Updated Bitmap header (#565)

* Updated Bitmap header

Updated the Bitmap header to BITMAPINFOHEADER according to https://en.wikipedia.org/wiki/BMP_file_format#DIB_header_(bitmap_information_header)

Slightly improved, now with bitmap size in header. Updating the header was necessary as inserting the previous version inside a PDF document wasn't possible.

* Fixed formatting (dotnet format checks)

---------

Co-authored-by: Raffael Herrmann <[email protected]>

Author: Apflkuacha

QRCoder/BitmapByteQRCode.cs

@@ -59,7 +59,7 @@ public byte[] GetGraphic(int pixelsPerModule, byte[] darkColorRgb, byte[] lightC
         var bmp = new List<byte>();
 
         //header
-        bmp.AddRange(new byte[] { 0x42, 0x4D, 0x4C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1A, 0x00, 0x00, 0x00, 0x0C, 0x00, 0x00, 0x00 });
+        bmp.AddRange(new byte[] { 0x42, 0x4D, 0x4C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x36, 0x00, 0x00, 0x00, 0x28, 0x00, 0x00, 0x00 });
 
         //width
         bmp.AddRange(IntTo4Byte(sideLength));
@@ -68,6 +68,7 @@ public byte[] GetGraphic(int pixelsPerModule, byte[] darkColorRgb, byte[] lightC
 
         //header end
         bmp.AddRange(new byte[] { 0x01, 0x00, 0x18, 0x00 });
+        bmp.AddRange(new byte[24]);
 
         //draw qr code
         for (var x = sideLength - 1; x >= 0; x -= pixelsPerModule)
@@ -93,12 +94,16 @@ public byte[] GetGraphic(int pixelsPerModule, byte[] darkColorRgb, byte[] lightC
             }
         }
 
-        //finalize with terminator
-        bmp.AddRange(new byte[] { 0x00, 0x00 });
-
+        // write filesize in header
+        var bmpFileSize = IntTo4Byte(bmp.Count);
+        for (int i = 0; i < bmpFileSize.Length; i++)
+        {
+            bmp[2 + i] = bmpFileSize[i];
+        }
         return bmp.ToArray();
     }
 
+
     /// <summary>
     /// Converts a hex color string to a byte array.
     /// </summary>
@@ -121,9 +126,11 @@ private byte[] HexColorToByteArray(string colorString)
     /// <returns>Returns the integer as a 4-byte array.</returns>
     private byte[] IntTo4Byte(int inp)
     {
-        byte[] bytes = new byte[2];
+        byte[] bytes = new byte[4];
         unchecked
         {
+            bytes[3] = (byte)(inp >> 24);
+            bytes[2] = (byte)(inp >> 16);
             bytes[1] = (byte)(inp >> 8);
             bytes[0] = (byte)(inp);
         }