Package com.openhtmltopdf.util

Class ImageUtil

java.lang.Object

com.openhtmltopdf.util.ImageUtil

public class ImageUtil
extends java.lang.Object

Static utility methods for working with images. Meant to suggest "best practices" for the most straightforward cases of working with images.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static class	ImageUtil.AbstractFastScaler
(package private) static class	ImageUtil.AreaAverageScaler	AWT-style one-step scaling, using area averaging
(package private) static class	ImageUtil.FastScaler	Fast but decent scaling
(package private) static class	ImageUtil.HighQualityScaler	Step-wise downscaling
(package private) static class	ImageUtil.OldScaler	Old AWT-style scaling, poor quality
(package private) static interface	ImageUtil.Scaler

Field Summary

Fields

Modifier and Type	Field	Description
private static java.util.Map<DownscaleQuality,ImageUtil.Scaler>	qual
private static java.util.regex.Pattern	WHITE_SPACE

Constructor Summary

Constructors

Constructor	Description
ImageUtil()

Method Summary

Modifier and Type	Method	Description
static java.awt.image.BufferedImage	convertToBufferedImage(java.awt.Image awtImg, int type)	Utility method to convert an AWT Image to a BufferedImage.
static java.awt.image.BufferedImage	createCompatibleBufferedImage(int width, int height, int biType)	Helper method to instantiate new BufferedImages; if the graphics environment is actually connected to real screen devices (e.g.
static java.awt.image.BufferedImage	createTransparentImage(int width, int height)
static byte[]	fromBase64Encoded(java.lang.String b64encoded)
static byte[]	getEmbeddedBase64Image(java.lang.String imageDataUri)	Get the binary content of an embedded base 64 image.
private static java.awt.GraphicsConfiguration	getGraphicsConfiguration()
static java.awt.image.BufferedImage	getScaledInstance(ScalingOptions opt, java.awt.image.BufferedImage orgImage)	Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels.
static java.awt.image.BufferedImage	getScaledInstance(java.awt.image.BufferedImage orgImage, int targetWidth, int targetHeight)	Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels.
static java.awt.image.BufferedImage	makeCompatible(java.awt.image.BufferedImage bimg)

Methods inherited from class java.lang.Object

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

Field Detail

qual

private static final java.util.Map<DownscaleQuality,ImageUtil.Scaler> qual

WHITE_SPACE

private static final java.util.regex.Pattern WHITE_SPACE

Constructor Detail

ImageUtil

public ImageUtil()

Method Detail

makeCompatible

public static java.awt.image.BufferedImage makeCompatible(java.awt.image.BufferedImage bimg)

createCompatibleBufferedImage

public static java.awt.image.BufferedImage createCompatibleBufferedImage(int width,
                                                                         int height,
                                                                         int biType)

Helper method to instantiate new BufferedImages; if the graphics environment is actually connected to real screen devices (e.g. not in headless mode), the image will be compatible with the screen device allowing for best performance. In a headless environment, simply creates a new BufferedImage. For non-headless environments, this just sets up and calls GraphicsConfiguration.createCompatibleImage(int,int,int). The image will not have anything drawn to it, not even a white background; you must do this yourself.

Parameters:

width - Target width for the image

height - Target height for the image

biType - Value from the BufferedImage class; see docs for BufferedImage(int,int,int). The actual type used will be the type specified in this parameter, if in headless mode, or the type most compatible with the screen, if in non-headless more.

Returns:

A BufferedImage compatible with the screen (best fit).

getGraphicsConfiguration

private static java.awt.GraphicsConfiguration getGraphicsConfiguration()

getScaledInstance

public static java.awt.image.BufferedImage getScaledInstance(ScalingOptions opt,
                                                             java.awt.image.BufferedImage orgImage)

Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels. If either width or height is <=0, the current image width or height will be used. This method assumes that, at the moment the method is called, the width and height of the image are available; it won't wait for them. Therefore, the method should be called once the image has completely loaded and not before.
Override this method in a subclass to optimize image scaling operations; note that the legacy Image.getScaledInstance(int,int,int) is considered to perform poorly compared to more recent developed techniques.
For a discussion of the options from a member of the Java2D team, see http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html

Parameters:

orgImage - The image to scale

Returns:

The scaled image instance.

getScaledInstance

public static java.awt.image.BufferedImage getScaledInstance(java.awt.image.BufferedImage orgImage,
                                                             int targetWidth,
                                                             int targetHeight)

Scales an image to the requested width and height, assuming these are both >= 1; size given in pixels. If either width or height is <=0, the current image width or height will be used. This method assumes y that, at the moment the method is called, the width and height of the image are available; it won't wait for them. Therefore, the method should be called once the image has completely loaded and not before.
Override this method in a subclass to optimize image scaling operations; note that the legacy Image.getScaledInstance(int,int,int) is considered to perform poorly compared to more recent developed techniques.
For a discussion of the options from a member of the Java2D team, see http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html

Parameters:

orgImage - The image to scale

targetWidth - The target width in pixels

targetHeight - The target height in pixels

Returns:

The scaled image instance.

convertToBufferedImage

public static java.awt.image.BufferedImage convertToBufferedImage(java.awt.Image awtImg,
                                                                  int type)

Utility method to convert an AWT Image to a BufferedImage. Size is preserved, BufferedImage is compatible with current display device.

Parameters:

awtImg - image to convert; if already a BufferedImage, returned unmodified

type - the type of BufferedImage to create; see BufferedImage(int,int,int)

Returns:

BufferedImage with same content.

createTransparentImage

public static java.awt.image.BufferedImage createTransparentImage(int width,
                                                                  int height)

fromBase64Encoded

public static byte[] fromBase64Encoded(java.lang.String b64encoded)

getEmbeddedBase64Image

public static byte[] getEmbeddedBase64Image(java.lang.String imageDataUri)

Get the binary content of an embedded base 64 image.

Parameters:

imageDataUri - URI of the embedded image

Returns:

The binary content