Transformable.js

/**
 * 提供变换扩展
 * @module zrender/mixin/Transformable
 * @author pissang (https://www.github.com/pissang)
 */

import * as matrix from '../core/matrix';
import * as vector from '../core/vector';

var mIdentity = matrix.identity;

var EPSILON = 5e-5;

function isNotAroundZero(val) {
    return val > EPSILON || val < -EPSILON;
}

/**
 * @alias module:zrender/mixin/Transformable
 * @constructor
 */
var Transformable = function (opts) {
    opts = opts || {};
    // If there are no given position, rotation, scale
    if (!opts.position) {
        /**
         * 平移
         * @type {Array.<number>}
         * @default [0, 0]
         */
        this.position = [0, 0];
    }
    if (opts.rotation == null) {
        /**
         * 旋转
         * @type {Array.<number>}
         * @default 0
         */
        this.rotation = 0;
    }
    if (!opts.scale) {
        /**
         * 缩放
         * @type {Array.<number>}
         * @default [1, 1]
         */
        this.scale = [1, 1];
    }
    /**
     * 旋转和缩放的原点
     * @type {Array.<number>}
     * @default null
     */
    this.origin = this.origin || null;
};

var transformableProto = Transformable.prototype;
transformableProto.transform = null;

/**
 * 判断是否需要有坐标变换
 * 如果有坐标变换, 则从position, rotation, scale以及父节点的transform计算出自身的transform矩阵
 */
transformableProto.needLocalTransform = function () {
    return isNotAroundZero(this.rotation)
        || isNotAroundZero(this.position[0])
        || isNotAroundZero(this.position[1])
        || isNotAroundZero(this.scale[0] - 1)
        || isNotAroundZero(this.scale[1] - 1);
};

transformableProto.updateTransform = function () {
    var parent = this.parent;
    var parentHasTransform = parent && parent.transform;
    var needLocalTransform = this.needLocalTransform();

    var m = this.transform;
    if (!(needLocalTransform || parentHasTransform)) {
        m && mIdentity(m);
        return;
    }

    m = m || matrix.create();

    if (needLocalTransform) {
        this.getLocalTransform(m);
    }
    else {
        mIdentity(m);
    }

    // 应用父节点变换
    if (parentHasTransform) {
        if (needLocalTransform) {
            matrix.mul(m, parent.transform, m);
        }
        else {
            matrix.copy(m, parent.transform);
        }
    }
    // 保存这个变换矩阵
    this.transform = m;

    this.invTransform = this.invTransform || matrix.create();
    matrix.invert(this.invTransform, m);
};

transformableProto.getLocalTransform = function (m) {
    return Transformable.getLocalTransform(this, m);
};

/**
 * 将自己的transform应用到context上
 * @param {CanvasRenderingContext2D} ctx
 */
transformableProto.setTransform = function (ctx) {
    var m = this.transform;
    var dpr = ctx.dpr || 1;
    if (m) {
        ctx.setTransform(dpr * m[0], dpr * m[1], dpr * m[2], dpr * m[3], dpr * m[4], dpr * m[5]);
    }
    else {
        ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    }
};

transformableProto.restoreTransform = function (ctx) {
    var dpr = ctx.dpr || 1;
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
};

var tmpTransform = [];

/**
 * 分解`transform`矩阵到`position`, `rotation`, `scale`
 */
transformableProto.decomposeTransform = function () {
    if (!this.transform) {
        return;
    }
    var parent = this.parent;
    var m = this.transform;
    if (parent && parent.transform) {
        // Get local transform and decompose them to position, scale, rotation
        matrix.mul(tmpTransform, parent.invTransform, m);
        m = tmpTransform;
    }
    var sx = m[0] * m[0] + m[1] * m[1];
    var sy = m[2] * m[2] + m[3] * m[3];
    var position = this.position;
    var scale = this.scale;
    if (isNotAroundZero(sx - 1)) {
        sx = Math.sqrt(sx);
    }
    if (isNotAroundZero(sy - 1)) {
        sy = Math.sqrt(sy);
    }
    if (m[0] < 0) {
        sx = -sx;
    }
    if (m[3] < 0) {
        sy = -sy;
    }
    position[0] = m[4];
    position[1] = m[5];
    scale[0] = sx;
    scale[1] = sy;
    this.rotation = Math.atan2(-m[1] / sy, m[0] / sx);
};

/**
 * Get global scale
 * @return {Array.<number>}
 */
transformableProto.getGlobalScale = function () {
    var m = this.transform;
    if (!m) {
        return [1, 1];
    }
    var sx = Math.sqrt(m[0] * m[0] + m[1] * m[1]);
    var sy = Math.sqrt(m[2] * m[2] + m[3] * m[3]);
    if (m[0] < 0) {
        sx = -sx;
    }
    if (m[3] < 0) {
        sy = -sy;
    }
    return [sx, sy];
};
/**
 * 变换坐标位置到 shape 的局部坐标空间
 * @method
 * @param {number} x
 * @param {number} y
 * @return {Array.<number>}
 */
transformableProto.transformCoordToLocal = function (x, y) {
    var v2 = [x, y];
    var invTransform = this.invTransform;
    if (invTransform) {
        vector.applyTransform(v2, v2, invTransform);
    }
    return v2;
};

/**
 * 变换局部坐标位置到全局坐标空间
 * @method
 * @param {number} x
 * @param {number} y
 * @return {Array.<number>}
 */
transformableProto.transformCoordToGlobal = function (x, y) {
    var v2 = [x, y];
    var transform = this.transform;
    if (transform) {
        vector.applyTransform(v2, v2, transform);
    }
    return v2;
};

/**
 * @static
 * @param {Object} target
 * @param {Array.<number>} target.origin
 * @param {number} target.rotation
 * @param {Array.<number>} target.position
 * @param {Array.<number>} [m]
 */
Transformable.getLocalTransform = function (target, m) {
    m = m || [];
    mIdentity(m);

    var origin = target.origin;
    var scale = target.scale || [1, 1];
    var rotation = target.rotation || 0;
    var position = target.position || [0, 0];

    if (origin) {
        // Translate to origin
        m[4] -= origin[0];
        m[5] -= origin[1];
    }
    matrix.scale(m, m, scale);
    if (rotation) {
        matrix.rotate(m, m, rotation);
    }
    if (origin) {
        // Translate back from origin
        m[4] += origin[0];
        m[5] += origin[1];
    }

    m[4] += position[0];
    m[5] += position[1];

    return m;
};

export default Transformable;