Motorola J2ME Specifications download pdf (Page 46)

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PalleteImage Class

PaletteImage provides methods for manipulating the color palette data of an image.

PaletteImages can only be created with palette-based image data (PNG color type 3,

or other palette image formats that a particular device may support).

A single palette entry or the entire palette can be retrieved as a series of RGB values in

0xRRGGBB format (MIDP color format). The effects of the palette changes will be visible

in the next Image that is generated.

The following will be supported:

• Single color transparency: the entire palette may be fully opaque, or a single

palette entry may be designated as being fully transparent. Alpha channels are

not supported.

Once the palette entries have been set to the desired values, a MIDP Image object is

retrieved that reflects the new palette settings.

PalleteImage Constructor

The PalleteImage class defines the following constructors:

• PalleteImage(byte[] data, int offset, int length)

throws IOException - Creates a new PalleteImage using the provided image

data.

• PalleteImage (java.lang.String name) throws IOException -

Creates a new PaletteImage using the provided image data in a named

resource.

PalleteImage Methods

The PalleteImage class defines the following methods:

• public Image getImage() - Creates and returns a new Image object

using this PaletteImage. The Image returned will reflect the PaletteImage’s original

pixel data and current palette data. This method enables the developer to easily

generate a series of differently colored images by adjusting palette data.

• public int getTransparentIndex() – Gets the current transparent

index. Pixels that reference the transparent index in the palette are not drawn when

the image is rendered. By default, the transparent index is -1 even if a transparent

color is specified in the original image data.

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Motorola J2ME Specifications Page 46