使用php动态调整图像大小

Question

I'v searched all day for a function to resize my pictures on the server on the fly, without saving them.The code works, it shows the full size images, now I want to make them smaller. This is the function:

function resize_image($file, $width, $height) {
    if (file_exists($file)){
        $image = imagecreatefromjpeg($file);
        list($orig_width, $orig_height) = getimagesize($file);
        $ratio = $orig_width / $orig_height;
        if ($ratio < 1) {
            $width = $height * $ratio;
        } else {
            $height = $width / $ratio;
        }
        $new_image = imagecreatetruecolor($width, $height);
        imagecopyresized($new_image, $image,
        0, 0, 0, 0,
        $width, $height,
        $orig_width, $orig_height);
        // header('Content-type: image/jpeg');
        imagejpeg($new_image, NULL, 80);
    }
}

From what I searched today I need to put the header (Content-type: image/jpeg') for the browser to recognize the output as an image but if I do that it stops the script.

This is the page using it:

<? include('resize.php');
 $chapter='test';
 $query=$db->prepare("SELECT * FROM `test_db` WHERE `test_db`.`Chapter` LIKE :? ORDER BY `id` ASC LIMIT 0, 6");
    $query->bindValue(1, $chapter, PDO::PARAM_STR);
    $query->execute();
    $rows= $query->fetchAll(PDO::FETCH_ASSOC);  
foreach ($rows as $row){       
    echo "<li><h2>".$row['Name']."</h2></li>" ;
    resize_image("_images/".$row['img_number'].".jpg", 300, 190);
  };  
?>

Answer 1

You cannot output html and images to the browser in the same script.

You should either:

• use a separate script to output the image and call that from the html like (simple example):

  <img src="your_script.php?id=XX&size_x=XX&size_y=XX">

• save the images to a file and link to that file from your html.

You could also encode the images as base64 strings and use that in your image tags but that would lead to a very large html file unless you are talking about simple buttons.

Answer 2

Don't put your closing tag in PHP. It will output whitespace after the closing tag which will alter the result.

Answer 3

Since when are headers stopping the script?

And yes, the reason why resized files are saved, is (1) you'll probably need them again, (2) the content type makes them an image in stead of text. If you want to resize those 'inline' you'll need two content types, and I guess that won't work that well...

What you could do, is resize and save the file, serve it and delete it. Like a temporary image file. A more direct way doesn't exist, according to me. But if I'm wrong, please point that out in the comments for me. I like to learn new stuff ;)

Edit: okay, EXCEPT when the script only handles the image resizing. Just thinking about that one right now. Sorry :)