I want to be able to preview a file (image) before it is uploaded. The preview action should be executed all in the browser without using Ajax to upload the image.
How can I do this?
转载于:https://stackoverflow.com/questions/4459379/preview-an-image-before-it-is-uploaded
Please take a look at the sample code below:
function readURL(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function(e) {
$('#blah').attr('src', e.target.result);
}
reader.readAsDataURL(input.files[0]);
}
}
$("#imgInp").change(function() {
readURL(this);
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="form1" runat="server">
<input type='file' id="imgInp" />
<img id="blah" src="#" alt="your image" />
</form>Also, you can try this sample here.
</div>
The answer of LeassTaTT works well in "standard" browsers like FF and Chrome. The solution for IE exists, but looks different. Here description of cross-browser solution:
In HTML we need two preview elements, img for standard browsers and div for IE
HTML:
<img id="preview"
src=""
alt=""
style="display:none; max-width: 160px; max-height: 120px; border: none;"/>
<div id="preview_ie"></div>
In CSS we specify the following IE specific thing:
CSS:
#preview_ie {
FILTER: progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)
}
In HTML we include the standard and the IE-specific Javascripts:
<script type="text/javascript">
{% include "pic_preview.js" %}
</script>
<!--[if gte IE 7]>
<script type="text/javascript">
{% include "pic_preview_ie.js" %}
</script>
The pic_preview.js is the Javascript from the LeassTaTT's answer. Replace the $('#blah') whith the $('#preview') and add the $('#preview').show()
Now the IE specific Javascript (pic_preview_ie.js):
function readURL (imgFile) {
var newPreview = document.getElementById('preview_ie');
newPreview.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = imgFile.value;
newPreview.style.width = '160px';
newPreview.style.height = '120px';
}
That's is. Works in IE7, IE8, FF and Chrome. Please test in IE9 and report. The idea of IE preview was found here: http://forums.asp.net/t/1320559.aspx
http://msdn.microsoft.com/en-us/library/ms532969(v=vs.85).aspx
How about creating a function that loads the file and fires a custom event. Then attach a listener to the input. This way we have more flexibility to use the file, not just for previewing images.
/**
* @param {domElement} input - The input element
* @param {string} typeData - The type of data to be return in the event object.
*/
function loadFileFromInput(input,typeData) {
var reader,
fileLoadedEvent,
files = input.files;
if (files && files[0]) {
reader = new FileReader();
reader.onload = function (e) {
fileLoadedEvent = new CustomEvent('fileLoaded',{
detail:{
data:reader.result,
file:files[0]
},
bubbles:true,
cancelable:true
});
input.dispatchEvent(fileLoadedEvent);
}
switch(typeData) {
case 'arraybuffer':
reader.readAsArrayBuffer(files[0]);
break;
case 'dataurl':
reader.readAsDataURL(files[0]);
break;
case 'binarystring':
reader.readAsBinaryString(files[0]);
break;
case 'text':
reader.readAsText(files[0]);
break;
}
}
}
function fileHandler (e) {
var data = e.detail.data,
fileInfo = e.detail.file;
img.src = data;
}
var input = document.getElementById('inputId'),
img = document.getElementById('imgId');
input.onchange = function (e) {
loadFileFromInput(e.target,'dataurl');
};
input.addEventListener('fileLoaded',fileHandler)
Probably my code isn't as good as some users but I think you will get the point of it. Here you can see an example
I have edited @Ivan's answer to display "No Preview Available" image, if it is not an image:
function readURL(input) {
var url = input.value;
var ext = url.substring(url.lastIndexOf('.') + 1).toLowerCase();
if (input.files && input.files[0]&& (ext == "gif" || ext == "png" || ext == "jpeg" || ext == "jpg")) {
var reader = new FileReader();
reader.onload = function (e) {
$('.imagepreview').attr('src', e.target.result);
}
reader.readAsDataURL(input.files[0]);
}else{
$('.imagepreview').attr('src', '/assets/no_preview.png');
}
}
Yes. It is possible.
Html
<input type="file" accept="image/*" onchange="showMyImage(this)" />
<br/>
<img id="thumbnil" style="width:20%; margin-top:10px;" src="" alt="image"/>
JS
function showMyImage(fileInput) {
var files = fileInput.files;
for (var i = 0; i < files.length; i++) {
var file = files[i];
var imageType = /image.*/;
if (!file.type.match(imageType)) {
continue;
}
var img=document.getElementById("thumbnil");
img.file = file;
var reader = new FileReader();
reader.onload = (function(aImg) {
return function(e) {
aImg.src = e.target.result;
};
})(img);
reader.readAsDataURL(file);
}
}
You can get Live Demo from here.
One-liner solution:
The following code uses object URLs, which is much more efficient than data URL for viewing large images (A data URL is a huge string containing all of the file data, whereas an object URL, is just a short string referencing the file data in-memory):
<img id="blah" alt="your image" width="100" height="100" />
<input type="file"
onchange="document.getElementById('blah').src = window.URL.createObjectURL(this.files[0])">Generated URL will be like:
blob:http%3A//localhost/7514bc74-65d4-4cf0-a0df-3de016824345
</div>
There are a couple ways you can do this. The most efficient way would be to use URL.createObjectURL() on the File from your <input>. Pass this URL to img.src to tell the browser to load the provided image.
Here's an example:
<input type="file" accept="image/*" onchange="loadFile(event)">
<img id="output"/>
<script>
var loadFile = function(event) {
var output = document.getElementById('output');
output.src = URL.createObjectURL(event.target.files[0]);
};
</script>You can also use FileReader.readAsDataURL() to parse the file from your <input>. This will create a string in memory containing a base64 representation of the image.
<input type="file" accept="image/*" onchange="loadFile(event)">
<img id="output"/>
<script>
var loadFile = function(event) {
var reader = new FileReader();
reader.onload = function(){
var output = document.getElementById('output');
output.src = reader.result;
};
reader.readAsDataURL(event.target.files[0]);
};
</script></div>
What about this solution?
Just add the data attribute "data-type=editable" to an image tag like this:
<img data-type="editable" id="companyLogo" src="http://www.coventrywebgraphicdesign.co.uk/wp-content/uploads/logo-here.jpg" height="300px" width="300px" />
And the script to your project off course...
function init() {
$("img[data-type=editable]").each(function (i, e) {
var _inputFile = $('<input/>')
.attr('type', 'file')
.attr('hidden', 'hidden')
.attr('onchange', 'readImage()')
.attr('data-image-placeholder', e.id);
$(e.parentElement).append(_inputFile);
$(e).on("click", _inputFile, triggerClick);
});
}
function triggerClick(e) {
e.data.click();
}
Element.prototype.readImage = function () {
var _inputFile = this;
if (_inputFile && _inputFile.files && _inputFile.files[0]) {
var _fileReader = new FileReader();
_fileReader.onload = function (e) {
var _imagePlaceholder = _inputFile.attributes.getNamedItem("data-image-placeholder").value;
var _img = $("#" + _imagePlaceholder);
_img.attr("src", e.target.result);
};
_fileReader.readAsDataURL(_inputFile.files[0]);
}
};
//
// IIFE - Immediately Invoked Function Expression
// https://stackoverflow.com/questions/18307078/jquery-best-practises-in-case-of-document-ready
(
function (yourcode) {
"use strict";
// The global jQuery object is passed as a parameter
yourcode(window.jQuery, window, document);
}(
function ($, window, document) {
"use strict";
// The $ is now locally scoped
$(function () {
// The DOM is ready!
init();
});
// The rest of your code goes here!
}));
I have made a plugin which can generate the preview effect in IE 7+ thanks to the internet, but has few limitations. I put it into a github page so that its easier to get it
$(function () {
$("input[name=file1]").previewimage({
div: ".preview",
imgwidth: 180,
imgheight: 120
});
$("input[name=file2]").previewimage({
div: ".preview2",
imgwidth: 90,
imgheight: 90
});
});.preview > div {
display: inline-block;
text-align:center;
}
.preview2 > div {
display: inline-block;
text-align:center;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script src="https://rawgit.com/andrewng330/PreviewImage/master/preview.image.min.js"></script>
Preview
<div class="preview"></div>
Preview2
<div class="preview2"></div>
<form action="#" method="POST" enctype="multipart/form-data">
<input type="file" name="file1">
<input type="file" name="file2">
<input type="submit">
</form></div>
Example with multiple images using JavaScript (jQuery) and HTML5
JavaScript (jQuery)
function readURL(input) {
for(var i =0; i< input.files.length; i++){
if (input.files[i]) {
var reader = new FileReader();
reader.onload = function (e) {
var img = $('<img id="dynamic">');
img.attr('src', e.target.result);
img.appendTo('#form1');
}
reader.readAsDataURL(input.files[i]);
}
}
}
$("#imgUpload").change(function(){
readURL(this);
});
}
Markup (HTML)
<form id="form1" runat="server">
<input type="file" id="imgUpload" multiple/>
</form>
Here's a multiple files version, based on Ivan Baev's answer.
The HTML
<input type="file" multiple id="gallery-photo-add">
<div class="gallery"></div>
JavaScript / jQuery
$(function() {
// Multiple images preview in browser
var imagesPreview = function(input, placeToInsertImagePreview) {
if (input.files) {
var filesAmount = input.files.length;
for (i = 0; i < filesAmount; i++) {
var reader = new FileReader();
reader.onload = function(event) {
$($.parseHTML('<img>')).attr('src', event.target.result).appendTo(placeToInsertImagePreview);
}
reader.readAsDataURL(input.files[i]);
}
}
};
$('#gallery-photo-add').on('change', function() {
imagesPreview(this, 'div.gallery');
});
});
Requires jQuery 1.8 due to the usage of $.parseHTML, which should help with XSS mitigation.
This will work out of the box, and the only dependancy you need is jQuery.
Following is the working code.
<input type='file' onchange="readURL(this);" />
<img id="ShowImage" src="#" />
Javascript:
function readURL(input) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$('#ShowImage')
.attr('src', e.target.result)
.width(150)
.height(200);
};
reader.readAsDataURL(input.files[0]);
}
}
Clean and simple JSfiddle
This will be useful when you want The event to triggered indirectly from a div or a button.
<img id="image-preview" style="height:100px; width:100px;" src="" >
<input style="display:none" id="input-image-hidden" onchange="document.getElementById('image-preview').src = window.URL.createObjectURL(this.files[0])" type="file" accept="image/jpeg, image/png">
<button onclick="HandleBrowseClick('input-image-hidden');" >UPLOAD IMAGE</button>
<script type="text/javascript">
function HandleBrowseClick(hidden_input_image)
{
var fileinputElement = document.getElementById(hidden_input_image);
fileinputElement.click();
}
</script>
It's my code.Support IE[6-9]、chrome 17+、firefox、Opera 11+、Maxthon3
HTML
<input type="file" id="netBarBig" onchange="changeFile(this)" />
<img src="" id="imagePreview" style="width:120px;height:80px;" alt=""/>
javascript:
<script>
function previewImage(fileObj, imgPreviewId) {
var allowExtention = ".jpg,.bmp,.gif,.png"; //allowed to upload file type
document.getElementById("hfAllowPicSuffix").value;
var extention = fileObj.value.substring(fileObj.value.lastIndexOf(".") + 1).toLowerCase();
var browserVersion = window.navigator.userAgent.toUpperCase();
if (allowExtention.indexOf(extention) > -1) {
if (fileObj.files) {
if (window.FileReader) {
var reader = new FileReader();
reader.onload = function (e) {
document.getElementById(imgPreviewId).setAttribute("src", e.target.result);
};
reader.readAsDataURL(fileObj.files[0]);
} else if (browserVersion.indexOf("SAFARI") > -1) {
alert("don't support Safari6.0 below broswer");
}
} else if (browserVersion.indexOf("MSIE") > -1) {
if (browserVersion.indexOf("MSIE 6") > -1) {//ie6
document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
} else {//ie[7-9]
fileObj.select();
fileObj.blur();
var newPreview = document.getElementById(imgPreviewId);
newPreview.style.border = "solid 1px #eeeeee";
newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod='scale',src='" + document.selection.createRange().text + "')";
newPreview.style.display = "block";
}
} else if (browserVersion.indexOf("FIREFOX") > -1) {//firefox
var firefoxVersion = parseFloat(browserVersion.toLowerCase().match(/firefox\/([\d.]+)/)[1]);
if (firefoxVersion < 7) {//firefox7 below
document.getElementById(imgPreviewId).setAttribute("src", fileObj.files[0].getAsDataURL());
} else {//firefox7.0+
document.getElementById(imgPreviewId).setAttribute("src", window.URL.createObjectURL(fileObj.files[0]));
}
} else {
document.getElementById(imgPreviewId).setAttribute("src", fileObj.value);
}
} else {
alert("only support" + allowExtention + "suffix");
fileObj.value = ""; //clear Selected file
if (browserVersion.indexOf("MSIE") > -1) {
fileObj.select();
document.selection.clear();
}
}
}
function changeFile(elem) {
//file object , preview img tag id
previewImage(elem,'imagePreview')
}
</script></div>
function assignFilePreviews() {
$('input[data-previewable=\"true\"]').change(function() {
var prvCnt = $(this).attr('data-preview-container');
if (prvCnt) {
if (this.files && this.files[0]) {
var reader = new FileReader();
reader.onload = function(e) {
var img = $('<img>');
img.attr('src', e.target.result);
img.error(function() {
$(prvCnt).html('');
});
$(prvCnt).html('');
img.appendTo(prvCnt);
}
reader.readAsDataURL(this.files[0]);
}
}
});
}
$(document).ready(function() {
assignFilePreviews();
});
HTML
<input type="file" data-previewable="true" data-preview-container=".prd-img-prv" />
<div class = "prd-img-prv"></div>
This also handles case when file with invalid type ( ex. pdf ) is choosen
for my app, with encryped GET url parameters, only this worked. I always got a TypeError: $(...) is null. Taken from https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsDataURL
function previewFile() {
var preview = document.querySelector('img');
var file = document.querySelector('input[type=file]').files[0];
var reader = new FileReader();
reader.addEventListener("load", function () {
preview.src = reader.result;
}, false);
if (file) {
reader.readAsDataURL(file);
}
}<input type="file" onchange="previewFile()"><br>
<img src="" height="200" alt="Image preview..."></div>
For Multiple image upload (Modification to the @IvanBaev's Solution)
function readURL(input) {
if (input.files && input.files[0]) {
var i;
for (i = 0; i < input.files.length; ++i) {
var reader = new FileReader();
reader.onload = function (e) {
$('#form1').append('<img src="'+e.target.result+'">');
}
reader.readAsDataURL(input.files[i]);
}
}
}
http://jsfiddle.net/LvsYc/12330/
Hope this helps someone.
Try this
window.onload = function() {
if (window.File && window.FileList && window.FileReader) {
var filesInput = document.getElementById("uploadImage");
filesInput.addEventListener("change", function(event) {
var files = event.target.files;
var output = document.getElementById("result");
for (var i = 0; i < files.length; i++) {
var file = files[i];
if (!file.type.match('image'))
continue;
var picReader = new FileReader();
picReader.addEventListener("load", function(event) {
var picFile = event.target;
var div = document.createElement("div");
div.innerHTML = "<img class='thumbnail' src='" + picFile.result + "'" +
"title='" + picFile.name + "'/>";
output.insertBefore(div, null);
});
picReader.readAsDataURL(file);
}
});
}
}<input type="file" id="uploadImage" name="termek_file" class="file_input" multiple/>
<div id="result" class="uploadPreview"></div>