matrix.js

/**
 * 3x2矩阵操作类
 * @exports zrender/tool/matrix
 */

var ArrayCtor = typeof Float32Array === 'undefined'
    ? Array
    : Float32Array;

/**
 * Create a identity matrix.
 * @return {Float32Array|Array.<number>}
 */
export function create() {
    var out = new ArrayCtor(6);
    identity(out);

    return out;
}

/**
 * 设置矩阵为单位矩阵
 * @param {Float32Array|Array.<number>} out
 */
export function identity(out) {
    out[0] = 1;
    out[1] = 0;
    out[2] = 0;
    out[3] = 1;
    out[4] = 0;
    out[5] = 0;
    return out;
}

/**
 * 复制矩阵
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} m
 */
export function copy(out, m) {
    out[0] = m[0];
    out[1] = m[1];
    out[2] = m[2];
    out[3] = m[3];
    out[4] = m[4];
    out[5] = m[5];
    return out;
}

/**
 * 矩阵相乘
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} m1
 * @param {Float32Array|Array.<number>} m2
 */
export function mul(out, m1, m2) {
    // Consider matrix.mul(m, m2, m);
    // where out is the same as m2.
    // So use temp variable to escape error.
    var out0 = m1[0] * m2[0] + m1[2] * m2[1];
    var out1 = m1[1] * m2[0] + m1[3] * m2[1];
    var out2 = m1[0] * m2[2] + m1[2] * m2[3];
    var out3 = m1[1] * m2[2] + m1[3] * m2[3];
    var out4 = m1[0] * m2[4] + m1[2] * m2[5] + m1[4];
    var out5 = m1[1] * m2[4] + m1[3] * m2[5] + m1[5];
    out[0] = out0;
    out[1] = out1;
    out[2] = out2;
    out[3] = out3;
    out[4] = out4;
    out[5] = out5;
    return out;
}

/**
 * 平移变换
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} a
 * @param {Float32Array|Array.<number>} v
 */
export function translate(out, a, v) {
    out[0] = a[0];
    out[1] = a[1];
    out[2] = a[2];
    out[3] = a[3];
    out[4] = a[4] + v[0];
    out[5] = a[5] + v[1];
    return out;
}

/**
 * 旋转变换
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} a
 * @param {number} rad
 */
export function rotate(out, a, rad) {
    var aa = a[0];
    var ac = a[2];
    var atx = a[4];
    var ab = a[1];
    var ad = a[3];
    var aty = a[5];
    var st = Math.sin(rad);
    var ct = Math.cos(rad);

    out[0] = aa * ct + ab * st;
    out[1] = -aa * st + ab * ct;
    out[2] = ac * ct + ad * st;
    out[3] = -ac * st + ct * ad;
    out[4] = ct * atx + st * aty;
    out[5] = ct * aty - st * atx;
    return out;
}

/**
 * 缩放变换
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} a
 * @param {Float32Array|Array.<number>} v
 */
export function scale(out, a, v) {
    var vx = v[0];
    var vy = v[1];
    out[0] = a[0] * vx;
    out[1] = a[1] * vy;
    out[2] = a[2] * vx;
    out[3] = a[3] * vy;
    out[4] = a[4] * vx;
    out[5] = a[5] * vy;
    return out;
}

/**
 * 求逆矩阵
 * @param {Float32Array|Array.<number>} out
 * @param {Float32Array|Array.<number>} a
 */
export function invert(out, a) {

    var aa = a[0];
    var ac = a[2];
    var atx = a[4];
    var ab = a[1];
    var ad = a[3];
    var aty = a[5];

    var det = aa * ad - ab * ac;
    if (!det) {
        return null;
    }
    det = 1.0 / det;

    out[0] = ad * det;
    out[1] = -ab * det;
    out[2] = -ac * det;
    out[3] = aa * det;
    out[4] = (ac * aty - ad * atx) * det;
    out[5] = (ab * atx - aa * aty) * det;
    return out;
}

/**
 * Clone a new matrix.
 * @param {Float32Array|Array.<number>} a
 */
export function clone(a) {
    var b = create();
    copy(b, a);
    return b;
}