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Open HTML to PDF is a CSS 2.1 renderer written in Java. This artifact contains the core rendering and layout code.
/*
* Copyright (c) 2004, 2005 Torbjoern Gannholm
* Copyright (c) 2006 Wisconsin Court System
*
* 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 com.openhtmltopdf.layout;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Pattern;
import com.openhtmltopdf.css.constants.CSSName;
import com.openhtmltopdf.css.constants.IdentValue;
import com.openhtmltopdf.css.style.CalculatedStyle;
import com.openhtmltopdf.render.InlineBox;
/**
* @author Torbjoern Gannholm
*/
public class WhitespaceStripper {
public final static String SPACE = " ";
public final static String EOL = "\n";
public final static char EOLC = '\n';
public final static Pattern linefeed_space_collapse = Pattern.compile("\\s+\\n\\s+");//Pattern is thread-safe
public final static Pattern linefeed_to_space = Pattern.compile("\\n");
public final static Pattern tab_to_space = Pattern.compile("\\t");
public final static Pattern space_collapse = Pattern.compile("(?: )+");
public final static Pattern space_before_linefeed_collapse = Pattern.compile("[\\s&&[^\\n]]\\n");
/**
* Strips whitespace early in inline content generation. This can be done
* because "whitespage" does not ally to :first-line and :first-letter. For
* dynamic pseudo-classes we are allowed to choose which properties apply.
*
* NOTE: The inlineContent parameter may be modified
*
* @param inlineContent the inline content to strip the whitespaces on
*/
public static void stripInlineContent(List inlineContent) {
boolean collapse = false;
boolean allWhitespace = true;
for (Styleable node : inlineContent) {
if (node.getStyle().isInline()) {
InlineBox iB = (InlineBox) node;
boolean collapseNext = stripWhitespace(iB, collapse);
if (! iB.isRemovableWhitespace()) {
allWhitespace = false;
}
collapse = collapseNext;
} else {
if (! canCollapseThrough(node)) {
allWhitespace = false;
collapse = false;
}
}
}
if (allWhitespace) {
stripTextContent(inlineContent);
}
}
private static boolean canCollapseThrough(Styleable styleable) {
CalculatedStyle style = styleable.getStyle();
return style.isFloated() || style.isAbsolute() || style.isFixed() || style.isRunning();
}
private static void stripTextContent(List stripped) {
boolean onlyAnonymous = true;
for (Styleable node : stripped) {
if (node.getStyle().isInline()) {
InlineBox iB = (InlineBox) node;
if (iB.getElement() != null) {
onlyAnonymous = false;
}
iB.truncateText();
}
}
if (onlyAnonymous) {
for (Iterator i = stripped.iterator(); i.hasNext(); ) {
Styleable node = i.next();
if (node.getStyle().isInline()) {
i.remove();
}
}
}
}
/**
* this function strips all whitespace from the text according to the CSS
* 2.1 spec on whitespace handling. It accounts for the different whitespace
* settings like normal, nowrap, pre, etc
*
* @param iB the InlineBox to strip. The text in it is
* modified.
* @return whether the next leading space should collapse or
* not.
*/
private static boolean stripWhitespace(InlineBox iB, boolean collapseLeading) {
IdentValue whitespace = iB.getStyle().getIdent(CSSName.WHITE_SPACE);
String text = iB.getText();
text = collapseWhitespace(iB, whitespace, text, collapseLeading);
boolean collapseNext = (text.endsWith(SPACE) &&
(whitespace == IdentValue.NORMAL || whitespace == IdentValue.NOWRAP || whitespace == IdentValue.PRE));
iB.setText(text);
if (text.trim().equals("")) {
if (whitespace == IdentValue.NORMAL || whitespace == IdentValue.NOWRAP) {
iB.setRemovableWhitespace(true);
} else if (whitespace == IdentValue.PRE) {
iB.setRemovableWhitespace(false);//actually unnecessary, is set to this by default
} else if (text.indexOf(EOL) < 0) {//and whitespace.equals("pre-line"), the only one left
iB.setRemovableWhitespace(true);
}
}
return text.equals("") ? collapseLeading : collapseNext;
}
/**
* Collapse whitespace for normal or no-wrap modes. Much faster (15x in simple testing)
* than using multiple regular expressions.
*
* NOTE: Slightly different behavior to using regular expressions as definition of space characters
* differ, but I believe this is the correct definition according to CSS specifications.
*/
private static String collapseWhitespaceNormalOrNoWrap(String text, boolean collapseLeading) {
char[] chs = text.toCharArray();
StringBuilder builder = new StringBuilder(chs.length);
boolean spaceAdded = collapseLeading;
for (int i = 0; i < chs.length; i++) {
char ch = chs[i];
if (spaceAdded) {
if (ch != '\n' &&
ch != '\t' &&
ch != ' ') {
builder.append(ch);
spaceAdded = false;
}
} else {
if (ch == '\n' ||
ch == '\t' ||
ch == ' ') {
builder.append(' ');
spaceAdded = true;
} else {
builder.append(ch);
}
}
}
return builder.toString();
}
private static String collapseWhitespace(InlineBox iB, IdentValue whitespace, String text, boolean collapseLeading) {
if (whitespace == IdentValue.NORMAL || whitespace == IdentValue.NOWRAP) {
return collapseWhitespaceNormalOrNoWrap(text, collapseLeading);
} else if (whitespace == IdentValue.PRE) {
text = space_before_linefeed_collapse.matcher(text).replaceAll(EOL);
}
if (whitespace == IdentValue.PRE || whitespace == IdentValue.PRE_WRAP) {
int tabSize = (int) iB.getStyle().asFloat(CSSName.TAB_SIZE);
char[] tabs = new char[tabSize];
Arrays.fill(tabs, ' ');
text = tab_to_space.matcher(text).replaceAll(new String(tabs));
} else if (whitespace == IdentValue.PRE_LINE) {
text = tab_to_space.matcher(text).replaceAll(SPACE);
text = space_collapse.matcher(text).replaceAll(SPACE);
}
return text;
}
}