1 files changed, 65 insertions, 0 deletions
diff --git a/src/jogl/classes/jogamp/graph/font/typecast/ot/LongDateTime.java b/src/jogl/classes/jogamp/graph/font/typecast/ot/LongDateTime.java
new file mode 100644
index 000000000..b5db921ff
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+++ b/src/jogl/classes/jogamp/graph/font/typecast/ot/LongDateTime.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2020 Business Operation Systems GmbH. All Rights Reserved.
+ */
+package jogamp.graph.font.typecast.ot;
+
+import java.time.ZoneId;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.GregorianCalendar;
+import java.util.TimeZone;
+
+/**
+ * Utility to convert number of seconds since 12:00 midnight that started
+ * January 1st 1904 in GMT/UTC time zone to a {@link Date} value.
+ *
+ * @author <a href="mailto:[email protected]">Bernhard Haumacher</a>
+ */
+public class LongDateTime {
+    
+    private static final long BASE;
+
+    static {
+        GregorianCalendar calendar = new GregorianCalendar(TimeZone.getTimeZone(ZoneId.of("UTC")));
+        calendar.set(Calendar.YEAR, 1904);
+        calendar.set(Calendar.MONTH, Calendar.JANUARY);
+        calendar.set(Calendar.DAY_OF_MONTH, 1);
+        calendar.set(Calendar.HOUR, 0);
+        calendar.set(Calendar.MINUTE, 0);
+        calendar.set(Calendar.SECOND, 0);
+        calendar.set(Calendar.MILLISECOND, 0);
+        
+        BASE = calendar.getTimeInMillis();
+    }
+
+    /**
+     * Converts a {@link LongDateTime} value to a {@link Date}.
+     */
+    public static Date toDate(long longDateTime) {
+        return new Date(toSystemMillis(longDateTime));
+    }
+
+    /**
+     * Converts a {@link LongDateTime} value to a Java system millis value compatible
+     * with {@link System#currentTimeMillis()}.
+     */
+    public static long toSystemMillis(long longDateTime) {
+        return BASE + 1000L * longDateTime;
+    }
+    
+    /**
+     * Converts a {@link Date} to a {@link LongDateTime} value.
+     */
+    public static long fromDate(Date date) {
+        return fromSystemMillis(date.getTime());
+    }
+    
+    /**
+     * Converts a Java system millis value compatible
+     * with {@link System#currentTimeMillis()} to a {@link LongDateTime} value.
+     */
+    public static long fromSystemMillis(long systemMillis) {
+        return (systemMillis - BASE) / 1000L;
+    }
+    
+}