Printing BITMAP using TSPL in Flutter (Dart)

Question

I'm trying to print BITMAP using TSPL in Flutter. The manual says, BITMAP command should be used like that:

BITMAP x,y,width,height,mode,bitmap data

In Flutter, I'm encoding the image like that:

    var f = (await rootBundle.load("lib/assets/yerli.bmp")).buffer.asUint8List();

    var str = hex.encode(f);

    String bytes = "SIZE 60 mm, 40 mm\nGAP 2 mm\nSET CUTTER 1\nCLS\nCODEPAGE 1254\nBITMAP 100,100,100,100,0,\"$str\"\"\nPRINT 1\n";

Output of str variable is below

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It can be copied to an online hexadecimal to image converter and can be seen it is valid. It generates an image.

But my printer does not see it as an image and it only prints characters.

Can anyone explain me how BITMAP command works? And how to convert BITMAP asset to bytes in order to send properly to mobile printer?