imagecreatefromstring

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

imagecreatefromstring — 从字符串中的图像流新建一图像

说明

resource imagecreatefromstring ( string $image )

imagecreatefromstring() 返回一个图像标识符，其表达了从给定字符串得来的图像。图像格式将自动检测，只要 PHP 支持：JPEG，PNG，GIF，WBMP 和 GD2。

参数

image: A string containing the image data.

返回值

An image resource will be returned on success. FALSE is returned if the image type is unsupported, the data is not in a recognised format, or the image is corrupt and cannot be loaded.

范例

Example #1 imagecreatefromstring() example


<?php
$data = 'iVBORw0KGgoAAAANSUhEUgAAABwAAAASCAMAAAB/2U7WAAAABl'
       . 'BMVEUAAAD///+l2Z/dAAAASUlEQVR4XqWQUQoAIAxC2/0vXZDr'
       . 'EX4IJTRkb7lobNUStXsB0jIXIAMSsQnWlsV+wULF4Avk9fLq2r'
       . '8a5HSE35Q3eO2XP1A1wQkZSgETvDtKdQAAAABJRU5ErkJggg==';
$data = base64_decode($data);

$im = imagecreatefromstring($data);
if ($im !== false) {
    header('Content-Type: image/png');
    imagepng($im);
    imagedestroy($im);
}
else {
    echo 'An error occurred.';
}
?>

以上例程的输出类似于：

参见

imagecreatefromjpeg() - 由文件或 URL 创建一个新图象。
imagecreatefrompng() - 由文件或 URL 创建一个新图象。
imagecreatefromgif() - 由文件或 URL 创建一个新图象。
imagecreatetruecolor() - 新建一个真彩色图像

User Contributed Notes

anon at dude dot com 07-Feb-2016 09:59


[Editor's note: BMP will be supported as of PHP 7.2.0.]





In case it's not obvious from the lack of "imagecreatefrombmp()" in GD, this function cannot handle plain old BMP files either.

hope at it-helps dot com 26-May-2011 01:29


Create an image resource from file, without knowing image type:





<?php


function imagecreatefromfile($imagepath=false) {


    if(!$imagepath || !$is_readable($imagepath) return false;


    return @imagecreatefromstring(file_get_contents($imagepath));


}


$img_resource=imagecreatefromfile($imagepath);


?>

php dot net at phor dot net 25-Oct-2009 08:12


My site allows anonymous uploads to a web-accessible location (that will execute a script if it finds one).



Naturally, I need to verify that only harmless content is accepted. I am expecting only images, so I use:



<?php

  $im = $imagecreatefromstring($USERFILE);

  $valid = ($im != FALSE);

  imagedestroy($im);

  return $valid;

?>

logan at logansbailey dot com 11-Aug-2009 03:00


So you guys don't spend an hour trying to figure out why your script keeps running out of memory when you're using this or the other imagecreatefrom functions.  GD uncompresses the image when you use these functions, and this can lead to your script running out of memory.



If you download a rawimage save it on your computer to jpeg so the file size comes down, GD will automatically convert it to the raw and you can possibly run out of memory.

ville dot jungman at gmail dot com 24-Sep-2008 11:01


While downloading images from internet, it's easiest to let php decide what is the file type. So, forget using imagecreatefromjpg, imagecreatefromgif and imagecreatefrompng. Instead, this is the way to go:



<?php

$src = "http://www.varuste.net/tiedostot/l_ylabanneri.jpg";

$image = imagecreatefromstring(file_get_contents($src));

?>

nfo[NOSPAM] at safernetworks dot net 09-Sep-2008 04:04


The only way I managed to resolve the loading of image files from file data either on local site or from off-site protocols is as follows. I hope this saves someone else the two hours of debugging and looking for good examples.

[PHP]



<?php

$sFile = "http://www.justgreatwine.co.uk/img/vineyard.jpg";

$imagedata = GetFileData($sFile); //load the file in 4k chunks

/*=======THE OUTPUT=========*/

ob_start();

// assuming you have image data in $imagedata

$length = strlen($imagedata);

header('Last-Modified: '.date('r'));

header('Accept-Ranges: bytes');

header('Content-Length: '.$length);

header('Content-Type: image/jpeg');

print($imagedata);

ob_end_flush();

/*======FUNCTIONS USED======*/

function GetFileData($sFilePath){

    $fp = fopen($sFilePath, 'rb') or die('404! Unable to open file!');

    $buf = '';

    while(!feof($fp)){

        $buf .= fgets($fp, 4096);

    }

    fclose($fp);

return $buf; //returns False if failed, else the contents up to FileSize bytes.

}

?>



[/PHP]

Blizzke at gmail dot com 13-Sep-2007 11:21


I use dynamically generated images that require a little touch-up before being displayed. So essentially I do some base work, then store the images in a memory cache (APC), reload the images again from the cache later on "into" GD, do final processing and then display the image. 

Since I wanted to avoid a lot of disc access I used the output buffering functions:



<?php

   // Do your image processing stuff

   

   // Start buffering

   ob_start ( );

   ImageGD ( $hImage );

   $sImage = ob_get_contents ( );

   ob_end_clean ( );



   // Put stuff into cache

 

   // Reload from cache and recreate image

   $hImage = imagecreatefromstring ( $sImage );



   // Do final editing stuff and output image

?>



Of course this is a condensed example but I just wanted to share the idea.

kanzure at gmail dot com 11-Jul-2006 06:18


Generating graphs in an external program (in this case, gnuplot) may cause problems. This is a solution hacked together in the late hours of night.



<?php

// get the values from, say, a database

$vals = "1 2\\\\n4 8\\\\n"; # etc

// construct the gnuplot_call variable, something like:

$gnuplot_call = "echo \"set term png; plot '<echo -e \\\"$vals\\\" ' ti 'Updated with' with line ; \" | gnuplot";

ob_start();

passthru($gnuplot_call, $gnuplot_call_output);

$image = imagecreatefromstring(ob_get_contents());

ob_end_clean();

imagepng($image); # display

?>

junkmail at pmobl dot com 25-Feb-2006 11:37


I know a lot of people have been having trouble using images from the Sprint PPC6700 with GD.  The jpeg library always thows an error about 16 bytes of extraneous data.  I decided to poke around in a hex editor and found those extraneous bytes occur right at the end of the exif data.



By removing this extraneous data, images can easily be manipulated by GD and the EXIF extension as a normal images.  This also removes any problems using the images with GIMP which must rely on the same jpeg libraries.



Here is a function that will check to see if an image is from the PPC6700 and then remove the extraneous data for you.  The result can successully be used with imagecreatefromstring



Author: Paul Visco

IM: paulsidekick

Created: 2-12-06



function checkFixPPC6700($orig){



    //get the file contents

    $data = file_get_contents($orig);



    //if its a PPC 6700 image cut out the extraneous 16 bits

    if(strstr($data, "\x41\x70\x61\x63\x68\x65\x00\x48")){

//this next line can all be one string I split it up so the form on php.net would accept it

        $bad_data ="\x00\x10\x4A\x46" . "\x49\x46\x00\x01\x01" . "\x00\x00\x01\x00\x01\x00\x00";

        return substr_replace($data, "", strpos($data, $bad_data),

        strlen($bad_data));

    } else {

        //if not from a PPC 6700 return data unaltered

         return $data;

    }



}

kakail at aei dot ca 27-Nov-2005 03:07


I found out that in PHP 4.3.2 and 4.3.4 that the 'imagecreatefromstring' function use a lot of memory when working with big image...

Try this piece of code with a big image (like 1Meg or more)

<?php

$loadFile = "http://bigimage.jpg";//Try with a big image 

$im = imagecreatefromstring(file_get_contents($loadFile));

imagejpeg($im);

?>



With a 400k image. I run with a 16M Mem_limit but for a 1.4M image, the mem_limit required jump to more that 32M

alexandrebr at ignorethis dot gmail dot com 29-Aug-2005 02:08


An easy example to help understanding this function...



<?

$loadFile = "http://static.php.net/images/php.gif";



$im = imagecreatefromstring(file_get_contents($loadFile));

// identical to imagecreatefromgif($loadFile);

imagegif($im);

?>



The function will try to auto-determine file format (jpg, gif, png....), and will return false if fails.

paul at epeeps dot net 26-Jul-2005 04:39


I run a blogging site that allowed users to publish images from their cell phones.  For some reason, the nokia 3220 produces jpegs with extrandeous data before the EOF 0xFFF9



I wrote this class to allow you to fix the images so that they can be used with GD to resize and manipulate.  Without applying the fix both GD and gimp report errors for the file.  If basically keeps eating bytes from the junk part till the file is a valid jpeg.  Here is an example bunk pic written by a nokia 3220 that you cna test it with http://www.shawnrider.com/moblog/cache/0854747001121624103.jpg



/*

Author: Paul Visco

Hompage: http://www.elmwoodstrip.com?u=paul

AIM: paulsidekick

Notes:  The file allows you fix the jpegs created by the Nokia 3220 picture phone so that they can be manipulated using the GD library with PHP.



Usage:  Simply instanitiate the class and then call the fix method for each image.

e.g. 

$nokia = new nokia;

$nokia->debug ="y";

$nokia->fix("yourpic.jpg");

*/



class nokia

{

    public $file;

    public $debug = "n";

    public $dir_name = "";

    private $img; //the image created from the string

    private $str;

    

    function fix($file)

    {

        

        //set the file to fix

        $this->file = $file;

    

        //load the file into a string

        $this->str = file_get_contents($this->file);

        

        //test to see if it is a nokia image or if it has been corrupted previously

        if (substr_count($this->str, chr(0x28).chr(0x36).chr(0x28).chr(0x2B)) == 0 || @imagecreatefromstring($this->str)) 

        { 

            if ($this->debug =="y")

            {

                echo "\n<br />".$this->file." is not a corrupted Nokia pic";

            }

            

            return true;

        }

        

        //make a directory for fixed images if it doesn't exist and is specified

        if(!empty($this->dir_name) && !is_dir($this->dir_name))

        {

            @mkdir($this->dir_name, 0777);

        }

        

        //strip out the funk e crap from the file

        $this->eat($this->str);

        

        //write the file back to itself

        file_put_contents($this->dir_name.$this->file, $this->str);



        //return true for fixed

        return true;



    }

    

    function eat()

    {

    

        //check the image

        $this->img = @imagecreatefromstring($this->str);

        

        //if the image doesn't work then keep striping out crap

        while(!$this->img)

        {

            //cut off the bad bytes one by one

            $this->str= substr_replace($this->str, "", -3, -2);

            

            //check the image again

            $this->img = @imagecreatefromstring($this->str);

        }  

        

        if ($this->debug =="y")

        {

            //notify the user it's fixed

            echo "\n<br />Nasty bits eaten!! ".$this->file." is fixed now thanks to p:labs!";

        }

        return true;

    }



}

not given 03-Aug-2003 11:14


A note to the previous question (if you still don't know it :))...



GIF's are 256 colors (or 8 bit), and the resample function needs true color I guess... that's why it works with JPG's and not with GIF's.



Next thing... you take a string, write it to file, open the file (imagecreatefromgif), and delete the file again.



if you do imagecreatefromstring($string) you can skip the temporary file part.

shiehj at yahoo dot com 12-Apr-2003 06:44


Here is the code I did to create a thumbnail image from the database blob field. The trick is to use "imagecreatefromstring()" to create an image file.



Jack Shieh



<?php

require("dbconfig.inc");



$id = $_GET['id'];



if($id) {



    $link = @mysql_connect($host, $user, $password) or die("Could not connect: " . mysql_error());

    @mysql_select_db($dbname, $link);



    $query = "select filetype, image from pictures where id = $id";

    $result = @mysql_query($query);



    $data = @mysql_result($result,0,"image");

    $type = @mysql_result($result,0,"filetype");

    

    Header( "Content-type: $type");    

    

    $size = 150;  // new image width

    $src = imagecreatefromstring($data); 

    $width = imagesx($src);

    $height = imagesy($src);

    $aspect_ratio = $height/$width;



    if ($width <= $size) {

      $new_w = $width;

      $new_h = $height;

    } else {

      $new_w = $size;

      $new_h = abs($new_w * $aspect_ratio);

    }



    $img = imagecreatetruecolor($new_w,$new_h); 

    imagecopyresized($img,$src,0,0,0,0,$new_w,$new_h,$width,$height);

 

    // determine image type and send it to the client    

    if ($type == "image/pjpeg") {    

      imagejpeg($img); 

    } else if ($type == "image/x-png") {

      imagepng($img);

    } else if ($type == "image/gif") {

      imagegif($img);

    }

    imagedestroy($img); 

    mysql_close($link);

};

?>

adrian_schmidt at yahoo dot com 06-Mar-2003 01:04


I'm trying to get the imagecreatefromstring to work with GIFs. Of course, it won't.

I've read the tips but can't get them to work either.

The following is what I tried, based on above tips:



---



    header('Content-Type: image/gif');

    header('Content-Disposition: inline; filename=file.gif');



    $temp = tmpfile();

    fwrite($temp, $line['image']);

    $src_img = imagecreatefromgif($temp);

    fclose($temp); // this removes the file

    $dst_img = imagecreatetruecolor(100, 100);

    imagecopyresampled($dst_img, $src_img, 0,0,0,0, 100,100, imagesx($src_img), imagesy($src_img));

    

    imagegif($dst_img);



---



where $line['image'] is the gif as taken from my MySQL database...



If anyone that has been able to make something like this work could give me a working piece of code I'd be really greatful!



I would be great if the tempfile could be excluded too...



Below is a working piece of code for jpeg:



---



    header('Content-Type: image/jpeg');

    header('Content-Disposition: inline; filename=file.jpg');

    

    $src_img = imagecreatefromstring($line['image']);

    $dst_img = imagecreatetruecolor(100, 100);

    imagecopyresampled($dst_img, $src_img, 0,0,0,0, 100,100, imagesx($src_img), imagesy($src_img));

    

    imagejpeg($dst_img);