基于layui+cropper.js实现上传图片的裁剪功能的方法

前端  /  管理员 发布于 4年前   543

前端的裁剪我知道的可以分为这么两种：flash一种，canvas一种。现在用的多的是canvas这种。

其实裁剪最本质的原理：通过工具获取到图片（不是JS那种获取DOM的方式，比如flash获取到图片，对图片任意操作，canvas也是一样，将图片放在画布上，任意操作）

本文使用的是canvas这种方式，借助的是cropper.js实现图片的裁剪。

由于前端页面使用的是layui这个框架，所有使用cropper时，最好的能够将cropper这个包作为一个layui的扩展嵌入到layui中，这样都省事，嵌入很简单，具体可以参考下面我封装好的代码

备注：cropper默认裁剪后的图片格式为png格式，如果需要自定义上传图片的格式，可以参考下面这段代码，如果不需要请直接忽略

cropper修改上传图片的格式：

var cas=imageEle.cropper('getCroppedCanvas');var base64url=cas.toDataURL('image/jpeg');console.log(base64url); //生成base64图片的格式// 展示裁剪的图片的两种方式// 方式一$('.cavans').html(cas)  //在body显示出canvas元素// 方式二$('.canvans').attr("src", base64url);

封装好的cropper源码如下，包括cropper-jQuery的

具体代码：

cropper-css

/*! * Cropper.js v1.4.3 * https://fengyuanchen.github.io/cropperjs * * Copyright 2015-present Chen Fengyuan * Released under the MIT license * * Date: 2018-10-24T13:07:11.429Z */.cropper-container {    direction: ltr;    font-size: 0;    line-height: 0;    position: relative;    -ms-touch-action: none;    touch-action: none;    -webkit-user-select: none;    -moz-user-select: none;    -ms-user-select: none;    user-select: none;}.cropper-container img {    display: block;    height: 100%;    image-orientation: 0deg;    max-height: none !important;    max-width: none !important;    min-height: 0 !important;    min-width: 0 !important;    width: 100%;}.cropper-wrap-box,.cropper-canvas,.cropper-drag-box,.cropper-crop-box,.cropper-modal {    bottom: 0;    left: 0;    position: absolute;    right: 0;    top: 0;}.cropper-wrap-box,.cropper-canvas {    overflow: hidden;}.cropper-drag-box {    background-color: #fff;    opacity: 0;}.cropper-modal {    background-color: #000;    opacity: .5;}.cropper-view-box {    display: block;    height: 100%;    outline-color: rgba(51, 153, 255, 0.75);    outline: 1px solid #39f;    overflow: hidden;    width: 100%;}.cropper-dashed {    border: 0 dashed #eee;    display: block;    opacity: .5;    position: absolute;}.cropper-dashed.dashed-h {    border-bottom-width: 1px;    border-top-width: 1px;    height: calc(100% / 3);    left: 0;    top: calc(100% / 3);    width: 100%;}.cropper-dashed.dashed-v {    border-left-width: 1px;    border-right-width: 1px;    height: 100%;    left: calc(100% / 3);    top: 0;    width: calc(100% / 3);}.cropper-center {    display: block;    height: 0;    left: 50%;    opacity: .75;    position: absolute;    top: 50%;    width: 0;}.cropper-center:before,.cropper-center:after {    background-color: #eee;    content: ' ';    display: block;    position: absolute;}.cropper-center:before {    height: 1px;    left: -3px;    top: 0;    width: 7px;}.cropper-center:after {    height: 7px;    left: 0;    top: -3px;    width: 1px;}.cropper-face,.cropper-line,.cropper-point {    display: block;    height: 100%;    opacity: .1;    position: absolute;    width: 100%;}.cropper-face {    background-color: #fff;    left: 0;    top: 0;}.cropper-line {    background-color: #39f;}.cropper-line.line-e {    cursor: ew-resize;    right: -3px;    top: 0;    width: 5px;}.cropper-line.line-n {    cursor: ns-resize;    height: 5px;    left: 0;    top: -3px;}.cropper-line.line-w {    cursor: ew-resize;    left: -3px;    top: 0;    width: 5px;}.cropper-line.line-s {    bottom: -3px;    cursor: ns-resize;    height: 5px;    left: 0;}.cropper-point {    background-color: #39f;    height: 5px;    opacity: .75;    width: 5px;}.cropper-point.point-e {    cursor: ew-resize;    margin-top: -3px;    right: -3px;    top: 50%;}.cropper-point.point-n {    cursor: ns-resize;    left: 50%;    margin-left: -3px;    top: -3px;}.cropper-point.point-w {    cursor: ew-resize;    left: -3px;    margin-top: -3px;    top: 50%;}.cropper-point.point-s {    bottom: -3px;    cursor: s-resize;    left: 50%;    margin-left: -3px;}.cropper-point.point-ne {    cursor: nesw-resize;    right: -3px;    top: -3px;}.cropper-point.point-nw {    cursor: nwse-resize;    left: -3px;    top: -3px;}.cropper-point.point-sw {    bottom: -3px;    cursor: nesw-resize;    left: -3px;}.cropper-point.point-se {    bottom: -3px;    cursor: nwse-resize;    height: 20px;    opacity: 1;    right: -3px;    width: 20px;}@media (min-width: 768px) {    .cropper-point.point-se {        height: 15px;        width: 15px;    }}@media (min-width: 992px) {    .cropper-point.point-se {        height: 10px;        width: 10px;    }}@media (min-width: 1200px) {    .cropper-point.point-se {        height: 5px;        opacity: .75;        width: 5px;    }}.cropper-point.point-se:before {    background-color: #39f;    bottom: -50%;    content: ' ';    display: block;    height: 200%;    opacity: 0;    position: absolute;    right: -50%;    width: 200%;}.cropper-invisible {    opacity: 0;}.cropper-bg {    background-image: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQAQMAAAAlPW0iAAAAA3NCSVQICAjb4U/gAAAABlBMVEXMzMz////TjRV2AAAACXBIWXMAAArrAAAK6wGCiw1aAAAAHHRFWHRTb2Z0d2FyZQBBZG9iZSBGaXJld29ya3MgQ1M26LyyjAAAABFJREFUCJlj+M/AgBVhF/0PAH6/D/HkDxOGAAAAAElFTkSuQmCC');}.cropper-hide {    display: block;    height: 0;    position: absolute;    width: 0;}.cropper-hidden {    display: none !important;}.cropper-move {    cursor: move;}.cropper-crop {    cursor: crosshair;}.cropper-disabled .cropper-drag-box,.cropper-disabled .cropper-face,.cropper-disabled .cropper-line,.cropper-disabled .cropper-point {    cursor: not-allowed;}cropper-css

cropper-js

/*! * Cropper.js v1.4.3 * https://fengyuanchen.github.io/cropperjs * * Copyright 2015-present Chen Fengyuan * Released under the MIT license * * Date: 2018-10-24T13:07:15.032Z */(function (global, factory) {    typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :        typeof define === 'function' && define.amd ? define(factory) :            global.layui && layui.define ? layui.define(function (exports) {                    exports('cropper', factory())                }) :                (global.Cropper = factory());}(this, (function () {    'use strict';    function _typeof(obj) {        if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") {            _typeof = function (obj) {                return typeof obj;            };        } else {            _typeof = function (obj) {                return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj;            };        }        return _typeof(obj);    }    function _classCallCheck(instance, Constructor) {        if (!(instance instanceof Constructor)) {            throw new TypeError("Cannot call a class as a function");        }    }    function _defineProperties(target, props) {        for (var i = 0; i < props.length; i++) {            var descriptor = props[i];            descriptor.enumerable = descriptor.enumerable || false;            descriptor.configurable = true;            if ("value" in descriptor) descriptor.writable = true;            Object.defineProperty(target, descriptor.key, descriptor);        }    }    function _createClass(Constructor, protoProps, staticProps) {        if (protoProps) _defineProperties(Constructor.prototype, protoProps);        if (staticProps) _defineProperties(Constructor, staticProps);        return Constructor;    }    function _toConsumableArray(arr) {        return _arrayWithoutHoles(arr) || _iterableToArray(arr) || _nonIterableSpread();    }    function _arrayWithoutHoles(arr) {        if (Array.isArray(arr)) {            for (var i = 0, arr2 = new Array(arr.length); i < arr.length; i++) arr2[i] = arr[i];            return arr2;        }    }    function _iterableToArray(iter) {        if (Symbol.iterator in Object(iter) || Object.prototype.toString.call(iter) === "[object Arguments]") return Array.from(iter);    }    function _nonIterableSpread() {        throw new TypeError("Invalid attempt to spread non-iterable instance");    }    var IN_BROWSER = typeof window !== 'undefined';    var WINDOW = IN_BROWSER ? window : {};    var NAMESPACE = 'cropper'; // Actions    var ACTION_ALL = 'all';    var ACTION_CROP = 'crop';    var ACTION_MOVE = 'move';    var ACTION_ZOOM = 'zoom';    var ACTION_EAST = 'e';    var ACTION_WEST = 'w';    var ACTION_SOUTH = 's';    var ACTION_NORTH = 'n';    var ACTION_NORTH_EAST = 'ne';    var ACTION_NORTH_WEST = 'nw';    var ACTION_SOUTH_EAST = 'se';    var ACTION_SOUTH_WEST = 'sw'; // Classes    var CLASS_CROP = "".concat(NAMESPACE, "-crop");    var CLASS_DISABLED = "".concat(NAMESPACE, "-disabled");    var CLASS_HIDDEN = "".concat(NAMESPACE, "-hidden");    var CLASS_HIDE = "".concat(NAMESPACE, "-hide");    var CLASS_INVISIBLE = "".concat(NAMESPACE, "-invisible");    var CLASS_MODAL = "".concat(NAMESPACE, "-modal");    var CLASS_MOVE = "".concat(NAMESPACE, "-move"); // Data keys    var DATA_ACTION = "".concat(NAMESPACE, "Action");    var DATA_PREVIEW = "".concat(NAMESPACE, "Preview"); // Drag modes    var DRAG_MODE_CROP = 'crop';    var DRAG_MODE_MOVE = 'move';    var DRAG_MODE_NONE = 'none'; // Events    var EVENT_CROP = 'crop';    var EVENT_CROP_END = 'cropend';    var EVENT_CROP_MOVE = 'cropmove';    var EVENT_CROP_START = 'cropstart';    var EVENT_DBLCLICK = 'dblclick';    var EVENT_POINTER_DOWN = WINDOW.PointerEvent ? 'pointerdown' : 'touchstart mousedown';    var EVENT_POINTER_MOVE = WINDOW.PointerEvent ? 'pointermove' : 'touchmove mousemove';    var EVENT_POINTER_UP = WINDOW.PointerEvent ? 'pointerup pointercancel' : 'touchend touchcancel mouseup';    var EVENT_READY = 'ready';    var EVENT_RESIZE = 'resize';    var EVENT_WHEEL = 'wheel mousewheel DOMMouseScroll';    var EVENT_ZOOM = 'zoom'; // Mime types    var MIME_TYPE_JPEG = 'image/jpeg'; // RegExps    var REGEXP_ACTIONS = /^(?:e|w|s|n|se|sw|ne|nw|all|crop|move|zoom)$/;    var REGEXP_DATA_URL = /^data:/;    var REGEXP_DATA_URL_JPEG = /^data:image\/jpeg;base64,/;    var REGEXP_TAG_NAME = /^(?:img|canvas)$/i;    var DEFAULTS = {        // Define the view mode of the cropper        viewMode: 0,        // 0, 1, 2, 3        // Define the dragging mode of the cropper        dragMode: DRAG_MODE_CROP,        // 'crop', 'move' or 'none'        // Define the initial aspect ratio of the crop box        initialAspectRatio: NaN,        // Define the aspect ratio of the crop box        aspectRatio: NaN,        // An object with the previous cropping result data        data: null,        // A selector for adding extra containers to preview        preview: '',        // Re-render the cropper when resize the window        responsive: true,        // Restore the cropped area after resize the window        restore: true,        // Check if the current image is a cross-origin image        checkCrossOrigin: false,        // Check the current image's Exif Orientation information        checkOrientation: true,        // Show the black modal        modal: true,        // Show the dashed lines for guiding        guides: true,        // Show the center indicator for guiding        center: true,        // Show the white modal to highlight the crop box        highlight: true,        // Show the grid background        background: true,        // Enable to crop the image automatically when initialize        autoCrop: true,        // Define the percentage of automatic cropping area when initializes        autoCropArea: 0.8,        // Enable to move the image        movable: true,        // Enable to rotate the image        rotatable: true,        // Enable to scale the image        scalable: true,        // Enable to zoom the image        zoomable: true,        // Enable to zoom the image by dragging touch        zoomOnTouch: true,        // Enable to zoom the image by wheeling mouse        zoomOnWheel: true,        // Define zoom ratio when zoom the image by wheeling mouse        wheelZoomRatio: 0.1,        // Enable to move the crop box        cropBoxMovable: true,        // Enable to resize the crop box        cropBoxResizable: true,        // Toggle drag mode between "crop" and "move" when click twice on the cropper        toggleDragModeOnDblclick: true,        // Size limitation        minCanvasWidth: 0,        minCanvasHeight: 0,        minCropBoxWidth: 0,        minCropBoxHeight: 0,        minContainerWidth: 200,        minContainerHeight: 100,        // Shortcuts of events        ready: null,        cropstart: null,        cropmove: null,        cropend: null,        crop: null,        zoom: null    };    var TEMPLATE = '<div class="cropper-container" touch-action="none">' + '<div class="cropper-wrap-box">' + '<div class="cropper-canvas"></div>' + '</div>' + '<div class="cropper-drag-box"></div>' + '<div class="cropper-crop-box">' + '<span class="cropper-view-box"></span>' + '<span class="cropper-dashed dashed-h"></span>' + '<span class="cropper-dashed dashed-v"></span>' + '<span class="cropper-center"></span>' + '<span class="cropper-face"></span>' + '<span class="cropper-line line-e" data-cropper-action="e"></span>' + '<span class="cropper-line line-n" data-cropper-action="n"></span>' + '<span class="cropper-line line-w" data-cropper-action="w"></span>' + '<span class="cropper-line line-s" data-cropper-action="s"></span>' + '<span class="cropper-point point-e" data-cropper-action="e"></span>' + '<span class="cropper-point point-n" data-cropper-action="n"></span>' + '<span class="cropper-point point-w" data-cropper-action="w"></span>' + '<span class="cropper-point point-s" data-cropper-action="s"></span>' + '<span class="cropper-point point-ne" data-cropper-action="ne"></span>' + '<span class="cropper-point point-nw" data-cropper-action="nw"></span>' + '<span class="cropper-point point-sw" data-cropper-action="sw"></span>' + '<span class="cropper-point point-se" data-cropper-action="se"></span>' + '</div>' + '</div>'; 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                   element.removeEventListener(event, _handler, options);                    for (var _len2 = arguments.length, args = new Array(_len2), _key2 = 0; _key2 < _len2; _key2++) {                        args[_key2] = arguments[_key2];                    }                    listener.apply(element, args);                };                if (!listeners[event]) {                    listeners[event] = {};                }                if (listeners[event][listener]) {                    element.removeEventListener(event, listeners[event][listener], options);                }                listeners[event][listener] = _handler;                element.listeners = listeners;            }            element.addEventListener(event, _handler, options);        });    }    /**     * Dispatch event on the target element.     * @param {Element} element - The event target.     * @param {string} type - The event type(s).     * @param {Object} data - The additional event data.     * @returns {boolean} Indicate if the event is default prevented or not.     */    function dispatchEvent(element, type, data) {        var event; // Event and CustomEvent on IE9-11 are global objects, not constructors        if (isFunction(Event) && isFunction(CustomEvent)) {            event = new CustomEvent(type, {                detail: data,                bubbles: true,                cancelable: true            });        } else {            event = document.createEvent('CustomEvent');            event.initCustomEvent(type, true, true, data);        }        return element.dispatchEvent(event);    }    /**     * Get the offset base on the document.     * @param {Element} element - The target element.     * @returns {Object} The offset data.     */    function getOffset(element) {        var box = element.getBoundingClientRect();        return {            left: box.left + (window.pageXOffset - document.documentElement.clientLeft),            top: box.top + (window.pageYOffset - document.documentElement.clientTop)        };    }    var location = WINDOW.location;    var REGEXP_ORIGINS = /^(https?:)\/\/([^:/?#]+):?(\d*)/i;    /**     * Check if the given URL is a cross origin URL.     * @param {string} url - The target URL.     * @returns {boolean} Returns `true` if the given URL is a cross origin URL, else `false`.     */    function isCrossOriginURL(url) {        var parts = url.match(REGEXP_ORIGINS);        return parts && (parts[1] !== location.protocol || parts[2] !== location.hostname || parts[3] !== location.port);    }    /**     * Add timestamp to the given URL.     * @param {string} url - The target URL.     * @returns {string} The result URL.     */    function addTimestamp(url) {        var timestamp = "timestamp=".concat(new Date().getTime());        return url + (url.indexOf('?') === -1 ? '?' : '&') + timestamp;    }    /**     * Get transforms base on the given object.     * @param {Object} obj - The target object.     * @returns {string} A string contains transform values.     */    function getTransforms(_ref) {        var rotate = _ref.rotate,            scaleX = _ref.scaleX,            scaleY = _ref.scaleY,            translateX = _ref.translateX,            translateY = _ref.translateY;        var values = [];        if (isNumber(translateX) && translateX !== 0) {            values.push("translateX(".concat(translateX, "px)"));        }        if (isNumber(translateY) && translateY !== 0) {            values.push("translateY(".concat(translateY, "px)"));        } // Rotate should come first before scale to match orientation transform        if (isNumber(rotate) && rotate !== 0) {            values.push("rotate(".concat(rotate, "deg)"));        }        if (isNumber(scaleX) && scaleX !== 1) {            values.push("scaleX(".concat(scaleX, ")"));        }        if (isNumber(scaleY) && scaleY !== 1) {            values.push("scaleY(".concat(scaleY, ")"));        }        var transform = values.length ? values.join(' ') : 'none';        return {            WebkitTransform: transform,            msTransform: transform,            transform: transform        };    }    /**     * Get the max ratio of a group of pointers.     * @param {string} pointers - The target pointers.     * @returns {number} The result ratio.     */    function getMaxZoomRatio(pointers) {        var pointers2 = assign({}, pointers);        var ratios = [];        forEach(pointers, function (pointer, pointerId) {            delete pointers2[pointerId];            forEach(pointers2, function (pointer2) {                var x1 = Math.abs(pointer.startX - poi