Upload FastSeekWpf/NativeInterop/Win32Api.cs

FastSeekWpf/NativeInterop/Win32Api.cs

@@ -31,7 +31,6 @@ internal static class Win32Api
     public const uint FILE_FLAG_BACKUP_SEMANTICS = 0x02000000;
     public const uint FILE_FLAG_SEQUENTIAL_SCAN = 0x08000000;
     public const uint FILE_FLAG_NO_BUFFERING = 0x20000000;
-    public const uint FILE_ATTRIBUTE_DIRECTORY = 0x00000010;
     public const uint FILE_ATTRIBUTE_NORMAL = 0x00000080;
 
     // IOCTL codes
@@ -74,6 +73,29 @@ internal static class Win32Api
         out uint lpNumberOfBytesRead,
         IntPtr lpOverlapped);
 
+    // Unsafe overload: read into a byte[] at a given offset via GCHandle
+    public static unsafe bool ReadFile(
+        IntPtr hFile,
+        byte[] lpBuffer,
+        int offset,
+        uint nNumberOfBytesToRead,
+        out uint lpNumberOfBytesRead,
+        IntPtr lpOverlapped)
+    {
+        fixed (byte* p = &lpBuffer[offset])
+        {
+            return ReadFilePointer(hFile, p, nNumberOfBytesToRead, out lpNumberOfBytesRead, lpOverlapped);
+        }
+    }
+
+    [DllImport("kernel32.dll", SetLastError = true, EntryPoint = "ReadFile")]
+    private static extern unsafe bool ReadFilePointer(
+        IntPtr hFile,
+        byte* lpBuffer,
+        uint nNumberOfBytesToRead,
+        out uint lpNumberOfBytesRead,
+        IntPtr lpOverlapped);
+
     [DllImport("kernel32.dll", SetLastError = true)]
     public static extern bool SetFilePointerEx(
         IntPtr hFile,