diff -r 3b8b1da2ff29 -r 12b1f4649ab1 src/Tools/GraphBrowser/graphbrowser/DefaultFontMetrics.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Tools/GraphBrowser/graphbrowser/DefaultFontMetrics.java	Fri Jul 16 12:55:02 2021 +0200
@@ -0,0 +1,48 @@
+/***************************************************************************
+  Title:      graphbrowser/DefaultFontMetrics.java
+  Author:     Stefan Berghofer, TU Muenchen
+  Options:    :tabSize=2:
+
+  Default font metrics which is used when no graphics context
+  is available (batch mode).
+***************************************************************************/
+
+package isabelle.graphbrowser;
+
+public class DefaultFontMetrics implements AbstractFontMetrics {
+
+  private static int[] chars =
+	{13, 13, 17, 27, 27, 43, 32, 11, 16, 16, 19, 28, 13, 28, 13, 13, 27,
+	 27, 27, 27, 27, 27, 27, 27, 27, 27, 13, 13, 28, 28, 28, 27, 49, 32,
+	 32, 35, 35, 32, 29, 37, 35, 13, 24, 32, 27, 40, 35, 37, 32, 37, 35,
+	 32, 29, 35, 32, 45, 32, 32, 29, 13, 13, 13, 22, 27, 11, 27, 27, 24,
+	 27, 27, 13, 27, 27, 11, 11, 24, 11, 40, 27, 27, 27, 27, 16, 24, 13,
+	 27, 24, 35, 24, 24, 24, 16, 12, 16, 28};
+
+  private int size;
+
+  public DefaultFontMetrics(int size)
+  { this.size = size; }
+
+  public int getLeading()
+  { return 1; }
+
+  public int getAscent()
+  { return (int)(Math.round(size * 46.0 / 48.0)); }
+  
+  public int getDescent() 
+  { return (int)(Math.round(size * 10.0 / 48.0)); }
+  
+  public int charWidth(char c) {
+    if (c < 32 || c > 126) { return 0; }
+    else {
+	    return (int)(Math.round(chars[c - 32] * size / 48.0));
+    }
+  }
+  
+  public int stringWidth(String s) {
+    int l=0, i;
+    for (i=0; i < s.length(); i++) { l += charWidth(s.charAt(i)); }
+    return l;
+  }
+}