apache · djberg96 · Feb 6, 2026
diff --git a/batik-bridge/src/main/java/org/apache/batik/bridge/GlyphLayout.java b/batik-bridge/src/main/java/org/apache/batik/bridge/GlyphLayout.java
@@ -132,6 +132,12 @@ public class GlyphLayout implements TextSpanLayout {
     private static final AttributedCharacterIterator.Attribute BASELINE_SHIFT
         = GVTAttributedCharacterIterator.TextAttribute.BASELINE_SHIFT;
 
+    private static final AttributedCharacterIterator.Attribute DOMINANT_BASELINE
+        = GVTAttributedCharacterIterator.TextAttribute.DOMINANT_BASELINE;
+
+    private static final AttributedCharacterIterator.Attribute ALIGNMENT_BASELINE
+        = GVTAttributedCharacterIterator.TextAttribute.ALIGNMENT_BASELINE;
+
     private static final AttributedCharacterIterator.Attribute WRITING_MODE
         = GVTAttributedCharacterIterator.TextAttribute.WRITING_MODE;
 
@@ -153,6 +159,8 @@ public class GlyphLayout implements TextSpanLayout {
         runAtts.add(DY);
         runAtts.add(ROTATION);
         runAtts.add(BASELINE_SHIFT);
+        runAtts.add(DOMINANT_BASELINE);
+        runAtts.add(ALIGNMENT_BASELINE);
     }
 
     protected static Set szAtts = new HashSet();
@@ -1084,6 +1092,8 @@ protected void doExplicitGlyphLayout() {
 
         Float x=null, y=null, dx=null, dy=null, rotation=null;
         Object baseline=null;
+        String dominantBl=null;
+        String alignmentBl=null;
 
         float shift_x_pos = 0;
         float shift_y_pos = 0;
@@ -1102,6 +1112,8 @@ protected void doExplicitGlyphLayout() {
                 dy       = (Float) aci.getAttribute(DY);
                 rotation = (Float) aci.getAttribute(ROTATION);
                 baseline = aci.getAttribute(BASELINE_SHIFT);
+                dominantBl = (String) aci.getAttribute(DOMINANT_BASELINE);
+                alignmentBl = (String) aci.getAttribute(ALIGNMENT_BASELINE);
             }
 
             GVTGlyphMetrics gm = gv.getGlyphMetrics(i);
@@ -1227,6 +1239,22 @@ protected void doExplicitGlyphLayout() {
                     }
                 }
 
+                // Apply dominant-baseline and alignment-baseline offsets.
+                // dominant-baseline shifts the element so the specified
+                // baseline sits at the coordinate position.
+                // alignment-baseline shifts a child element so its specified
+                // baseline aligns with the parent's dominant baseline.
+                float dbOffset = getBaselineOffset(dominantBl, metrics);
+                float abOffset = getBaselineOffset(alignmentBl, metrics);
+                float blAdjust = dbOffset - abOffset;
+                if (blAdjust != 0f) {
+                    if (vertical) {
+                        ox += blAdjust;
+                    } else {
+                        oy -= blAdjust;
+                    }
+                }
+
                 if (vertical) {
                     // offset due to rotation of first character
                     oy += verticalFirstOffset;
@@ -2046,4 +2074,54 @@ public boolean isReversed(){
     public void maybeReverse(boolean mirror){
         gv.maybeReverse(mirror);
     }
+
+    /**
+     * Returns the vertical offset (positive = above the alphabetic baseline)
+     * for the named SVG baseline value, using the given font metrics.
+     * Returns 0 for null, "auto", "baseline", or unrecognized values.
+     *
+     * @param baselineValue the SVG baseline identifier string
+     * @param metrics       the line metrics for the current font
+     * @return the offset from the alphabetic baseline (positive = up)
+     */
+    protected static float getBaselineOffset(String baselineValue,
+                                             GVTLineMetrics metrics) {
+        if (baselineValue == null) {
+            return 0f;
+        }
+        float ascent  = metrics.getAscent();
+        float descent = metrics.getDescent();
+        switch (baselineValue) {
+        case "alphabetic":
+        case "auto":
+        case "baseline":
+            return 0f;
+        case "ideographic":
+            // Bottom of the ideographic em box ≈ descent below alphabetic
+            return -descent;
+        case "hanging":
+            // Hanging baseline — near the top of the em box
+            return ascent * 0.8f;
+        case "mathematical":
+            // Mathematical baseline — approximately at the math axis
+            return metrics.getStrikethroughOffset()
+                   + ascent * 0.1f;
+        case "central":
+            // Midpoint between ascent and descent
+            return (ascent - descent) / 2.0f;
+        case "middle":
+            // SVG middle ≈ x-height / 2 ≈ strikethrough offset
+            return metrics.getStrikethroughOffset();
+        case "text-before-edge":  // SVG 1.1 name
+        case "text-top":          // CSS name
+        case "before-edge":
+            return ascent;
+        case "text-after-edge":   // SVG 1.1 name
+        case "text-bottom":       // CSS name
+        case "after-edge":
+            return -descent;
+        default:
+            return 0f;
+        }
+    }
 }
diff --git a/batik-bridge/src/main/java/org/apache/batik/bridge/SVGTextElementBridge.java b/batik-bridge/src/main/java/org/apache/batik/bridge/SVGTextElementBridge.java
@@ -129,6 +129,14 @@ public class SVGTextElementBridge extends AbstractGraphicsNodeBridge
         AttributedCharacterIterator.Attribute BASELINE_SHIFT
         = GVTAttributedCharacterIterator.TextAttribute.BASELINE_SHIFT;
 
+    public static final
+        AttributedCharacterIterator.Attribute DOMINANT_BASELINE
+        = GVTAttributedCharacterIterator.TextAttribute.DOMINANT_BASELINE;
+
+    public static final
+        AttributedCharacterIterator.Attribute ALIGNMENT_BASELINE
+        = GVTAttributedCharacterIterator.TextAttribute.ALIGNMENT_BASELINE;
+
     protected AttributedString laidoutText;
 
     // This is used to track the TextPainterInfo for each element
@@ -709,8 +717,10 @@ public void handleCSSEngineEvent(CSSEngineEvent evt) {
         // first try to find CSS properties that change the layout
         for (int property : properties) {
             switch (property) {         // fall-through is intended
+                case SVGCSSEngine.ALIGNMENT_BASELINE_INDEX:
                 case SVGCSSEngine.BASELINE_SHIFT_INDEX:
                 case SVGCSSEngine.DIRECTION_INDEX:
+                case SVGCSSEngine.DOMINANT_BASELINE_INDEX:
                 case SVGCSSEngine.DISPLAY_INDEX:
                 case SVGCSSEngine.FONT_FAMILY_INDEX:
                 case SVGCSSEngine.FONT_SIZE_INDEX:
@@ -1604,6 +1614,18 @@ protected Map getAttributeMap(BridgeContext ctx,
             result.put(BASELINE_SHIFT, bs);
         }
 
+        // Dominant baseline
+        String db = TextUtilities.convertDominantBaseline(element);
+        if (db != null) {
+            result.put(DOMINANT_BASELINE, db);
+        }
+
+        // Alignment baseline
+        String ab = TextUtilities.convertAlignmentBaseline(element);
+        if (ab != null) {
+            result.put(ALIGNMENT_BASELINE, ab);
+        }
+
         // Unicode-bidi mode
         Value val =  CSSUtilities.getComputedStyle
             (element, SVGCSSEngine.UNICODE_BIDI_INDEX);

diff --git a/batik-bridge/src/main/java/org/apache/batik/bridge/TextUtilities.java b/batik-bridge/src/main/java/org/apache/batik/bridge/TextUtilities.java
@@ -286,6 +286,42 @@ public static Object convertBaselineShift(Element e) {
         }
     }
 
+    /**
+     * Converts the dominant-baseline CSS value to a string usable as a
+     * text attribute, or null if the value is "auto".
+     * @param e the element
+     */
+    public static String convertDominantBaseline(Element e) {
+        Value v = CSSUtilities.getComputedStyle
+            (e, SVGCSSEngine.DOMINANT_BASELINE_INDEX);
+        if (v.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT) {
+            String s = v.getStringValue();
+            if (CSS_AUTO_VALUE.equals(s)) {
+                return null;
+            }
+            return s;
+        }
+        return null;
+    }
+
+    /**
+     * Converts the alignment-baseline CSS value to a string usable as a
+     * text attribute, or null if the value is "auto" or "baseline".
+     * @param e the element
+     */
+    public static String convertAlignmentBaseline(Element e) {
+        Value v = CSSUtilities.getComputedStyle
+            (e, SVGCSSEngine.ALIGNMENT_BASELINE_INDEX);
+        if (v.getPrimitiveType() == CSSPrimitiveValue.CSS_IDENT) {
+            String s = v.getStringValue();
+            if (CSS_AUTO_VALUE.equals(s) || CSS_BASELINE_VALUE.equals(s)) {
+                return null;
+            }
+            return s;
+        }
+        return null;
+    }
+
     /**
      * Converts a kerning CSS value to a value usable as a text
      * attribute, or null.

diff --git a/batik-gvt/src/main/java/org/apache/batik/gvt/text/GVTAttributedCharacterIterator.java b/batik-gvt/src/main/java/org/apache/batik/gvt/text/GVTAttributedCharacterIterator.java
@@ -310,6 +310,16 @@ public TextAttribute(String s) {
         public static final TextAttribute BASELINE_SHIFT =
                                           new TextAttribute("BASELINE_SHIFT");
 
+        /** Dominant baseline for this character span (String value from CSS).
+         */
+        public static final TextAttribute DOMINANT_BASELINE =
+                                          new TextAttribute("DOMINANT_BASELINE");
+
+        /** Alignment baseline for this character span (String value from CSS).
+         */
+        public static final TextAttribute ALIGNMENT_BASELINE =
+                                          new TextAttribute("ALIGNMENT_BASELINE");
+
         /** Directional writing mode applied to this character span.
          */
         public static final TextAttribute WRITING_MODE =