Blackberry Java Development Environment 4.7.0 Overview - Page 8

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Feature and Technical Overview

Accelerometer

The BlackBerry® Storm device includes an acclerometer that senses the orientation and acceleration of the device. When a

BlackBerry device user moves the device, the accelerometer senses the movement in 3-D space along the x, y, and z axis. A

BlackBerry device user can change the orientation of the device which can change the display direction of a screen for a BlackBerry

device application between portrait and landscape.

The Accelerometer APIs in the net.rim.device.api.system package let a BlackBerry device application respond to

the orientation and acceleration of a BlackBerry device. For example, you can manipulate a game application to change the

direction and speed of a moving object on the screen as a BlackBerry device user moves and rotates the BlackBerry device at

different speeds.

Screen display direction

When the orientation of the BlackBerry® Storm device changes, the display direction of the screen of a BlackBerry device

application can also change. The display direction refers to the top of the drawing area of the screen relative to the location of

the BlackBerry logo on the BlackBerry device. The display direction of an application screen can be north, south, east, west,

landscape, or portrait.

The BlackBerry® UI APIs now let a BlackBerry device application retrieve the display direction of the screen and prevent a

BlackBerry device from changing the display direction of the screen.

A BlackBerry device application can use the net.rim.device.api.system.Display.getOrientation()

method to retrieve the display direction of the screen. A BlackBerry device application can use

the net.rim.device.api.ui.UiEngineInstance .setAcceptableDirections(int) method to

set the screen to only display in certain directions when a BlackBerry device user changes the orientation of the BlackBerry Storm

device. For example, an application that displays a document could set the screen to always display in landscape mode.

Home screen background image

The BlackBerry® UI APIs now let a BlackBerry device application set the image that appears as the background of the Home

screen on a BlackBerry device.

A BlackBerry device application can use net.rim.blackberry.api.homescreen.HomeScreen.

setBackgroundImage(String uri) with an image file that resides in flash memory or a microSD Card to set the

background image. A typical format for the URI is "file:///store/home/user/pictures/file.jpg." Invoking

net.rim.blackberry.api.homescreen.HomeScreen. setBackgroundImage(String uri) will

override images that other applications have set.

Screen and UI