Double underline (#1256)

Author: Jugen

richtextfx/src/main/java/org/fxmisc/richtext/ParagraphText.java

@@ -216,7 +216,7 @@ public ObjectProperty<Paint> highlightTextFillProperty() {
                         underlineShape.getStrokeDashArray().setAll(attributes.dashArray);
                     }
                     PathElement[] shape = getUnderlineShape(tuple._2.getStart(), tuple._2.getEnd(),
-                                                            attributes.offset, attributes.waveRadius);
+                                          attributes.offset, attributes.waveRadius, attributes.doubleGap);
                     underlineShape.getElements().setAll(shape);
                 },
                 addToForeground,
@@ -604,24 +604,32 @@ private static class UnderlineAttributes extends LineAttributesBase {
         final StrokeLineCap cap;
         final double offset;
         final double waveRadius;
+        final double doubleGap;
 
         UnderlineAttributes(TextExt text) {
             super(text.getUnderlineColor(), text.getUnderlineWidth(), text.underlineDashArrayProperty());
             cap = text.getUnderlineCap();
+
             Number waveNumber = text.getUnderlineWaveRadius();
             waveRadius = waveNumber == null ? 0 : waveNumber.doubleValue();
+
             Number offsetNumber = text.getUnderlineOffset();
             offset = offsetNumber == null ? waveRadius * 0.5 : offsetNumber.doubleValue();
             // The larger the radius the bigger the offset needs to be, so
             // a reasonable default is provided if no offset is specified.
+
+            Number doubleGapNumber = text.getUnderlineDoubleGap();
+            if (doubleGapNumber == null) doubleGap = 0;
+            else doubleGap = doubleGapNumber.doubleValue() + width;
         }
 
         /**
          * Same as {@link #equals(Object)} but no need to check the object for its class
          */
         public boolean equalsFaster(UnderlineAttributes attr) {
             return super.equalsFaster(attr) && Objects.equals(cap, attr.cap)
-                   && offset == attr.offset && waveRadius == attr.waveRadius;
+                   && offset == attr.offset && waveRadius == attr.waveRadius
+                   && doubleGap == attr.doubleGap;
         }
 
         @Override

richtextfx/src/main/java/org/fxmisc/richtext/TextExt.java

@@ -46,6 +46,7 @@ public class TextExt extends Text {
         styleables.add(StyleableProperties.UNDERLINE_OFFSET);
         styleables.add(StyleableProperties.UNDERLINE_WAVE_RADIUS);
         styleables.add(StyleableProperties.UNDERLINE_DASH_ARRAY);
+        styleables.add(StyleableProperties.UNDERLINE_DOUBLE_GAP);
         styleables.add(StyleableProperties.UNDERLINE_CAP);
 
         CSS_META_DATA_LIST = Collections.unmodifiableList(styleables);
@@ -91,6 +92,10 @@ public class TextExt extends Text {
             null, "underlineDashArray", this, StyleableProperties.UNDERLINE_DASH_ARRAY
     );
 
+    private final StyleableObjectProperty<Number> underlineDoubleGap = new CustomStyleableProperty<>(
+            null, "underlineDoubleGap", this, StyleableProperties.UNDERLINE_DOUBLE_GAP
+    );
+
     private final StyleableObjectProperty<StrokeLineCap> underlineCap = new CustomStyleableProperty<>(
             null, "underlineCap", this, StyleableProperties.UNDERLINE_CAP
     );
@@ -266,6 +271,22 @@ public ObjectProperty<Paint> borderStrokeColorProperty() {
      */
     public ObjectProperty<Number> underlineWaveRadiusProperty() { return underlineWaveRadius; }
 
+    public Number getUnderlineDoubleGap() { return underlineDoubleGap.get(); }
+    public void setUnderlineDoubleGap(Number radius) { underlineDoubleGap.set(radius); }
+
+    /**
+     * The size of the gap between two parallel underline lines or wave forms.  If null or zero, the
+     * underline will be a single line or wave form.
+     *
+     * Can be styled from CSS using the "-rtfx-underline-double-gap" property.
+     *
+     * <p>Note that the underline properties specified here are orthogonal to the {@link #underlineProperty()} inherited
+     * from {@link Text}.  The underline properties defined here in {@link TextExt} will cause an underline to be
+     * drawn if {@link #underlineWidthProperty()} is non-null and greater than zero, regardless of
+     * the value of {@link #underlineProperty()}.</p>
+     */
+    public ObjectProperty<Number> underlineDoubleGapProperty() { return underlineDoubleGap; }
+
     // Dash array for the text underline
     public Number[] getUnderlineDashArray() { return underlineDashArray.get(); }
     public void setUnderlineDashArray(Number[] dashArray) { underlineDashArray.set(dashArray); }
@@ -315,7 +336,7 @@ private static class StyleableProperties {
         );
 
         private static final CssMetaData<TextExt, StrokeType> BORDER_TYPE = new CustomCssMetaData<>(
-                "-rtfx-border-stroke-type", (StyleConverter<?, StrokeType>) StyleConverter.getEnumConverter(StrokeType.class),
+                "-rtfx-border-stroke-type", StyleConverter.getEnumConverter(StrokeType.class),
                 StrokeType.INSIDE, n -> n.borderStrokeType
         );
 
@@ -349,8 +370,13 @@ private static class StyleableProperties {
                 new Double[0], n -> n.underlineDashArray
         );
 
+        private static final CssMetaData<TextExt, Number> UNDERLINE_DOUBLE_GAP = new CustomCssMetaData<>(
+                "-rtfx-underline-double-gap", StyleConverter.getSizeConverter(),
+                0, n -> n.underlineDoubleGap
+        );
+
         private static final CssMetaData<TextExt, StrokeLineCap> UNDERLINE_CAP = new CustomCssMetaData<>(
-                "-rtfx-underline-cap", (StyleConverter<?, StrokeLineCap>) StyleConverter.getEnumConverter(StrokeLineCap.class),
+                "-rtfx-underline-cap", StyleConverter.getEnumConverter(StrokeLineCap.class),
                 StrokeLineCap.SQUARE, n -> n.underlineCap
         );
     }

richtextfx/src/main/java/org/fxmisc/richtext/TextFlowExt.java

@@ -69,7 +69,7 @@ PathElement[] getUnderlineShape(IndexRange range) {
     }
 
     PathElement[] getUnderlineShape(int from, int to) {
-        return getUnderlineShape(from, to, 0, 0);
+        return getUnderlineShape(from, to, 0, 0, 0);
     }
 
     /**
@@ -80,14 +80,17 @@ PathElement[] getUnderlineShape(int from, int to) {
      * @return An array with the PathElement objects which define an
      *         underline from the first to the last character.
      */
-    PathElement[] getUnderlineShape(int from, int to, double offset, double waveRadius) {
+    PathElement[] getUnderlineShape(int from, int to, double offset, double waveRadius, double doubleGap) {
         // get a Path for the text underline
         List<PathElement> result = new ArrayList<>();
 
         PathElement[] shape = rangeShape( from, to );
         // The shape is a closed Path for one or more rectangles AROUND the selected text. 
         // shape: [MoveTo origin, LineTo top R, LineTo bottom R, LineTo bottom L, LineTo origin, *]
 
+        boolean doubleLine = (doubleGap > 0.0);
+        List<PathElement> result2 = new ArrayList<>();
+
         // Extract the bottom left and right coordinates for each rectangle to get the underline path.
         for ( int ele = 2; ele < shape.length; ele += 5 )
         {
@@ -100,12 +103,20 @@ PathElement[] getUnderlineShape(int from, int to, double offset, double waveRadi
             if (waveRadius <= 0) {
                 result.add(new MoveTo( leftx, y ));
                 result.add(new LineTo( snapSizeX( br.getX() ), y ));
+                if (doubleLine) {
+                    y += doubleGap;
+                    result2.add(new MoveTo( leftx, y ));
+                    result2.add(new LineTo( snapSizeX( br.getX() ), y ));
+                }
             }
             else {
                 // For larger wave radii increase the X radius to stretch out the wave.
                 double radiusX = waveRadius > 1 ? waveRadius * 1.25 : waveRadius;
                 double rightx = br.getX();
                 result.add(new MoveTo( leftx, y ));
+                if (doubleLine) {
+                    result2.add(new MoveTo( leftx, y+doubleGap ));
+                }
                 boolean sweep = true;
                 while ( leftx < rightx ) {
                     leftx += waveRadius * 2;
@@ -127,10 +138,15 @@ PathElement[] getUnderlineShape(int from, int to, double offset, double waveRadi
                         leftx = rightx;
                     }
                     result.add(new ArcTo( radiusX, waveRadius, 0.0, leftx, y, false, sweep ));
+                    if (doubleLine) {
+                        result2.add(new ArcTo( radiusX, waveRadius, 0.0, leftx, y+doubleGap, false, sweep ));
+                    }
                     sweep = !sweep;
                 }
             }
         }
+    	
+        if (doubleLine) result.addAll( result2 );
 
         return result.toArray(new PathElement[0]);
     }