src/java.desktop/share/classes/sun/font/CharToGlyphMapper.java

*** 34,43 ****
--- 34,47 ----
  
      public static final int HI_SURROGATE_START = 0xD800;
      public static final int HI_SURROGATE_END = 0xDBFF;
      public static final int LO_SURROGATE_START = 0xDC00;
      public static final int LO_SURROGATE_END = 0xDFFF;
+     public static final int VS_START = 0xFE00;
+     public static final int VS_END = 0xFE0F;
+     public static final int VSS_START = 0xE0100;
+     public static final int VSS_END = 0xE01FF;
  
      public static final int UNINITIALIZED_GLYPH = -1;
      public static final int INVISIBLE_GLYPH_ID = 0xffff;
      public static final int INVISIBLE_GLYPHS   = 0xfffe; // and above
  
*** 86,91 ****
--- 90,125 ----
                                              char[] unicodes, int[] glyphs);
  
      public abstract void charsToGlyphs(int count,
                                         int[] unicodes, int[] glyphs);
  
+     // Based on Unicode 10.0.0 chapter 23.4
+     public static boolean isVSBaseChar(int charCode) {
+         int type = Character.getType(charCode);
+         if (type == Character.UNASSIGNED ||
+             type == Character.CONTROL ||
+             type == Character.FORMAT ||
+             type == Character.NON_SPACING_MARK) { 
+             return false;
+         }
+         return java.text.Normalizer.isNormalized(
+                    java.nio.CharBuffer.wrap(Character.toChars(charCode)),
+                    java.text.Normalizer.Form.NFD);
+     }
+ 
+     public static boolean isVariationSelector(int charCode) {
+         return ((charCode >= VSS_START && charCode <= VSS_END) ||
+                 (charCode >= VS_START && charCode <= VS_END));
+     }
+ 
+     public static boolean isVariationSelectorBMP(char charCode) {
+         return (charCode >= VS_START && charCode <= VS_END);
+     }
+ 
+     public static boolean isVariationSelectorExt(char charCode1,
+                                                  char charCode2) {
+         return (charCode1 == 0xDB40 &&
+                 (charCode2 >= 0xDD00 && charCode2 <= 0xDDEF));
+                 // VSS_START - VSS_END
+     }
+ 
  }