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Kinetic JS - Loading multiple images on canvas


I want to load and display multiple images on a canvas. The image sources are saved in an array:

var sources = {"../src/img/IMG_1284.JPG", "../src/img/IMG_1285.JPG", "../src/img/IMG_1286.JPG", "../src/img/IMG_1287.JPG", "../src/img/IMG_1288.JPG"}

I found this tutorial: http://www.html5canvastutorials.com/tutorials/html5-canvas-image-loader

But I don't know how I can adapt this code to my sources array. Additionally, I want to set every image draggable, but I think this is not possible with context.drawImage(..).

Hope my problem is understandable. Thanks for your help...


Solution

  • I see you tagged your question with KineticJS.

    KineticJS makes your task easy by keeping track of your images and allows your users to drag them.

    Simple as:

    • use an image loader to be sure that all you images a fully loaded before trying to draw them
    • when loaded, create a Kinetic.Image using each image.
    • put the draggable property on the Kinetic.Image and it will automatically be draggable

    Here's code and a Demo: http://jsfiddle.net/m1erickson/3es4Z/

    <!DOCTYPE html>
    <html>
      <head>
        <meta charset="utf-8">
        <title>Prototype</title>
        <script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
        <script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.7.2.min.js"></script>
    <style>
    body{padding:20px;}
    #container{
      border:solid 1px #ccc;
      margin-top: 10px;
      width:350px;
      height:350px;
    }
    </style>        
    <script>
    $(function(){
    
        // create the Kinetic stage and layer
        var stage = new Kinetic.Stage({
            container: 'container',
            width: 350,
            height: 350
        });
        var layer = new Kinetic.Layer();
        stage.add(layer);
    
        // put the paths to your images in imageURLs
        var imageURLs=[];
        imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-1.jpg");
        imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-2.jpg");
        imageURLs.push("https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-3.jpg");
        var imagesOK=0;
        var imgs=[];
    
        // fully load every image, then call the start function
        loadAllImages(start);
    
        function loadAllImages(callback){
            for (var i=0; i<imageURLs.length; i++) {
                var img = new Image();
                imgs.push(img);
                img.onload = function(){ 
                    imagesOK++; 
                    if (imagesOK>=imageURLs.length ) {
                        callback();
                    }
                };
                img.onerror=function(){alert("image load failed");} 
                img.crossOrigin="anonymous";
                img.src = imageURLs[i];
            }      
        }
    
        function start(){
            // the imgs[] array holds fully loaded images
            // the imgs[] are in the same order as imageURLs[]
    
            // make each image into a draggable Kinetic.Image
            for(var i=0;i<imgs.length;i++){
                var img=new Kinetic.Image({
                    x:i*75+15,
                    y:i*75+15,
                    width:60,
                    height:60,
                    image:imgs[i],
                    draggable:true
                });
                layer.add(img);
            }
            layer.draw();
        }
    
    }); // end $(function(){});
    </script>       
    </head>
    <body>
        <button id="myButton">Button</button>
        <div id="container"></div>
    </body>
    </html>