If you know your hexadecimal to decimal conversions, and decimal to
hexadecimal, it's easy:
To begin we need to undertsand that #00FF00 separates to:
Hex color Dec
=== ===== ===
00 red 0
FF green 255
00 blue 0
we get 255 because the characters 0 - 9 and A - F are used in hexidecimal
notation. The numbers 0 - 9 in hexadecimal represent their correspnding
values in decimal. The letters A - F in hexadecimal represent the numbers
10 - 15 in decimal respectively. The units in hexadecimal are base 16 so
starting at the right and working toward the left you have 1's (16 raised
to the power of 0; i.e. 16^0), 16's (16 raised to the power of 1; 16^1),
256's (16 raised to the power of 2; 16^2), 4096 (16 raised to the power of
4; 16^4), etc. for hexidecimal just as in decimal it is (starting from the
right) 1's (10^0), 10's (10^1), 100's (10^2), 1000's (10^3),
etc. Therefore FF in hexidecimal is (15 * 1) + (15*16) = 255 in decimal.
Using this idea you do the same thing for converting the decimal number
65280 into the hexadecimal representation but work backwards. Also instead
of working in base 16 you are working in base 256 with each pair of
hexadecimal numbers. Also you are working from left to right. The "red
column" is 1's (256^0), the "green column" is 256's (256^1), and the "blue
column" is 25536's (256^2). In your example 00 (red) in hex is 0 in
decimal so we have (0 * 1 = 0), next you have FF (green) in hex is 255 in
decimal so we have (256 * 255 = 65280), and finally 00 (blue) in hex is 0
in decimal so we have (0 * 65536 = 0). Putting this altogether you have 0
+ 65280 + 0 = 65280.
Of course you wanted to know how to convert the other way. This is just as
easy. You just work with the opposite idea. You had 65280 so you divide
by the highest possible power which is 65536, the result is 0.99609375, the
integer portion is 0 so we know we have 0 for the blue column, then you
subtract the inter value you receive (in this case 0) and we are still left
with 0.99609375, which we multiply by the next highest power (256) and we
get 255 for our green column, then you subtract the integer value from the
result (255 - 255 = 0), and the result is the red columns value. Of course
all the values you get are in decimal so you will need to convert these
smaller values into their hexadecimal equivalents: 0 -> 0, 255 -> FF, 0 ->
0 and join these values together: 00FF00.
It's pretty simple if you understand powers and bases.
If you want I could write a little script that would do the conversion for
you but I thought I would explain how the result is achieved so that you
can understand it better.
This whole description might be a little confusing so if anyone can explain
it better or has an easier way to do the conversion please go ahead and
post it.
Jonathan
========================
Jonathan Southwick
[EMAIL PROTECTED]
Technical & Network Services
Allegheny College
Meadville, PA 16335
(814) 332-2755
At 3/10/2003 03:56 AM, you wrote:
From the win32 gui example colors.gpl
$color = GUI::ChooseColor(-owner => $w);
Any idea how I can convert the decimal RGB value, $color to the HTML HEX
format ?
ie: selecting the colour green returns 65280 How do I convert this to the
HTML HEX value: #00FF00 ?
Thanks!
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