Learn How Resize An Image While Uploading With PHP

<form action="" method="post" enctype="multipart/form-data">
    <input type="file" name="image"><br>
    <input type="submit" class="btn btn-primary" value="Upload">
</form>

<?php
require_once("resize-image.php");

$form_field = "image";
$upload_path = "upload/";

//assume uploading a jpeg image file.
//This can be determined by file type while uploading and here we do not care about the image since it's not a big deal here.
$image_name = uniqid().".jpg";
$width = 1366;
$height = 768;

//Create an object of 'Image' class and call to 'upload_image' function which we are going to use here for our process.
$imgObj = new Image();
$upload = $imgObj->upload_image($form_field, $upload_path, $image_name, $width, $height);

if($upload)
{
echo "<div class='container'><div class=\"alert icon-alert with-arrow alert-success form-alter\" role=\"alert\">
<i class=\"fa fa-fw fa-check-circle\"></i>
<strong> Success ! </strong> <span class=\"success-message\"> Image Resize Successfully </span>
</div></div><br>";
    ?>
    <div class='container'>
        <div class="portrait">
        <img src="upload/<?php echo $image_name; ?>"
        </div>
        </div>
    <?php
}
else
{
    echo "<div class='container'><div class=\"alert icon-alert with-arrow alert-danger form-alter\" role=\"alert\">
<i class=\"fa fa-fw fa-check-circle\"></i>
<strong> failed ! </strong> <span class=\"success-message\"> Image uploading was failed. </span>
</div></div>";
}
?>

<?php
class resize_image
{
    function upload_image($form_field, $upload_path, $image_name, $width, $height)
    {
        //image upload
        if(isset($_FILES[$form_field]))
        {
            //get uploading file's extention
            $extention=strtolower($_FILES[$form_field]["type"]);

            $exp_del = "."; //end delimiter
            $file_name = $_FILES[$form_field]["name"];
            $file_name = explode($exp_del, $file_name);
            $extention = strtolower(end($file_name));

            //validate uploading file
            $validate=$this->validate_file($form_field, $extention);

            if($validate)
            {
                //build path if does not exists
                if(!is_dir($upload_path)){ mkdir($upload_path, 0755); }

                //here you can use two types of methods to resize image
                //first one is resize image to the aspect ratio
                //second one is crop image to the provided width and height
                //you can use one of the following two methods to perform above operations

                //resize image and save
                $this->GenerateThumbnail($_FILES[$form_field]["tmp_name"], $upload_path.$image_name, $width, $height, $extention);

                return true;
            }
            else
            {
                return false;
            }
        }
        else
        {
            return false;
        }
    }

    /**
     * @param string path_to_image - Path for the source image
     * @param string path_to_thumb - Path for the saving image
     * @param string thumb_width - New width for the saving image
     * @param string thumb_height - New height for the saving image
     * @param string extension - image file's extension
     */
    function GenerateThumbnail($path_to_image, $path_to_thumb, $thumb_width, $thumb_height, $extention)
    {
        $thumb_width=intval($thumb_width);
        $thumb_height=intval($thumb_height);

        $x1_source=0;
        $y1_source=0;

        //get uploading image's width and height
        list($width, $height, $img) = $this->get_image_width_height($extention, $path_to_image);

        //resize image for the aspect ratio
        if($width > $height)
        {
            if($thumb_height>$thumb_width)
            {
                $new_height=$height;
                $new_width=floor($new_height*($thumb_width/$thumb_height));

                $x1_source=floor(($width-$new_width)/2);
            }
            else
            {
                $new_width=$width;
                $new_height=floor($new_width*($thumb_height/$thumb_width));

                $y1_source=floor(($height-$new_height)/2);
            }
        }
        else
        {
            if($thumb_height>$thumb_width)
            {
                $new_width=$width;
                $new_height=floor($new_width*($thumb_height/$thumb_width));

                $y1_source=floor(($height-$new_height)/2);
            }
            else
            {
                $new_height=$height;
                $new_width=floor($new_height*($thumb_width/$thumb_height));

                $x1_source=floor(($width-$new_width)/2);
            }
        }

        if($thumb_width > $width)
        {
            $thumb_width=$width;
            $new_width=$width;

            $x1_source=0;
        }
        else
        {
            $x1_source=floor(($width-$new_width)/2);
        }

        if($thumb_height > $height)
        {
            $thumb_height=$height;
            $new_height=$height;

            $y1_source=0;
        }
        else
        {
            $y1_source=floor(($height-$new_height)/2);
        }

        $tmp_img=$this->create_temp_image($thumb_width, $thumb_height);

        // copy and resize old image into new image
        imagecopyresampled($tmp_img, $img, 0, 0, $x1_source, $y1_source, $thumb_width, $thumb_height, $new_width, $new_height);

        $this->save_image($extention, $path_to_thumb, $tmp_img);
    }

    /**
     * @param string extension - Uploading image's extension
     * @param string path_to_image - Path for of the source image
     */
    function get_image_width_height($extension, $path_to_image)
    {
        $extension=strtolower($extension);

        // load image and get image size
        if($extension == "jpg" || $extension == "jpeg")
        {
            $img = imagecreatefromjpeg($path_to_image);
        }
        else if( $extension == "gif")
        {
            $img = imagecreatefromgif($path_to_image);
        }
        else if( $extension == "png")
        {
            $img = imagecreatefrompng($path_to_image);
        }

        $width = imagesx($img);
        $height= imagesy($img);

        return array($width, $height, $img);
    }

    /**
     * @param string width - Width for the temporary image
     * @param string height - Height for the temporary image
     */
    function create_temp_image($width, $height)
    {
        // create a new temporary image
        $tmp_img = imagecreatetruecolor($width, $height);

        //making a transparent background for image
        imagealphablending($tmp_img, false);
        $color_transparent = imagecolorallocatealpha($tmp_img, 0, 0, 0, 127);
        imagefill($tmp_img, 0, 0, $color_transparent);
        imagesavealpha($tmp_img, true);

        return $tmp_img;
    }

    /**
     * @param string extension - image file's extension
     * @param string path - Path for the image which should be uploaded
     * @param string tmp_img - Temporary image which was created using GD libarary
     */
    function save_image($extension, $path, $tmp_img)
    {
        $extension=strtolower($extension) ;

        // save thumbnail into a file
        if( $extension == "jpg" || $extension == "jpeg" )
        {
            imagejpeg( $tmp_img, $path, 100 );
        }
        else if( $extension == "gif")
        {
            imagegif( $tmp_img, $path, 100 );
        }
        else if( $extension == "png")
        {
            imagepng( $tmp_img, $path, 9 );
        }
    }

    /**
     * @param string $field - The HTML form field name to check.
     * @param string extension - image file's extension
     */
    function validate_file($field, $extension)
    {
        //assume uploading file is not a valid image
        $match_found=false;

        //set valid file types and extensions for image upload
        $file_types=array();

        $file_types[]=array("type" => "image/jpeg", "ext" => "jpg");
        $file_types[]=array("type" => "image/png", "ext" => "png");
        $file_types[]=array("type" => "image/jpg", "ext" => "jpg");
        $file_types[]=array("type" => "image/gif", "ext" => "gif");

        foreach($file_types as $file_type)
        {
            $this_file_type=strtolower($_FILES[$field]["type"]);

            if($this_file_type == strtolower($file_type["type"]) && $extension == strtolower($file_type["ext"]))
            {
                $match_found=true;
                break;
            }
        }

        return $match_found;
    }

    /**
     * @param string path_to_image - Path for the source image
     */
    function is_valid_image($path_to_image)
    {
        //assume uploading file is not a valid image
        $valid = false;

        //check if file exists
        if(@file_exists($path_to_image))
        {
            try{
                //validate uploading file
                $image_size = getimagesize($path_to_image);

                if(isset($image_size[2]) && in_array($image_size[2], array(IMAGETYPE_GIF , IMAGETYPE_JPEG ,IMAGETYPE_PNG , IMAGETYPE_BMP)))
                {
                    $valid = true;
                }
            }
            catch(Exception $e)
            {
            }
        }

        return $valid;
    }
}
?>

<!DOCTYPE html>
<html lang="en">
<head>
    <title>resize images while uploading </title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
</head>
<style>
    img {
        /*max-width: 100%;*/
        max-height: 100%;
    }
    .portrait {
        height: 150px;
    }
</style>
<body>
<div class="container " style="margin-top: 70px">
    <div class="text-center">
        <h1>Resize images while uploading it in php</h1>
    </div>
    <br>
    <br>
    <h4></h4>
    <div class="well">
        <form action="" method="post" enctype="multipart/form-data">
            <input type="file" name="image"><br>
            <input type="submit" class="btn btn-primary" value="Upload">
        </form>
        <br>
    </div>
</div>
</body>
</html>

<?php
require_once("resize-image.php");

$form_field = "image";
$upload_path = "upload/";

//assume uploading a jpeg image file.
//This can be determined by file type while uploading and here we do not care about the image since it's not a big deal here.
$image_name = uniqid().".jpg";
$width = 1366;
$height = 768;

//Create an object of 'Image' class and call to 'upload_image' function which we are going to use here for our process.
$imgObj = new Image();
$upload = $imgObj->upload_image($form_field, $upload_path, $image_name, $width, $height);

if($upload)
{
echo "<div class='container'><div class=\"alert icon-alert with-arrow alert-success form-alter\" role=\"alert\">
<i class=\"fa fa-fw fa-check-circle\"></i>
<strong> Success ! </strong> <span class=\"success-message\"> Image Resize Successfully </span>
</div></div><br>";
    ?>
    <div class='container'>
        <div class="portrait">
        <img src="upload/<?php echo $image_name; ?>"
        </div>
        </div>
    <?php
}
else
{
    echo "<div class='container'><div class=\"alert icon-alert with-arrow alert-danger form-alter\" role=\"alert\">
<i class=\"fa fa-fw fa-check-circle\"></i>
<strong> failed ! </strong> <span class=\"success-message\"> Image uploading was failed. </span>
</div></div>";
}
?>