make byte array input bytes behave correctly when seeking rather than forcing the consumer to work around it.

src/UglyToad.Pdf/Fonts/TrueType/Tables/GlyphDataTable.cs

@@ -25,7 +25,7 @@
         public static GlyphDataTable Load(TrueTypeDataBytes data, TrueTypeHeaderTable table, HeaderTable headerTable,
             IndexToLocationTable indexToLocationTable)
         {
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
 
             var offsets = indexToLocationTable.GlyphOffsets;
 
@@ -43,7 +43,7 @@
                     continue;
                 }
 
-                data.Seek(offsets[i] - 1 + table.Offset);
+                data.Seek(offsets[i] + table.Offset);
 
                 var contourCount = data.ReadSignedShort();
 

src/UglyToad.Pdf/Fonts/TrueType/Tables/HeaderTable.cs

@@ -87,7 +87,7 @@
 
         public static HeaderTable Load(TrueTypeDataBytes data, TrueTypeHeaderTable table)
         {
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
             var version = data.Read32Fixed();
             var fontRevision = data.Read32Fixed();
             var checkSumAdjustment = data.ReadUnsignedInt();

src/UglyToad.Pdf/Fonts/TrueType/Tables/HorizontalHeaderTable.cs

@@ -99,7 +99,7 @@
 
         public static HorizontalHeaderTable Load(TrueTypeDataBytes data, TrueTypeHeaderTable table)
         {
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
             var majorVersion = data.ReadUnsignedShort();
             var minorVersion = data.ReadUnsignedShort();
 

src/UglyToad.Pdf/Fonts/TrueType/Tables/IndexToLocationTable.cs

@@ -29,7 +29,7 @@
             const short shortFormat = 0;
             const short longFormat = 1;
 
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
 
             var format = headerTable.IndexToLocFormat;
 

src/UglyToad.Pdf/Fonts/TrueType/Tables/MaximumProfileTable.cs

@@ -32,7 +32,7 @@
 
         public static BasicMaximumProfileTable Load(TrueTypeDataBytes data, TrueTypeHeaderTable table)
         {
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
 
             var version = data.Read32Fixed();
             var numberOfGlyphs = data.ReadUnsignedShort();

src/UglyToad.Pdf/Fonts/TrueType/Tables/PostScriptTable.cs

@@ -81,7 +81,7 @@
 
         public static PostScriptTable Load(TrueTypeDataBytes data, TrueTypeHeaderTable table, BasicMaximumProfileTable maximumProfileTable)
         {
-            data.Seek(table.Offset - 1);
+            data.Seek(table.Offset);
             var formatType = data.Read32Fixed();
             var italicAngle = data.Read32Fixed();
             var underlinePosition = data.ReadSignedShort();

src/UglyToad.Pdf/IO/ByteArrayInputBytes.cs

@@ -45,7 +45,7 @@
 
         public void Seek(long position)
         {
-            CurrentOffset = (int)position;
+            CurrentOffset = (int)position - 1;
             CurrentByte = CurrentOffset < 0 ? (byte)0 : bytes[CurrentOffset];
         }
     }