I followed the steps at https://www.w3schools.com/php/php_file_upload.asp and http://www.w3bees.com/2013/03/resize-image-while-upload-using-php.html to produce this solution:
In my view (I am using the MVC paradigm, but it could be your .html or .php file, or the technology that you use for your front-end):
<form action="../../photos/upload.php" method="post" enctype="multipart/form-data">
<label for="quantity">Width:</label>
<input type="number" id="picture_width" name="picture_width" min="10" max="800" step="1" value="500">
Select image to upload:
<input type="file" name="fileToUpload" id="fileToUpload">
<input type="submit" value="Upload Image" name="submit">
</form>
My upload.php:
<?php
/* Get original image x y*/
list($w, $h) = getimagesize($_FILES['fileToUpload']['tmp_name']);
$new_height=$h*$_POST['picture_width']/$w;
/* calculate new image size with ratio */
$ratio = max($_POST['picture_width']/$w, $new_height/$h);
$h = ceil($new_height / $ratio);
$x = ($w - $_POST['picture_width'] / $ratio) / 2;
$w = ceil($_POST['picture_width'] / $ratio);
/* new file name */
//$path = 'uploads/'.$_POST['picture_width'].'x'.$new_height.'_'.basename($_FILES['fileToUpload']['name']);
$path = 'uploads/'.basename($_FILES['fileToUpload']['name']);
/* read binary data from image file */
$imgString = file_get_contents($_FILES['fileToUpload']['tmp_name']);
/* create image from string */
$image = imagecreatefromstring($imgString);
$tmp = imagecreatetruecolor($_POST['picture_width'], $new_height);
imagecopyresampled($tmp, $image,
0, 0,
$x, 0,
$_POST['picture_width'], $new_height,
$w, $h);
$uploadOk = 1;
$imageFileType = strtolower(pathinfo($path,PATHINFO_EXTENSION));
// Check if image file is a actual image or fake image
if(isset($_POST["submit"])) {
$check = getimagesize($_FILES["fileToUpload"]["tmp_name"]);
if($check !== false) {
//echo "File is an image - " . $check["mime"] . ".";
$uploadOk = 1;
} else {
//echo "File is not an image.";
$uploadOk = 0;
}
}
// Check if file already exists
if (file_exists($path)) {
echo "Sorry, file already exists.";
$uploadOk = 0;
}
// Check file size
if ($_FILES["fileToUpload"]["size"] > 500000) {
echo "Sorry, your file is too large.";
$uploadOk = 0;
}
// Allow certain file formats
if($imageFileType != "jpg" && $imageFileType != "png" && $imageFileType != "jpeg"
&& $imageFileType != "gif" ) {
echo "Sorry, only JPG, JPEG, PNG & GIF files are allowed.";
$uploadOk = 0;
}
// Check if $uploadOk is set to 0 by an error
if ($uploadOk == 0) {
echo "Sorry, your file was not uploaded.";
// if everything is ok, try to upload file
} else {
/* Save image */
switch ($_FILES['fileToUpload']['type']) {
case 'image/jpeg':
imagejpeg($tmp, $path, 100);
break;
case 'image/png':
imagepng($tmp, $path, 0);
break;
case 'image/gif':
imagegif($tmp, $path);
break;
default:
exit;
break;
}
echo "The file ". basename( $_FILES["fileToUpload"]["name"]). " has been uploaded.";
/* cleanup memory */
imagedestroy($image);
imagedestroy($tmp);
}
?>
The name of the folder where pictures are stored is called 'uploads/'. You need to have that folder previously created and that is where you will see your pictures. It works great for me.
NOTE: This is my form:
The code is uploading and resizing pictures properly. I used this link as a guide: http://www.w3bees.com/2013/03/resize-image-while-upload-using-php.html. I modified it because in that code they specify both width and height of resized pictures. In my case, I only wanted to specify width. The height I automatically calculated it proportionally, just keeping proper picture proportions. Everything works perfectly. I hope this helps.