CODEWITHSUNDEEP
javascripthtmlcanvas
MickDom
MickDom

Reputation: 157

Check to see if pixel is black on HTML5 Canvas

I'm trying to find if a pixel is black or not on a canvas

    var check = function(player,keyPressed) {
//series of ifs to determine what pixel to check. 
    }

I would need to return either true or false if the pixel is false, I've tried getImageData but I wasn't able to figure out how to use it properly.

Upvotes: 3

Views: 2255

Answers (1)

Abdennour TOUMI
Abdennour TOUMI

Reputation: 93203

var canvas= document.getElementById('myCanv');
var pixelData = canvas.getContext('2d').getImageData(event.clientX, event.clientY, 1, 1).data;

That is it !!

Of course, Assuming that , you have : 

   <canvas id="myCanv"></canvas>

FIDDLE

Then : 

function isBlack(dataPixel){
   if(dataPixel[0]==dataPixel[1] && dataPixel[1]==dataPixel[2] && dataPixel[2]===0 ){
      return true
   }
}

http://jsfiddle.net/abdennour/4kdLfooj/11/

Upvotes: 6

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