View source

__NOTOC__
__NOEDITSECTION__

{{KBCS}}
{{CodeSnippet
|id=CS001248;
|platform=S60 3rd Edition, FP2, S60 5th Edition
|devices=Nokia E90 Communicator (v.210.34.75 and later), Nokia 5800 XpressMusic
|category=Web Runtime (WRT)
|subcategory=Hardware
|creationdate=November 24, 2008
|keywords=x-systeminfo-widget, SystemInfo.lightblink(), SystemInfo.lighton()
}}

==Overview==

This code snippet demonstrates how to control the backlight of a device by using the SystemInfo Service API of the Web Runtime version 1.0. 

The API is supported from S60 3rd Edition, Feature Pack 2 onwards. It is also supported in select S60 3rd Edition, Feature Pack 1 devices or their newest firmware versions (for example, Nokia E90 Communicator, from v.210.34.75 onwards). 

==Source==

Embed the SystemInfo widget into the document:

<code xml>
<body>
    <embed type="application/x-systeminfo-widget" hidden="yes" />
</body>
</code>

Add three buttons to control the backlight:

<code xml>
<input type="button" onclick="lightOn();" value="Light on" />
<input type="button" onclick="blink();" value="Blink" />
<input type="button" onclick="lightOff();" value="Light off" />
</code>

The JavaScript code:

<code javascript>
var sysInfo = null;

window.onload = init;

var SMOOTH = true;

function init() {
    // Obtain the SystemInfo object
    try {
        sysInfo = document.embeds[0];
    } catch (ex) {
        alert("SystemInfo object cannot be found.");
        return;
    }
}

// Switches the display light on
function lightOn() {
    if (sysInfo == undefined) {
        alert("SystemInfo object is undefined.");
        return;
    }
    
    // Reset the backlight state to default
    resetLight();

    sysInfo.lighton(sysInfo.lighttargetsystem, sysInfo.lightinfiniteduration,
        sysInfo.lightmaxintensity, SMOOTH);
}

// Starts blinking the display 
function blink() {
    if (sysInfo == undefined) {
        alert("SystemInfo object is undefined.");
        return;
    }
    
    // Reset the backlight state to default
    resetLight();

    sysInfo.lightblink(sysInfo.lighttargetsystem,
        sysInfo.lightinfiniteduration, sysInfo.lightdefaultcycletime,
        sysInfo.lightdefaultcycletime, sysInfo.lightmaxintensity);
}

// Switches the display light off
function lightOff() {
    if (sysInfo == undefined) {
        alert("SystemInfo object is undefined.");
        return;
    }
    
    sysInfo.lightoff(sysInfo.lighttargetsystem, sysInfo.lightinfiniteduration,
        SMOOTH);
}

// Sets the backlight of the display to default value
function resetLight() {
    if (sysInfo == undefined) {
        alert("SystemInfo object is undefined.");
        return;
    }
    
    sysInfo.lighton(sysInfo.lighttargetsystem, sysInfo.lightinfiniteduration,
        sysInfo.lightdefaultintensity, SMOOTH);
}
</code>

==Postconditions==

Different possibilities to control the backlight are demonstrated.

==Supplementary material==

For a complete example that makes use of the SystemInfo Service API to control the backlight, see [[Media:Blinking_flashing_increasing_brightness_of_backlight_in_WRT.zip|Blinking_flashing_increasing_brightness_of_backlight_in_WRT.zip]]

[[Category:Web Runtime (WRT)]][[Category:Code Examples]][[Category:Hardware]][[Category:S60 3rd Edition, Feature Pack 1]][[Category:S60 3rd Edition, Feature Pack 2]][[Category:S60 5th Edition]]