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Added style sheet parser

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M66B
2020-04-20 15:01:05 +02:00
parent d464d858f7
commit 2deb6e18fd
4 changed files with 119 additions and 4 deletions
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109
app/src/main/java/eu/faircode/email/HtmlHelper.java
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@@ -45,6 +45,12 @@ import androidx.core.text.HtmlCompat;
import androidx.core.util.PatternsCompat;
import androidx.preference.PreferenceManager;
import com.steadystate.css.dom.CSSStyleRuleImpl;
import com.steadystate.css.parser.CSSOMParser;
import com.steadystate.css.parser.SACParserCSS3;
import com.steadystate.css.parser.selectors.ClassConditionImpl;
import com.steadystate.css.parser.selectors.ConditionalSelectorImpl;
import org.jsoup.nodes.Attribute;
import org.jsoup.nodes.Comment;
import org.jsoup.nodes.Document;
@@ -56,12 +62,21 @@ import org.jsoup.safety.Whitelist;
import org.jsoup.select.NodeFilter;
import org.jsoup.select.NodeTraversor;
import org.jsoup.select.NodeVisitor;
import org.w3c.css.sac.CSSException;
import org.w3c.css.sac.CSSParseException;
import org.w3c.css.sac.ErrorHandler;
import org.w3c.css.sac.InputSource;
import org.w3c.css.sac.Selector;
import org.w3c.dom.css.CSSRule;
import org.w3c.dom.css.CSSRuleList;
import org.w3c.dom.css.CSSStyleSheet;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
@@ -74,6 +89,7 @@ import java.util.regex.Pattern;
import static androidx.core.text.HtmlCompat.FROM_HTML_SEPARATOR_LINE_BREAK_LIST_ITEM;
import static androidx.core.text.HtmlCompat.TO_HTML_PARAGRAPH_LINES_CONSECUTIVE;
import static org.w3c.css.sac.Condition.SAC_CLASS_CONDITION;
public class HtmlHelper {
private static final int PREVIEW_SIZE = 500; // characters
@@ -356,8 +372,42 @@ public class HtmlHelper {
.text(context.getString(R.string.title_show_full));
}
// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/style
CSSStyleSheet sheet = null;
for (Element style : parsed.head().select("style")) {
Log.i("Style=" + style.data());
try {
InputSource source = new InputSource(new StringReader(style.data()));
CSSOMParser parser = new CSSOMParser(new SACParserCSS3());
parser.setErrorHandler(new ErrorHandler() {
@Override
public void warning(CSSParseException ex) throws CSSException {
Log.w(ex);
}
@Override
public void error(CSSParseException ex) throws CSSException {
Log.e(ex);
}
@Override
public void fatalError(CSSParseException ex) throws CSSException {
Log.e(ex);
}
});
// TODO: media queries
CSSStyleSheet s = parser.parseStyleSheet(source, null, null);
if (s.getMedia() != null && "all".equals(s.getMedia().getMediaText()))
sheet = s;
} catch (Throwable ex) {
Log.w(ex);
}
}
Whitelist whitelist = Whitelist.relaxed()
.addTags("hr", "abbr", "big", "font", "dfn", "del", "s", "tt")
.addAttributes(":all", "class")
.addAttributes(":all", "style")
.addAttributes("font", "size")
.removeTags("col", "colgroup", "thead", "tbody")
@@ -412,16 +462,46 @@ public class HtmlHelper {
// Sanitize styles
for (Element element : document.select("*")) {
String clazz = element.attr("class");
String style = element.attr("style");
// Process class
if (!TextUtils.isEmpty(clazz) && sheet != null) {
CSSRuleList rules = sheet.getCssRules();
for (int i = 0; rules != null && i < rules.getLength(); i++) {
CSSRule rule = rules.item(i);
if (rule.getType() == CSSRule.STYLE_RULE) {
CSSStyleRuleImpl srule = (CSSStyleRuleImpl) rule;
for (int j = 0; j < srule.getSelectors().getLength(); j++) {
Selector selector = srule.getSelectors().item(j);
switch (selector.getSelectorType()) {
case Selector.SAC_ANY_NODE_SELECTOR:
style = mergeStyles(srule.getStyle().getCssText(), style);
break;
case Selector.SAC_CONDITIONAL_SELECTOR:
ConditionalSelectorImpl cselector = (ConditionalSelectorImpl) selector;
if (cselector.getCondition().getConditionType() == SAC_CLASS_CONDITION) {
ClassConditionImpl ccondition = (ClassConditionImpl) cselector.getCondition();
if (clazz.equals(ccondition.getValue()))
style = mergeStyles(srule.getStyle().getCssText(), style);
}
break;
}
}
}
}
}
// Process style
if (!TextUtils.isEmpty(style)) {
StringBuilder sb = new StringBuilder();
String[] params = style.split(";");
for (String param : params) {
int semi = param.indexOf(':');
if (semi > 0) {
String key = param.substring(0, semi).trim().toLowerCase(Locale.ROOT);
String value = param.substring(semi + 1).toLowerCase(Locale.ROOT)
int colon = param.indexOf(':');
if (colon > 0) {
String key = param.substring(0, colon).trim().toLowerCase(Locale.ROOT);
String value = param.substring(colon + 1).toLowerCase(Locale.ROOT)
.replace("!important", "")
.trim()
.replaceAll("\\s+", " ");
@@ -845,6 +925,27 @@ public class HtmlHelper {
return document;
}
private static String mergeStyles(String base, String style) {
Map<String, String> result = new HashMap<>();
List<String> params = new ArrayList<>();
if (!TextUtils.isEmpty(base))
params.addAll(Arrays.asList(base.split(";")));
if (!TextUtils.isEmpty(style))
params.addAll(Arrays.asList(style.split(";")));
for (String param : params) {
int colon = param.indexOf(':');
if (colon > 0) {
String key = param.substring(0, colon).trim().toLowerCase(Locale.ROOT);
result.put(key, param);
} else
Log.w("Invalid style param=" + param);
}
return TextUtils.join(";", result.values());
}
private static Integer getFontWeight(String value) {
if (TextUtils.isEmpty(value))
return null;