javascript實現放大鏡功能
阿新 • • 發佈:2020-12-11
本文例項為大家分享了javascript實現放大鏡功能的具體程式碼,供大家參考,具體內容如下
描述:當滑鼠在小圖片上移動時,通過捕捉滑鼠在小圖片上的位置,使放大鏡的移動方向與大圖的水平和垂直方向相反
如何設計
- 頁面元素
- 技術要點:事件捕捉和定位
- 難點:計算
涉及技術
- onmouseover:當滑鼠指標移動到指定的物件上時發生
- onmouseout:滑鼠指標移出指定物件時發生
- onmousemove:滑鼠指標移動時發生
- offsetLeft | offsetTop | offsetWidth | offsetHeight
- event.clientX | event.clientY
偏移量與style.left
- style.left返回字串,例如30px,而offsetLeft返回數字30。
- style.left可以讀和寫,offsetLeft是隻讀的。如果我們想改變div的位置,我們可以修改style.left.
- style.left應事先定義,否則值為空。
需要考慮
- 如何使小畫面上的放大鏡與大圖同步移動
- IE相容性問題
程式碼實現
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width,initial-scale=1.0"> <title>Magnifier Effect</title> <style> *{ margin: 0; padding: 0; } #wrap{ width: 400px; height: 255px; margin: 50px; border: 1px solid #ccc; display: block; position: relative; } #small-box{ position: relative; z-index: 1; } #float-box{ width: 160px; height: 120px; position: absolute; background-color: #ffffcc; border:1px solid #ccc; filter: alpha(opacity = 50); opacity: .5; display: none; } #mask{ position: absolute; display: block; width: 400px; height: 255px; z-index: 10; background-color: #ffffff; filter: alpha(opacity = 0); opacity: 0; cursor: move; } #big-box{ position: absolute; top: 0; left: 460px; width: 400px; height: 300px; overflow: hidden; border: 1px solid #ccc; z-index: 1; display: none; } #big-box img{ position: absolute; z-index: 5; } </style> </head> <script> // 頁面載入完畢之後執行 window.onload = function(){ // 獲取父元素wrap,小盒子,遮罩層,放大鏡,大盒子,大圖片 var wrap = document.getElementById('wrap'); var smallBox = document.getElementById('small-box'); var mask = document.getElementById('mask'); var floatBox = document.getElementById('float-box'); var bigBox = document.getElementById('big-box'); var bigImg = bigBox.getElementsByTagName('img')[0]; console.log(wrap,smallBox,mask,floatBox,bigBox,bigImg); // 滑鼠移動到小盒子上時,放大鏡顯示,大盒子顯示 mask.onmouseover = function(){ floatBox.style.display = 'block'; bigBox.style.display = 'block'; } // 滑鼠移出小盒子時,放大鏡隱藏,大盒子隱藏 mask.onmouseout = function(){ floatBox.style.display = 'none'; bigBox.style.display = 'none'; } // 新增滑鼠移動事件 mask.onmousemove = function(ev){ // 獲取當前滑鼠移動的位置並考慮IE相容性 var _event = ev || window.event; // 獲取放大鏡向左移動的距離 var left = _event.clientX - wrap.offsetLeft - smallBox.offsetLeft - floatBox.offsetWidth / 2; var top = _event.clientY - wrap.offsetTop - smallBox.offsetTop - floatBox.offsetHeight / 2; // console.log(left,top); // 考慮邊界情況 if(left < 0){ left = 0; }else if(left > (mask.offsetWidth - floatBox.offsetWidth)){ left = mask.offsetWidth - floatBox.offsetWidth; } if(top < 0){ top = 0; }else if(top > (mask.offsetHeight - floatBox.offsetHeight)){ top = mask.offsetHeight - floatBox.offsetHeight; } floatBox.style.left = left + 'px'; floatBox.style.top = top + 'px'; // calculate percentage var percentX = left / (mask.offsetWidth - floatBox.offsetWidth); var percentY = top / (mask.offsetHeight - floatBox.offsetHeight); // calculate displacement of big image,big image has opposite direction of magnifying glass bigImg.style.left = -percentX * (bigImg.offsetWidth - bigBox.offsetWidth) + 'px'; bigImg.style.top = -percentY * (bigImg.offsetHeight - bigBox.offsetHeight) + 'px'; } } </script> <body> <div id="wrap"> <div id="small-box"> <div id="mask"></div> <div id="float-box"></div> <img src="./img/macbook-small.jpg" alt="smallMac"> </div> <div id="big-box"> <img src="./img/macbook-big.jpg" alt="bigMac"> </div> </div> </body> </html>
以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支援我們。