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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.
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/*
* {{{ header & license
* Copyright (c) 2006 Wisconsin Court System and 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.swing;
import org.jspecify.annotations.Nullable;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xhtmlrenderer.extend.NamespaceHandler;
import org.xhtmlrenderer.extend.UserInterface;
import org.xhtmlrenderer.layout.BoxBuilder;
import org.xhtmlrenderer.layout.LayoutContext;
import org.xhtmlrenderer.layout.SharedContext;
import org.xhtmlrenderer.render.BlockBox;
import org.xhtmlrenderer.render.Box;
import org.xhtmlrenderer.render.RenderingContext;
import org.xhtmlrenderer.render.ViewportBox;
import org.xhtmlrenderer.simple.extend.XhtmlNamespaceHandler;
import org.xhtmlrenderer.util.Configuration;
import org.xhtmlrenderer.util.ImageUtil;
import org.xml.sax.SAXException;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import static java.nio.charset.StandardCharsets.UTF_8;
import static org.xhtmlrenderer.util.ImageUtil.withGraphics;
/**
* Renders an XML files, formatted with CSS, as an image. Input is a document in the form of file or URL,
* and output is a BufferedImage. A Java2DRenderer is not intended to be re-used for multiple document
* sources; just create new Java2DRenderers for each one you need. Java2DRenderer is not thread-safe.
* Standard usage pattern is
*
*
* File xhtml = ...
* Java2DRenderer rend = new Java2DRenderer(xhtml);
* BufferedImage image = rend.getImage();
*
*
* The document is not loaded, and layout and render don't take place, until {@link #getImage()} is called.
* Subsequent calls to {@link #getImage()} don't result in a reload; create a new Java2DRenderer instance to do so.
*
* As with {@link org.xhtmlrenderer.swing.RootPanel}, you can access the
* {@link org.xhtmlrenderer.layout.SharedContext} instance that will be used by this renderer and change settings
* to control the rendering process; use {@link #getSharedContext()}.
*
* By default, this renderer will render to an RGB image which does not support transparency. To use another type
* of BufferedImage, either set the image type in constructor before calling
* {@link #getImage()}, or else override the {@link #createBufferedImage(int, int)} to have full control over
* the image we render to.
*
* Not thread-safe.
*/
public class Java2DRenderer {
private static final int DEFAULT_HEIGHT = 1000;
private static final int DEFAULT_DOTS_PER_POINT = 1;
private static final int DEFAULT_DOTS_PER_PIXEL = 1;
private static final int DEFAULT_IMAGE_TYPE = BufferedImage.TYPE_INT_RGB;
private final SharedContext sharedContext;
private Java2DOutputDevice outputDevice;
@Nullable
private Document doc;
@Nullable
private Box root;
private BufferedImage outputImage;
private final int bufferedImageType;
/**
* Whether we've completed rendering; image will only be rendered once.
*/
private boolean rendered;
@Nullable
private String sourceDocument;
@Nullable
private String sourceDocumentBase;
private final int width;
private final int height;
private static final int NO_HEIGHT = -1;
public Java2DRenderer(String url, String baseUrl, int width, int height) {
this(url, baseUrl, width, height, DEFAULT_IMAGE_TYPE);
}
/**
* Creates a new instance for a given URL. Does not render until {@link #getImage()} is called for
* the first time.
*
* @param url The location of the document to be rendered.
* @param baseUrl The base url for the document, against which relative paths are resolved.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* @param height Target height, in pixels, for the image; required to provide vertical bounds for the layout.
*/
public Java2DRenderer(String url, String baseUrl, int width, int height, int bufferedImageType) {
// bypass scaling routines based on DPI -- see PDFRenderer and compare--dotsPerPoint is not implemented
// in all subordinate classes and interfaces for Java2D, so leaving it out
// leaving this constructor call here as a TODO
this(width, height, bufferedImageType);
this.sourceDocument = url;
this.sourceDocumentBase = baseUrl;
}
/**
* Creates a new instance for a given File. Does not render until {@link #getImage()} is called for
* the first time.
*
* @param file The file to be rendered.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* @param height Target height, in pixels, for the image
*/
public Java2DRenderer(File file, int width, int height) throws IOException {
this(file.toURI().toURL().toExternalForm(), width, height);
}
/**
* Creates a new instance pointing to the given Document. Does not render until {@link #getImage()} is called for
* the first time.
*
* @param doc The document to be rendered.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* @param height Target height, in pixels, for the image.
*/
public Java2DRenderer(Document doc, int width, int height) {
this(width, height, DEFAULT_IMAGE_TYPE);
this.doc = doc;
}
public Java2DRenderer(Document doc, int width) {
this(doc, width, NO_HEIGHT);
}
/**
* Creates a new instance pointing to the given Document. Does not render until {@link #getImage()} is called for
* the first time.
*
* @param doc The document to be rendered.
* @param baseUrl The base url for the document, against which relative paths are resolved.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* @param height Target height, in pixels, for the image.
*/
public Java2DRenderer(Document doc, String baseUrl, int width, int height) {
this(doc, width, height);
this.sourceDocumentBase = baseUrl;
}
/**
* Creates a new instance for a given File. Does not render until {@link #getImage()} is called for
* the first time.
*
* @param file The file to be rendered.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* Height is calculated based on content
*/
public Java2DRenderer(File file, int width) throws IOException {
this(file.toURI().toURL().toExternalForm(), width, NO_HEIGHT);
}
public static Java2DRenderer fromFile(File file, int width, int bufferedImageType) throws IOException {
String url = file.toURI().toURL().toExternalForm();
return new Java2DRenderer(url, url, width, NO_HEIGHT, bufferedImageType);
}
/**
* Renderer for a given URL (which is also used as the base) and a specified width; height is calculated
* automatically.
*
* @param url The location of the document to be rendered.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* Height is calculated based on content
*/
public Java2DRenderer(String url, int width) {
this(url, url, width, NO_HEIGHT);
}
/**
* Renderer for a given URL and a specified width; height is calculated
* automatically.
*
* @param url The location of the document to be rendered.
* @param baseurl The base url for the document, against which relative paths are resolved.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* Height is calculated based on content
*/
public Java2DRenderer(String url, String baseurl, int width) {
this(url, baseurl, width, NO_HEIGHT);
}
/**
* Renderer for a given URL and a specified width; height is calculated
* automatically.
*
* @param url The location of the document to be rendered.
* @param width Target width, in pixels, for the image; required to provide horizontal bounds for the layout.
* @param height Target height, in pixels, for the image
*/
public Java2DRenderer(String url, int width, int height) {
this(url, url, width, height);
}
/**
* Returns the SharedContext to be used by renderer. Is instantiated along with the class, so can be accessed
* before {@link #getImage()} is called to tune the rendering process.
*
* @return the SharedContext instance that will be used by this renderer
*/
public SharedContext getSharedContext() {
return sharedContext;
}
/**
* Renders the XML document if necessary and returns the resulting image. If already rendered, same image
* reference will be returned.
*
* @return The XML rendered as a BufferedImage.
*/
public BufferedImage getImage() {
if (!rendered) {
setDocument((doc == null ? loadDocument(sourceDocument) : doc), sourceDocumentBase, new XhtmlNamespaceHandler());
layout(this.width);
int height = this.height == -1 ? root.getHeight() : this.height;
outputImage = createBufferedImage(this.width, height);
outputDevice = new Java2DOutputDevice(outputImage);
withGraphics(outputImage, newG -> {
RenderingContext rc = sharedContext.newRenderingContextInstance(outputDevice, new Java2DFontContext(newG));
sharedContext.getTextRenderer().setup(rc.getFontContext());
root.getLayer().paint(rc);
});
rendered = true;
}
return outputImage;
}
/**
* Returns a BufferedImage using the specified width and height. By default, this returns an image compatible
* with the screen (if not in "headless" mode) using the BufferedImage type specified in constructor,
* or else RGB if none is specified.
*
* @param width target width
* @param height target height
* @return new BI
*/
protected BufferedImage createBufferedImage(int width, int height) {
BufferedImage image = ImageUtil.createCompatibleBufferedImage(width, height, this.bufferedImageType);
ImageUtil.clearImage(image);
return image;
}
private void setDocument(Document doc, String url, NamespaceHandler nsh) {
this.doc = doc;
sharedContext.reset();
if (Configuration.isTrue("xr.cache.stylesheets", true)) {
sharedContext.getCss().flushStyleSheets();
} else {
sharedContext.getCss().flushAllStyleSheets();
}
sharedContext.setBaseURL(url);
sharedContext.setNamespaceHandler(nsh);
sharedContext.getCss().setDocumentContext(
sharedContext,
sharedContext.getNamespaceHandler(),
doc,
new NullUserInterface()
);
}
private void layout(int width) {
Rectangle rect = new Rectangle(0, 0, width, DEFAULT_HEIGHT);
sharedContext.setTemporaryCanvas(rect);
LayoutContext c = newLayoutContext();
BlockBox root = BoxBuilder.createRootBox(c, doc);
root.setContainingBlock(new ViewportBox(rect));
root.layout(c);
this.root = root;
}
private Document loadDocument(final String uri) {
return sharedContext.getUac().getXMLResource(uri).getDocument();
}
private LayoutContext newLayoutContext() {
Java2DFontContext fontContext = new Java2DFontContext(outputDevice.getGraphics());
LayoutContext result = sharedContext.newLayoutContextInstance(fontContext);
sharedContext.getTextRenderer().setup(fontContext);
return result;
}
private Java2DRenderer(int width, int height, int bufferedImageType) {
this.width = width;
this.height = height;
this.bufferedImageType = bufferedImageType;
outputImage = ImageUtil.createCompatibleBufferedImage(DEFAULT_DOTS_PER_POINT, DEFAULT_DOTS_PER_POINT);
outputDevice = new Java2DOutputDevice(outputImage);
sharedContext = new SharedContext(
new NaiveUserAgent(),
72 * (float) DEFAULT_DOTS_PER_POINT,
DEFAULT_DOTS_PER_PIXEL
);
sharedContext.setPrint(false);
sharedContext.setInteractive(false);
}
private static final class NullUserInterface implements UserInterface {
@Override
public boolean isHover(Element e) {
return false;
}
@Override
public boolean isActive(Element e) {
return false;
}
@Override
public boolean isFocus(Element e) {
return false;
}
}
public static BufferedImage htmlAsImage(String html, int widthInPixels) throws SAXException {
try (InputStream in = new ByteArrayInputStream(html.getBytes(UTF_8))) {
return htmlAsImage(in, widthInPixels);
} catch (IOException | ParserConfigurationException e) {
throw new RuntimeException(e);
}
}
public static BufferedImage htmlAsImage(InputStream source, int widthInPixels) throws SAXException, IOException, ParserConfigurationException {
Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(source);
return new Java2DRenderer(document, widthInPixels).getImage();
}
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