Class RGBImage

java.lang.Object

com.codename1.ui.Image

com.codename1.ui.RGBImage

All Implemented Interfaces:

ActionSource

public class RGBImage
extends Image

An image that stores its data as an integer RGB array internally, this image cannot be manipulated via Graphics primitives however its array is accessible and modifiable programmatically. This is very useful for 2 distinct use cases.

The first use case allows us to manipulate images in a custom way while still preserving alpha information where applicable.

The second use case allows us to store images in the Java heap which is useful for some constrained devices. In small devices images are often stored in a separate "heap" which runs out eventually, this allows us to place the image in the Java heap which is potentially more wasteful but might sometimes be more abundant.

Note that unless specified otherwise most methods inherited from Image will fail when invoked on this subclass often with a NullPointerException. This image can be drawn on graphics as usual

Constructor Summary

Constructors

Constructor	Description
RGBImage(int[] rgb, int width, int height)	Creates an RGB image from scratch the array isn't copied and can be saved and manipulated
RGBImage(Image img)	Converts an image to an RGB image after which the original image can be GC'd

Method Summary

Modifier and Type	Method	Description
protected void	drawImage(Graphics g, Object nativeGraphics, int x, int y)	Callback invoked internally by Codename One to draw the image/frame onto the display.
Graphics	getGraphics()	This method is unsupported in this image type
int	getHeight()	Returns the height of the image
int[]	getRGB()	Returns a mutable array that can be used to change the appearance of the image arranged as AARRGGBB.
int	getWidth()	Returns the width of the image
boolean	isOpaque()	Indicates if an image should be treated as opaque, this can improve support for fast drawing of RGB images without alpha support.
Image	modifyAlpha(byte alpha)	Creates a new image instance with the alpha channel of opaque/translucent pixels within the image using the new alpha value.
boolean	requiresDrawImage()	New label optimizations don't invoke drawImage and instead just pass the native image directly to the underlying renderer.
Image	rotate(int degrees)	Unsupported in the current version, this method will be implemented in a future release
void	scale(int width, int height)	Scale the image to the given width and height, this is a fast algorithm that preserves translucent information
Image	scaled(int width, int height)	Returns a scaled version of this image image using the given width and height, this is a fast algorithm that preserves translucent information.
void	setOpaque(boolean opaque)
Image	subImage(int x, int y, int width, int height, boolean processAlpha)	Extracts a subimage from the given image allowing us to breakdown a single large image into multiple smaller images in RAM, this actually creates a standalone version of the image for use.

Methods inherited from class Image

addActionListener, animate, applyMask, applyMask, applyMaskAutoScale, asyncLock, createImage, createImage, createImage, createImage, createImage, createImage, createImage, createIndexed, createMask, createSVG, dispose, drawImage, exifRotation, exifRotation, exifRotation, fill, fireChangedEvent, flipHorizontally, flipVertically, getExifOrientationTag, getExifOrientationTag, getImage, getImageName, getRGB, getRGBCached, getSVGDocument, isAlphaMutableImageSupported, isAnimation, isJPEG, isLocked, isPNG, isSVG, isSVGSupported, lock, mirror, modifyAlpha, modifyAlphaWithTranslucency, removeActionListener, rotate180Degrees, rotate270Degrees, rotate90Degrees, scaledHeight, scaledLargerRatio, scaledSmallerRatio, scaledWidth, setImageName, toRGB, unlock

Methods inherited from class Object

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

Constructor Details

RGBImage

public RGBImage(Image img)

Converts an image to an RGB image after which the original image can be GC'd

Parameters

• img: the image to convert to an RGB image

RGBImage

public RGBImage(int[] rgb,
 int width,
 int height)

Creates an RGB image from scratch the array isn't copied and can be saved and manipulated

Parameters

• rgb: AARRGGBB array

• width: width of image

• height: height of image

Method Details

subImage

public Image subImage(int x,
 int y,
 int width,
 int height,
 boolean processAlpha)

Extracts a subimage from the given image allowing us to breakdown a single large image into multiple smaller images in RAM, this actually creates a standalone version of the image for use.

Parameters

• x: the x offset from the image

• y: the y offset from the image

• width: the width of internal images

• height: the height of internal images

• processAlpha: whether alpha should be processed as well as part of the cutting

Returns

An array of all the possible images that can be created from the source

Overrides:

subImage in class Image

scaled

public Image scaled(int width,
 int height)

Returns a scaled version of this image image using the given width and height, this is a fast algorithm that preserves translucent information. The method accepts -1 to preserve aspect ratio in the given axis.

Parameters

• width: width for the scaling

• height: height of the scaled image

Returns

new image instance scaled to the given height and width

Overrides:

scaled in class Image

scale

public void scale(int width,
 int height)

Scale the image to the given width and height, this is a fast algorithm that preserves translucent information

Parameters

• width: width for the scaling

• height: height of the scaled image

Deprecated

Overrides:

scale in class Image

rotate

public Image rotate(int degrees)

Unsupported in the current version, this method will be implemented in a future release

Overrides:

rotate in class Image

modifyAlpha

public Image modifyAlpha(byte alpha)

Creates a new image instance with the alpha channel of opaque/translucent pixels within the image using the new alpha value. Transparent (alpha == 0) pixels remain transparent. All other pixels will have the new alpha value.

Parameters

• alpha: New value for the entire alpha channel

Returns

Overrides:

modifyAlpha in class Image

Returns:

Translucent/Opaque image based on the alpha value and the pixels of this image

getGraphics

public Graphics getGraphics()

This method is unsupported in this image type

Overrides:

getGraphics in class Image

getRGB

public int[] getRGB()

Returns a mutable array that can be used to change the appearance of the image arranged as AARRGGBB.

Returns

ARGB int array

Overrides:

getRGB in class Image

drawImage

protected void drawImage(Graphics g,
 Object nativeGraphics,
 int x,
 int y)

Callback invoked internally by Codename One to draw the image/frame onto the display. Image subclasses can override this method to perform drawing of custom image types.

Parameters

• g: the graphics object

• nativeGraphics: the underlying native graphics which might be essential for some image types

• x: the x coordinate

• y: the y coordinate

Overrides:

drawImage in class Image

isOpaque

public boolean isOpaque()

Indicates if an image should be treated as opaque, this can improve support for fast drawing of RGB images without alpha support.

Overrides:

isOpaque in class Image

setOpaque

public void setOpaque(boolean opaque)

getWidth

public int getWidth()

Returns the width of the image

Returns

the width of the image

Overrides:

getWidth in class Image

getHeight

public int getHeight()

Returns the height of the image

Returns

the height of the image

Overrides:

getHeight in class Image

requiresDrawImage

public boolean requiresDrawImage()

New label optimizations don't invoke drawImage and instead just pass the native image directly to the underlying renderer. This is problematic for some image types specifically timeline & FontImage and this method allows these classes to indicate that they need that legacy behavior of calling drawImage.

Returns

true if a drawImage call is a required

Overrides:

requiresDrawImage in class Image