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I want to know how to make a color picker with jQuery that will allow you to click somewhere on the page and return the hex color value of the color that you clicked on.

I know that it is possible with either javascript or jquery as not only do they have lots of color picker plugins, but I have and extension for Chrome that has that same exact functionality.

Any ideas?

watzon
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  • Related: http://stackoverflow.com/questions/1740700/get-hex-value-rather-than-rgb-value-using-jquery – Colin Brock Oct 07 '11 at 16:50
  • but what if the item you click on doesn't have a background color? Or is an image? – watzon Oct 07 '11 at 16:51
  • Admittedly, the question I linked to doesn't provide everything you're looking for, but I thought it was relevant enough to add as a comment. – Colin Brock Oct 07 '11 at 17:09

3 Answers3

5

Bind a global click or mouseup event listener. Then, use canvas to obtain the pixel information. The pixel positions can be retrieved through the event object (event.pageX, event.pageY).

See below for an example, which should work in future versions of FireFox. Currently, for security reasons, the drawWindow method is disabled for web pages. It should work in extensions, though. If you're truly interested, see the links for the similar methods in Chrome, Safari and Internet Explorer.

var canvas = $("<canvas>"); //Create the canvas element

//Create a layer which overlaps the whole window
canvas.css({position:"fixed", top:"0", left:"0",
            width:"100%", height:"100%", "z-index":9001});

//Add an event listener to the canvas element
canvas.click(function(ev){
    var x = ev.pageX, y = ev.pageY;
    var canvas = this.getContext("2d");
    canvas.drawWindow(window, x, y, 1, 1, "transparent");
    var data = canvas.getImageData(0, 0, 1, 1).data;
    var hex = rgb2hex(data[0], data[1], data[2]);
    alert(hex);
    $(this).remove();
});

canvas.appendTo("body:first"); //:first, in case of multiple <body> tags (hmm?)

//Functions used for conversion from RGB to HEX
function rgb2hex(R,G,B){return num2hex(R)+num2hex(G)+num2hex(B);}
function num2hex(n){
    if (!n || !parseInt(n)) return "00";
    n = Math.max(0,Math.floor(Math.round(n),255)).toString(16);
    return n.length == 1 ? "0"+n : n;
}

References

Community
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Rob W
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Those plugins don't work by knowing the color of the pixel under the mouse; they work because the colors in the picker are laid out according to a mathematical formula, and by knowing that formula and where you clicked the mouse, the plugin can find out what color belongs there. JavaScript doesn't give you any way to get an image of the page or the "color under the cursor".

hobbs
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0

I had this problem recently, by default IE returns hex colours whereas all the good browsers return rgb values, I simply put conditions to deal with both strings, this would be more efficient..

however I think this function does the trick if you really need it 

function RGBToHex(rgb) { 
var char = "0123456789ABCDEF"; 
return String(char.charAt(Math.floor(rgb / 16))) + String(char.charAt(rgb - (Math.floor(rgb / 16) * 16))); 
}
Tules
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  • Ahh, but what I want to do per say is not convert rgb to hex. I want to get the color of the element that was clicked on whether it be a div, span, a, img, or whatever else. – watzon Oct 07 '11 at 16:53
  • ah yes sorry, I read that in a hurry, my mistake! Here's what ur looking for I think http://www.eyecon.ro/colorpicker/ – Tules Oct 07 '11 at 16:56
  • Since it's pretty generic I would just use that one maybe customize the styling rather than reinventing it which could take ages. If you really need to know how it works just go through the source code, it hasn't been minimized – Tules Oct 07 '11 at 17:00