Simple sample code to crop and store images using Javascript

Cropping pictures is very familiar to us. I have encountered this need again at work recently, so I thought I would simply sort it out. The method can be referenced by everyone and myself when needed, so this article mainly introduces it. In order to use Javascript to crop pictures and store them in a simple way, I use the THINKPHP framework for back-end PHP processing. Friends in need can refer to it.

Preface

As far as I am concerned, there are not many parts of the page that are more flexible in design, such as sliding verification codes and image cropping. Waiting for better interaction design.

When I first started working, I wanted to understand these things, but I never had the need. I took advantage of my free time today and studied it all afternoon. During this period, I encountered problems of all sizes, and I have been preparing for them. Being tortured actually reflects a problem. My

is still relatively weak.

Achievement effect:

After the user clicks to upload the image, the page displays the uploaded image, and a cropping box and two preview areas appear. Finally, click the crop button to save the cropped image to the server.

The effect is very simple. There are two difficulties I encountered in the whole process. The first is the JS effect of cropping, and the second is the processing of image data.

For the first question, I quoted a plug-in on the Internet. As far as I feel, the user satisfaction in the cropping process can only be considered average, because it can only crop square areas. , even though there are eight pull settings on the border, the frame still scales according to the square when pulling the frame, which is not very satisfactory to me.

The implementation method is as follows:

The following is a simple page design:

<p style="float:left;"><img  src="/static/imghwm/default1.png"  data-src="/plug/js/jquery.min.js"  class="lazy"  id="target" alt="Simple sample code to crop and store images using Javascript" ></p>
<p style="width:48px;height:48px;margin:10px;overflow:hidden; float:left;"><img  src="/static/imghwm/default1.png"  data-src="/plug/js/jquery.min.js"  class="lazy"    style="max-width:90%" id="preview"  alt="Simple sample code to crop and store images using Javascript" ></p>
<p style="width:190px;height:195px;margin:10px;overflow:hidden; float:left;"><img  src="/static/imghwm/default1.png"  data-src="/plug/js/jquery.min.js"  class="lazy"    style="max-width:90%" id="preview2"  alt="Simple sample code to crop and store images using Javascript" ></p>
<form action="{:U(&#39;/test/crop_deal&#39;)}" method="post" onsubmit="return checkCoords()" enctype="multipart/form-data" id="form">
<input type="file" name="file" onchange="change_image(this)">
<input type="hidden" id="x" name="x" />
<input type="hidden" id="y" name="y" />
<input type="hidden" id="w" name="w" />
<input type="hidden" id="h" name="h" />
<input type="submit" value="裁剪"/>
</form>

The following is the JS code:

function change_image(file){
var reader = new FileReader();
reader.onload = function(evt){
$("#target").attr('src',evt.target.result);
$('#preview').attr('src',evt.target.result);
$('#preview2').attr('src',evt.target.result);
// $('#target').css({"height":"600px","width":"600px"});
// 限制了大小会影响到截图的效果
};
reader.readAsDataURL(file.files[0]);

var jcrop_api, boundx, boundy;

setTimeout(function(){


$('#target').Jcrop({
minSize: [48,48],
setSelect: [0,0,190,190],
onChange: updatePreview,
onSelect: updatePreview,
onSelect: updateCoords,
aspectRatio: 1
},
function(){
// Use the API to get the real image size
var bounds = this.getBounds();
boundx = bounds[0];
boundy = bounds[1];
// Store the API in the jcrop_api variable
jcrop_api = this;
});

function updatePreview(c){
if (parseInt(c.w) > 0)
{
var rx = 48 / c.w; //小头像预览p的大小
var ry = 48 / c.h;

$('#preview').css({
width: Math.round(rx * boundx) + 'px',
height: Math.round(ry * boundy) + 'px',
marginLeft: '-' + Math.round(rx * c.x) + 'px',
marginTop: '-' + Math.round(ry * c.y) + 'px'
});
}
{
var rx = 199 / c.w; //大头像预览p的大小
var ry = 199 / c.h;
$('#preview2').css({
width: Math.round(rx * boundx) + 'px',
height: Math.round(ry * boundy) + 'px',
marginLeft: '-' + Math.round(rx * c.x) + 'px',
marginTop: '-' + Math.round(ry * c.y) + 'px'
});
}
};


function updateCoords(c)
{
$('#x').val(c.x);
$('#y').val(c.y);
$('#w').val(c.w);
$('#h').val(c.h);
};

},500);

}

Here are two reminders:

One: Don’t forget to put it in the header of the page Introducing plug-ins:

　　<script  type="text/javascript"></script>
　　<script src="/plug/js/jquery.Jcrop.min.js" type="text/javascript"></script>
　　<link rel="stylesheet" href="/plug/css/Jcrop.css" rel="external nofollow" type="text/css" />

Second: Some people with sharp eyes may have seen a timing in JS, and at the same time they are confused, isn't this a bit unnecessary? Actually no, it takes time to upload the image to JS and load it on the page. The meaning of this timing is to wait until the image is loaded on the page by JS before loading the cropping effect. This is also obtained after repeated experiments. way of doing.

I use the THINKPHP framework for back-end PHP processing, the version is 3.1.3

Paste the code:

function crop_deal(){
　　ob_clean();
　　import ( 'ORG.Net.UploadFile' );
　　$upload = new UploadFile ();
　　$upload->maxSize = 2000000;
　　$upload->allowExts = array (
　　　　'jpg',
　　　　'gif',
　　　　'png',
　　　　'jpeg'
　　);
　　$upload->savePath = './upload/test/';
　　$upload->autoSub = true;
　　$upload->subType = 'date';
　　$upload->dateFormat = 'Ymd';
　　if ($upload->upload () ) {
　　　　$info = $upload->getUploadFileInfo();
　　　　$new_path = "./upload/test/thumb".date('Ymd');
　　　　$file_store = $new_path."/".date('YmdHis').".jpg";
　　　　if(!file_exists($new_path)){
　　　　　　mkdir($new_path,0777,true);
　　　　}
　　　　$source_path = "http://".$_SERVER['HTTP_HOST']."/upload/test/".$info[0]['savename'];
　　　　$img_size = getimagesize($source_path);
　　　　$width = $img_size[0];
　　　　$height = $img_size[1];　　
　　　　$mime = $img_size['mime'];
　　　　$srcImg = imagecreatefromstring(file_get_contents($source_path));
　　　　$cropped_img = imagecreatetruecolor($_POST['w'], $_POST['h']);
　　　　//缩放
　　　　// imagecopyresampled($cropped_img,$srcImg,0,0,$_POST['x'],$_POST['y'],$_POST['w'],$_POST['h'],$width,$height);
　　　　//裁剪
　　　　imagecopy($cropped_img,$srcImg,0,0,$_POST['x'],$_POST['y'],$_POST['w'],$_POST['h']);
　　　　header("Content-Type:image/jpeg");
　　　　imagejpeg($cropped_img,$file_store);
　　　　imagedestroy($srcImg);
　　　　imagedestroy($cropped_img);
　　}

}

Here is the call to the GD library There are a series of methods to create images, the most important one is

imagecopy()

, which copies the original image to a new image according to the specified cropping position and cropping size. This also explains one thing, the page When the user cuts the image , the front end does not actually operate on the image. Instead, it obtains the coordinate position when cropping, the cropping size, and then submits it to PHP for operation! !

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