move code into correct directory structure

src/UglyToad.Pdf/IO/RandomAccessInputStream.cs

@@ -0,0 +1,83 @@
+namespace UglyToad.Pdf.IO
+{
+    public class RandomAccessInputStream : IInputStream
+    {
+        private readonly IRandomAccessRead input;
+        private long position;
+
+        /**
+         * Creates a new RandomAccessInputStream, with a position of zero. The InputStream will maintain
+         * its own position independent of the RandomAccessRead.
+         *
+         * @param randomAccessRead The RandomAccessRead to read from.
+         */
+        public RandomAccessInputStream(IRandomAccessRead randomAccessRead)
+        {
+            input = randomAccessRead;
+            position = 0;
+        }
+
+        void restorePosition()
+        {
+            input.Seek(position);
+        }
+
+        public long available()
+        {
+            restorePosition();
+            long available = input.Length() - input.GetPosition();
+            if (available > int.MaxValue)
+            {
+                return int.MaxValue;
+            }
+            return available;
+        }
+
+        public int read()
+        {
+            restorePosition();
+            if (input.IsEof())
+            {
+                return -1;
+            }
+            int b = input.Read();
+            position += 1;
+            return b;
+        }
+
+        public int read(byte[] b)
+        {
+            return read(b, 0, b.Length);
+        }
+
+        public int read(byte[] b, int off, int len)
+        {
+            restorePosition();
+            if (input.IsEof())
+            {
+                return -1;
+            }
+            int n = input.Read(b, off, len);
+            position += n;
+            return n;
+        }
+
+        public long skip(long n)
+        {
+            restorePosition();
+            input.Seek(position + n);
+            position += n;
+            return n;
+        }
+
+        public void Dispose()
+        {
+            input.Dispose();
+        }
+
+        long IInputStream.available()
+        {
+            throw new System.NotImplementedException();
+        }
+    }
+}