macOS: Set CoreText underline property when creating native text layout

modules/juce_graphics/native/juce_mac_Fonts.mm

@@ -234,6 +234,15 @@ namespace CoreTextTypeLayout
                 ctFontRef = getFontWithPointSize (ctFontRef, attr.font.getHeight() * getHeightToPointsFactor (ctFontRef));
                 CFAttributedStringSetAttribute (attribString, range, kCTFontAttributeName, ctFontRef);
 
+                if (attr.font.isUnderlined())
+                {
+                    auto underline = kCTUnderlineStyleSingle;
+
+                    auto numberRef = CFNumberCreate (nullptr, kCFNumberIntType, &underline);
+                    CFAttributedStringSetAttribute (attribString, range, kCTUnderlineStyleAttributeName, numberRef);
+                    CFRelease (numberRef);
+                }
+
                 auto extraKerning = attr.font.getExtraKerningFactor();
 
                 if (extraKerning != 0)
@@ -463,6 +472,26 @@ namespace CoreTextTypeLayout
                                            String::fromCFString (cfsFontStyle),
                                            (float) (CTFontGetSize (ctRunFont) / fontHeightToPointsFactor));
 
+                    auto isUnderlined = [&]
+                    {
+                        CFNumberRef underlineStyle;
+
+                        if (CFDictionaryGetValueIfPresent (runAttributes, kCTUnderlineStyleAttributeName, (const void**) &underlineStyle))
+                        {
+                            if (CFGetTypeID (underlineStyle) == CFNumberGetTypeID())
+                            {
+                                int value = 0;
+                                CFNumberGetValue (underlineStyle, kCFNumberLongType, (void*) &value);
+
+                                return value != 0;
+                            }
+                        }
+
+                        return false;
+                    }();
+
+                    glyphRun->font.setUnderline (isUnderlined);
+
                     CFRelease (cfsFontStyle);
                     CFRelease (cfsFontFamily);
                 }