File	Doc	Category	Size	Date	Package
Image.java	API Doc	J2ME MIDP 2.0	43199	Thu Nov 07 12:02:26 GMT 2002	javax.microedition.lcdui

Image

• java.lang.Object

Image source; // the image to be copied
source = Image.createImage(...);
Image copy = Image
.createImage(source.getWidth(), source.getHeight());
Graphics g = copy.getGraphics();
g.drawImage(source, 0, 0, TOP|LEFT); 

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sBIT sPLT sRGB tEXt tIME zTXt 

Fields Summary
int	width The width, height of this Image
int	height
int	imgData Native image data
private static final int	INVALID_TRANSFORM_BITS Valid transforms possible are 0 - 7

Constructors Summary
Image() Construct a new, empty Image

Methods Summary
public static javax.microedition.lcdui.Image	createImage(java.io.InputStream stream) Creates an immutable image from decoded image data obtained from an InputStream. This method blocks until all image data has been read and decoded. After this method completes (whether by returning or by throwing an exception) the stream is left open and its current position is undefined. param stream the name of the resource containing the image data in one of the supported image formats return the created image throws NullPointerException if stream is null throws java.io.IOException if an I/O error occurs, if the image data cannot be loaded, or if the image data cannot be decoded since MIDP 2.0 try { return new ImmutableImage(stream); } catch (IllegalArgumentException e) { throw new java.io.IOException(); }
public static javax.microedition.lcdui.Image	createImage(int width, int height) Creates a new, mutable image for off-screen drawing. Every pixel within the newly created image is white. The width and height of the image must both be greater than zero. param width the width of the new image, in pixels param height the height of the new image, in pixels return the created image throws IllegalArgumentException if either width or height is zero or less if (width <= 0 || height <= 0) { throw new IllegalArgumentException(); } // SYNC NOTE: Not accessing any shared data, no locking necessary return new MutableImage(width, height);
public static javax.microedition.lcdui.Image	createImage(javax.microedition.lcdui.Image source) Creates an immutable image from a source image. If the source image is mutable, an immutable copy is created and returned. If the source image is immutable, the implementation may simply return it without creating a new image. If an immutable source image contains transparency information, this information is copied to the new image unchanged. This method is useful for placing the contents of mutable images into Choice objects. The application can create an off-screen image using the {@link #createImage(int, int) createImage(w, h)} method, draw into it using a Graphics object obtained with the {@link #getGraphics() getGraphics()} method, and then create an immutable copy of it with this method. The immutable copy may then be placed into Choice objects. param source the source image to be copied return the new, immutable image throws NullPointerException if source is null // SYNC NOTE: Not accessing any shared data, no locking necessary return new ImmutableImage(source);
public static javax.microedition.lcdui.Image	createImage(java.lang.String name) Creates an immutable image from decoded image data obtained from the named resource. The name parameter is a resource name as defined by {@link Class#getResourceAsStream(String) Class.getResourceAsStream(name)}. The rules for resolving resource names are defined in the Application Resource Files section of the java.lang package documentation. param name the name of the resource containing the image data in one of the supported image formats return the created image throws NullPointerException if name is null throws java.io.IOException if the resource does not exist, the data cannot be loaded, or the image data cannot be decoded try { // SYNC NOTE: Not accessing any shared data, no locking necessary return new ImmutableImage(name); } catch (IllegalArgumentException e) { throw new java.io.IOException(); }
public static javax.microedition.lcdui.Image	createImage(byte[] imageData, int imageOffset, int imageLength) Creates an immutable image which is decoded from the data stored in the specified byte array at the specified offset and length. The data must be in a self-identifying image file format supported by the implementation, such as PNG. The imageoffset and imagelength parameters specify a range of data within the imageData byte array. The imageOffset parameter specifies the offset into the array of the first data byte to be used. It must therefore lie within the range [0..(imageData.length-1)]. The imageLength parameter specifies the number of data bytes to be used. It must be a positive integer and it must not cause the range to extend beyond the end of the array. That is, it must be true that imageOffset + imageLength < imageData.length. This method is intended for use when loading an image from a variety of sources, such as from persistent storage or from the network. param imageData the array of image data in a supported image format param imageOffset the offset of the start of the data in the array param imageLength the length of the data in the array return the created image throws ArrayIndexOutOfBoundsException if imageOffset and imageLength specify an invalid range throws NullPointerException if imageData is null throws IllegalArgumentException if imageData is incorrectly formatted or otherwise cannot be decoded if (imageOffset < 0 || imageOffset >= imageData.length || imageLength < 0 || imageOffset + imageLength > imageData.length) { throw new ArrayIndexOutOfBoundsException(); } // SYNC NOTE: Not accessing any shared data, no locking necessary return new ImmutableImage(imageData, imageOffset, imageLength);
public static javax.microedition.lcdui.Image	createImage(javax.microedition.lcdui.Image image, int x, int y, int width, int height, int transform) Creates an immutable image using pixel data from the specified region of a source image, transformed as specified. The source image may be mutable or immutable. For immutable source images, transparency information, if any, is copied to the new image unchanged. On some devices, pre-transformed images may render more quickly than images that are transformed on the fly using drawRegion. However, creating such images does consume additional heap space, so this technique should be applied only to images whose rendering speed is critical. The transform function used must be one of the following, as defined in the {@link javax.microedition.lcdui.game.Sprite Sprite} class: Sprite.TRANS_NONE - causes the specified image region to be copied unchanged Sprite.TRANS_ROT90 - causes the specified image region to be rotated clockwise by 90 degrees. Sprite.TRANS_ROT180 - causes the specified image region to be rotated clockwise by 180 degrees. Sprite.TRANS_ROT270 - causes the specified image region to be rotated clockwise by 270 degrees. Sprite.TRANS_MIRROR - causes the specified image region to be reflected about its vertical center. Sprite.TRANS_MIRROR_ROT90 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 90 degrees. Sprite.TRANS_MIRROR_ROT180 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 180 degrees. Sprite.TRANS_MIRROR_ROT270 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 270 degrees. The size of the returned image will be the size of the specified region with the transform applied. For example, if the region is 100 x 50 pixels and the transform is TRANS_ROT90, the returned image will be 50 x 100 pixels. Note: If all of the following conditions are met, this method may simply return the source Image without creating a new one: the source image is immutable; the region represents the entire source image; and the transform is TRANS_NONE. param image the source image to be copied from param x the horizontal location of the region to be copied param y the vertical location of the region to be copied param width the width of the region to be copied param height the height of the region to be copied param transform the transform to be applied to the region return the new, immutable image throws NullPointerException if image is null throws IllegalArgumentException if the region to be copied exceeds the bounds of the source image throws IllegalArgumentException if either width or height is zero or less throws IllegalArgumentException if the transform is not valid since MIDP 2.0 if ((transform & INVALID_TRANSFORM_BITS) != 0) { throw new IllegalArgumentException(); } if (x < 0 || y < 0 || (x + width) > image.width || // throws NPE if image is null (y + height) > image.height || width <= 0 || height <= 0) { throw new IllegalArgumentException(); } if (x == 0 && y == 0 && width == image.width && height == image.height && transform == Sprite.TRANS_NONE) { return image; } return new ImmutableImage(image, x, y, width, height, transform);
public static javax.microedition.lcdui.Image	createRGBImage(int[] rgb, int width, int height, boolean processAlpha) Creates an immutable image from a sequence of ARGB values, specified as 0xAARRGGBB. The ARGB data within the rgb array is arranged horizontally from left to right within each row, row by row from top to bottom. If processAlpha is true, the high-order byte specifies opacity; that is, 0x00RRGGBB specifies a fully transparent pixel and 0xFFRRGGBB specifies a fully opaque pixel. Intermediate alpha values specify semitransparency. If the implementation does not support alpha blending for image rendering operations, it must replace any semitransparent pixels with fully transparent pixels. (See Alpha Processing for further discussion.) If processAlpha is false, the alpha values are ignored and all pixels must be treated as fully opaque. Consider P(a,b) to be the value of the pixel located at column a and row b of the Image, where rows and columns are numbered downward from the top starting at zero, and columns are numbered rightward from the left starting at zero. This operation can then be defined as: P(a, b) = rgb[a + b * width]; for 0 <= a < width 0 <= b < height param rgb an array of ARGB values that composes the image param width the width of the image param height the height of the image param processAlpha true if rgb has an alpha channel, false if all pixels are fully opaque return the created image throws NullPointerException if rgb is null. throws IllegalArgumentException if either width or height is zero or less throws ArrayIndexOutOfBoundsException if the length of rgb is less than width * height. since MIDP 2.0 if (width <= 0 || height <= 0) { throw new IllegalArgumentException(); } if ((width * height) > rgb.length) { throw new ArrayIndexOutOfBoundsException(); } return new ImmutableImage(rgb, width, height, processAlpha);
public Graphics	getGraphics() Creates a new Graphics object that renders to this image. This image must be mutable; it is illegal to call this method on an immutable image. The mutability of an image may be tested with the isMutable() method. The newly created Graphics object has the following properties: the destination is this Image object; the clip region encompasses the entire Image; the current color is black; the font is the same as the font returned by {@link Font#getDefaultFont() Font.getDefaultFont()}; the stroke style is {@link Graphics#SOLID SOLID}; and the origin of the coordinate system is located at the upper-left corner of the Image. The lifetime of Graphics objects created using this method is indefinite. They may be used at any time, by any thread. return a Graphics object with this image as its destination throws IllegalStateException if the image is immutable // SYNC NOTE: Not accessing any shared data, no locking necessary throw new IllegalStateException();
public int	getHeight() Gets the height of the image in pixels. The value returned must reflect the actual height of the image when rendered. return height of the image // SYNC NOTE: return of atomic value, no locking necessary return height;
public native void	getRGB(int[] rgbData, int offset, int scanlength, int x, int y, int width, int height) Obtains ARGB pixel data from the specified region of this image and stores it in the provided array of integers. Each pixel value is stored in 0xAARRGGBB format, where the high-order byte contains the alpha channel and the remaining bytes contain color components for red, green and blue, respectively. The alpha channel specifies the opacity of the pixel, where a value of 0x00 represents a pixel that is fully transparent and a value of 0xFF represents a fully opaque pixel. The returned values are not guaranteed to be identical to values from the original source, such as from createRGBImage or from a PNG image. Color values may be resampled to reflect the display capabilities of the device (for example, red, green or blue pixels may all be represented by the same gray value on a grayscale device). On devices that do not support alpha blending, the alpha value will be 0xFF for opaque pixels and 0x00 for all other pixels (see Alpha Processing for further discussion.) On devices that support alpha blending, alpha channel values may be resampled to reflect the number of levels of semitransparency supported. The scanlength specifies the relative offset within the array between the corresponding pixels of consecutive rows. In order to prevent rows of stored pixels from overlapping, the absolute value of scanlength must be greater than or equal to width. Negative values of scanlength are allowed. In all cases, this must result in every reference being within the bounds of the rgbData array. Consider P(a,b) to be the value of the pixel located at column a and row b of the Image, where rows and columns are numbered downward from the top starting at zero, and columns are numbered rightward from the left starting at zero. This operation can then be defined as: rgbData[offset + (a - x) + (b - y) * scanlength] = P(a, b); for x <= a < x + width y <= b < y + height The source rectangle is required to not exceed the bounds of the image. This means: x >= 0 y >= 0 x + width <= image width y + height <= image height If any of these conditions is not met an IllegalArgumentException is thrown. Otherwise, in cases where width <= 0 or height <= 0, no exception is thrown, and no pixel data is copied to rgbData. param rgbData an array of integers in which the ARGB pixel data is stored param offset the index into the array where the first ARGB value is stored param scanlength the relative offset in the array between corresponding pixels in consecutive rows of the region param x the x-coordinate of the upper left corner of the region param y the y-coordinate of the upper left corner of the region param width the width of the region param height the height of the region throws ArrayIndexOutOfBoundsException if the requested operation would attempt to access an element in the rgbData array whose index is either negative or beyond its length (the contents of the array are unchanged) throws IllegalArgumentException if the area being retrieved exceeds the bounds of the source image throws IllegalArgumentException if the absolute value of scanlength is less than width throws NullPointerException if rgbData is null since MIDP 2.0
public int	getWidth() Gets the width of the image in pixels. The value returned must reflect the actual width of the image when rendered. return width of the image // SYNC NOTE: return of atomic value, no locking necessary return width;
public boolean	isMutable() Check if this image is mutable. Mutable images can be modified by rendering to them through a Graphics object obtained from the getGraphics() method of this object. return true if the image is mutable, false otherwise // SYNC NOTE: return of atomic value, no locking necessary return false;