Image upload and crop
There are several features about
1: achieve picture upload
2: Implement image preview
3: implement image cropping
Use the knowledge
file objects, <input type='file'/>, cropper.js,
Reference: https://fengyuanchen.github.io/cropperjs/
code show as below:
<!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, shrink-to-fit=no">
<title>Cropper.js</title>
<link rel="stylesheet" href="../css/cropper.css">
<style>
.container {
margin: 20px auto;
max-width: 640px;
}
img {
max-width: 100%;
}
.cropper-view-box,
.cropper-face {
border-radius: 50%;
}
#image {
width: auto;
height: auto;
}
</style>
</head>
<body>
<div class="container">
<label>
上传图片：<input type='file' id="upImg" />
</label>
<h1>裁剪图片</h1>
<div id='chooseImg'>
</div>
<h3>裁剪的结果</h3>
<p>
<button type="button" id="button">Crop</button>
</p>
<div id="result"></div>
</div>
<script src="../js/cropper.js"></script>
<script>
var upImg = document.getElementById('upImg');
//上传选择的文件
upImg.addEventListener('change', function() {
var objImage = '';
objImage = upImg.files[0];
var reader = new FileReader();
reader.addEventListener('load', function() {
var imgUrl = reader.result;
var imgBox = document.getElementById('chooseImg');
// 重新选择图片进行裁剪，如果裁剪的模块有内容，进行情况
if (document.getElementById('image')) {
imgBox.innerHTML = '';
}
//实现图片预览
imageObj = document.createElement('img');
imageObj.setAttribute('id', 'image');
imageObj.src = imgUrl;
imgBox.appendChild(imageObj);
//选择后的图片进行裁剪
cropperEvent(imageObj);
});
if (objImage) {
reader.readAsDataURL(objImage);
}
}, false);
function getRoundedCanvas(sourceCanvas) {
var canvas = document.createElement('canvas');
var context = canvas.getContext('2d');
var width = sourceCanvas.width;
var height = sourceCanvas.height;
canvas.width = width;
canvas.height = height;
context.imageSmoothingEnabled = true;
context.drawImage(sourceCanvas, 0, 0, width, height);
context.globalCompositeOperation = 'destination-in';
context.beginPath();
context.arc(width / 2, height / 2, Math.min(width, height) / 2, 0, 2 * Math.PI, true);
context.fill();
return canvas;
}
function cropperEvent(image) {
var button = document.getElementById('button');
var result = document.getElementById('result');
var croppable = false;
var cropper = new Cropper(image, {
aspectRatio: 1,
viewMode: 1,
ready: function() {
croppable = true;
},
});
button.onclick = function() {
var croppedCanvas;
var roundedCanvas;
var roundedImage;
if (!croppable) {
return;
}
// Crop
croppedCanvas = cropper.getCroppedCanvas();
// Round
roundedCanvas = getRoundedCanvas(croppedCanvas);
// Show
roundedImage = document.createElement('img');
roundedImage.src = roundedCanvas.toDataURL();
result.innerHTML = '';
result.appendChild(roundedImage);
};
}
</script>
</body>
</html>
</html>
Achieve results:
