This topic describes multitasking, which allows you to save the application state when the user launches another application or TV channel, and to restore it when the application is resumed. You can also monitor for changes in the visibility of your application.
When the user switches from your application to another application or TV channel, JavaScript execution is paused, and your application must save its current state to RAM and hide in the background. The application state is recovered when the application is resumed.
The following table lists the Samsung TV models that support multitasking. Multitasking is also supported on the TV emulator since Tizen TV Extension 2.1.2.
Table 1. Samsung TV model groups supporting multitasking
If you want to know more about TV Seller Office Model Groups, please refer to TV Model Groups.
A running application can be hidden based on the application logic, or through user interaction:
To hide the current application, call the hide() method:
hide()
tizen.application.getCurrentApplication().hide();
To monitor the visibility state of your application, create a listener for the visibilitychange event. The listener is notified each time your application is hidden or resumed, for example due to user interaction.
visibilitychange
document.addEventListener('visibilitychange', function() { if (document.hidden) { // Behavior when application is hidden } else { // Behavior when application is resumed } });
Some special scenarios can occur during multitasking. You must pay attention to these and ensure that your application responds appropriately.
During media playbackWhen the application is hidden during media playback, implement the same behavior as clicking the "Return" key during playback.
document.addEventListener('visibilitychange', function() { if (document.hidden) { // Same behavior as "Return" key click // For example, stop playback and return to previous page } else { // Behavior when application is resumed } });
Checking network statusThe network connection status can change while your application is hidden, preventing the application from functioning properly when it is resumed.To check for network connectivity when your application resumes:
document.addEventListener('visibilitychange', function() { if (document.hidden) { ... } else { var gatewayStatus = webapis.network.isConnectedToGateway(); if (!gatewayStatus) { // Behavior when the network is disconnected } } });
If the network is disconnected, you must stop jobs requiring a network connection, such as network media playback and server request sending. Return the user to the previous page, inform them of the disconnected status using a popup, and monitor for network reconnection. For more information, see Checking Network Status.
Handling expired dataIf an application is hidden for a long time, stored runtime data can become invalid because of the service's security policy. You must check whether this data is still valid when the application is resumed. The following are examples of situations where you need to handle expired data:
Calculating timeBe careful when using the time() method. When an application is in the hidden state, JavaScript execution is paused, potentially affecting time calculations:
time()