Has anyone used .animateWith() in Raphael to successfully keep fast animations in sync? It is poorly documented. The library's creator has a video demonstration but no code I can find.

I have a Javascript metronome that consists of a line (the arm of the metronome) and a trapezoidal shaped "weight" that will eventually move up and down to signify tempo. I have a working fiddle here, and the lines in question are:

        var ticktock = Raphael.animation({
            "50%": { transform:"R20 " + x + "," + y, easing: "sinoid", callback: function() { tick(this, repeats, done); }},
            "100%": { transform:"R-20 " + x + "," + y, easing: "sinoid", callback: function() { tick(this, repeats, done); }}
        }, interval).repeat(repeats / 2);
        arm.animate(ticktock);
        weight.animateWith(arm, ticktock, ticktock);    

If you check out the fiddle and give it a high tempo and about 20 ticks, you should see the weight lag behind the arm. (Please try it a few times if not -- Murphy's Law etc.) I thought this was precisely what animateWith() prevented. Maybe I am using it incorrectly.

If you look at the Raphael source for the .animateWith() function, you see it syncs the .start param of each animation, FWIW.

Has anyone used .animateWith() in Raphael to successfully keep fast animations in sync? It is poorly documented. The library's creator has a video demonstration but no code I can find.

I have a Javascript metronome that consists of a line (the arm of the metronome) and a trapezoidal shaped "weight" that will eventually move up and down to signify tempo. I have a working fiddle here, and the lines in question are:

        var ticktock = Raphael.animation({
            "50%": { transform:"R20 " + x + "," + y, easing: "sinoid", callback: function() { tick(this, repeats, done); }},
            "100%": { transform:"R-20 " + x + "," + y, easing: "sinoid", callback: function() { tick(this, repeats, done); }}
        }, interval).repeat(repeats / 2);
        arm.animate(ticktock);
        weight.animateWith(arm, ticktock, ticktock);    

If you check out the fiddle and give it a high tempo and about 20 ticks, you should see the weight lag behind the arm. (Please try it a few times if not -- Murphy's Law etc.) I thought this was precisely what animateWith() prevented. Maybe I am using it incorrectly.

If you look at the Raphael source for the .animateWith() function, you see it syncs the .start param of each animation, FWIW.

• javascript
• animation
• raphael

1 Answer 1

From the Raphael documentation:

Parameters:

element - [object] element to sync with

anim - [object] animation to sync with

animation - [object] animation object, see Raphael.animation

So I think your code just need to separate the animation and pass that into second parameter for .animateWith():

The animation portion is just:

{
    "50%": { transform:"R20 " + x + "," + y, easing: "sinoid", callback: animationDone },
    "100%": { transform:"R-20 " + x + "," + y, easing: "sinoid", callback: animationDone }
} 

So you can do this:

var animationDone = function() { 
    tick(this, repeats, done); 
};

var ticktockAnimationParam = {
    "50%": { transform:"R20 " + x + "," + y, easing: "sinoid", callback: animationDone },
    "100%": { transform:"R-20 " + x + "," + y, easing: "sinoid", callback: animationDone }
};
var ticktock = Raphael.animation(ticktockAnimationParam, interval).repeat(repeats / 2);
arm.animate(ticktock);
weight.animateWith(arm, ticktockAnimationParam, ticktock);    

See fiddle: http://jsfiddle/wDwsW/7/

Fyi , I moved the callback function outside, instead of using anonymous functions.