Phaser Source: src/gameobjects/components/ScaleMinMax.js

# Source: src/gameobjects/components/ScaleMinMax.js

    /**
    * @author       Richard Davey <rich@photonstorm.com>
    * @copyright    2016 Photon Storm Ltd.
    * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
    */

    /**
    * The ScaleMinMax component allows a Game Object to limit how far it can be scaled by its parent.
    *
    * @class
    */
    Phaser.Component.ScaleMinMax = function () {};

    Phaser.Component.ScaleMinMax.prototype = {

        /**
        * The callback that will apply any scale limiting to the worldTransform.
        * @property {function} transformCallback
        */
        transformCallback: null,

        /**
        * The context under which `transformCallback` is called.
        * @property {object} transformCallbackContext
        */
        transformCallbackContext: this,

        /**
        * The minimum scale this Game Object will scale down to.
        *
        * It allows you to prevent a parent from scaling this Game Object lower than the given value.
        *
        * Set it to `null` to remove the limit.
        * @property {Phaser.Point} scaleMin
        */
        scaleMin: null,

        /**
        * The maximum scale this Game Object will scale up to.
        *
        * It allows you to prevent a parent from scaling this Game Object higher than the given value.
        *
        * Set it to `null` to remove the limit.
        * @property {Phaser.Point} scaleMax
        */
        scaleMax: null,

        /**
         * Adjust scaling limits, if set, to this Game Object.
         *
         * @method
         * @private
         * @param {PIXI.Matrix} wt - The updated worldTransform matrix.
         */
        checkTransform: function (wt) {

            if (this.scaleMin)
            {
                if (wt.a < this.scaleMin.x)
                {
                    wt.a = this.scaleMin.x;
                }

                if (wt.d < this.scaleMin.y)
                {
                    wt.d = this.scaleMin.y;
                }
            }

            if (this.scaleMax)
            {
                if (wt.a > this.scaleMax.x)
                {
                    wt.a = this.scaleMax.x;
                }

                if (wt.d > this.scaleMax.y)
                {
                    wt.d = this.scaleMax.y;
                }
            }

        },

        /**
         * Sets the scaleMin and scaleMax values. These values are used to limit how far this Game Object will scale based on its parent.
         *
         * For example if this Game Object has a `minScale` value of 1 and its parent has a `scale` value of 0.5, the 0.5 will be ignored
         * and the scale value of 1 will be used, as the parents scale is lower than the minimum scale this Game Object should adhere to.
         *
         * By setting these values you can carefully control how Game Objects deal with responsive scaling.
         *
         * If only one parameter is given then that value will be used for both scaleMin and scaleMax:
         * `setScaleMinMax(1)` = scaleMin.x, scaleMin.y, scaleMax.x and scaleMax.y all = 1
         *
         * If only two parameters are given the first is set as scaleMin.x and y and the second as scaleMax.x and y:
         * `setScaleMinMax(0.5, 2)` = scaleMin.x and y = 0.5 and scaleMax.x and y = 2
         *
         * If you wish to set `scaleMin` with different values for x and y then either modify Game Object.scaleMin directly,
         * or pass `null` for the `maxX` and `maxY` parameters.
         *
         * Call `setScaleMinMax(null)` to clear all previously set values.
         *
         * @method
         * @param {number|null} minX - The minimum horizontal scale value this Game Object can scale down to.
         * @param {number|null} minY - The minimum vertical scale value this Game Object can scale down to.
         * @param {number|null} maxX - The maximum horizontal scale value this Game Object can scale up to.
         * @param {number|null} maxY - The maximum vertical scale value this Game Object can scale up to.
         */
        setScaleMinMax: function (minX, minY, maxX, maxY) {

            if (minY === undefined)
            {
                //  1 parameter, set all to it
                minY = maxX = maxY = minX;
            }
            else if (maxX === undefined)
            {
                //  2 parameters, the first is min, the second max
                maxX = maxY = minY;
                minY = minX;
            }

            if (minX === null)
            {
                this.scaleMin = null;
            }
            else
            {
                if (this.scaleMin)
                {
                    this.scaleMin.set(minX, minY);
                }
                else
                {
                    this.scaleMin = new Phaser.Point(minX, minY);
                }
            }

            if (maxX === null)
            {
                this.scaleMax = null;
            }
            else
            {
                if (this.scaleMax)
                {
                    this.scaleMax.set(maxX, maxY);
                }
                else
                {
                    this.scaleMax = new Phaser.Point(maxX, maxY);
                }
            }

            if (this.scaleMin === null)
            {
                this.transformCallback = null;
            }
            else
            {
                this.transformCallback = this.checkTransform;
                this.transformCallbackContext = this;
            }

        }

    };