# all files / ol/ transform.js

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     goog.provide('ol.transform');

    goog.require('ol.asserts');

    /**
     * Collection of affine 2d transformation functions. The functions work on an
     * array of 6 elements. The element order is compatible with the [SVGMatrix
     * interface](https://developer.mozilla.org/en-US/docs/Web/API/SVGMatrix) and is
     * a subset (elements a to f) of a 3x3 martrix:
     * ```
     * [ a c e ]
     * [ b d f ]
     * [ 0 0 1 ]
     * ```
     */

    /**
     * @private
     * @type {ol.Transform}
     */
    ol.transform.tmp_ = new Array(6);

    /**
     * Create an identity transform.
     * @return {!ol.Transform} Identity transform.
     */
    ol.transform.create = function() {
      return [1, 0, 0, 1, 0, 0];
    };

    /**
     * Resets the given transform to an identity transform.
     * @param {!ol.Transform} transform Transform.
     * @return {!ol.Transform} Transform.
     */
    ol.transform.reset = function(transform) {
      return ol.transform.set(transform, 1, 0, 0, 1, 0, 0);
    };

    /**
     * Multiply the underlying matrices of two transforms and return the result in
     * the first transform.
     * @param {!ol.Transform} transform1 Transform parameters of matrix 1.
     * @param {!ol.Transform} transform2 Transform parameters of matrix 2.
     * @return {!ol.Transform} transform1 multiplied with transform2.
     */
    ol.transform.multiply = function(transform1, transform2) {
      var a1 = transform1[0];
      var b1 = transform1[1];
      var c1 = transform1[2];
      var d1 = transform1[3];
      var e1 = transform1[4];
      var f1 = transform1[5];
      var a2 = transform2[0];
      var b2 = transform2[1];
      var c2 = transform2[2];
      var d2 = transform2[3];
      var e2 = transform2[4];
      var f2 = transform2[5];

      transform1[0] = a1 * a2 + c1 * b2;
      transform1[1] = b1 * a2 + d1 * b2;
      transform1[2] = a1 * c2 + c1 * d2;
      transform1[3] = b1 * c2 + d1 * d2;
      transform1[4] = a1 * e2 + c1 * f2 + e1;
      transform1[5] = b1 * e2 + d1 * f2 + f1;

      return transform1;
    };

    /**
     * Set the transform components a-f on a given transform.
     * @param {!ol.Transform} transform Transform.
     * @param {number} a The a component of the transform.
     * @param {number} b The b component of the transform.
     * @param {number} c The c component of the transform.
     * @param {number} d The d component of the transform.
     * @param {number} e The e component of the transform.
     * @param {number} f The f component of the transform.
     * @return {!ol.Transform} Matrix with transform applied.
     */
    ol.transform.set = function(transform, a, b, c, d, e, f) {
      transform[0] = a;
      transform[1] = b;
      transform[2] = c;
      transform[3] = d;
      transform[4] = e;
      transform[5] = f;
      return transform;
    };

    /**
     * Set transform on one matrix from another matrix.
     * @param {!ol.Transform} transform1 Matrix to set transform to.
     * @param {!ol.Transform} transform2 Matrix to set transform from.
     * @return {!ol.Transform} transform1 with transform from transform2 applied.
     */
    ol.transform.setFromArray = function(transform1, transform2) {
      transform1[0] = transform2[0];
      transform1[1] = transform2[1];
      transform1[2] = transform2[2];
      transform1[3] = transform2[3];
      transform1[4] = transform2[4];
      transform1[5] = transform2[5];
      return transform1;
    };

    /**
     * Transforms the given coordinate with the given transform returning the
     * resulting, transformed coordinate. The coordinate will be modified in-place.
     *
     * @param {ol.Transform} transform The transformation.
     * @param {ol.Coordinate|ol.Pixel} coordinate The coordinate to transform.
     * @return {ol.Coordinate|ol.Pixel} return coordinate so that operations can be
     *     chained together.
     */
    ol.transform.apply = function(transform, coordinate) {
      var x = coordinate[0], y = coordinate[1];
      coordinate[0] = transform[0] * x + transform[2] * y + transform[4];
      coordinate[1] = transform[1] * x + transform[3] * y + transform[5];
      return coordinate;
    };

    /**
     * Applies rotation to the given transform.
     * @param {!ol.Transform} transform Transform.
     * @param {number} angle Angle in radians.
     * @return {!ol.Transform} The rotated transform.
     */
    ol.transform.rotate = function(transform, angle) {
      var cos = Math.cos(angle);
      var sin = Math.sin(angle);
      return ol.transform.multiply(transform,
          ol.transform.set(ol.transform.tmp_, cos, sin, -sin, cos, 0, 0));
    };

    /**
     * Applies scale to a given transform.
     * @param {!ol.Transform} transform Transform.
     * @param {number} x Scale factor x.
     * @param {number} y Scale factor y.
     * @return {!ol.Transform} The scaled transform.
     */
    ol.transform.scale = function(transform, x, y) {
      return ol.transform.multiply(transform,
          ol.transform.set(ol.transform.tmp_, x, 0, 0, y, 0, 0));
    };

    /**
     * Applies translation to the given transform.
     * @param {!ol.Transform} transform Transform.
     * @param {number} dx Translation x.
     * @param {number} dy Translation y.
     * @return {!ol.Transform} The translated transform.
     */
    ol.transform.translate = function(transform, dx, dy) {
      return ol.transform.multiply(transform,
          ol.transform.set(ol.transform.tmp_, 1, 0, 0, 1, dx, dy));
    };

    /**
     * Creates a composite transform given an initial translation, scale, rotation, and
     * final translation (in that order only, not commutative).
     * @param {!ol.Transform} transform The transform (will be modified in place).
     * @param {number} dx1 Initial translation x.
     * @param {number} dy1 Initial translation y.
     * @param {number} sx Scale factor x.
     * @param {number} sy Scale factor y.
     * @param {number} angle Rotation (in counter-clockwise radians).
     * @param {number} dx2 Final translation x.
     * @param {number} dy2 Final translation y.
     * @return {!ol.Transform} The composite transform.
     */
    ol.transform.compose = function(transform, dx1, dy1, sx, sy, angle, dx2, dy2) {
      var sin = Math.sin(angle);
      var cos = Math.cos(angle);
      transform[0] = sx * cos;
      transform[1] = sy * sin;
      transform[2] = -sx * sin;
      transform[3] = sy * cos;
      transform[4] = dx2 * sx * cos - dy2 * sx * sin + dx1;
      transform[5] = dx2 * sy * sin + dy2 * sy * cos + dy1;
      return transform;
    };

    /**
     * Invert the given transform.
     * @param {!ol.Transform} transform Transform.
     * @return {!ol.Transform} Inverse of the transform.
     */
    ol.transform.invert = function(transform) {
      var det = ol.transform.determinant(transform);
      ol.asserts.assert(det !== 0, 32); // Transformation matrix cannot be inverted

      var a = transform[0];
      var b = transform[1];
      var c = transform[2];
      var d = transform[3];
      var e = transform[4];
      var f = transform[5];

      transform[0] = d / det;
      transform[1] = -b / det;
      transform[2] = -c / det;
      transform[3] = a / det;
      transform[4] = (c * f - d * e) / det;
      transform[5] = -(a * f - b * e) / det;

      return transform;
    };

    /**
     * Returns the determinant of the given matrix.
     * @param {!ol.Transform} mat Matrix.
     * @return {number} Determinant.
     */
    ol.transform.determinant = function(mat) {
      return mat[0] * mat[3] - mat[1] * mat[2];
    };