Question

我正在使用墨水文件选择器来挑选单个iamge。我想限制用户上传宽度为100和高度为300的图片。如果图像尺寸不合适，则发送错误消息。如何限制用户？

Answer 1

您可以使用FileReader()和jquery

查看图片尺寸

function readImage(file) {

    var reader = new FileReader();
    var image  = new Image();

    reader.readAsDataURL(file);  
    reader.onload = function(_file) {
        image.src    = _file.target.result;              // url.createObjectURL(file);
        image.onload = function() {
            var w = this.width,
                h = this.height,
                t = file.type,                           // ext only: // file.type.split('/')[1],
                n = file.name,
                s = ~~(file.size/1024) +'KB';
          if(w!=100 || h!=100){
            alert("invalid height or width");

          }

            $('#uploadPreview').append('<img src="'+ this.src +'"> '+w+'x'+h+' '+s+' '+t+' '+n+'<br>');
        };
        image.onerror= function() {
            alert('Invalid file type: '+ file.type);
        };      
    };

}
$("#choose").change(function (e) {
    if(this.disabled) return alert('File upload not supported!');
    var F = this.files;
    if(F && F[0]) for(var i=0; i<F.length; i++) readImage( F[i] );
});

HTML

<script src="http://ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script>
<meta charset=utf-8 />
<title>Multiple image upload with preview by Roko C.B.</title>
</head>
<body>
  <input type="file" id="choose" multiple="multiple" />
<br>
<div id="uploadPreview"></div>

JS BIN示例JSBIN

如何限制用户在墨水文件选择器中上传图像？

1 个答案: