This article introduces an example based on JQUERY extension, image upload preview plug-in, currently compatible browser (IE Google Firefox) does not support safari, share for your reference, the specific content is as follows
HTML code:
<html>
<head>
<title> Photo upload preview demo </title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>
<script src="16/uploadPreview.js" type="text/javascript"></script>
<script>
$(function () {
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120 });
});
</script>
</head>
<body>
<div style="width:500px;margin:0px auto;"><h2> Photo upload preview demo </h2>
<a href="# target="_blank"> The original </a>
<div><img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
</div>
</body>
</html>js code:
* Parameters that : Img: The picture ID;Width: Preview the width ;Height: Preview the height ;ImgType: Supported file types ;Callback: Select the file display image callback method ;
* Method of use :
<div>
<img id="ImgPr" width="120" height="120" /></div>
<input type="file" id="up" />
Put the need to preview IMG Outside the label Set of 1 a DIV Then give the upload control ID To give uploadPreview The event
$("#up").uploadPreview({ Img: "ImgPr", Width: 120, Height: 120, ImgType: ["gif", "jpeg", "jpg", "bmp", "png"], Callback: function () { }});
*/
jQuery.fn.extend({
uploadPreview: function (opts) {
var _self = this,
_this = $(this);
opts = jQuery.extend({
Img: "ImgPr",
Width: 100,
Height: 100,
ImgType: ["gif", "jpeg", "jpg", "bmp", "png"],
Callback: function () {}
}, opts || {});
_self.getObjectURL = function (file) {
var url = null;
if (window.createObjectURL != undefined) {
url = window.createObjectURL(file)
} else if (window.URL != undefined) {
url = window.URL.createObjectURL(file)
} else if (window.webkitURL != undefined) {
url = window.webkitURL.createObjectURL(file)
}
return url
};
_this.change(function () {
if (this.value) {
if (!RegExp("\.(" + opts.ImgType.join("|") + ")$", "i").test(this.value.toLowerCase())) {
alert(" File selection error , The image type must be " + opts.ImgType.join(" . ") + " In the 1 Kind of ");
this.value = "";
return false
}
if ($.browser.msie) {
try {
$("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
} catch (e) {
var src = "";
var obj = $("#" + opts.Img);
var div = obj.parent("div")[0];
_self.select();
if (top != self) {
window.parent.document.body.focus()
} else {
_self.blur()
}
src = document.selection.createRange().text;
document.selection.empty();
obj.hide();
obj.parent("div").css({
'filter': 'progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)',
'width': opts.Width + 'px',
'height': opts.Height + 'px'
});
div.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = src
}
} else {
$("#" + opts.Img).attr('src', _self.getObjectURL(this.files[0]))
}
opts.Callback()
}
})
}
});The jquery js implementation previews the local images before uploading them
<style type="text/css">
#preview_wrapper{
display:inline-block;
width:300px;
height:300px;
background-color:#CCC;
}
#preview_fake{
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale);
}
#preview_size_fake{
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=image);
visibility:hidden;
}
#preview{
width:300px;
height:300px;
}
</style>
<script type="text/javascript">
function onUploadImgChange(sender){
if( !sender.value.match( /.jpg|.gif|.png|.bmp/i ) ){
alert(' Invalid image format! ');
return false;
}
var objPreview = document.getElementByIdx_x('preview');
var objPreviewFake = document.getElementByIdx_x('preview_fake');
var objPreviewSizeFake = document.getElementByIdx_x('preview_size_fake');
if( sender.files && sender.files[0] ){
objPreview.style.display = 'block';
objPreview.style.width = 'auto';
objPreview.style.height = 'auto';
// Firefox Can't pass directly due to security problem input[file].value Gets the full file path
objPreview.src = sender.files[0].getAsDataURL();
}else if( objPreviewFake.filters ){
// IE7,IE8 In setting the local image address is img.src When there are inexplicable consequences
// (The same environment is sometimes displayed, sometimes not), so it can only be resolved with filters
// IE7, IE8 Can't pass directly due to security problem input[file].value Gets the full file path
sender.select();
var imgSrc = document.selection.createRange().text;
objPreviewFake.filters.item(
'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;
objPreviewSizeFake.filters.item(
'DXImageTransform.Microsoft.AlphaImageLoader').src = imgSrc;
autoSizePreview( objPreviewFake,
objPreviewSizeFake.offsetWidth, objPreviewSizeFake.offsetHeight );
objPreview.style.display = 'none';
}
}
function onPreviewLoad(sender){
autoSizePreview( sender, sender.offsetWidth, sender.offsetHeight );
}
function autoSizePreview( objPre, originalWidth, originalHeight ){
var zoomParam = clacImgZoomParam( 300, 300, originalWidth, originalHeight );
objPre.style.width = zoomParam.width + 'px';
objPre.style.height = zoomParam.height + 'px';
objPre.style.marginTop = zoomParam.top + 'px';
objPre.style.marginLeft = zoomParam.left + 'px';
}
function clacImgZoomParam( maxWidth, maxHeight, width, height ){
var param = { width:width, height:height, top:0, left:0 };
if( width>maxWidth || height>maxHeight ){
rateWidth = width / maxWidth;
rateHeight = height / maxHeight;
if( rateWidth > rateHeight ){
param.width = maxWidth;
param.height = height / rateWidth;
}else{
param.width = width / rateHeight;
param.height = maxHeight;
}
}
param.left = (maxWidth - param.width) / 2;
param.top = (maxHeight - param.height) / 2;
return param;
}
</script>
<input name="localfile" type="file" id="localfile" size="28" onchange="onUploadImgChange(this)"/>
<!-- Here is what the preview image is for -->
<div id="preview_wrapper">
<div id="preview_fake">
<img id="preview" src="" onload="onPreviewLoad(this)"/>
</div>
</div>
<br/>
<img id="preview_size_fake" />Above is the entire content of this article, I hope to help you with your study.