PHP crop pictures and store them in mysql-PHP Tutorial-php.cn

PHP crop pictures and store them in mysql

WBOY

Release： 2016-08-08 09:30:33

Original

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When using PHP to process images, you often need to crop them. How to store cropped pictures into the mysql database is an interesting question. First, get the uploaded file:

$picFile = $_FILES["picFileName"];
$picType = $picFile["type"];  
$picData = file_get_contents($tempFile);

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If you don’t need to change the image size and store it directly in mysql, you can simply implement it as follows

$tempFile = $picFile["tmp_name"];  
$picData = base64_encode($picData);  

$query = "INSERT INTO image  
   (imgid, image, imgtype) 
   values( 
       null, 
       '$picData', 
       '$picType' 
    );"; 
$link->query($query);

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But if you want to change the image size and get the image data in the form of a character stream, you need a little Tips:
First complete the cropping of the image and obtain the image object

list($picW, $picH) = getimagesize($tempFile);  
if($picW>600){ //超出大小  
    $src = imagecreatefromjpeg($tempFile); //获取原图数据  
    $nW =550;  
    $nH = $picH*$nW/$picW;  
    $newPicTemp = imagecreatetruecolor($nW,$nH);  //创建彩色图片对象  
    imagecopyresampled($newPicTemp,$src,0,0,0,0,$nW,$nH,$picW,$picH);  
}

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After this step, newPicTemp is the resource type image data. Here comes the problem. Observe the code above. The type returned by file_get_contents is string, which is also the parameter type of base64_encode. How to convert resource to string type. After studying, I found that PHP has this function

string ob_get_contents ( void )

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which returns the contents of the output buffer in the form of a string.
So, the idea is to output the resource image to the buffer, and then use an object to obtain its content. The code is as follows

ob_start(); //开启输出缓冲区  
imagejpeg($newPicTemp); //这个函数可以显示出图片，同时也是把数据输出  
$imgContent = ob_get_contents(); //获取字符流  
ob_end_clean();  //关闭并清除缓冲区  

$picData = base64_encode($imgContent); //不要忘记转码

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In this way, you will get the image character stream after the size is changed, which can be stored in mysql
Finally destroy the temporary data

imagedestroy($src);  
imagedestroy($newPicTemp);

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If you need to read and display the image, you can use the following code

$query = "SELECT image, imgtype from image where imgid = $imgid ;";  
$result = $link->query($query);  
$row = mysqli_fetch_array($result);  
$data = base64_decode( $row["image"]);  
$type = $row["imgtype"];  
  
ob_clean();  
header("Content-Type:'$type'");  
echo $data;

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As you can see Several key functions contain the ob identifier. ob is output buffer, which is a very critical and useful tool in PHPRefer to php.net

The above introduces PHP to crop pictures and store them in mysql, including the relevant aspects. I hope it will be helpful to friends who are interested in PHP tutorials.