[收集]关于背景灯的文章收集

最近由于工作需要，需要对背景灯进行操作。对于背景灯设置API说得并不清晰而且缺少例子，网上能找到的资料也不多，这里放上一些最近搜集到的，以作备忘。

CS000957 - Flashing the backlight

From Forum Nokia Wiki

ID	CS000957	Creation date	May 14, 2008
Platform	S60 3rd Edition, MR S60 3rd Edition, FP1	Tested on devices	Nokia E61i Nokia N95 8GB
Category	Java ME	Subcategory	Hardware

 

Keywords (APIs, classes, methods, functions) : javax.microedition.lcdui.Display, javax.microedition.lcdui.Display.flashBacklight()

Overview

This snippet demonstrates how to flash the backlight of the device for a specified duration. In practice, the MIDlet constructs a menu item through which the user can flash the backlight.

Source

Flashing the backlight can be implemented as follows:

// Flash the backlight for 5 seconds

Display.getDisplay
(
this
)
.flashBacklight
(
5000)
;

Here is a complete example:

import
 
javax.microedition.lcdui.Command
;

import
 
javax.microedition.lcdui.CommandListener
;

import
 javax.microedition.lcdui.Display
;

import
 javax.microedition.lcdui.Displayable
;

import
 javax.microedition.lcdui.Form
;

import
 javax.microedition.midlet.MIDlet
;

public
 class
 ExampleMIDlet extends
 MIDlet implements
 CommandListener {


    private
 Command flashCommand;

    private
 Command exitCommand;

    private
 Form mainForm;


    /**
     * Constructor. Constructs the object and initializes displayables.
     */

    public
 ExampleMIDlet(
)
 
{

        mainForm =
 new
 Form(
"ExampleMIDlet"
)
;

        flashCommand =
 new
 Command(
"Flash"
, Command.SCREEN
, 0)
;

        mainForm.addCommand
(
flashCommand)
;

        exitCommand =
 new
 Command(
"Exit"
, Command.EXIT
, 0)
;

        mainForm.addCommand
(
exitCommand)
;

        mainForm.setCommandListener
(
this
)
;

    }

 
    /**
     * Called when the MIDlet is started.
     */

    public
 void
 startApp(
)
 {

        Display.getDisplay
(
this
)
.setCurrent
(
mainForm)
;

    }


     // Other inherited methods omitted for brevity

    // ...

 
    /**
     * From CommandListener.
     * Called by the system to indicate that a command has been invoked on a
     * particular displayable.
     * @param command the command that was invoked
     * @param displayable the displayable where the command was invoked
     */

    public
 void
 commandAction(
Command command, Displayable displayable)
 {

        if
 (
command ==
 flashCommand)
 {

            // Flash the backlight for 5 seconds

            boolean
 flashAllowed =
 Display.getDisplay
(
this
)
.flashBacklight
(
5000)
;

            if
 (
!
flashAllowed)
 {

                // TODO: Flashing is not allowed. Inform the user.

            }

        }
 else
 if
 (
command ==
 exitCommand)
 {

            // Exit the MIDlet

            destroyApp(
true
)
;

            notifyDestroyed(
)
;

        }

    }

Postconditions

If the user selects the Flash menu item, the backlight is flashed for 5 seconds.

 

原文连接：http://wiki.forum.nokia.com/index.php/CS000957_-_Flashing_the_backlight

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How to block the screen saver

From Forum Nokia Wiki

If your application doesn't demand constant key presses, after a while the screen saver on a J2ME phone will start automatically.

To make sure that the display light is turned on, the setLights method should be called before the screen saver is started and this must be done in a loop since the screen saver is not disabled just interrupted.

import
 com.nokia.mid.ui.DeviceControl
;

import
 javax.microedition.lcdui.*
;

import
 javax.microedition.midlet.*
;

 
public
 class
 BacklightWorkaround extends
 MIDlet {


   private
 SimpleCanvas canvas;


   /**
   * Keeps the backlight on by repeatedly setting
   */

  class
 LightThread extends
 Thread

 {


    public
 void
 run(
)
 {

      while
(
true
)
{

        DeviceControl.setLights
(
0, 100)
;
       
        try
 {

          Thread

.sleep
(
5000)
;

        }
 catch
 
(
InterruptedException

 ex)
 {

          ex.printStackTrace
(
)
;

        }

      }

    }

  }


   private
 class
 SimpleCanvas extends
 Canvas

 implements
 CommandListener{


    private
 Command exitCmd;

    private
 MIDlet midlet;

 
    public
 SimpleCanvas(
MIDlet midlet)
 {

      this
.midlet
 =
 midlet;

      exitCmd =
 new
 Command(
"Exit"
,Command.EXIT
, 1)
;

      addCommand(
exitCmd)
;

      setCommandListener(
this
)
;

    }


    public
 void
 paint(
Graphics

 g)
 {
 
      g.drawString
(
"Let there be light."
, 0, 0, Graphics

.LEFT
|
Graphics.TOP
)
;

    }


     public
 void
 commandAction(
Command command, Displayable displayable)
 {

      if
(
command ==
 exitCmd)
{

        midlet.notifyDestroyed
(
)
;

      }

    }

  }

 
  public
 void
 startApp(
)
 {

    if
(
canvas ==
 null
)
{

      canvas =
 new
 SimpleCanvas(
this
)
;

      new
 LightThread(
)
.start
(
)
;

    }
 
    Display.getDisplay
(
this
)
.setCurrent
(
canvas)
;

  }


   public
 
void
 pauseApp(
)
 {
 }

 
  public
 void
 destroyApp(
boolean
 unconditional)
 {
 }


}

  

   原文连接：http://wiki.forum.nokia.com/index.php/How_to_block_the_screen_saver

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Table 6.1. com.nokia.mid.ui.DeviceControl

Method

Description

static void flashLights(long duration)	Flashes the lights.
static void setLights(int num, int level)	Turns the lights on and off.
static void startVibra(int freq, long duration)	Vibrates for a given frequency and time.
static void stopVibra()	Stops vibrating.

The two device elements you can control are the lights and vibration. To temporarily flash the lights on and off, use the flashLights method. For example:

import com.nokia.mid.ui.DeviceControl;
…
    DeviceControl.flashLights(5000);

This code will cause the lights (such as the LEDs) to flash. If there is no support for this feature, then nothing will happen (duh). The integer value specifies the length of time (in milliseconds) to keep the lights on, although the device might override this value if you specify a number that is too large.

The other method relating to lights, setLights , allows you to control any of the lights on the device individually, such as the backlight or the LEDs …in theory. In reality, Nokia only gives you the ability to control the device's backlight (if it has one). To do this, call the method with the light number (the first integer) set to 0 for the backlight and the level integer set to a number between 0 and 100 (where 0 is off and 100 is the brightest level). For devices that don't support graded backlighting, all values between 1 and 100 just translate to on. Here's an example of setLights in action:

DeviceControl.setLights(0, 100);

NOTE

 

Tip

A word of warning about playing with the backlight: There is no method to determine the current backlighting level; therefore, you have no way of restoring the lighting to the level the user previously had. Be careful using this function. A user won't be impressed if, while playing in a dark place, you turn the lights out to reward them for completing a level.

If you really want to add this function to your game, consider making it an option the player can enable or disable. This applies to the vibration function as well.

 

原文连接：http://j2megame.atw.hu/ch06lev1sec122.html