modifying image on backbuffer

Okay, I'm stuck. I'm trying to create a ASCII emulator; the reason is that OSX doesn't have support for ASCII and I want to convert some of my old ASCII Turbo Pascal games over to BM.

I'm taking a text file that has the pixel data and plotting it out on the pixmap. I then grab a 8x8 image and put it into an array, which I can use to print a character to the screen.

That works fine. But now I want to have code that can change the color of the text. NOT text that's already shown to the user, but go back and change the text color (foreground and background) for all future printed text. And that's where I'm stuck.

Any help?

P.S., one of the main reasons that I'm using a text file to store the data is I also plan on re-using this to create character sets that look like Atari and Commodore character sets for other conversion projects.

You'll need this text file for testing:

Click here!

' IBM ASCII Simulator

SetGraphicsDriver GLMax2DDriver()
Global GrabLine:String=""
Global Lop   :Int=0            ' Generic looping variable.  Re-useable.
Global Lop1  :Int=0            ' Generic looping variable.  Re-useable.
Global AscNum:Int=-1
Global AscRow:Int=0
Global AscCol         :Int=-1
Global xPos           :Int=-1
Global MoveToNextChar :Int=0   
Global Char_Array[256]         ' Stores graphics in an array that corresponds to ASCII codes
Global r1,g1,b1       :Int=1
Global r2,g2,b2       :Int=1
Global bgcolor        :Int=1   ' background color of text
Global fgcolor        :Int=1   ' foreground color of text

  Graphics 640,480,0,60
  Load_N_Plot(4,5) ' Syntax: Load_N_Plot(foreground color[range 0-16], background color[range 0-16]) 
  Snag
  Cls  
  put_xy(072,100,100)
  put_xy(105,108,100)
  put_xy(105,116,100)
  WaitKey

  put_xy(105,128,100)
  WaitKey
End


Function Load_N_Plot(fgcolor,bgcolor) 
  file=OpenFile("IBM_ASCII.txt")
  If Not file
    Print "Could not load"
  Else
    While Not Eof(file)
      xPos=-1
      AscNum=AscNum+1
      GrabLine = ReadLine(file)
      ConvertFromLineToGFX(GrabLine,fgcolor,bgcolor)
    Wend
    CloseStream file
  End If
End Function

' function put_xy   SYNTAX: put_xy(character, x, y)
'   - character : ascii code for the character you wish to plot
'   - x         : draw character at x-coord
'   - y         : draw character at y-coord
'
Function put_xy(cc:Int, xx:Int, yy:Int)
  DrawPixmap(Char_Array[cc], xx, yy)
  Flip
End Function

' function Snag - converts the plotted image into individual array elements.
Function Snag()
  Local xx=0
  Local yy=0
  For lop=0 To 255
    Select lop
      Case 64  ;xx=0 ;yy=10
      Case 128 ;xx=0 ;yy=20
      Case 192 ;xx=0 ;yy=30
    End Select
    Char_Array[lop]=GrabPixmap(xx, yy, 10, 10)
    xx=xx+10
  Next
End Function

Function WipeCharArray()
  For lop=0 To 255
    Char_Array[lop]=Null
  Next
End Function

Function ConvertFromLineToGFX(GrabLine$,fgcolor,bgcolor)
  Local IncLine=0
  AscCol=AscCol+1
  For Lop=0 To 63   'length of charset data (8x8=64)
    Local temp$=GrabLine[Lop..Lop+1]
    xPos=xPos+1
    Select fgcolor
      Case  0 ;r1=000 ;g1=000 ;b1=000 
      Case  1 ;r1=000 ;g1=000 ;b1=170 
      Case  2 ;r1=000 ;g1=170 ;b1=000 
      Case  3 ;r1=000 ;g1=170 ;b1=170 
      Case  4 ;r1=170 ;g1=000 ;b1=000 
      Case  5 ;r1=170 ;g1=000 ;b1=170 
      Case  6 ;r1=170 ;g1=085 ;b1=000 
      Case  7 ;r1=170 ;g1=170 ;b1=170 
      Case  8 ;r1=170 ;g1=170 ;b1=170 
      Case  9 ;r1=170 ;g1=170 ;b1=255 
      Case 10 ;r1=170 ;g1=255 ;b1=170 
      Case 11 ;r1=170 ;g1=255 ;b1=255 
      Case 12 ;r1=255 ;g1=170 ;b1=170 
      Case 13 ;r1=255 ;g1=170 ;b1=255 
      Case 14 ;r1=255 ;g1=255 ;b1=170 
      Case 15 ;r1=255 ;g1=255 ;b1=255 
    End Select
    Select bgcolor
      Case  0 ;r2=000 ;g2=000 ;b2=000 
      Case  1 ;r2=000 ;g2=000 ;b2=170 
      Case  2 ;r2=000 ;g2=170 ;b2=000 
      Case  3 ;r2=000 ;g2=170 ;b2=170 
      Case  4 ;r2=170 ;g2=000 ;b2=000 
      Case  5 ;r2=170 ;g2=000 ;b2=170 
      Case  6 ;r2=170 ;g2=085 ;b2=000 
      Case  7 ;r2=170 ;g2=170 ;b2=170 
      Case  8 ;r2=170 ;g2=170 ;b2=170 
      Case  9 ;r2=170 ;g2=170 ;b2=255 
      Case 10 ;r2=170 ;g2=255 ;b2=170 
      Case 11 ;r2=170 ;g2=255 ;b2=255 
      Case 12 ;r2=255 ;g2=170 ;b2=170 
      Case 13 ;r2=255 ;g2=170 ;b2=255 
      Case 14 ;r2=255 ;g2=255 ;b2=170 
      Case 15 ;r2=255 ;g2=255 ;b2=255 
    End Select
    If temp$="." Then SetColor r2,b2,g2
    If temp$="X" Then SetColor r1,b1,g1
    Select Lop     ' This part plots each line from data into each image character
      Case 8  ;IncLine=1 ;xPos=0
      Case 16 ;IncLine=2 ;xPos=0
      Case 24 ;IncLine=3 ;xPos=0
      Case 32 ;IncLine=4 ;xPos=0
      Case 40 ;IncLine=5 ;xPos=0
      Case 48 ;IncLine=6 ;xPos=0
      Case 56 ;IncLine=7 ;xPos=0
      Case 64 ;IncLine=8 ;xPos=0
    End Select
    Select AscNum    'Positioning on Window
      Case 64  ;AscRow=10 ;AscCol=0
      Case 128 ;AscRow=20 ;AscCol=0
      Case 192 ;AscRow=30 ;AscCol=0
    End Select  
    Plot xPos+(AscCol)*10,IncLine+AscRow
  Next
End Function