Flemming Flemming - 3 months ago 9
Javascript Question

How do i get image data from external url - and return colors

Im using clusterfck.js to analyze and return colors. I wan't to grap images from search-results, but it seems to be a problem with the way clusterfck does the data reading. Here's the code from clusterfck:

$(".kmeans-button").click(function() {
if (!colors) {
colors = getImageColors();
}
var k = $(this).attr("data-k"); // $.data() returned undefined
$("#clusters").empty().append("<div>calculating distances...</div>");
kmeans.clusterColors(colors, k); // Threaded analyzing (worker)
})

function getImageColors() {
var img = $("#test-image");
var width = img.width();
var height = img.height();
var canvas = document.createElement('canvas');
canvas.width = width;
canvas.height = height;

var context = canvas.getContext("2d");
context.drawImage(img.get(0), 0, 0);

var data = context.getImageData(0, 0, width, height).data;
var colors = [];
for(var x = 0; x < width-12; x += 3) {
for(var y = 0; y < height-12; y += 3) { // sample image, every 3rd row and column
var offs = x*4 + y*4*width;
var color = [data[offs + 0], data[offs + 1], data[offs + 2]];
colors.push(color);
}
}
return colors;
}


I tried to put in img.crossOrigin = "Anonymous"; with no luck. I guess it needs to be loaded in af function and somehow callback colors. This is the best i could come up with, but it's not working.

$(".kmeans-button").click(function() {
if (!colors) {
getImageColors2(function(colors2) {
colors=colors2.slice(0);
var k = $(this).attr("data-k-e"); // $.data() returned undefined
$("#clusters").empty().append("<div>calculating colors...</div>");
kmeans.clusterColors(colors, k);
})
}
})


function getImageColors2(callback) {
var img2= document.getElementById("test-image");
var img = new Image();
img.onload = function () {
var width = img.width();
var height = img.height();

var canvas = document.createElement('canvas');
canvas.width = width;
canvas.height = height;

var context = canvas.getContext("2d");
context.drawImage(img.get(0), 0, 0);

var data = context.getImageData(0, 0, width, height).data;
var colors = [];
for(var x = 0; x < width-12; x += 3) {
for(var y = 0; y < height-12; y += 3) { // sample image, every 3rd row and column
var offs = x*4 + y*4*width;
var color = [data[offs + 0], data[offs + 1], data[offs + 2]];
colors.push(color);
}
}
callback(colors);
}
img.src=img2.src;
}


I assume that it can't access the data without loading into a image when on a external server. What am i missing her ? Maybe i got it all wrong ?

Answer

Thanks for your comments! I got it working now with the callback function :-)

function getpalette(colors) {
        $("#clusters").empty().append("<div>calculating colors...</div>");
        kmeans_paint.clusterColors(colors, k);
    }

$(".kmeans-error-button").click(function() {
    k = $(this).attr("data-k-e");

    if (!colors) {   
        getImageColors(getpalette);
    }
}) 

function getImageColors(callback) {
  var img = new Image();  
  img.setAttribute('crossOrigin', 'anonymous');
  img.onload = function () {

  var width = img.width;
  var height = img.height;

  var canvas = document.createElement("canvas");
  canvas.width = width;
  canvas.height = height;
  var context = canvas.getContext("2d");
   context.drawImage(img, 0, 0);

  var data = context.getImageData(0, 0, width, height).data;
  var colors = [];
  for(var x = 0; x < width-12; x += 3) {
    for(var y = 0; y < height-12; y += 3) { // sample image, every 3rd row and column
     var offs = x*4 + y*4*width;
     var color = [data[offs + 0], data[offs + 1], data[offs + 2]];
     colors.push(color);
    }
  }
  callback(colors);
  }
img.src=document.getElementById("test-image").src;
}
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