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How to convert Color code into RGB

I had a problem recently where I had to convert a color code selected by a user using GETCOLOR ( ) into an RGB setting for use in a report.

I am across this code and then rewrote it into VFP.

Update - until of course, Ted, took me here instead where I should have started all along, in the Wiki.

(don't bother reading below unless you want to see the other ways people do this.

LPARAMETERS tnColor,tcVal

LOCAL R1, G1, B1
LOCAL R2, G2, B2
LOCAL A As Long

R2 = 0
G2 = 0
B2 = 0

If tncolor = -1
&& DEfault to 255 regardless
RETURN 255
ENDIF

For B1 = 0 To 255
A = RGB(R2, G2, B1)
DO CASE
CASE A > tnColor
B2 = (B1 - 1)
Exit
CASE A = tnColor
B2 = B1
Exit
Endcase
Next B1

For G1 = 0 To 255
A = RGB(R2, G1, B2)
DO CASE
CASE A > tnColor
G2 = (G1 - 1)
Exit
CASE A = tnColor
G2 = G1
Exit
Endcase
Next G1

For R1 = 0 To 255
A = RGB(R1, G2, B2)
IF A = tnColor
R2 = (R1)
Exit
EndIf
Next R1

DO CASE
CASE tcVal = "R"
RETURN r2
CASE tcVal = "G"
RETURN g2
CASE tcVal = "B"
RETURN b2
ENDCASE

It works great but I was surprised that there wasn't a built-in way to do this in VFP. Of course, the above code isn't very intelligent but it relies on the fact that a PC can process 255 x 3 extremely quickly and thus return the correct result.

I then came across this code which looked a little more algorithmically correct and as a result MUCH faster.

LPARAMETERS lnColor, tcType

DO CASE
CASE tcType = "R"
RETURN INT(MOD(lnColor ,0x100))
CASE tcType = "G"
lnColor = lnColor/0x100
RETURN INT(MOD(lnColor ,0x100))
CASE tcType = "B"
lnColor = lnColor/0x100
lnColor = lnColor/0x100

RETURN INT(MOD(lnColor ,0x100))

ENDCASE

Same results and the performance is good on both but obviously the second one is the

Keep in mind that RGB colors can't be used reliably for all color settings but at least on the VFP FRX , they work well.


How to convert Color code into RGB - visual basic, vb, vbscript

Comments

Ted Roche said…
The source,Andrew, use the source:

http://fox.wikis.com/wc.dll?Wiki~VFPFunctionRGB~VFP
May 30, 2005 at 8:49 PM
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