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Copyright © 2006 Sun Microsystems, Inc. All rights reserved.

javax.microedition.lcdui
Class ImageItem

java.lang.Object
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  +--javax.microedition.lcdui.Item
        |
        +--javax.microedition.lcdui.ImageItem

public class ImageItem

extends Item

A class that provides layout control when Image objects are added to a Form or to an Alert.

Each ImageItem object contains a reference to an Image object. This image must be immutable. (If the image object were not required to be immutable, the application could paint into it at any time, potentially requiring the containing Form or Alert to be updated on every graphics call.) See the definition of the Image object for further details on image mutability how to create immutable images.

The value null may be specified for the image contents of an ImageItem. If this occurs (and if the label is also null) the ImageItem will occupy no space on the screen.

Each ImageItem object contains a layout field that is combined from the following values: LAYOUT_LEFT, LAYOUT_RIGHT, LAYOUT_CENTER, LAYOUT_NEWLINE_BEFORE, and LAYOUT_NEWLINE_AFTER. LAYOUT_LEFT + LAYOUT_RIGHT is equal to LAYOUT_CENTER. LAYOUT_DEFAULT may be specified, which indicates that the system should use its default layout policy for this ImageItem. The value of the layout field is merely a hint. Because of device constraints, such as limited screen size, the implementation may choose to ignore layout directions.

There are some implicit rules on how the layout directives can be combined:

• LAYOUT_DEFAULT cannot not be combined with any other directive. In fact, any other value will override LAYOUT_DEFAULT since its value is 0.
• LAYOUT_LEFT, LAYOUT_RIGHT and LAYOUT_CENTER are meant to be mutually exclusive.
• It usually makes sense to combine LAYOUT_LEFT, LAYOUT_RIGHT and LAYOUT_CENTER with LAYOUT_NEWLINE_BEFORE and LAYOUT_NEWLINE_AFTER.

The altText parameter specifies a string to be displayed in place of the image if the image exceeds the capacity of the display. The altText parameter may be null.

Field Summary

static int	LAYOUT_CENTER Image should be horizontally centered.
static int	LAYOUT_DEFAULT Use the default formatting of the "container" of the image.
static int	LAYOUT_LEFT Image should be close to left-edge of the drawing area.
static int	LAYOUT_NEWLINE_AFTER A new line should be started after the image is drawn.
static int	LAYOUT_NEWLINE_BEFORE A new line should be started before the image is drawn.
static int	LAYOUT_RIGHT Image should be close to right-edge of the drawing area.

Constructor Summary

ImageItem(String label, Image img, int layout, String altText)
Creates a new ImageItem with the given label, image, layout directive, and alternate text string.

Method Summary

String	getAltText() Gets the text string to be used if the image exceeds the device's capacity to display it.
Image	getImage() Gets the image contained within the ImageItem, or null if there is no contained image.
int	getLayout() Gets the layout directives used for placing the image.
void	setAltText(String text) Sets the alternate text of the ImageItem, or null if no alternate text is provided.
void	setImage(Image img) Sets the image object contained within the ImageItem.
void	setLayout(int layout) Sets the layout directives.

Methods inherited from class javax.microedition.lcdui.Item

getLabel, setLabel

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LAYOUT_DEFAULT

public static final int LAYOUT_DEFAULT

Use the default formatting of the "container" of the image.

Value 0 is assigned to LAYOUT_DEFAULT.

LAYOUT_LEFT

public static final int LAYOUT_LEFT

Image should be close to left-edge of the drawing area.

Value 1 is assigned to LAYOUT_LEFT.

LAYOUT_RIGHT

public static final int LAYOUT_RIGHT

Image should be close to right-edge of the drawing area.

Value 2 is assigned to LAYOUT_RIGHT.

LAYOUT_CENTER

public static final int LAYOUT_CENTER

Image should be horizontally centered.

Value 3 is assigned to LAYOUT_CENTER.

LAYOUT_NEWLINE_BEFORE

public static final int LAYOUT_NEWLINE_BEFORE

A new line should be started before the image is drawn.

Value 0x100 is assigned to LAYOUT_NEWLINE_BEFORE.

LAYOUT_NEWLINE_AFTER

public static final int LAYOUT_NEWLINE_AFTER

A new line should be started after the image is drawn.

Value 0x200 is assigned to LAYOUT_DEFAULT.

Constructor Detail

ImageItem

public ImageItem(String label,
                 Image img,
                 int layout,
                 String altText)

Creates a new ImageItem with the given label, image, layout directive, and alternate text string.

Parameters:

label - the label string

img - the image, must be immutable

layout - a combination of layout directives

altText - the text that may be used in place of the image

Throws:

IllegalArgumentException - if the image is mutable

IllegalArgumentException - if the layout value is not a legal combination of directives

Method Detail

getImage

public Image getImage()

Gets the image contained within the ImageItem, or null if there is no contained image.

Returns:

image used by the ImageItem

setImage

public void setImage(Image img)

Sets the image object contained within the ImageItem. The image must be immutable. If img is null, the ImageItem is set to be empty.

Parameters:

img - the new image

Throws:

IllegalArgumentException - if the image is mutable

getAltText

public String getAltText()

Gets the text string to be used if the image exceeds the device's capacity to display it.

Returns:

the alternate text value, or null if none

setAltText

public void setAltText(String text)

Sets the alternate text of the ImageItem, or null if no alternate text is provided.

Parameters:

text - the new alternate text

getLayout

public int getLayout()

Gets the layout directives used for placing the image.

Returns:

a combination of layout directive values

setLayout

public void setLayout(int layout)

Sets the layout directives.

Parameters:

layout - a combination of layout directive values

Throws:

IllegalArgumentException - if the value of layout is not a valid combination of layout directives