js-dicom/src/ImageUtility/internal/transform.js

this is js-dicom

// Last updated November 2011
// By Simon Sarris
// www.simonsarris.com
// sarris@acm.org
//
// Free to use and distribute at will
// So long as you are nice to people, etc

// Simple class for keeping track of the current transformation matrix

// For instance:
//    var t = new Transform();
//    t.rotate(5);
//    var m = t.m;
//    ctx.setTransform(m[0], m[1], m[2], m[3], m[4], m[5]);

// Is equivalent to:
//    ctx.rotate(5);

// But now you can retrieve it :)



    // Remember that this does not account for any CSS transforms applied to the canvas
    function Transform() {
        this.reset();
    }

    Transform.prototype.reset = function() {
        this.m = [1,0,0,1,0,0];
    };

    Transform.prototype.clone = function() {
        var transform = new Transform();
        transform.m[0] = this.m[0];
        transform.m[1] = this.m[1];
        transform.m[2] = this.m[2];
        transform.m[3] = this.m[3];
        transform.m[4] = this.m[4];
        transform.m[5] = this.m[5];
        return transform;
    };


    Transform.prototype.multiply = function(matrix) {
        var m11 = this.m[0] * matrix.m[0] + this.m[2] * matrix.m[1];
        var m12 = this.m[1] * matrix.m[0] + this.m[3] * matrix.m[1];

        var m21 = this.m[0] * matrix.m[2] + this.m[2] * matrix.m[3];
        var m22 = this.m[1] * matrix.m[2] + this.m[3] * matrix.m[3];

        var dx = this.m[0] * matrix.m[4] + this.m[2] * matrix.m[5] + this.m[4];
        var dy = this.m[1] * matrix.m[4] + this.m[3] * matrix.m[5] + this.m[5];

        this.m[0] = m11;
        this.m[1] = m12;
        this.m[2] = m21;
        this.m[3] = m22;
        this.m[4] = dx;
        this.m[5] = dy;
    };

    Transform.prototype.invert = function() {
        var d = 1 / (this.m[0] * this.m[3] - this.m[1] * this.m[2]);
        var m0 = this.m[3] * d;
        var m1 = -this.m[1] * d;
        var m2 = -this.m[2] * d;
        var m3 = this.m[0] * d;
        var m4 = d * (this.m[2] * this.m[5] - this.m[3] * this.m[4]);
        var m5 = d * (this.m[1] * this.m[4] - this.m[0] * this.m[5]);
        this.m[0] = m0;
        this.m[1] = m1;
        this.m[2] = m2;
        this.m[3] = m3;
        this.m[4] = m4;
        this.m[5] = m5;
    };

    Transform.prototype.rotate = function(rad) {
        var c = Math.cos(rad);
        var s = Math.sin(rad);
        var m11 = this.m[0] * c + this.m[2] * s;
        var m12 = this.m[1] * c + this.m[3] * s;
        var m21 = this.m[0] * -s + this.m[2] * c;
        var m22 = this.m[1] * -s + this.m[3] * c;
        this.m[0] = m11;
        this.m[1] = m12;
        this.m[2] = m21;
        this.m[3] = m22;
    };

    Transform.prototype.translate = function(x, y) {
        this.m[4] += this.m[0] * x + this.m[2] * y;
        this.m[5] += this.m[1] * x + this.m[3] * y;
    };

    Transform.prototype.scale = function(sx, sy) {
        this.m[0] *= sx;
        this.m[1] *= sx;
        this.m[2] *= sy;
        this.m[3] *= sy;
    };

    Transform.prototype.transformPoint = function(px, py) {
        var x = px;
        var y = py;
        px = x * this.m[0] + y * this.m[2] + this.m[4];
        py = x * this.m[1] + y * this.m[3] + this.m[5];
        return {x: px, y: py};
    };

    export  default Transform ;