Package org.hippoecm.frontend.plugins.gallery.imageutil

Class ImageUtils

java.lang.Object

org.hippoecm.frontend.plugins.gallery.imageutil.ImageUtils

public class ImageUtils
extends Object

Generic image manipulation utility methods.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	ImageUtils.ScalingStrategy	The available strategies for scaling images.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	ImageUtils()	Prevent instantiation

Method Summary

Modifier and Type	Method	Description
static InputStream	convertToRGB(InputStream is, ColorModel colorModel)	Converts image raster data to a JPEG with RGB color space.
static BufferedImage	cropImage(BufferedImage image, Rectangle cropArea)	Returns a cropped instance of the BufferedImage provided by the ImageReader.
static double	determineResizeRatio(double sourceWidth, double sourceHeight, int targetWidth, int targetHeight)	Determine the ratio by which the source dimensions should be multiplied to fit into the target dimensions.
static double	determineScalingFactor(double width, double height, double maxWidth, double maxHeight)	Determine the scaling factor of an image, so that it fits within the max boundaries of the preview container (e.g.
static ImageReader	getImageReader(String aMimeType)	Returns an image reader for a MIME type.
static ImageWriter	getImageWriter(String aMimeType)	Returns an image writer for a MIME type.
static Dimension	normalizeDimension(Dimension original, Dimension variant)	If height or width in the variant dimension is equal to 0 it is a special case.
static BufferedImage	scaleImage(BufferedImage img, int xOffset, int yOffset, int sourceWidth, int sourceHeight, int targetWidth, int targetHeight, Object hint, boolean highQuality)	Deprecated. Use scaleImage(BufferedImage, Rectangle, Dimension, Object, boolean) instead.
static BufferedImage	scaleImage(BufferedImage img, int targetWidth, int targetHeight, ImageUtils.ScalingStrategy strategy)	Returns a scaled instance of the provided BufferedImage.
static BufferedImage	scaleImage(BufferedImage original, Rectangle rectangle, Dimension targetDimension, Object hint, boolean highQuality)	Deprecated. Use cropImage(BufferedImage, Rectangle) combined with scaleImage(BufferedImage, int, int, ScalingStrategy) instead
static ByteArrayOutputStream	writeImage(ImageWriter writer, BufferedImage image)	Returns the data of a BufferedImage as a binary output stream.
static ByteArrayOutputStream	writeImage(ImageWriter writer, BufferedImage image, float compressionQuality)	Returns the data of a BufferedImage as a binary output stream.

Methods inherited from class java.lang.Object

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

Constructor Details

ImageUtils

protected ImageUtils()

Prevent instantiation

Method Details

getImageReader

public static ImageReader getImageReader(String aMimeType)

Returns an image reader for a MIME type.

Parameters:

aMimeType - MIME type

Returns:

an image reader for the given MIME type, or null if no image reader could be created for the given MIME type.

getImageWriter

public static ImageWriter getImageWriter(String aMimeType)

Returns an image writer for a MIME type.

Parameters:

aMimeType - MIME type

Returns:

an image writer for the given MIME type, or null if no image writer could be created for the given MIME type.

writeImage

public static ByteArrayOutputStream writeImage(ImageWriter writer,
 BufferedImage image,
 float compressionQuality)
                                        throws IOException

Returns the data of a BufferedImage as a binary output stream. If the image is null, a stream of zero bytes is returned.

Parameters:

writer - the writer to use for writing the image data.

image - the image to write.

compressionQuality - a float between 0 and 1 that indicates the desired compression quality. Values lower than 0 will be interpreted as 0, values higher than 1 will be interpreted as 1.

Returns:

an output stream with the data of the given image.

Throws:

IOException - when creating the binary output stream failed.

writeImage

public static ByteArrayOutputStream writeImage(ImageWriter writer,
 BufferedImage image)
                                        throws IOException

Returns the data of a BufferedImage as a binary output stream. If the image is null, a stream of zero bytes is returned. The data is written with a compression quality of 1.

Parameters:

writer - the writer to use for writing the image data.

image - the image to write.

Returns:

an output stream with the data of the given image.

Throws:

IOException - when creating the binary output stream failed.

scaleImage

public static BufferedImage scaleImage(BufferedImage img,
 int targetWidth,
 int targetHeight,
 ImageUtils.ScalingStrategy strategy)

Returns a scaled instance of the provided BufferedImage.

Parameters:

img - the original image to be scaled

targetWidth - the desired width of the scaled instance, in pixels

targetHeight - the desired height of the scaled instance, in pixels

strategy - the strategy to use for scaling the image

Returns:

a scaled version of the original BufferedImage, or null if either the target width or target height is 0 or less.

scaleImage

@Deprecated
public static BufferedImage scaleImage(BufferedImage original,
 Rectangle rectangle,
 Dimension targetDimension,
 Object hint,
 boolean highQuality)

Deprecated.

Use cropImage(BufferedImage, Rectangle) combined with scaleImage(BufferedImage, int, int, ScalingStrategy) instead

Returns a scaled instance of the provided BufferedImage.

Parameters:

original - the original image to be scaled

rectangle - the rectangle to use for the scaled instance

targetDimension - the desired dimensions of the scaled instance, in pixels

hint - one of the rendering hints that corresponds to RenderingHints.KEY_INTERPOLATION (e.g. RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR, RenderingHints.VALUE_INTERPOLATION_BILINEAR, RenderingHints.VALUE_INTERPOLATION_BICUBIC)

highQuality - if true, this method will use a multi-step scaling technique that provides higher quality than the usual one-step technique (only useful in downscaling cases, where targetWidth or targetHeight is smaller than the original dimensions, and generally only when the BILINEAR hint is specified)

Returns:

a scaled version of the original BufferedImage, or null if either the target width or target height is 0 or less.

determineScalingFactor

public static double determineScalingFactor(double width,
 double height,
 double maxWidth,
 double maxHeight)

Determine the scaling factor of an image, so that it fits within the max boundaries of the preview container (e.g. #MAX_PREVIEW_WIDTH by #MAX_PREVIEW_HEIGHT).

Parameters:

width - width of image

height - height of image

maxWidth - max width of image

maxHeight - max height of image

Returns:

the scaling factor of the image

normalizeDimension

public static Dimension normalizeDimension(Dimension original,
 Dimension variant)

If height or width in the variant dimension is equal to 0 it is a special case. The value 0 represents a value that according to the dimension of the original image.

With this function a new dimension is created according to the original dimension.

Parameters:

original - dimension of the original image

variant - dimension of the variant image

Returns:

scaled dimension based on width or height value

determineResizeRatio

public static double determineResizeRatio(double sourceWidth,
 double sourceHeight,
 int targetWidth,
 int targetHeight)

Determine the ratio by which the source dimensions should be multiplied to fit into the target dimensions.

Parameters:

sourceWidth - The width of the source image

sourceHeight - The height of the source image

targetWidth - The width of the target image

targetHeight - The height of the target image

Returns:

The resize ratio

cropImage

public static BufferedImage cropImage(BufferedImage image,
 Rectangle cropArea)

Returns a cropped instance of the BufferedImage provided by the ImageReader.

Parameters:

image - The original image

cropArea - The rectangle used to crop the image

Returns:

a cropped version of the original image.

scaleImage

@Deprecated
public static BufferedImage scaleImage(BufferedImage img,
 int xOffset,
 int yOffset,
 int sourceWidth,
 int sourceHeight,
 int targetWidth,
 int targetHeight,
 Object hint,
 boolean highQuality)

Deprecated.

Use scaleImage(BufferedImage, Rectangle, Dimension, Object, boolean) instead.

Returns a scaled instance of the provided BufferedImage.

Parameters:

img - the original image to be scaled

xOffset - the X-coordinate of the top-left corner in the source image, in pixels, to use for the scaled instance.

yOffset - the Y-coordinate of the top-left corner in the source image, in pixels, to use for the scaled instance.

sourceWidth - the width of the source image, in pixels relative to xOffset, to use for the scaled instance.

sourceHeight - the height of the source image, in pixels relative to yOffset, to use for the scaled instance.

targetWidth - the desired width of the scaled instance, in pixels

targetHeight - the desired height of the scaled instance, in pixels

hint - one of the rendering hints that corresponds to RenderingHints.KEY_INTERPOLATION (e.g. RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR, RenderingHints.VALUE_INTERPOLATION_BILINEAR, RenderingHints.VALUE_INTERPOLATION_BICUBIC)

highQuality - if true, this method will use a multi-step scaling technique that provides higher quality than the usual one-step technique (only useful in downscaling cases, where targetWidth or targetHeight is smaller than the original dimensions, and generally only when the BILINEAR hint is specified)

Returns:

a scaled version of the original BufferedImage, or null if either the target width or target height is 0 or less.

convertToRGB

public static InputStream convertToRGB(InputStream is,
 ColorModel colorModel)
                                throws IOException,
UnsupportedImageException

Converts image raster data to a JPEG with RGB color space. Only images with color space CMYK and YCCK are converted, other images are left untouched.

Rationale: Java's ImageIO can't process 4-component images and Java2D can't apply AffineTransformOp either, so we have to convert raster data to a JPG with RGB color space.

The technique used in this method is due to Mark Stephens, and free for any use. See http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4799903 or http://www.mail-archive.com/java2d-interest@capra.eng.sun.com/msg03247.html

Parameters:

is - the image data

colorModel - the color model of the image

Returns:

the RGB version of the supplied image

Throws:

IOException

UnsupportedImageException