如何在PHP中从高内存图像URL创建缩略图？

Question

嗨朋友们我想在php中创建来自图片网址的缩略图，我找到一个代码从网址生成拇指图像，它适用于内存较小的图片网址，不适合高内存大小的图片网址，请为此提供一些解决方案问题

<?php

// function created by www.thewebhelp.com

if(!function_exists("create_square_image")){
    function create_square_image($original_file, $destination_file=thumb, $square_size = 96){

        if(isset($destination_file) and $destination_file!=NULL){
            if(!is_writable($destination_file)){
                echo '<p style="color:#FF0000">Oops, the destination path is not writable. Make that file or its parent folder wirtable.</p>'; 
            }
        }

        // get width and height of original image
        $imagedata = getimagesize($original_file);
        $original_width = $imagedata[0];    
        $original_height = $imagedata[1];

        if($original_width > $original_height){
            $new_height = $square_size;
            $new_width = $new_height*($original_width/$original_height);
        }
        if($original_height > $original_width){
            $new_width = $square_size;
            $new_height = $new_width*($original_height/$original_width);
        }
        if($original_height == $original_width){
            $new_width = $square_size;
            $new_height = $square_size;
        }

        $new_width = round($new_width);
        $new_height = round($new_height);

        // load the image
        if(substr_count(strtolower($original_file), ".jpg") or substr_count(strtolower($original_file), ".jpeg")){
            $original_image = imagecreatefromjpeg($original_file);
        }
        if(substr_count(strtolower($original_file), ".gif")){
            $original_image = imagecreatefromgif($original_file);
        }
        if(substr_count(strtolower($original_file), ".png")){
            $original_image = imagecreatefrompng($original_file);
        }

        $smaller_image = imagecreatetruecolor($new_width, $new_height);
        $square_image = imagecreatetruecolor($square_size, $square_size);

        imagecopyresampled($smaller_image, $original_image, 0, 0, 0, 0, $new_width, $new_height, $original_width, $original_height);

        if($new_width>$new_height){
            $difference = $new_width-$new_height;
            $half_difference =  round($difference/2);
            imagecopyresampled($square_image, $smaller_image, 0-$half_difference+1, 0, 0, 0, $square_size+$difference, $square_size, $new_width, $new_height);
        }
        if($new_height>$new_width){
            $difference = $new_height-$new_width;
            $half_difference =  round($difference/2);
            imagecopyresampled($square_image, $smaller_image, 0, 0-$half_difference+1, 0, 0, $square_size, $square_size+$difference, $new_width, $new_height);
        }
        if($new_height == $new_width){
            imagecopyresampled($square_image, $smaller_image, 0, 0, 0, 0, $square_size, $square_size, $new_width, $new_height);
        }


        // if no destination file was given then display a png      
        if(!$destination_file){
            imagepng($square_image,NULL,9);
        }

        // save the smaller image FILE if destination file given
        if(substr_count(strtolower($destination_file), ".jpg")){
            imagejpeg($square_image,$destination_file,100);
        }
        if(substr_count(strtolower($destination_file), ".gif")){
            imagegif($square_image,$destination_file);
        }
        if(substr_count(strtolower($destination_file), ".png")){
            imagepng($square_image,$destination_file,9);
        }

        imagedestroy($original_image);
        imagedestroy($smaller_image);
        imagedestroy($square_image);

    }
}



create_square_image("imageurl","thumbname.jpg",200);
?>