If you need a way to convert the JointJS mouse position to the canvas matrix coordinates, this is a simple way to do it (in combination with an angular mouse wheel event):
angular.element("#paper").bind("mousewheel", function (event) {
var svgPoint = this.paper.svg.createSVGPoint();
svgPoint.x = event.offsetX;
svgPoint.y = event.offsetY;
var pointTransformed = svgPoint.matrixTransform(this.paper.viewport.getCTM().inverse());
console.log(svgPoint);
console.log(pointTransformed);
});
Short, but hopefully helpful! Cheers!