◄Contents►  ◄Index►  ◄Back►
─────────────────────────────────────────────────────────────────────────────
                           ◄Knowledge Base Contents►  ◄Knowledge Base Index►
 
 How to Print Visual BASIC Video Screens to Epson Printers, Example
 
 Printing VGA Screen Mode 13:
 
 Example
 -------
 
 To try this example in VBDOS.EXE:
 
    1. From the File menu, choose New Project.
    2. Copy the code example to the Code window.
    3. Press F5 to run the program.
 
    ' To run this program in the environment, you must invoke the
    ' environment with the /L switch to load the default Quick library:
    ' VBDOS.EXE /L for Visual Basic 1.0 for MS-DOS
 
    DECLARE SUB VGAtoEpson (f$, flip%)
 
    '--- VGAEPSON.BAS
    '--- Demonstrates the use of VGAtoEpson, a subprogram that
    '--- dumps a SCREEN 13 image to an Epson printer.
    '--- Copyright (c) 1988 Microsoft Corp.
 
    ' Use the following include file for Visual Basic 1.0 for MS-DOS:
    REM $INCLUDE: 'VBDOS.BI'
    DIM SHARED inregs AS regtype
    DIM SHARED outregs AS regtype
 
    SCREEN 13
    '--- Draw picture on screen.
    xmax% = 319
    ymax% = 199
    halfx% = xmax% / 2
    halfy% = ymax% / 2
    x% = halfx%
    c% = 1
    FOR y% = ymax% TO halfy% STEP -2
      LINE (halfx%, y%)-(x%, halfy%), c%
      LINE (x%, ymax%)-(xmax%, y%), c% + 20
      LINE (halfx%, (ymax% - y%))-(x%, halfy%), c% + 40
      LINE (x%, 0)-(xmax%, (ymax% - y%)), c% + 60
      LINE (halfx% + 1, y%)-((xmax% - x%), halfy%), c% + 80
      LINE ((xmax% - x%), ymax%)-(0, y%), c% + 100
      LINE (halfx%, (ymax% - y%))-((xmax% - x%), halfy% + 1), c% + 120
      LINE ((xmax% - x%), 0)-(0, (ymax% - y%)), c% + 140
      x% = x% + (((xmax% + 1) / (ymax% + 1)) * 5)
      c% = c% + 1
    NEXT y%
 
    CALL VGAtoEpson("LPT1", 1)
    SCREEN 0
    END
 
    SUB VGAtoEpson (f$, flip%) STATIC
    '--- Sends the image on SCREEN 13 to an Epson graphics printer.
    '--- Parameters:
    '         f$    -   Name of file or device to send image to
    '         flip% -   Invert flag (0 = normal, not 0 = invert)
 
      OPEN f$ FOR BINARY AS 1         ' Open the output file.
      WIDTH #1, 255
      esc$ = CHR$(27)
      line$ = esc$ + "A" + CHR$(8)
      PUT #1, , line$   ' Set printer to 8/72 lpi.
      DEF SEG = &HA000                ' Start of VGA screen memory.
      '--- This loop is the horizontal byte location.
      FOR Col% = 0 TO 79
         '--- Set the printer to receive 800 bytes of graphics data.
         line$ = esc$ + "L" + MKI$(800)
         PUT #1, , line$  '(for init)
 
         '--- This loop is the vertical byte position.
         FOR row% = 199 TO 0 STEP -1
 
            place& = row% * 320&
            place& = place& + Col% * 4
            ' 4 bytes of pixel information are read in. Each
            '  of these bytes is broken up across 4 variables
            '  that are used to fire the printer pins. 2 bits
            '  from each pixel byte are stored to each of the
            '  variables.
            mem1% = 0           ' Initialize storage bytes for
            mem2% = 0           '   color information.
            mem3% = 0
            mem4% = 0
            FOR byte% = 0 TO 3
               newplace& = place& + byte%
               shift% = 2 ^ ((7 - 2 * byte%) - 1)
               mem% = PEEK(newplace&)
               mem% = mem% AND 3
               mem% = mem% * shift%
               mem1% = mem1% OR mem%
 
               mem% = PEEK(newplace&)
               mem% = (mem% AND 12) / 4
               mem% = mem% * shift%
               mem2% = mem2% OR mem%
 
               mem% = PEEK(newplace&)
               mem% = (mem% AND 48) / 16
               mem% = mem% * shift%
               mem3% = mem3% OR mem%
 
               mem% = PEEK(newplace&)
               mem% = (mem% AND 192) / 64
               mem% = mem% * shift%
               mem4% = mem4% OR mem%
            NEXT
 
            '--- Flip the byte, if called from.
            IF flip% <> 0 THEN
               mem1% = 255 - mem1%
               mem2% = 255 - mem2%
               mem3% = 255 - mem3%
               mem4% = 255 - mem4%
            END IF
 
            '--- Send bytes to device.
            line$ = CHR$(mem1%) + CHR$(mem2%)
 
            line$ = line$ + CHR$(mem3%) + CHR$(mem4%)
            PUT #1, , line$
         NEXT
         line$ = CHR$(13) + CHR$(10)
         PUT #1, , line$
      NEXT
      ResetPrn$ = esc$ + "@"
      PUT #1, , ResetPrn$  ' Reset printer.
      line$ = CHR$(12)
      PUT #1, , line$      ' Send formfeed (page eject).
      CLOSE 1              ' All done.
    END SUB