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 How to Print Visual BASIC Video Screens to Epson Printers, Example
 
 Printing EGA or VGA Screen Modes 7 Through 12:
 
 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.
 
    DECLARE SUB ScreenParams (scrn%, ScreenWidth%, ScreenLength%, NP%)
    DECLARE SUB DRAWPIC (scrn%)
    DECLARE SUB VGAtoEpson (scrn%, f$, flip%, border%)
    ' Demonstrates the use of VGAtoEpson, a subprogram that dumps
    ' a SCREEN 7, 8, 9, 10, 11 or 12 image to an Epson printer.
 
    CLS : scrn% = 0
    WHILE (scrn% < 7) OR (scrn% > 12)
       INPUT "Enter Screen Mode: (7, 8, 9, 10, 11 or 12)"; scrn%
    WEND
 
    SCREEN scrn% : CALL DRAWPIC(scrn%)      ' Draw the picture.
    CALL VGAtoEpson(scrn%, "LPT1", 0, 255)  ' Do the VGA screen print.
    END
 
    SUB DRAWPIC (scrn%)                     ' Draw picture on screen.
      CALL ScreenParams(scrn%, ScreenWidth%, ScreenLength%, NumPlanes%)
      IF NumPlanes% = 2 THEN ci% = 0 ELSE ci% = 1  ' Color increment.
      xmax% = ScreenWidth% : ymax% = ScreenLength%
      halfx% = xmax% / 2 : halfy% = ymax% / 2
      x% = halfx% : c% = 1
       FOR y% = ymax% TO halfy% STEP -5
          deltax% = xmax% - x% : deltay% = ymax% - y%
          LINE (halfx%, y%)-(x%, halfy%), c%
          LINE (x%, ymax%)-(xmax%, y%), c% + ci%
          LINE (halfx%, deltay%)-(x%, halfy%), c% + 2 * ci%
          LINE (x%, 0)-(xmax%, deltay%), c% + 3 * ci%
          LINE (halfx% + 1, y%)-(deltax%, halfy%), c% + 4 * ci%
          LINE (deltax%, ymax%)-(0, y%), c% + 5 * ci%
          LINE (halfx%, deltay%)-(deltax%, halfy% + 1), c% + 6 * ci%
          LINE (deltax%, 0)-(0, deltay%), c% + 7 * ci%
          x% = x% + (((xmax% + 1) / (ymax% + 1)) * 5)
       NEXT y%
    END SUB
 
    SUB ScreenParams (scrn%, ScreenWidth%, ScreenLength%, NumPlanes%)
      ' Return the screen dimensions in pixels
      ' and the number of planes.
      NumPlanes% = 4          ' Set default values for SCREEN 12.
      ScreenWidth% = 640 : ScreenLength% = 480
      SELECT CASE scrn%       ' Change values for other SCREEN modes.
         CASE 7
            ScreenWidth% = 320 : ScreenLength% = 200
         CASE 8
            ScreenLength% = 200
         CASE 9
            ScreenLength% = 350
         CASE 10
            NumPlanes% = 2 : ScreenLength% = 350
         CASE 11
            NumPlanes% = 2
      END SELECT
    END SUB
 
    SUB VGAtoEpson (scrn%, fileN$, flip%, border%) STATIC
    ' Sends the image on SCREEN 7, 8, 9, 10, 11 or 12
    ' to an Epson printer.
    ' Parameters:
    '    scrn%   - SCREEN video mode of screen to print (7 through 12).
    '    fileN$  - Name of file or device to send image to.
    '    flip%   - Invert flag (0 = normal, not 0 = invert).
    '    border% - Character to use for border drawing on screens
    '              9 and 10 (0 = none, 255 = solid, etc.)
      OPEN fileN$ FOR BINARY AS 1            ' Open the output file.
      WIDTH #1, 255
      esc$ = CHR$(27) : crlf$ = CHR$(13) + CHR$(10)
      line$ = esc$ + "A" + CHR$(8)           ' Set printer to 8/72 lpi".
      PUT #1, , line$
      CALL ScreenParams(scrn%, ScreenWidth%, ScreenLength%, NumPlanes%)
 
      IF ScreenLength% < 480 THEN       ' Figure how many bytes to send
         numbyte% = ScreenLength% * 2 + 16   ' to printer for one
         maxy% = ScreenLength% - 1           '  line of graphics.
      ELSE
         numbyte% = 960 : maxy% = 479
      END IF
 
      DEF SEG = &HA000               ' Start of EGA/VGA screen memory.
      BorderOffset% = (960 - numbyte%) / (2 * 8)
      IF ScreenLength% < 480 THEN
         ' Print top line for border on screens where border will fit.
         line$ = SPACE$(BorderOffset%)           ' (For margin).
         PUT #1, , line$
         line$ = esc$ + "L" + MKI$(numbyte%)
         line$ = line$ + STRING$(numbyte%, border%) + crlf$
         PUT #1, , line$
      END IF
 
      ' This loop is the horizontal byte location.
      colend% = (ScreenWidth% / 8) - 1
      FOR col% = 0 TO colend%
        ' Set the printer up to receive 716 or 960 bytes
        ' of graphics data.
        IF ScreenLength% < 480 THEN
           line$ = SPACE$(BorderOffset%)
           PUT #1, , line$  '(for border)
        END IF
 
        line$ = esc$ + "L" + MKI$(numbyte%)  '(for init)
        PUT #1, , line$
        IF ScreenLength% < 480 THEN
           line$ = STRING$(8, border%)
           PUT #1, , line$    '(for border)
        END IF
 
        '--- This loop is the vertical byte position.
        FOR row% = maxy% TO 0 STEP -1
          ' For 4 plane screens (7, 8, 9 and 12) logically OR the blue
          ' plane with the red plane, send that byte, then OR the green
          ' plane with the intensity plane and send that byte.
 
          ' For screens 10 and 11, the video planes are sent directly
          ' to the printer.
          FOR plane% = 0 TO 1                ' Plane (* 2) set.
            OUT &H3CE, 4 : OUT &H3CF, plane%
            place& = row%                   ' Figure out screen memory
            place& = place& * (colend% + 1) ' location to read - use
            place& = place& + col%          ' a long to avoid overflow.
            mem% = PEEK(place&)
 
            IF NumPlanes% = 4 THEN ' OR color planes together.
               OUT &H3CE, 4 : OUT &H3CF, plane% + 2
               mem% = mem% OR PEEK(place&)
            END IF
 
            '--- Flip the byte if need be (inverses printed picture).
            IF flip% <> 0 THEN mem% = 255 - mem%
            line$ = CHR$(mem%) : PUT #1, , line$
          NEXT plane%
        NEXT row%
 
        line$ = crlf$    ' Default for no border.
        IF ScreenLength% < 480 THEN
           line$ = STRING$(8, border%) + crlf$   ' Righthand border.
        END IF
        PUT #1, , line$
      NEXT col%
 
      IF ScreenLength% < 480 THEN     '--- Print bottom line for border.
         line$ = SPACE$(BorderOffset%)       ' (For margin).
         PUT #1, , line$
         line$ = esc$ + "L" + MKI$(numbyte%)
         line$ = line$ + STRING$(numbyte%, border%) + crlf$
         PUT #1, , line$
      END IF
      ResetPrn$ = esc$ + "@"
      PUT #1, , ResetPrn$                 ' Reset printer.
      line$ = CHR$(12) : PUT #1, , line$  ' Send formfeed (page eject).
      CLOSE 1                             ' All done.
    END SUB