Add shorthand text decoration support

DEVSIX-3933

Author: BlackEgoist

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/css/CommonCssConstants.java

@@ -573,6 +573,21 @@ public class CommonCssConstants {
      */
     public static final String TEXT_DECORATION = "text-decoration";
 
+    /**
+     * The Constant TEXT_DECORATION_LINE.
+     */
+    public static final String TEXT_DECORATION_LINE = "text-decoration-line";
+
+    /**
+     * The Constant TEXT_DECORATION_STYLE.
+     */
+    public static final String TEXT_DECORATION_STYLE = "text-decoration-style";
+
+    /**
+     * The Constant TEXT_DECORATION_COLOR.
+     */
+    public static final String TEXT_DECORATION_COLOR = "text-decoration-color";
+
     /**
      * The Constant TEXT_INDENT.
      */
@@ -675,6 +690,11 @@ public class CommonCssConstants {
      */
     public static final String AUTO = "auto";
 
+    /**
+     * The Constant BLINK.
+     */
+    public static final String BLINK = "blink";
+
     /**
      * The Constant BOLD.
      */
@@ -859,6 +879,11 @@ public class CommonCssConstants {
      */
     public static final String LIGHTER = "lighter";
 
+    /**
+     * The Constant value LINE_THROUGH.
+     */
+    public static final String LINE_THROUGH = "line-through";
+
     /**
      * The Constant LOCAL.
      */
@@ -954,6 +979,11 @@ public class CommonCssConstants {
      */
     public static final String OUTSET = "outset";
 
+    /**
+     * The Constant value OVERLINE.
+     */
+    public static final String OVERLINE= "overline";
+
     /**
      * The Constant PADDING_BOX.
      */
@@ -1109,6 +1139,11 @@ public class CommonCssConstants {
      */
     public static final String TRANSPARENT = "transparent";
 
+    /**
+     * The Constant value UNDERLINE
+     */
+    public static final String UNDERLINE = "underline";
+
     /**
      * The Constant UPPER_ALPHA.
      */
@@ -1129,6 +1164,11 @@ public class CommonCssConstants {
      */
     public static final String VISIBLE = "visible";
 
+    /**
+     * The Constant value WAVY.
+     */
+    public static final String WAVY = "wavy";
+
     /**
      * The Constant X_LARGE.
      */

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/css/resolve/CssDefaults.java

@@ -136,8 +136,10 @@ public class CssDefaults {
 
         defaultValues.put(CommonCssConstants.TEXT_ALIGN, CommonCssConstants.START);
         defaultValues.put(CommonCssConstants.TEXT_DECORATION, CommonCssConstants.NONE);
+        defaultValues.put(CommonCssConstants.TEXT_DECORATION_LINE, CommonCssConstants.NONE);
+        defaultValues.put(CommonCssConstants.TEXT_DECORATION_STYLE, CommonCssConstants.SOLID);
+        defaultValues.put(CommonCssConstants.TEXT_DECORATION_COLOR, CommonCssConstants.CURRENTCOLOR);
         defaultValues.put(CommonCssConstants.TEXT_TRANSFORM, CommonCssConstants.NONE);
-        defaultValues.put(CommonCssConstants.TEXT_DECORATION, CommonCssConstants.NONE);
 
         defaultValues.put(CommonCssConstants.WHITE_SPACE, CommonCssConstants.NORMAL);
         defaultValues.put(CommonCssConstants.WIDTH, CommonCssConstants.AUTO);

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/css/resolve/shorthand/ShorthandResolverFactory.java

@@ -60,6 +60,7 @@ This file is part of the iText (R) project.
 import com.itextpdf.styledxmlparser.css.resolve.shorthand.impl.MarginShorthandResolver;
 import com.itextpdf.styledxmlparser.css.resolve.shorthand.impl.OutlineShorthandResolver;
 import com.itextpdf.styledxmlparser.css.resolve.shorthand.impl.PaddingShorthandResolver;
+import com.itextpdf.styledxmlparser.css.resolve.shorthand.impl.TextDecorationShorthandResolver;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -88,7 +89,7 @@ public class ShorthandResolverFactory {
         shorthandResolvers.put(CommonCssConstants.MARGIN, new MarginShorthandResolver());
         shorthandResolvers.put(CommonCssConstants.OUTLINE, new OutlineShorthandResolver());
         shorthandResolvers.put(CommonCssConstants.PADDING, new PaddingShorthandResolver());
-        // TODO text-decoration is a shorthand in CSS3, however it is not yet supported in any major browsers
+        shorthandResolvers.put(CommonCssConstants.TEXT_DECORATION, new TextDecorationShorthandResolver());
     }
 
     /**

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/css/resolve/shorthand/impl/TextDecorationShorthandResolver.java

@@ -0,0 +1,73 @@
+package com.itextpdf.styledxmlparser.css.resolve.shorthand.impl;
+
+import com.itextpdf.styledxmlparser.css.CommonCssConstants;
+import com.itextpdf.styledxmlparser.css.CssDeclaration;
+import com.itextpdf.styledxmlparser.css.resolve.shorthand.IShorthandResolver;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+public class TextDecorationShorthandResolver implements IShorthandResolver {
+
+    private static final Set<String> TEXT_DECORATION_LINE_VALUES = new HashSet<>(Arrays.asList(
+            CommonCssConstants.UNDERLINE, CommonCssConstants.OVERLINE, CommonCssConstants.LINE_THROUGH,
+            CommonCssConstants.BLINK
+    ));
+
+    private static final Set<String> TEXT_DECORATION_STYLE_VALUES = new HashSet<>(Arrays.asList(
+            CommonCssConstants.SOLID, CommonCssConstants.DOUBLE, CommonCssConstants.DOTTED,
+            CommonCssConstants.DASHED, CommonCssConstants.WAVY
+    ));
+
+    @Override
+    public List<CssDeclaration> resolveShorthand(String shorthandExpression) {
+        if (CommonCssConstants.INITIAL.equals(shorthandExpression) || CommonCssConstants.INHERIT
+                .equals(shorthandExpression)) {
+            return Arrays.asList(
+                    new CssDeclaration(CommonCssConstants.TEXT_DECORATION_LINE, shorthandExpression),
+                    new CssDeclaration(CommonCssConstants.TEXT_DECORATION_STYLE, shorthandExpression),
+                    new CssDeclaration(CommonCssConstants.TEXT_DECORATION_COLOR, shorthandExpression));
+        }
+
+        //regexp for separating line by spaces that are not inside the parentheses, so rgb()
+        // and hsl() color declarations are parsed correctly
+        String[] props = shorthandExpression.split("\\s+(?![^\\(]*\\))");
+
+        List<String> textDecorationLineValues = new ArrayList<>();
+        String textDecorationStyleValue = null;
+        String textDecorationColorValue = null;
+
+        for (String value : props) {
+            //For text-decoration-line attributes several attributes may be present at once.
+            //However when "none" attribute is present, all the other attributes become invalid
+            if (TEXT_DECORATION_LINE_VALUES.contains(value)
+                    || CommonCssConstants.NONE.equals(value)) {
+                textDecorationLineValues.add(value);
+            } else if (TEXT_DECORATION_STYLE_VALUES.contains(value)) {
+                textDecorationStyleValue = value;
+            } else if (!value.isEmpty()) {
+                textDecorationColorValue = value;
+            }
+        }
+
+        List<CssDeclaration> resolvedDecl = new ArrayList<>();
+        if (textDecorationLineValues.isEmpty()) {
+            resolvedDecl.add(new CssDeclaration(CommonCssConstants.TEXT_DECORATION_LINE, CommonCssConstants.INITIAL));
+        } else {
+            StringBuilder resultLine = new StringBuilder();
+            for (String line : textDecorationLineValues) {
+                resultLine.append(line).append(" ");
+            }
+            resolvedDecl.add(new CssDeclaration(CommonCssConstants.TEXT_DECORATION_LINE, resultLine.toString().trim()));
+        }
+
+        resolvedDecl.add(new CssDeclaration(CommonCssConstants.TEXT_DECORATION_STYLE,
+                textDecorationStyleValue == null ? CommonCssConstants.INITIAL : textDecorationStyleValue));
+        resolvedDecl.add(new CssDeclaration(CommonCssConstants.TEXT_DECORATION_COLOR,
+                textDecorationColorValue == null ? CommonCssConstants.INITIAL : textDecorationColorValue));
+        return resolvedDecl;
+    }
+}

styled-xml-parser/src/main/java/com/itextpdf/styledxmlparser/util/StyleUtil.java

@@ -0,0 +1,99 @@
+package com.itextpdf.styledxmlparser.util;
+
+import com.itextpdf.io.util.DecimalFormatUtil;
+import com.itextpdf.styledxmlparser.css.CommonCssConstants;
+import com.itextpdf.styledxmlparser.css.resolve.CssPropertyMerger;
+import com.itextpdf.styledxmlparser.css.resolve.IStyleInheritance;
+import com.itextpdf.styledxmlparser.css.util.CssUtils;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+public final class StyleUtil {
+
+    private StyleUtil() {
+
+    }
+
+    /**
+     * List to store the properties whose value can depend on parent or element font-size
+     */
+    private static final List<String> fontSizeDependentPercentage = new ArrayList<String>(2);
+
+    static {
+        fontSizeDependentPercentage.add(CommonCssConstants.FONT_SIZE);
+        fontSizeDependentPercentage.add(CommonCssConstants.LINE_HEIGHT);
+    }
+
+    /**
+     * Merge parent CSS declarations.
+     *
+     * @param styles          the styles map
+     * @param styleProperty     the CSS property
+     * @param parentPropValue the parent properties value
+     * @param inheritanceRules set of inheritance rules
+     *
+     * @return a map of updated styles after merging parent and child style declarations
+     */
+    public static  Map<String, String> mergeParentStyleDeclaration(Map<String, String> styles, String styleProperty, String parentPropValue, String parentFontSizeString, Set<IStyleInheritance> inheritanceRules) {
+        String childPropValue = styles.get(styleProperty);
+        if ((childPropValue == null && checkInheritance(styleProperty, inheritanceRules)) || CommonCssConstants.INHERIT.equals(childPropValue)) {
+            if (valueIsOfMeasurement(parentPropValue, CommonCssConstants.EM)
+                    || valueIsOfMeasurement(parentPropValue, CommonCssConstants.EX)
+                    || valueIsOfMeasurement(parentPropValue, CommonCssConstants.PERCENTAGE) && fontSizeDependentPercentage.contains(styleProperty)) {
+                float absoluteParentFontSize = CssUtils.parseAbsoluteLength(parentFontSizeString);
+                // Format to 4 decimal places to prevent differences between Java and C#
+                styles.put(styleProperty, DecimalFormatUtil
+                        .formatNumber(CssUtils.parseRelativeValue(parentPropValue, absoluteParentFontSize),
+                                "0.####") + CommonCssConstants.PT);
+            } else {
+                styles.put(styleProperty, parentPropValue);
+            }
+        } else if (CommonCssConstants.TEXT_DECORATION_LINE.equals(styleProperty)
+                && !CommonCssConstants.INLINE_BLOCK.equals(styles.get(CommonCssConstants.DISPLAY))) {
+            // Note! This property is formally not inherited, but the browsers behave very similar to inheritance here.
+            // Text decorations on inline boxes are drawn across the entire element,
+            // going across any descendant elements without paying any attention to their presence.
+            // Also, when, for example, parent element has text-decoration:underline, and the child text-decoration:overline,
+            // then the text in the child will be both overline and underline. This is why the declarations are merged
+            // See TextDecorationTest#textDecoration01Test
+            styles.put(styleProperty, CssPropertyMerger.mergeTextDecoration(childPropValue, parentPropValue));
+        }
+
+        return styles;
+    }
+
+    /**
+     * Check all inheritance rule-sets to see if the passed property is inheritable
+     *
+     * @param styleProperty property identifier to check
+     * @param inheritanceRules a set of inheritance rules
+     * @return True if the property is inheritable by one of the rule-sets,
+     * false if it is not marked as inheritable in all rule-sets
+     */
+    private static boolean checkInheritance(String styleProperty, Set<IStyleInheritance> inheritanceRules) {
+        for (IStyleInheritance inheritanceRule : inheritanceRules) {
+            if (inheritanceRule.isInheritable(styleProperty)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Check to see if the passed value is a measurement of the type based on the passed measurement symbol string
+     *
+     * @param value       string containing value to check
+     * @param measurement measurement symbol (e.g. % for relative, px for pixels)
+     * @return True if the value is numerical and ends with the measurement symbol, false otherwise
+     */
+    private static boolean valueIsOfMeasurement(String value, String measurement) {
+        if (value == null) {
+            return false;
+        }
+        return value.endsWith(measurement) && CssUtils
+                .isNumericValue(value.substring(0, value.length() - measurement.length()).trim());
+    }
+}