HTML5技术实现剪切+上传图片的功能

       我们曾经被几个读者问到同一个问题——如何将照片传到网上。我认为这是一个很有趣的问题，我决定在本文中解决掉这个问题。但是，我认为只是单纯的实现上传功能可能会有些单调，所以我决定添加一个很重要的元素—剪切功能。相信这样应该更有魅力的说。

       html

       第一步，我们先画一个表头

       现在再描绘主体部分

Step1: Please select image file

Step2: Please select a crop region

File size
Type
Image dimension
W
H

       CSS

.bheader {
background-color: #DDDDDD;
border-radius: 10px 10px 0 0;
padding: 10px 0;
text-align: center;
}
.bbody {
color: #000;
overflow: hidden;
padding-bottom: 20px;
text-align: center;

background: -moz-linear-gradient(#ffffff, #f2f2f2);
background: -ms-linear-gradient(#ffffff, #f2f2f2);
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #ffffff), color-stop(100%, #f2f2f2));
background: -webkit-linear-gradient(#ffffff, #f2f2f2);
background: -o-linear-gradient(#ffffff, #f2f2f2);
filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#f2f2f2');
-ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#f2f2f2')";
background: linear-gradient(#ffffff, #f2f2f2);
}
.bbody h2, .info, .error {
margin: 10px 0;
}
.step2, .error {
display: none;
}
.error {
font-size: 18px;
font-weight: bold;
color: red;
}
.info {
font-size: 14px;
}
label {
margin: 0 5px;
}
input {
border: 1px solid #CCCCCC;
border-radius: 10px;
padding: 4px 8px;
text-align: center;
width: 70px;
}
.jcrop-holder {
display: inline-block;
}
input[type=submit] {
background: #e3e3e3;
border: 1px solid #bbb;
border-radius: 3px;
-webkit-box-shadow: inset 0 0 1px 1px #f6f6f6;
box-shadow: inset 0 0 1px 1px #f6f6f6;
color: #333;
font: bold 12px/1 "helvetica neue", helvetica, arial, sans-serif;
padding: 8px 0 9px;
text-align: center;
text-shadow: 0 1px 0 #fff;
width: 150px;
}
input[type=submit]:hover {
background: #d9d9d9;
-webkit-box-shadow: inset 0 0 1px 1px #eaeaea;
box-shadow: inset 0 0 1px 1px #eaeaea;
color: #222;
cursor: pointer;
}
input[type=submit]:active {
background: #d0d0d0;
-webkit-box-shadow: inset 0 0 1px 1px #e3e3e3;
box-shadow: inset 0 0 1px 1px #e3e3e3;
color: #000;
}

       JS

// convert bytes into friendly format
function bytesToSize(bytes) {
var sizes = ['Bytes', 'KB', 'MB'];
if (bytes == 0) return 'n/a';
var i = parseInt(Math.floor(Math.log(bytes) / Math.log(1024)));
return (bytes / Math.pow(1024, i)).toFixed(1) + ' ' + sizes[i];
};

// check for selected crop region
function checkForm() {
if (parseInt($('#w').val())) return true;
$('.error').html('Please select a crop region and then press Upload').show();
return false;
};

// update info by cropping (onChange and onSelect events handler)
function updateInfo(e) {
$('#x1').val(e.x);
$('#y1').val(e.y);
$('#x2').val(e.x2);
$('#y2').val(e.y2);
$('#w').val(e.w);
$('#h').val(e.h);
};

// clear info by cropping (onRelease event handler)
function clearInfo() {
$('.info #w').val('');
$('.info #h').val('');
};

function fileSelectHandler() {

// get selected file
var oFile = $('#image_file')[0].files[0];

// hide all errors
$('.error').hide();

// check for image type (jpg and png are allowed)
var rFilter = /^(image\/jpeg|image\/png)$/i;
if (! rFilter.test(oFile.type)) {
$('.error').html('Please select a valid image file (jpg and png are allowed)').show();
return;
}

// check for file size
if (oFile.size > 250 * 1024) {
$('.error').html('You have selected too big file, please select a one smaller image file').show();
return;
}

// preview element
var oImage = document.getElementById('preview');

// prepare HTML5 FileReader
var oReader = new FileReader();
oReader.onload = function(e) {

// e.target.result contains the DataURL which we can use as a source of the image
oImage.src = e.target.result;
oImage.onload = function () { // onload event handler

// display step 2
$('.step2').fadeIn(500);

// display some basic image info
var sResultFileSize = bytesToSize(oFile.size);
$('#filesize').val(sResultFileSize);
$('#filetype').val(oFile.type);
$('#filedim').val(oImage.naturalWidth + ' x ' + oImage.naturalHeight);

// Create variables (in this scope) to hold the Jcrop API and image size
var jcrop_api, boundx, boundy;

// destroy Jcrop if it is existed
if (typeof jcrop_api != 'undefined')
jcrop_api.destroy();

// initialize Jcrop
$('#preview').Jcrop({
minSize: [32, 32], // min crop size
aspectRatio : 1, // keep aspect ratio 1:1
bgFade: true, // use fade effect
bgOpacity: .3, // fade opacity
onChange: updateInfo,
onSelect: updateInfo,
onRelease: clearInfo
}, function(){

// use the Jcrop API to get the real image size
var bounds = this.getBounds();
boundx = bounds[0];
boundy = bounds[1];

// Store the Jcrop API in the jcrop_api variable
jcrop_api = this;
});
};
};

// read selected file as DataURL
oReader.readAsDataURL(oFile);
}

       PHP

function uploadImageFile() { // Note: GD library is required for this function

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
$iWidth = $iHeight = 200; // desired image result dimensions
$iJpgQuality = 90;

if ($_FILES) {

// if no errors and size less than 250kb
if (! $_FILES['image_file']['error'] && $_FILES['image_file']['size'] if (is_uploaded_file($_FILES['image_file']['tmp_name'])) {

// new unique filename
$sTempFileName = 'cache/' . md5(time().rand());

// move uploaded file into cache folder
move_uploaded_file($_FILES['image_file']['tmp_name'], $sTempFileName);

// change file permission to 644
@chmod($sTempFileName, 0644);

if (file_exists($sTempFileName) && filesize($sTempFileName) > 0) {
$aSize = getimagesize($sTempFileName); // try to obtain image info
if (!$aSize) {
@unlink($sTempFileName);
return;
}

// check for image type
switch($aSize[2]) {
case IMAGETYPE_JPEG:
$sExt = '.jpg';

// create a new image from file
$vImg = @imagecreatefromjpeg($sTempFileName);
break;
case IMAGETYPE_PNG:
$sExt = '.png';

// create a new image from file
$vImg = @imagecreatefrompng($sTempFileName);
break;
default:
@unlink($sTempFileName);
return;
}

// create a new true color image
$vDstImg = @imagecreatetruecolor( $iWidth, $iHeight );

// copy and resize part of an image with resampling
imagecopyresampled($vDstImg, $vImg, 0, 0, (int)$_POST['x1'], (int)$_POST['y1'], $iWidth, $iHeight, (int)$_POST['w'], (int)$_POST['h']);

// define a result image filename
$sResultFileName = $sTempFileName . $sExt;

// output image to file
imagejpeg($vDstImg, $sResultFileName, $iJpgQuality);
@unlink($sTempFileName);

return $sResultFileName;
}
}
}
}
}
}

$sImage = uploadImageFile();
echo '';

       这样，带剪切功能的上传图片就已经完成了，若有疑问，请留言。大家共勉。