Kinetic.js get shape hit region with color change

Question

First of all, I have images with different shapes and i have to recolour them, and set the hit region (for onclick event) only when the mouse is on the shape. So after investigate the problem separately, i have found both solutions, but i dont know how to use both together.

-to use only shape hit region, i use .cache(), to store the image on cache and redraw it without transparent pixels.

-to change the color, i iterate on imageData pixels, to change them one by one inside a for loop.

For testing, i'm using original blue image (.png format) and i want red image with hit regions set properly, also i'm using kinetic-v5.0.2.

this is my code.

    function makeKineticImage(imageObj){


    var dImage = new Kinetic.Shape({
        sceneFunc: function (context) {
            context.beginPath();
            console.log("sceneFunc");
            var x = 100;
            var y = 100;
            context.drawImage(imageObj, x, y, imageObj.width, imageObj.height);
            var imageData = context.getImageData(x, y, imageObj.width, imageObj.height);
            var data = imageData.data;

                            //Here i'm changing the color
            for (var i = 0; i < data.length; i += 4) {
                //var brightness = 0.9 * data[i] + 0 * data[i + 1] + 0 * data[i + 2];
                data[i] = 255;
                data[i + 1] = 25;
                data[i + 2] = 25;
            }
            context.putImageData(imageData, x, y);
            context.rect(x, y, imageObj.width, imageObj.height);
            context.closePath();
            context.fillStrokeShape(this);
        }
    });

    dImage.on("click", function() {
      console.log("Click dImage");
    }); 

    layer.add(dImage);

    /*dImage.cache({
        width: 79,
        height: 73,
        x: 100,
        y: 100
    });

    dImage.drawHitFromCache();*/

    layer.draw();
    layer.drawHit();
}

Now I get my shape filled in other color (red) but hit region dont fit the shape (get all image square), but If I uncomment .cache() and .drawHitFromCache() i get my original image (blue) with hit region only on the shape.

Could you help me? Thank you very much.

Answer 1

try this!!!

The relavant part of code is:

dataURL = context.getCanvas().toDataURL("image/png");

var imageObj = new Image(); imageObj.src = dataURL;

function makeKineticImage(imageObj){
        var dataURL;
        var dImage = new Kinetic.Shape({
            sceneFunc: function (context) {
                context.beginPath();
                console.log("sceneFunc");
                var x = 100;
                var y = 100;
                context.drawImage(imageObj, x, y, imageObj.width, imageObj.height);
                var imageData = context.getImageData(x, y, imageObj.width, imageObj.height);
                var data = imageData.data;
                for (var i = 0; i < data.length; i += 4) {
                    //var brightness = 0.9 * data[i] + 0 * data[i + 1] + 0 * data[i + 2];
                    data[i] = 255;
                    data[i + 1] = 25;
                    data[i + 2] = 25;
                }
                context.putImageData(imageData, x, y);
                context.rect(x, y, imageObj.width, imageObj.height);
                context.closePath();
                context.fillStrokeShape(this);
                dataURL = context.getCanvas().toDataURL("image/png");
                console.log(dataURL);

            },
            hitFunc: function(context) {
                console.log("hitFunc");
                context.beginPath();
                var x = 100;
                var y = 100;
                context.drawImage(imageObj, x, y, imageObj.width, imageObj.height);
                var imageData = context.getImageData(x, y, imageObj.width, imageObj.height);
                var data = imageData.data;
                for (var i = 0; i < data.length; i += 4) {
                    //var brightness = 0.9 * data[i] + 0 * data[i + 1] + 0 * data[i + 2];
                    data[i] = 255;
                    data[i + 1] = 25;
                    data[i + 2] = 25;
                }
                context.putImageData(imageData, x, y);
                context.rect(x, y, imageObj.width, imageObj.height);
                context.closePath();
                context.fillStrokeShape(this);
            }
        });

        layer.add(dImage);
        layer.draw();
        layer.removeChildren();
        var imageObj = new Image();
        imageObj.src = dataURL;
        var kImage = new Kinetic.Image({
            image: imageObj,
            //x: 100,
            //y: 100,
        });

        kImage.on("click", function() {
            console.log("Click dImage");
        });

        layer.add(kImage);
        kImage.cache();
        kImage.drawHitFromCache();
        layer.draw();
        layer.drawHit();
    }

Answer 2

I offer an alternative:

• recolor your image using an offscreen canvas

• create a Kinetic.Image instead of a Kinetic.Shape

• set the Image's image property to reference the offscreen canvas

• do dImage.cache, dImage.drawHitFromCach & drawHit to create the custom hit region

Here's example code and a Demo: http://jsfiddle.net/m1erickson/kv5Lg/

<!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-v5.1.0.min.js"></script>
<style>
body{padding:20px;}
#container{
  border:solid 1px #ccc;
  margin-top: 10px;
  width:350px;
  height:350px;
}
</style>        
<script>
$(function(){

    var stage = new Kinetic.Stage({
        container: 'container',
        width: 350,
        height: 350
    });
    var layer = new Kinetic.Layer();
    stage.add(layer);

    var canvas=document.createElement("canvas");

    var imageObj=new Image();
    imageObj.crossOrigin="anonymous";
    imageObj.onload=start;
    imageObj.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house100x100.png";
    function start(){

        canvas.width=imageObj.width;
        canvas.height=imageObj.height;
        var ctx=canvas.getContext("2d");

        ctx.drawImage(imageObj,0,0);
        var imageData = ctx.getImageData(0,0,canvas.width,canvas.height);
        var data = imageData.data;
        for (var i = 0; i < data.length; i += 4) {
            data[i] = 255;
            data[i + 1] = 25;
            data[i + 2] = 25;
        }
        ctx.putImageData(imageData,0,0);

        var dImage=new Kinetic.Image({
            x:100,
            y:100,
            image:canvas,
        });
        dImage.on("click", function() {
          console.log("Click dImage");
        }); 
        layer.add(dImage);
        layer.draw();

        dImage.cache();
        dImage.drawHitFromCache();
        layer.drawHit();

    }


}); // end $(function(){});

</script>       
</head>
<body>
    <div id="container"></div>
</body>
</html>