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Flying Saucer is a CSS 2.1 renderer written in Java. This artifact contains the core rendering and layout code as well as Java2D output.
/*
* {{{ header & license
* Copyright (c) 2007 Patrick Wright
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
* }}}
*/
package org.xhtmlrenderer.util;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.logging.Level;
import javax.imageio.ImageIO;
import javax.xml.bind.DatatypeConverter;
/**
* Static utility methods for working with images. Meant to suggest "best practices" for the most straightforward
* cases of working with images.
*
* @author pwright
*/
public class ImageUtil {
private static final Map qual;
static {
qual = new HashMap();
qual.put(DownscaleQuality.FAST, new OldScaler());
qual.put(DownscaleQuality.HIGH_QUALITY, new HighQualityScaler());
qual.put(DownscaleQuality.LOW_QUALITY, new FastScaler());
qual.put(DownscaleQuality.AREA, new AreaAverageScaler());
}
/**
* Sets the background of the image to the specified color
*
* @param image the image
* @param bgColor the color
*/
public static void clearImage(BufferedImage image, Color bgColor) {
Graphics2D g2d = (Graphics2D) image.getGraphics();
g2d.setColor(bgColor);
g2d.fillRect(0, 0, image.getWidth(), image.getHeight());
g2d.dispose();
}
/**
* Sets the background of the image to white.
*
* @param image the image
*/
public static void clearImage(BufferedImage image) {
clearImage(image, Color.WHITE);
}
public static BufferedImage makeCompatible(BufferedImage bimg) {
BufferedImage cimg = null;
if (GraphicsEnvironment.isHeadless()) {
cimg = createCompatibleBufferedImage(bimg.getWidth(), bimg.getHeight(), bimg.getTransparency());
} else {
GraphicsConfiguration gc = getGraphicsConfiguration();
if (bimg.getColorModel().equals(gc.getColorModel())) {
return bimg;
}
cimg = gc.createCompatibleImage(bimg.getWidth(), bimg.getHeight(), bimg.getTransparency());
}
Graphics cg = cimg.getGraphics();
cg.drawImage(bimg, 0, 0, null);
cg.dispose();
return cimg;
}
/**
* 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
* {@link java.awt.GraphicsConfiguration#createCompatibleImage(int,int,int)}. The image will not have anything
* drawn to it, not even a white background; you must do this yourself. The {@link #clearBackground(BufferedImage)}
* method will do this for you if you like.
*
* @param width Target width for the image
* @param height Target height for the image
* @param biType Value from the {@link java.awt.image.BufferedImage} class; see docs for
* {@link java.awt.image.BufferedImage#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.
* @return A BufferedImage compatible with the screen (best fit).
*/
public static BufferedImage createCompatibleBufferedImage(int width, int height, int biType) {
BufferedImage bimage = null;
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
if (ge.isHeadlessInstance()) {
bimage = new BufferedImage(width, height, biType);
} else {
GraphicsConfiguration gc = getGraphicsConfiguration();
// TODO: check type using image type - can be sniffed; see Filthy Rich Clients
int type = (biType == BufferedImage.TYPE_INT_ARGB || biType == BufferedImage.TYPE_INT_ARGB_PRE ?
Transparency.TRANSLUCENT : Transparency.OPAQUE);
bimage = gc.createCompatibleImage(width, height, type);
}
return bimage;
}
private static GraphicsConfiguration getGraphicsConfiguration() {
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
GraphicsDevice gs = ge.getDefaultScreenDevice();
GraphicsConfiguration gc = gs.getDefaultConfiguration();
return gc;
}
/**
* Creates a BufferedImage compatible with the local graphics environment; this is a helper method for a
* common process and just sets up and calls
* {@link java.awt.GraphicsConfiguration#createCompatibleImage(int,int,int)}. The image will support
* transparent pixels.
*
* @param width Target width for the image
* @param height Target height for the image
* @return A BufferedImage compatible with the screen (best fit) supporting transparent pixels.
*/
public static BufferedImage createCompatibleBufferedImage(int width, int height) {
return createCompatibleBufferedImage(width, height, Transparency.BITMASK);
}
/**
* 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
* {@link java.awt.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
*
* @param orgImage The image to scale
* @return The scaled image instance.
*/
public static BufferedImage getScaledInstance(ScalingOptions opt, BufferedImage orgImage) {
int w = orgImage.getWidth(null);
int h = orgImage.getHeight(null);
if (opt.sizeMatches(w, h)) {
return orgImage;
}
w = (opt.getTargetWidth() <= 0 ? w : opt.getTargetWidth());
h = (opt.getTargetHeight() <= 0 ? h : opt.getTargetHeight());
Scaler scaler = (ImageUtil.Scaler) qual.get(opt.getDownscalingHint());
opt.setTargetWidth(w);
opt.setTargetHeight(h);
return scaler.getScaledInstance(orgImage, opt);
}
/**
* 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
* {@link java.awt.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
*
* @param orgImage The image to scale
* @param targetWidth The target width in pixels
* @param targetHeight The target height in pixels
* @return The scaled image instance.
*/
public static BufferedImage getScaledInstance(BufferedImage orgImage, int targetWidth, int targetHeight) {
String downscaleQuality = Configuration.valueFor("xr.image.scale", DownscaleQuality.HIGH_QUALITY.asString());
DownscaleQuality quality = DownscaleQuality.forString(downscaleQuality, DownscaleQuality.HIGH_QUALITY);
Object hint = Configuration.valueFromClassConstant("xr.image.render-quality",
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
ScalingOptions opt = new ScalingOptions(targetWidth, targetHeight, BufferedImage.TYPE_INT_ARGB, quality, hint);
return getScaledInstance(opt, orgImage);
}
/**
* Scales one image to multiple dimensions, using the same ScalingOptions for each. The method follows the same
* process for scaling as {@link #getScaledInstance(ScalingOptions,java.awt.Image)}.
*
* @param opt Options to apply to control scaling process.
* @param img The original image to scale
* @param dimensions List of dimensions to scale to; one output image will be produced for each dimension. Will
* not check for duplicate dimensions.
* @return List of buffered images in the given dimensions.
*/
public static java.util.List scaleMultiple(ScalingOptions opt, BufferedImage img, java.util.List dimensions) {
java.util.List scaledImages = new ArrayList(dimensions.size());
Iterator iter = dimensions.iterator();
while (iter.hasNext()) {
Dimension dim = (Dimension) iter.next();
opt.setTargetDimensions(dim);
BufferedImage scaled = getScaledInstance(opt, img);
scaledImages.add(scaled);
}
return scaledImages;
}
/**
* Utility method to convert an AWT Image to a BufferedImage. Size is preserved, BufferedImage is compatible
* with current display device.
*
* @param awtImg image to convert; if already a BufferedImage, returned unmodified
* @param type the type of BufferedImage to create; see
* {@link java.awt.image.BufferedImage#BufferedImage(int,int,int)}
* @return BufferedImage with same content.
*/
public static BufferedImage convertToBufferedImage(Image awtImg, int type) {
BufferedImage bimg;
if (awtImg instanceof BufferedImage) {
bimg = (BufferedImage) awtImg;
} else {
bimg = createCompatibleBufferedImage(awtImg.getWidth(null), awtImg.getHeight(null), type);
Graphics2D g = bimg.createGraphics();
g.drawImage(awtImg, 0, 0, null, null);
g.dispose();
}
return bimg;
}
public static BufferedImage createTransparentImage(int width, int height) {
BufferedImage bi = createCompatibleBufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = bi.createGraphics();
// Make all filled pixels transparent
Color transparent = new Color(0, 0, 0, 0);
g2d.setColor(transparent);
g2d.setComposite(AlphaComposite.Src);
g2d.fillRect(0, 0, width, height);
g2d.dispose();
return bi;
}
/**
* Detect if an URI represents an embedded base 64 image.
*
* @param uri URI of the image
* @return A boolean
*/
public static boolean isEmbeddedBase64Image(String uri) {
return (uri != null && uri.startsWith("data:image/"));
}
/**
* Get the binary content of an embedded base 64 image.
*
* @param imageDataUri URI of the embedded image
* @return The binary content
*/
public static byte[] getEmbeddedBase64Image(String imageDataUri) {
int b64Index = imageDataUri.indexOf("base64,");
if (b64Index != -1) {
String b64encoded = imageDataUri.substring(b64Index + "base64,".length());
return DatatypeConverter.parseBase64Binary(b64encoded);
} else {
XRLog.load(Level.SEVERE, "Embedded XHTML images must be encoded in base 64.");
}
return null;
}
/**
* Get the BufferedImage of an embedded base 64 image.
*
* @param imageDataUri URI of the embedded image
* @return The BufferedImage
*/
public static BufferedImage loadEmbeddedBase64Image(String imageDataUri) {
try {
byte[] buffer = getEmbeddedBase64Image(imageDataUri);
if (buffer != null) {
return ImageIO.read(new ByteArrayInputStream(buffer));
}
} catch (IOException ex) {
XRLog.exception("Can't read XHTML embedded image", ex);
}
return null;
}
interface Scaler {
/**
* Convenience method that returns a scaled instance of the
* provided {@code BufferedImage}, taken from article on java.net by Chris Campbell
* http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html. Expects the image
* to be fully loaded (e.g. no need to wait for loading on requesting height or width.
*
* @param img the original image to be scaled
* @param imageType type of image from {@link java.awt.image.BufferedImage} (values starting with TYPE)
* @param hint one of the rendering hints that corresponds to
* {@code RenderingHints.KEY_INTERPOLATION} (e.g.
* {@code RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR},
* {@code RenderingHints.VALUE_INTERPOLATION_BILINEAR},
* {@code RenderingHints.VALUE_INTERPOLATION_BICUBIC})
* @param higherQuality 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
* {@code targetWidth} or {@code targetHeight} is
* smaller than the original dimensions, and generally only when
* the {@code BILINEAR} hint is specified)
* @param targetWidth the desired width of the scaled instance,
* in pixels
* @param targetHeight the desired height of the scaled instance,
* in pixels
* @return a scaled version of the original {@code BufferedImage}
*/
BufferedImage getScaledInstance(BufferedImage img, ScalingOptions opt);
}
abstract static class AbstractFastScaler implements Scaler {
public BufferedImage getScaledInstance(BufferedImage img, ScalingOptions opt) {
// target is always >= 1
Image scaled = img.getScaledInstance(opt.getTargetWidth(), opt.getTargetHeight(), getImageScalingMethod());
return ImageUtil.convertToBufferedImage(scaled, img.getType());
}
abstract protected int getImageScalingMethod();
}
/**
* Old AWT-style scaling, poor quality
*/
static class OldScaler extends AbstractFastScaler {
protected int getImageScalingMethod() {
return Image.SCALE_FAST;
}
}
/**
* AWT-style one-step scaling, using area averaging
*/
static class AreaAverageScaler extends AbstractFastScaler {
protected int getImageScalingMethod() {
return Image.SCALE_AREA_AVERAGING;
}
}
/**
* Fast but decent scaling
*/
static class FastScaler implements Scaler {
public BufferedImage getScaledInstance(BufferedImage img, ScalingOptions opt) {
int w, h;
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = opt.getTargetWidth();
h = opt.getTargetHeight();
BufferedImage scaled = ImageUtil.createCompatibleBufferedImage(w, h, img.getType());
Graphics2D g2 = scaled.createGraphics();
opt.applyRenderingHints(g2);
g2.drawImage(img, 0, 0, w, h, null);
g2.dispose();
return scaled;
}
}
/**
* Step-wise downscaling
*/
static class HighQualityScaler implements Scaler {
public BufferedImage getScaledInstance(BufferedImage img, ScalingOptions opt) {
int w, h;
int imgw = img.getWidth(null);
int imgh = img.getHeight(null);
// multi-pass only if higher quality requested and we are shrinking image
if (opt.getTargetWidth() < imgw && opt.getTargetHeight() < imgh) {
// Use multi-step technique: start with original size, then
// scale down in multiple passes with drawImage()
// until the target size is reached
w = imgw;
h = imgh;
} else {
// Use one-step technique: scale directly from original
// size to target size with a single drawImage() call
w = opt.getTargetWidth();
h = opt.getTargetHeight();
}
BufferedImage scaled = img;
do {
if (w > opt.getTargetWidth()) {
w /= 2;
if (w < opt.getTargetWidth()) {
w = opt.getTargetWidth();
}
}
if (h > opt.getTargetHeight()) {
h /= 2;
if (h < opt.getTargetHeight()) {
h = opt.getTargetHeight();
}
}
BufferedImage tmp = ImageUtil.createCompatibleBufferedImage(w, h, img.getType());
Graphics2D g2 = tmp.createGraphics();
opt.applyRenderingHints(g2);
g2.drawImage(scaled, 0, 0, w, h, null);
g2.dispose();
scaled = tmp;
} while (w != opt.getTargetWidth() || h != opt.getTargetHeight());
return scaled;
}
}
}