Arranging UI components

You can arrange the UI components on an application screen by using BlackBerry® API layout managers. The following classes extend the Manager class that is provided in the net.rim.device.apu.ui package and provide predefined layouts for the UI components on your application's screen.

Layout manager

Description

FlowFieldManager

This layout manager arranges UI components vertically and then horizontally depending on the size of the screen. The first UI component is positioned in the upper-left corner of the screen and subsequent components are placed horizontally to the right of the first component until the width of the screen is reached. Once UI components can no longer fit on the first row, the next UI component is placed below the first row of components on a row that has a height that is equal to the tallest component of the row above it. You can apply vertical style bits (for example, Field.FIELD_TOP, Field.FIELD_BOTTOM, or Field.FIELD_VCENTER) to align UI components vertically within their row.

HorizontalFieldManager

This layout manager arranges UI components in a single horizontal row starting at the left side of the screen and ending at the right side of the screen. Because this layout manager arranges UI components horizontally, you cannot apply horizontal style bits to UI components (for example, Field.FIELD_LEFT, Field.FIELD_HCENTER, or Field.FIELD_RIGHT). You can apply vertical style bits (for example, Field.FIELD_TOP, Field.FIELD_BOTTOM, or Field.FIELD_VCENTER).

If the UI components do not fit the available width of the screen, you should use the Manager.HORIZONTAL_SCROLL style bit to enable horizontal scrolling. Otherwise, the screen displays as many UI components as possible within the available screen width, and the rest are not shown. The UI components exist but are not visible. This situation can create unexpected scrolling behavior for your users.

VerticalFieldManager

This layout manager arranges UI components in a single vertical column starting at the top of the screen and ending at the bottom of the screen. Because this layout manager is designed to arrange items vertically, you cannot apply vertical style bits to UI components (for example, Field.FIELD_TOP, Field.FIELD_BOTTOM, or Field.FIELD_VCENTER). You can apply horizontal style bits (for example, Field.FIELD_LEFT, Field.FIELD_HCENTER, or Field.FIELD_RIGHT).

You can use additional layout managers to arrange UI components in your application. For example, you can use the GridFieldManager layout manager to position UI components in rows and columns on a screen to create a grid. You can use the EyelidFieldManager layout manager to display UI components on a pair of managers that appear at the top and bottom of the screen temporarily.


Was this information helpful? Send us your comments.