndicator."/>
            <s:Button label="Busy" 
                click="{bi.visible = !bi.visible}" />

In this example, the visible property of the BusyIndicator control is initially set to false to hide it. Click the Busy button to set the visible property to true to show the control.

The BusyIndicator control only spins when it is visible. Therefore, when you set the visible property to false, the control does not require any processing cycles.

Note: Setting the visible property to false hides the control, but the control is still included in the layout of its parent container. To exclude the control from layout, set the visible and includeInLayout properties to false.

The Spark BusyIndicator control does not support skinning. However, you can use styles to set the color and rotation interval of the spinner. In the previous example, you set the color of the indicator by using the symbolColor property.