Is there js plugin convert the matrix parameter to css3 transform property?

Question

Suppose I have css3 transform style:

img
{
   -webkit-transform:rotate(10deg) translate(100px,20px);
   -moz-transform:rotate(10deg) translate(100px,20px);
}         


        

Answer 1

You can decompose the numbers back into various components. There are two common techniques to do this called QR and LU for short.

If you feed it the current matrix values you could do:

function decompose(a, b, c, d, e, f, useLU) {

    var acos = Math.acos, // caching for readability below
        atan = Math.atan,
        sqrt = Math.sqrt,
        pi   = Math.PI,

        translate = {x: e, y: f},
        rotation  = 0,
        scale     = {x: 1, y: 1},
        skew      = {x: 0, y: 0},

        determ = a * d - b * c;   // get determinant

    if (useLU) {
        if (a) {
            skew =  {x: atan(c / a), y: atan(b / a)};
            scale = {x: a,           y: determ / a};
        }
        else if (b) {
            rotation = pi * 0.5;
            scale    = {x: b, y: determ / b};
            skew.x   = atan(d / b);
        }
        else { // a = b = 0
            scale  = {x: c, y: d};
            skew.x = pi * 0.25;
        }
    }
    else {
        // Apply the QR-like decomposition.
        if (a || b) {
            var r = sqrt(a*a + b*b);
            rotation = b > 0 ? acos(a / r) : -acos(a / r);
            scale    = {x: r, y: determ / r};
            skew.x   = atan((a*c + b*d) / (r*r));
        }
        else if (c || d) {
            var s = sqrt(c*c + d*d);
            rotation = pi * 0.5 - (d > 0 ? acos(-c / s) : -acos(c / s));
            scale    = {x: determ/s, y: s};
            skew.y   = atan((a*c + b*d) / (s*s));
        }
        else { // a = b = c = d = 0
            scale = {x:0, y:0};     // = invalid matrix
        }
    }

    return {
        scale    : scale,
        translate: translate,
        rotation : rotation,
        skew     : skew
    };
}

Now you can use the object and its values to set rotate, scale etc.

See also my transformation-matrix-js and Decomposition of 2D transform-matrices for more details.