Download images and resize

I have built a system which downloads images from a bunch of URLs, depending on the user, and fetch's them asynchronously - if they're wider than the device's screen we resize. Trouble is some of these images can be huge 1MB + and many of them and downloading large files and processing them is causing the older devices to struggle.

So I thought I'd introduce a server side level which can handle the downloading and resizing...but my PHP is not great. I'm guessing this is possible but I cant find any solutions after a few days research. There are an abundance of PHP resize scripts, but none from a URL, they are all from a database or inside HTML . I need it to be sent a URL of an image, download it, if its too big resize, then send back to the device.

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Updated with cURL

<?php

$imgurl = $_GET["url"];

function curl_do开发者_开发技巧wnload($Url){

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $Url);
    curl_setopt($ch, CURLOPT_USERAGENT, "MozillaXYZ/1.0");
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, false);
    curl_setopt($ch, CURLOPT_TIMEOUT, 10);

    $output = curl_exec($ch);

    $im = imagecreatefromstring($output);

    if ($im !== false)
    {
        header('Content-Type: image/jpeg');

        list($width, $height) = getimagesize($im);
        $new_width = 320;
        $new_height = 320;

        // Resample
        $image_p = imagecreatetruecolor($new_width, $new_height);
        $image = imagecreatefromjpeg($im);
        imagecopyresampled($image_p, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

        imagejpeg($image_p, null, 100);
    }
    else
    {
        echo 'An error occurred.';
    }
    curl_close($ch);

    return $image_p;
}

?>

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You can fetch the image with cURL with CURLOPT_RETURN_TRANSFER passed to curl_setopt to get the image data. Then the following steps should do for generating the resized image:

1. imagecreatefromstring will allow you to construct an image object
2. imagecreate to create a new image of the appropriate size
3. imagecopyresampled for the resize
4. imagejpeg on the resized image to send it to the browser

As @Paul notes, you'll want to set the content type to image/jpeg.

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you can use cURL or socket to download the html page and images in it, then use GD2 to resize the images, and return to browser with

header("Content-type:image/jpeg");

after that, your application on iphone load this php created image from your php server. i think this is the solution for manipulating all the images from other servers the way you want.