gistfile1.js

        var self = this;

        var setupCanvas = function() {
            var w = this.naturalWidth,
                h = this.naturalHeight,
                aspectRatio = w / h;
            
            var scaled = (h != this.naturalHeight || w != this.naturalWidth);

            var sixteenByNine = 16 / 9;

            if (aspectRatio > sixteenByNine) {
                // scale down to match container height (landscape)
                w = self.props.width;
                h = Math.min(self.props.width / aspectRatio, this.naturalWidth);
            } else if (aspectRatio <= sixteenByNine) {
                // scale down to match container width (portrait)
                h = Math.min(w / aspectRatio, self.props.height);
                w = self.props.width;
            }

            // for a dynamically shown and sized canvas element
            self.setState({ scaled: scaled, width: w, height: h }, function() {
                var canvas = self.refs.bg.getDOMNode();
                var canvasContext = canvas.getContext('2d');
                canvasContext.drawImage(this, 0, 0, w, h);
                if (scaled) {
                    // get original and blur it
                    var imageData = canvasContext.getImageData(0, 0, w, h);
                    stackblur(imageData.data, w, h, self.props.blurRadius);
                    canvasContext.putImageData(imageData, 0, 0);

                    var destX = canvas.width / 2 - this.naturalWidth / 2;

                    // draw cropped original back in
                    canvasContext.drawImage(this, 0, 0, w, h, destX, 0, w, h);
                }
            }.bind(this));

        };

        setupCanvas.call(e.target);