Simple implementation of cropping images and storing them using Javascript

This article mainly introduces the simple implementation of using Javascript to crop pictures and store them. It has a certain reference value. Now I share it with you. Friends in need can refer to it.

Crop pictures for us I am very familiar with it. 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. Therefore, this article mainly introduces the simple method of cropping pictures and storing them using Javascript. For implementation, 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 implementation of cropping images and storing them 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 implementation of cropping images and storing them 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 implementation of cropping images and storing them 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 a few thoughts Click to remind:

First: Don’t forget to introduce the plug-in at the head of the page:

　　<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 If you have a sharp eye, you may have noticed that there is a timing in JS, and at the same time, you 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 are a series of methods to call the GD library to create images. The most important thing is

imagecopy()

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

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