Raphael paper zoom animation

Question

I managed to do some hack in order to zoom raphael paper, as setviewbox wasn't working for me, here is the function I wrote:

function setCTM(element, matrix) {
    var s = "matrix(" + matrix.a + "," + matrix.b + "," + matrix.c + "," + matrix.d + "," + matrix.e + "," + matrix.f + ")";

    element.setAttribute("transform", s);
}

Raphael.fn.zoomAndMove = function(coordx,coordy,zoom) {

    var svg = document.getElementsByTagName("svg")[0];

    var z = zoom;

    var g = document.getElementById("viewport1");
    var p = svg.createSVGPoint();

    p.x = coordx; 
    p.y = coordy;

    p = p.matrixTransform(g.getCTM().inverse());

    var k = svg.createSVGMatrix().scale(z).translate(-p.x, -p.y);
    setCTM(g, g.getCTM().multiply(k));
} 

where the viewport1 element was defined as :

var gelem = document.createElementNS('http://www.w3.org/2000/svg', 'g');
gelem.id = 'viewport1';

paper.canvas.appendChild(gelem);
paper.canvas = gelem;

Then I can call: paper.zoomAndMove(minx,miny,zoomRatio);

Is it possible to transform the function to make it zoom smoothly?

Answer 1

For anybody (like me) who wanted to have the zooming & panning smoothly animated have a look here:

https://groups.google.com/forum/?fromgroups#!topic/raphaeljs/7eA9xq4enDo

this snipped helped me to automate and animate zooming and panning to a specific point on the canvas. (Props to Will Morgan)

Raphael.fn.animateViewBox = function(currentViewBox, viewX, viewY, width, height, duration, callback) {

    duration = duration || 250;

    var originals = currentViewBox, //current viewBox Data from where the animation should start
        differences = {
                x: viewX - originals.x,
                y: viewY - originals.y,
                width: width - originals.width,
                height: height - originals.height
        },
        delay = 13,
        stepsNum = Math.ceil(duration / delay),
        stepped = {
                x: differences.x / stepsNum,
                y: differences.y / stepsNum,
                width: differences.width / stepsNum,
                height: differences.height / stepsNum
        }, i,
        canvas = this;

    /**
     * Using a lambda to protect a variable with its own scope.
     * Otherwise, the variable would be incremented inside the loop, but its
     * final value would be read at run time in the future.
     */
    function timerFn(iterator) {
            return function() {
                    canvas.setViewBox(
                            originals.x + (stepped.x * iterator),
                            originals.y + (stepped.y * iterator),
                            originals.width + (stepped.width * iterator),
                            originals.height + (stepped.height * iterator)
                    );
                    // Run the callback as soon as possible, in sync with the last step
                    if(iterator == stepsNum && callback) {
                            callback(viewX, viewY, width, height);
                    }
            }
    }

    // Schedule each animation step in to the future
    // Todo: use some nice easing
    for(i = 1; i <= stepsNum; ++i) {
            setTimeout(timerFn(i), i * delay);
    }

} 

Answer 2

See this JS Fiddle example for utilizing jQuery and Raphael's setViewBox which does both zooming and panning smoothly. We use the exact same functionality in a much more complicated and larger context and it works perfect and remains smooth even with a large number of items drawn on screen.

Basically, don't try and re-invent the wheel. I know this may not be the answer you are looking for, but it's almost certainly your best option.

EDIT: I've fixed the attached fiddle (it was broken due to changes JSFiddle made to the site) but apparently SO won't let me save JSFiddle links without including some code, so...

console.log("hello world!");

Answer 3

Minor mod to patrics' answer to get rid of "currentViewBox"... this works with Raphael 2.1.0:

Raphael.fn.animateViewBox = function(viewX, viewY, width, height, duration, callback) {

    duration = duration || 250;

    //current viewBox Data from where the animation should start
    var originals = {
            x: this._viewBox[0], 
            y: this._viewBox[1], 
            width: this._viewBox[2], 
            height: this._viewBox[3]
    }, 
    differences = {
            x: viewX - originals.x,
            y: viewY - originals.y,
            width: width - originals.width,
            height: height - originals.height
    },
    delay = 13,
    stepsNum = Math.ceil(duration / delay),
    stepped = {
            x: differences.x / stepsNum,
            y: differences.y / stepsNum,
            width: differences.width / stepsNum,
            height: differences.height / stepsNum
    }, i,
    canvas = this;

    /**
     * Using a lambda to protect a variable with its own scope.
     * Otherwise, the variable would be incremented inside the loop, but its
     * final value would be read at run time in the future.
     */
    function timerFn(iterator) {
        return function() {
                canvas.setViewBox(
                        originals.x + (stepped.x * iterator),
                        originals.y + (stepped.y * iterator),
                        originals.width + (stepped.width * iterator),
                        originals.height + (stepped.height * iterator),
                        true
                );
                // Run the callback as soon as possible, in sync with the last step
                if(iterator == stepsNum && callback) {
                        callback(viewX, viewY, width, height);
                }
        }
    }

    // Schedule each animation step in to the future
    // Todo: use some nice easing
    for(i = 1; i <= stepsNum; ++i) {
        setTimeout(timerFn(i), i * delay);
    }
} 

Sry if it's bad etiquette to post a mod. Feel free to merge it in patrics' version, but then the comments don't make sense.