使用純javascript實現放大鏡效果_javascript技巧

jd或淘寶的具體商品有個放大鏡的效果。雖然網路上類似插件琳瑯滿目，應用在專案上有諸多不便，自己抽點時間自己寫了個類似插件，累積下程式碼，何樂而不為呢!!let‘go:

打算把此特效封裝成個插件，先把最基本的演算法實現，然後再一步步封裝吧：

最終實現效果：

html 代碼：

複製程式碼 程式碼如下:

css 代碼：

複製程式碼 程式碼如下:

 

似乎什麼都沒有，開始咱們強大的js之旅吧：

javascript 程式碼：

複製程式碼 程式碼如下:

  函數 createElement(MagnifierId, sImg, bImg) {
            var 放大鏡 = $(MagnifierId);
            Magnifier.style.position = '相對';
            //小圖div
            var SmallDiv = $Create("div");
            smallDiv.setAttribute("id", "small");
            SmallDiv.style.position = "絕對";
            //遮罩層
            var mask = $Create("div");
            mask.setAttribute("id", "mask");
            mask.style.position = "絕對";
            // 鏡頭
            varmirror = $Create("div");
            mirror.setAttribute("id", "mirror");
            mirror.style.opacity = 0.3;
            mirror.style.position = "絕對";
            mirror.style.display = "無";
            //小圖
            var SmallImg = $Create("img");
            SmallImg.setAttribute("src", sImg);
            smallImg.setAttribute("id", "smallImg");
            SmallImg.onload = function () {
                //如果沒有設定放大鏡的高度或寬度依小圖大小設定放大鏡大小
                if (!Magnifier.offsetHeight) {
                    Magnifier.style.width = this.offsetWidth "px";
                    Magnifier.style.height = this.offsetHeight "px";
                }
                //遮罩層大小與小圖相同
                mask.style.opacity = "0";
                mask.style.width = this.width 'px';
                mask.style.height = this.height "px";
                mask.style.zIndex = 2;
                bigDiv.style.left = this.width 5 "px";
                bigDiv.style.top = "-5px";
            }
            SmallDiv.appendChild(mask);
            SmallDiv.appendChild(mirror);
            SmallDiv.appendChild(smallImg);
            // 視窗
            var bigDiv = $Create("div");
            bigDiv.setAttribute("id", "big");
            bigDiv.style.position = "絕對";
            bigDiv.style.overflow = "隱藏";
            bigDiv.style.display = "none";
            var bigImg = $Create("img");
            bigImg.setAttribute("src", bImg);
            bigImg.setAttribute("id", "bigImg");
            bigImg.style.position = "絕對";
            bigDiv.appendChild(bigImg);
            Magnifier.appendChild(smallDiv);
            Magnifier.appendChild(bigDiv);
        }
        function setMagnifierStyle(mirrorStyle,shichuangStyle) {
            // 鏡子
            for (mirrorStyle 中的 var item) {
                mirror.style[item] =mirrorStyle[item];
            }
            for (shichuangStyle 中的 var item) {
                $("big").style[item] = shichuangStyle[item];
            }
        }
        函數registerEvent() {
            $("mask").onmouseover = function () {
                $("big").style.display = "block";
                mirror.style.display = "block";
            }
            $("mask").onmouseout = function () {
                $("big").style.display = "none";
                mirror.style.display = "無";
            }
            $("mask").onmousemove = function (evt) {
                var oEvent = evt ||事件；
                var disX = oEvent.offsetX;
                var disY = oEvent.offsetY;
                varmirrorLeft=disX-mirror.offsetWidth/2;
                varmirrorTop=disY-mirror.offsetHeight/2;
                if (mirrorLeft                     鏡像左 = 0;
                }
                else if (mirrorLeft > mask.offsetWidth -mirror.offsetWidth) {
                    mirrorLeft = mask.offsetWidth -mirror.offsetWidth;
                }
                if (mirrorTop                     鏡像頂部 = 0;
                }
                else if (mirrorTop > mask.offsetHeight -mirror.offsetHeight) {
                    mirrorTop = mask.offsetHeight -mirror.offsetHeight;
                }
                mirror.style.top =mirrorTop "px";
                mirror.style.left =mirrorLeft "px";
                var paX =mirrorTop / (mask.offsetHeight -mirror.offsetHeight);
                var paY =mirrorLeft / (mask.offsetWidth -mirror.offsetWidth);
                $("bigImg").style.top = -paX * ($("bigImg").offsetHeight - $("big").offsetHeight) "px";
                $("bigImg").style.left = -paY * ($("bigImg").offsetWidth - $("big").offsetWidth) "px";
            }
        }
        函數 $(id) {
            return document.getElementById(id);
        }
        函數 $Create(類型) {
            return document.createElement(type);
        }

最後重新加載搶奪：

複製程式碼程式碼如下：

 window.onload = function () {
            createElement("放大鏡", "images/Magnifier/small.jpg", "images/Magnifier/big.jpg");
            setMagnifierStyle({ "width": "30px", "height": "30px", "backgroundColor": "#fff" }, { "width": "250px", "height": "250px" });
            註冊事件();
        }

算效果總出來了耶，

2. 我們接下來的封裝：

放大鏡類別代碼：

複製程式碼程式碼如下：

        function Magnifier(
            MagnifierId,                                    sImg,                                    Img,                                     mirrorStyle,                                   ViewStyle                                    ) {
            var _this = this;
            this.MagnifierContainer = null;         //容器
            this.smallDiv = null;                   //小圖容器
            this.mask = null;                                  this.mirror = null;                     //小圖鏡片
            this.smallImg = null;                   //小圖
            this.bigDiv = null;                                 this.bigImg = null;                     //大圖
            var init = function () {
                _this.MagnifierContainer = _this.$(MagnifierId);
                _this.createElement(sImg, bImg);
                _this.setMagnifierStyle(mirrorStyle, ViewStyle);
                _this.MainEvent();
            }
            init();
        }
        Magnifier.prototype.createElement = function (sImg, bImg) {
            var _this = this;
            var $Create = this.$Create;
            this.MagnifierContainer.style.position = 'relative';   //脫離文件流，視情況修改
            this.smallDiv = $Create("div");
            this.smallDiv.setAttribute("id", "small");
            this.smallDiv.style.position = "absolute";
            this.mask = $Create("div");
            this.mask.setAttribute("id", "mask");
            this.mask.style.position = "absolute";
            this.mirror = $Create("div");
            this.mirror.setAttribute("id", "mirror");
            this.mirror.style.opacity = 0.3;
            this.mirror.style.position = "absolute";
            this.mirror.style.display = "none";
            this.smallImg = $Create("img");
            this.smallImg.setAttribute("src", sImg);
            this.smallImg.setAttribute("id", "smallImg");
            this.smallImg.onload = function () {
                //如果沒有設定放大鏡的height或width 依照小圖大小設定放大鏡大小
                if (!_this.MagnifierContainer.offsetHeight) {
                    _this.MagnifierContainer.style.width = this.offsetWidth "px";
                    _this.MagnifierContainer.style.height = this.offsetHeight "px";
                }
                //遮罩層大小與小圖相同
                _this.mask.style.opacity = "0";
                _this.mask.style.width = this.offsetWidth 'px';
                _this.mask.style.height = this.offsetHeight "px";
                _this.mask.style.zIndex = 2;
                _this.bigDiv.style.left = this.offsetWidth 5 "px";
                _this.bigDiv.style.top = "-5px";
            }
            this.smallDiv.appendChild(this.mask);
            this.smallDiv.appendChild(this.mirror);
            this.smallDiv.appendChild(this.smallImg);
            this.bigDiv = $Create("div");
            this.bigDiv.setAttribute("id", "big");
            this.bigDiv.style.position = "absolute";
            this.bigDiv.style.overflow = "hidden";
            this.bigDiv.style.display = "none";
            this.bigImg = $Create("img");
            this.bigImg.setAttribute("src", bImg);
            this.bigImg.setAttribute("id", "bigImg");
            this.bigImg.style.position = "absolute";
            this.bigDiv.appendChild(this.bigImg);
            this.MagnifierContainer.appendChild(this.smallDiv);
            this.MagnifierContainer.appendChild(this.bigDiv);
        }
        Magnifier.prototype.setMagnifierStyle = function (mirrorStyle, ViewStyle) {
            for (mirrorStyle 中的 var item) {
                this.mirror.style[item] =mirrorStyle[item];
            }
            刪除項目；
            for (ViewStyle 中的 var item) {
                this.bigDiv.style[item] = ViewStyle[item];
            }
        }
        Magnifier.prototype.MainEvent = function () {
            var _this = this;
            this.mask.onmouseover = function () {
                _this.bigDiv.style.display = "block";
                _this.mirror.style.display = "block";
            }
            this.mask.onmouseout = function () {
                _this.bigDiv.style.display = "none";
                _this.mirror.style.display = "無";
            }
            this.mask.onmousemove = function (evt) {
                var oEvent = evt ||事件；
                var disX = oEvent.offsetX || oEvent.layerX;  //相容ff
                var disY = oEvent.offsetY || oEvent.layerY;
                varmirrorLeft = disX - _this.mirror.offsetWidth / 2;
                varmirrorTop = disY - _this.mirror.offsetHeight / 2;
                if (mirrorLeft                     鏡像左 = 0;
                }
                else if (mirrorLeft > this.offsetWidth - _this.mirror.offsetWidth) {
                    mirrorLeft = this.offsetWidth -mirror.offsetWidth;
                }
                if (mirrorTop                     鏡像頂部 = 0;
                }
                else if (mirrorTop > this.offsetHeight - _this.mirror.offsetHeight) {
                    mirrorTop = this.offsetHeight - _this.mirror.offsetHeight;
                }
                _this.mirror.style.top =mirrorTop "px";
                _this.mirror.style.left =mirrorLeft "px";
                var paX = mirrorTop / (this.offsetHeight - _this.mirror.offsetHeight);
                var paY = MirrorLeft / (this.offsetWidth - _this.mirror.offsetWidth);
                _this.bigImg.style.top = -paX * (_this.bigImg.offsetHeight - _this.bigDiv.offsetHeight) "px";
                _this.bigImg.style.left = -paY * (_this.bigImg.offsetWidth - _this.bigDiv.offsetWidth) "px";
            }
        }
        Magnifier.prototype.$ = 関数 (id) {
            return document.getElementById(id);
        }
        Magnifier.prototype.$Create = 関数 (型) {
            return document.createElement(type);
        }

最後にonload调用下：

复制代 代码如下:

window.onload = function () {
            新しい拡大鏡(
                        「拡大鏡」、
                        "images/Magnifier/small.jpg",
                        "images/Magnifier/big.jpg",
                        { "幅": "30px"、"高さ": "30px"、"backgroundColor": "#fff" },
                        { "幅": "250px"、"高さ": "250px" }
                );
        }

以上が本明細書に記載されている内容のすべてです。