printing scanned signature in dot matrix printer?

Marco,

the following code prints a black and white image got from SCREEN 11 by
means of a GET statement. I adapted it from a QBasic program I wrote
time ago (never thought I would use it again!). It works fine on my
Epson 24-pin printer which uses the ESC-P2 command language. You will
have to check if the commands for your printer are identical.

In fact, all you need to know are the details of the printer instructions,
and the exact data format how the image is stored and how the printer
receives data, and then convert the former format into the latter.

The format of an array got by GET is:
WORD = image width in pixels
WORD = image height in pixels
Image data follows line by line, starting at the top left corner. Detail
(for B+W images): The first pixel corresponds to the value of Bit 7 (not
0) in the first byte (which is the fifth byte in the array).

The printer (24-pin) receives data in columns of 24 dots, which correspond
to 3 bytes each. Here also, the top-most dot corresponds to Bit 7 (not 0)
in the first byte.

If you want to print images from other formats (e.g. BMP files), all you
need is the information about the data format and you can write a similar
conversion routine. For a B+W standard BMP file, your program will have to
check the following:
- Signature "BM" at offset 0
- Offset of image data = LONG at offset 10 (should be 62 for B+W)
- Image width in pixels = LONG at offset 18
- Image height in pixels = LONG at offset 22
- Bits per pixel = WORD at offset 28 (should be 1 for B+W)
- Size of image data in bytes = LONG at offset 34
- Image data: line by line, starting at the BOTTOM left corner and each
line padded with zero-bytes up to a multiple of 4 bytes.

Hope this helps you!

Hans Ruegg.

P.S: Does anybody know a more effective way of sending binary data to the
printer, instead of PRINT CHR$(n) ? Using PUT did not work, opening the
printer in binary mode did neither.

Code follows:
=============

Code:

DEFINT A-Z
DECLARE SUB PrintGraph (graph?())
DECLARE SUB PrintGraphLine (graph?(), prn?(), w, h, StartLine, PrinterHandle)

SCREEN 11

FOR x = 5 TO 45 STEP 5    '(draw something on the screen ...)
   LINE (x,100)-(x+4,150)
NEXT x

REDIM g?(1000), p?(0)
GET (0,100)-(49,149), g?  '(... GET it ...)
PrintGraph g?()           '(... and print it.)

DO WHILE INKEY$="": LOOP
SCREEN 0
END

'=========================================================================
SUB PrintGraph (graph?())
'Prints a black and white image stored in graph?() by a GET statement in
'a monochrome screen mode (e.g. SCREEN 11).
'For 24-pin dot-matrix ESC-P2 Printer on port LPT 1.
'(Tested with Printer Epson LQ-1070+.)

Handle = FREEFILE
OPEN "LPT1:" AS #Handle
WIDTH #Handle, 255   		      '(suppress automatic CR/LF)
PRINT #Handle, CHR$(27)+"@";          'Initialize Printer
PRINT #Handle, CHR$(27)+"U"+CHR$(1);  '(Unidirectional printing)
PRINT #Handle, CHR$(27)+"3"+CHR$(24); '(Set Line Spacing to 24 dots)

w = graph?(0) + 256*graph?(1)         'image width in pixels
h = graph?(2) + 256*graph?(3)         'image height in pixels
REDIM p?(0)
FOR PrintLine = 0 TO (h-1)\24
  PrintGraphLine graph?(), p?(), w, h, PrintLine*24, Handle
NEXT PrintLine
PRINT #Handle, CHR$(12);              '(Form Feed = Eject sheet)
CLOSE #Handle

END SUB

'=========================================================================
SUB PrintGraphLine (graph?(), prn?(), w, h, StartLine, PrinterHandle)
'Prints a 24-dot graphics line from the image stored in graph?().
'Array prn?() is returned by this subroutine in case you want to store
'the printer data for future use.
'See other comments under SUB PrintGraph.

BytesPerLine = (w+7)\8
BitsPerLine = BytesPerLine * 8
BitOffset = BitsPerLine * StartLine
MaxBitOffset = BitsPerLine * h
REDIM prn?(3*BitsPerLine)
counter = 0
FOR GraphByte = 1 TO BytesPerLine
  FOR Column = 0 TO 7
    OffsetNow = BitOffset + 7 - Column
    FOR PrnByte = 0 TO 2
       prn?(counter) = 0
       FOR PrnBit = 7 TO 0 STEP -1
          SHIFT LEFT prn?(counter), 1
          IF OffsetNow < MaxBitOffset THEN
            prn?(counter) = prn?(counter) OR BIT(graph?(4), OffsetNow)
          END IF
          OffsetNow = OffsetNow + BitsPerLine
       NEXT PrnBit
       INCR counter
    NEXT PrnByte
  NEXT Column
  BitOffset = BitOffset + 8
NEXT GraphByte

PRINT #PrinterHandle, CHR$(27); "*'"; CHR$(w AND 255); CHR$(w\256);
	'(Instruction "Print BitImage 180x180 dpi, w columns")
FOR i = 0 TO 3*w-1
  PRINT #PrinterHandle, CHR$(prn?(i));
	'(Sending image data to the printer)
NEXT i
PRINT #PrinterHandle, CHR$(13); CHR$(10);
	'(Carriage return and Line feed)
END SUB

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