file+canvas實現圖片展示和下載
阿新 • • 發佈：2022-03-30
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title> </head> <body> <input type="file" id="fileselect" name="fileselect[]" multiple="multiple" /> <div id="c"></div> <script> var div = document.getElementById('c') var fileselect = document.getElementById('fileselect') function downloadHandler(e) { var url = e.target.toDataURL();var a = document.createElement('a'); a.href = url a.download = e.target.getAttribute('file-name').replace('.svg', '.png'); a.click() } function handleFile(f) { //圖片展示 和點選下載 var reader = new FileReader(); var canvas = document.createElement('canvas'); div.appendChild(canvas) reader.onload= function(e) { var image = new Image() image.onload = function() { canvas.setAttribute('file-name', f.name) canvas.addEventListener('click', downloadHandler); canvas.width = image.width canvas.height = image.height canvas.getContext('2d').drawImage(image, 0, 0) } image.src = e.target.result } reader.readAsDataURL(f) } function FileSelectHandler(e) { var files = e.target.files || e.dataTransfer.files //dataTransfer主要用於在源物件和目標物件之間傳遞資料 for (var i = 0, f; f = files[i]; i++) { handleFile(f) } } //input新增監聽事件 fileselect.addEventListener('change', FileSelectHandler, false) //true - 事件控制代碼在捕獲階段執行 false- false- 預設。事件控制代碼在冒泡階段執行 </script> </body> </html>