famo.us scale and rescale, save scale data from event to event - famo.us

Question

I have a simple problem I am stuck on. I want to implement a ScaleSync on an ImageSurface. Everytime I end the scale action the data value is reset to 1 and if I perform another scale the ImageSurfaces starts transforming from 1.
define(function(require, exports, module) {
var Engine = require('famous/core/Engine');
var Modifier = require('famous/core/Modifier');
var Transform = require('famous/core/Transform');
var ImageSurface = require('famous/surfaces/ImageSurface');
var Surface = require('famous/core/Surface');
var ScaleSync = require("famous/inputs/ScaleSync");
var mainContext = Engine.createContext();
var start = 1;
var update = 0;
var end = 0;
var growShrink = "";
var objectScale = 1;
var scaleSync = new ScaleSync();
var logo = new ImageSurface({
size: [200, 200],
content: '/content/images/famous_logo.png',
classes: ['backfaceVisibility']
});
var centerModifier = new Modifier({
align: [0.5, 0.5],
origin: [0.5, 0.5]
});
logo.pipe(scaleSync);
scaleSync.on("update", function(data) {
objectScale = data.scale
centerModifier.setTransform(
Transform.scale( objectScale, objectScale, 1)
);
});
scaleSync.on("start", function(){
start ++;
});
scaleSync.on("end", function() {
end++;
});
mainContext.add(centerModifier).add(logo);
});
I tried achieving this using an Accumulator, but I think that's for different purposes. I think I have to somehow alter the data in the on.update callback, but have no clue how to do that.
Your help is much appreciated!

Answer 1

I found the solution. Hope this helps anybody with similar issues. The modifier should have a scale variable that is referenced as follows:
var scale = 1;
var centerModifier = new Modifier({
align: [0.5, 0.5],
origin: [0.5, 0.5],
transform: function(){
return Transform.scale(scale, scale, 1);
}
});
And the state of the variable is changed on event update (I divide data.delta by 10 to normalize the value):
scaleSync.on("update", function(data) {
scale += data.delta / 10;
});