How Does The Inheritance Model Of KineticJS Work?

I am a little new to JavaScript, and I know that there are different inheritance models that can be used. I have a project I used KineticJS for and I noticed in their changelog tha

Solution 1:

I would recommend following the method that is done inside the KineticJS source. This blog post explains how but is a little outdated so I'll include an up to date example that also shows how to add properties to your custom shapes.

The code below shows gives an example of creating a new Shape.Arc object. This sample shows how to add both new functions and properties.

var Shape = {};
(function () {
    Shape.Arc = function (config) {
        this.initArc(config);
    };
    Shape.Arc.prototype = {
        initArc: function (config) {
            Kinetic.Shape.call(this, config);
            this._setDrawFuncs();
            this.shapeType = 'Arc;'
            drc.ui.utils.setupShape(this);
        },
        drawFunc: function (context) {
            context.beginPath();
            context.arc(0,0, this.getRadius(), this.getStartAngle(), 
                this.getEndAngle(), true);
            context.fillStrokeShape(this);
        }
    };
    Kinetic.Util.extend(Shape.Arc, Kinetic.Shape);

    //Add properties to shape.
    //The code below adds the getRadius(), getStartAngle() functions above.
    Kinetic.Factory.addGetterSetter(Shape.Arc, 'radius', 0);
    Kinetic.Factory.addGetterSetter(Shape.Arc, 'startAngle', 0);
    Kinetic.Factory.addGetterSetter(Shape.Arc, 'endAngle', 180);
})();

It is important that it is wrapped in an anonymous function so more than one instance can be created.

To create an arc:

var arc = new Shape.Arc({
                radius: radius,
                x: centreX,
                y: centreY,
                startAngle: 0,
                endAngle: Math.PI * 2
            });

Solution 2:

You can use different ways.

1 Kineticjs way. Example from kineticjs source:

Kinetic.Circle = function(config) {
    this._initCircle(config);
};

Kinetic.Circle.prototype = {
    _initCircle: function(config) {
        this.createAttrs();
        // call super constructor
        Kinetic.Shape.call(this, config);
        this.shapeType = 'Circle';
        this._setDrawFuncs();
    },
    drawFunc: function(canvas) {
      /*some code*/
    }
    /* more methods*/
};
Kinetic.Global.extend(Kinetic.Circle, Kinetic.Shape);

2 Also you can inheritance it with coffeescript: coffeescript Class But in js it looks not good:

var Gallery,
 __hasProp = {}.hasOwnProperty,
 __extends = function(child, parent) { for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; } function ctor() { this.constructor = child; } ctor.prototype = parent.prototype; child.prototype = new ctor(); child.__super__ = parent.prototype; return child; };

Gallery = (function(_super) {

__extends(Gallery, _super);

function Gallery(config) {
  Kinetic.Stage.call(this, config);
}

Gallery.prototype.add = function(item) {
  console.log(item);
  return Gallery.__super__.add.call(this, item);
};

Gallery.prototype.method = function() {
  return console.log('test');
};

return Gallery;

})(Kinetic.Stage);