Converting RGB value to BGR for PB 7.04

[Paul Dixon]

MACRO swapcolour(colour)  'colour is assumed to be a LONG or DWORD
!mov eax,colour    'get colour into a register
!bswap eax         'swap the bytes so 1234 -> 4321
!ror eax,8         'rotate by 1 byte so 4321 -> 1432 as required
!mov colour,eax    'write the result back
END MACRO
       
FUNCTION PBMAIN () AS LONG

  LOCAL x AS LONG

  x=&h112233     '11,22,33 are the R,G and B values

  MSGBOX HEX$(x) 'display values
  swapcolour(x)  'swap RGB to BGR
  MSGBOX HEX$(x) 'display again to show it's worked
             
END FUNCTION

[Arthur Gomide]

Another way

FUNCTION PBMAIN() AS LONG
    LOCAL value AS LONG
    LOCAL red   AS INTEGER
    LOCAL green AS INTEGER
    LOCAL blue  AS INTEGER
    LOCAL pr    AS BYTE POINTER
    LOCAL pb    AS BYTE POINTER
    LOCAL vl    AS STRING
    
    red   = 58%     '&H3A
    green = 110%    '&H6E
    blue  = 165%    '&HA5
    
    value = RGB(red, green, blue)
    vl = HEX$(value,8) + $CRLF
    pr = VARPTR(value)
    pb = VARPTR(value)+2
    SWAP @pr, @pb   ' now value is BGR
    vl = vl + HEX$(value,8)
    
    MSGBOX vl

END FUNCTION

[BOB MECHLER]

Useful example.

Thanks,

Bob Mechler

[Ian Cairns]

Hey Bob, since I'm always looking for a hard way to do a simple thing, this is a way I used to keep things sort of straight in my twisted mind.

Regards, Ian

#COMPILE EXE
#DIM ALL
#INCLUDE "win32api.inc"

TYPE KolorBitTYPE ' equivalent to a long/dword
  rVal AS BYTE
  gVal AS BYTE
  bVal AS BYTE
  dum1 AS BYTE
END TYPE

UNION KolorAccessU ' make data type transfers simple
  Kolor AS LONG
  KolorBits AS KolorBitTYPE
END UNION
'-------------------------------
'###############################
'-------------------------------
FUNCTION PBMAIN () AS LONG

 DIM RGBKolor AS LONG, _
     GBRKolor AS LONG, _
     rVal AS LONG, _
     gVal AS LONG, _
     bVal AS LONG

' Just make some values to play with
  rVal = 15
  gVal = 20
  bVal = 30
' make our original colour
  CALL CreateKolor(rVal, gVal, bVal, RGBKolor)
' split it into RGB values
  CALL RGBExtract(rVal, gVal, bVal, RGBKolor)
' Did we get it right?
  MSGBOX "Constituent Colors: R, G, B:" + $CR + FORMAT$(rVal) + ", " + FORMAT$(gVal) + ", " + FORMAT$(bVal)
' Reverse it
  CALL RBG_GBR_Swap(RGBKolor, GBRKolor)
' Split it again
  CALL RGBExtract(rVal, gVal, bVal, GBRKolor)
' Check that it is reversed.
  MSGBOX "Reversed Colors: R, G, B:" + $CR + FORMAT$(rVal) + ", " + FORMAT$(gVal) + ", " + FORMAT$(bVal)
' done

END FUNCTION
'-------------------------------
'###############################
'-------------------------------
SUB CreateKolor(rVal AS LONG, gVal AS LONG, bVal AS LONG, RGBKolor AS LONG)
  DIM KolorBits AS LOCAL KolorBitTYPE
  DIM KolorAccess AS LOCAL KolorAccessU

' place the individual colors into the TYPE
  KolorBits.rVal = rVal
  KolorBits.gVal = gVal
  KolorBits.bVal = bVal
' put the TYPE into a union
  KolorAccess.Kolorbits = KolorBits
' extract our colour value
  RGBKolor = KolorAccess.Kolor
END SUB
'-------------------------------
'###############################
'-------------------------------
SUB RGBExtract(rVal AS LONG, gVal AS LONG, bVal AS LONG, RGBKolor AS LONG)
  DIM KolorBits AS LOCAL KolorBitTYPE
  DIM KolorAccess AS LOCAL KolorAccessU

' place the colour value into our union
  KolorAccess.Kolor = RGBKolor
' extract the Type, which contains individual colour values
  KolorBits = KolorAccess.KolorBits
' Extract individual colour values from our TYPE
  rVal = KolorBits.rVal
  gVal = KolorBits.gVal
  bVal = KolorBits.bVal
END SUB
'-------------------------------
'###############################
'-------------------------------
SUB RBG_GBR_Swap(RGBKolor AS LONG, GBRKolor AS LONG)
  DIM KolorBits AS LOCAL KolorBitTYPE
  DIM KolorAccess AS LOCAL KolorAccessU

' Put our original colour value into the union
  KolorAccess.Kolor = RGBKolor
' Extract the TYPE for access to individual colours
  KolorBits = KolorAccess.KolorBits
' SWAP the Red/Blue values (Green remains in place)
  SWAP KolorBits.rVal, KolorBits.bVal
' Put the reversed TYPE into the union
  KolorAccess.KolorBits = KolorBits
' Extract our Reversed Colour value
  GBRKolor = KolorAccess.Kolor
END SUB
'-------------------------------
'###############################
'-------------------------------

[BOB MECHLER]

I know PB 8 has the BGR conversion function but the set of programs I need this in are 7.04 and code I want to use from the forum is for PB 8 and 9. Anyway the sample code uses the BGR function and from what I can glean this might be a replacement function. Looking for verification and/or correction as always

Thanks,

Bob Mechler

FUNCTION ToBGR(OldRGB AS LONG) AS LONG
  LOCAL NewBGR&,cRed&,cGreen&,cBlue&

  cRed&   = OldRGB& MOD 256
  cGreen& = (OldRGB& \ 256) MOD 256
  cBlue&  = ((OldRGB& \ 256) \ 256) MOD 256
  NewBGR& = cBlue& * 65536 + cGreen& * 256 + cRed&
  
  FUNCTION = NewBGR&
END FUNCTION