Mac Automation Scripting Guide: Converting RGB to HTML Color

Converting RGB to HTML Color

In HTML documents, colors are typically represented as hex values. The handlers in Listing 31-1 and Listing 31-2 show how to convert 8-bit or 256 color-based RGB values to hex values. Provide an RGB color represented by a list of three numbers, each with a value between 0 and 65535.

APPLESCRIPT

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Listing 31-1AppleScript: Handler that converts an RGB color to a hex value

on convertRGBColorToHexValue(theRGBValues)
set theHexList to {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F"}
set theHexValue to ""
repeat with a from 1 to count of theRGBValues
set theCurrentRGBValue to (item a of theRGBValues) div 256
if theCurrentRGBValue is 256 then set theCurrentRGBValue to 255
set theFirstItem to item ((theCurrentRGBValue div 16) + 1) of theHexList
set theSecondItem to item (((theCurrentRGBValue / 16 mod 1) * 16) + 1) of theHexList
set theHexValue to (theHexValue & theFirstItem & theSecondItem) as string
end repeat
return ("#" & theHexValue) as string
end convertRGBColorToHexValue

JAVASCRIPT

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Listing 31-2JavaScript: Function that converts an RGB color to a hex value

function convertRGBColorToHexValue(rgbValues) {
var r = parseInt(rgbValues[0], 10).toString(16).slice(-2)
if (r.length == 1)
r = "0" + r
var g = parseInt(rgbValues[1], 10).toString(16).slice(-2)
if (g.length == 1)
g = "0" + g
var b = parseInt(rgbValues[2], 10).toString(16).slice(-2)
if (b.length == 1)
b = "0" + b
return ("#" + r + g + b)
}

Listing 31-3 shows how to call the handlers in Listing 31-1 to convert a specified RGB color to a hex value for use in HTML.

APPLESCRIPT

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Listing 31-3AppleScript: Calling a handler to convert an RGB color to a hex value

set theRGBValues to (choose color default color {65535, 0, 0})
convertRGBColorToHexValue(theRGBValues)
--> Result: "#FF0000"

JAVASCRIPT

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Listing 31-4JavaScript: Calling a function to convert an RGB color to a hex value

var app = Application.currentApplication()
app.includeStandardAdditions = true
var color = app.chooseColor({defaultColor: [1, 0, 0]})
color = [Math.trunc(color[0] * 65535), Math.trunc(color[1] * 65535), Math.trunc(color[2] * 65535)]
convertRGBColorToHexValue(color)
// Result: "#FF0000"

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