Image Resize Function Tutorial jpg gif png Change Size
Master PHP Image Processing with Adam Khoury in this Video Textbook Series. In this video we learn how to script a universal PHP image resizing function that uses a handful of functions from the GD library in PHP. In our example the function will work for resizing JPG, GIF, and PNG type of images.
Watch the video to find out how to apply the code below if it is not clear from the code comments.
my_file.php
<form enctype="multipart/form-data" method="post" action="image_upload_script.php">
Choose your file here:
<input name="uploaded_file" type="file"/><br /><br />
<input type="submit" value="Upload It"/>
</form>
image_upload_script.php
<?php
// Access the $_FILES global variable for this specific file being uploaded
// and create local PHP variables from the $_FILES array of information
$fileName = $_FILES["uploaded_file"]["name"]; // The file name
$fileTmpLoc = $_FILES["uploaded_file"]["tmp_name"]; // File in the PHP tmp folder
$fileType = $_FILES["uploaded_file"]["type"]; // The type of file it is
$fileSize = $_FILES["uploaded_file"]["size"]; // File size in bytes
$fileErrorMsg = $_FILES["uploaded_file"]["error"]; // 0 for false... and 1 for true
$kaboom = explode(".", $fileName); // Split file name into an array using the dot
$fileExt = end($kaboom); // Now target the last array element to get the file extension
// START PHP Image Upload Error Handling --------------------------------------------------
if (!$fileTmpLoc) { // if file not chosen
echo "ERROR: Please browse for a file before clicking the upload button.";
exit();
} else if($fileSize > 5242880) { // if file size is larger than 5 Megabytes
echo "ERROR: Your file was larger than 5 Megabytes in size.";
unlink($fileTmpLoc); // Remove the uploaded file from the PHP temp folder
exit();
} else if (!preg_match("/.(gif|jpg|png)$/i", $fileName) ) {
// This condition is only if you wish to allow uploading of specific file types
echo "ERROR: Your image was not .gif, .jpg, or .png.";
unlink($fileTmpLoc); // Remove the uploaded file from the PHP temp folder
exit();
} else if ($fileErrorMsg == 1) { // if file upload error key is equal to 1
echo "ERROR: An error occured while processing the file. Try again.";
exit();
}
// END PHP Image Upload Error Handling ----------------------------------------------------
// Place it into your "uploads" folder mow using the move_uploaded_file() function
$moveResult = move_uploaded_file($fileTmpLoc, "uploads/$fileName");
// Check to make sure the move result is true before continuing
if ($moveResult != true) {
echo "ERROR: File not uploaded. Try again.";
unlink($fileTmpLoc); // Remove the uploaded file from the PHP temp folder
exit();
}
unlink($fileTmpLoc); // Remove the uploaded file from the PHP temp folder
// ---------- Include Universal Image Resizing Function --------
include_once("ak_php_img_lib_1.0.php");
$target_file = "uploads/$fileName";
$resized_file = "uploads/resized_$fileName";
$wmax = 200;
$hmax = 150;
ak_img_resize($target_file, $resized_file, $wmax, $hmax, $fileExt);
// ----------- End Universal Image Resizing Function -----------
// Display things to the page so you can see what is happening for testing purposes
echo "The file named <strong>$fileName</strong> uploaded successfuly.<br /><br />";
echo "It is <strong>$fileSize</strong> bytes in size.<br /><br />";
echo "It is an <strong>$fileType</strong> type of file.<br /><br />";
echo "The file extension is <strong>$fileExt</strong><br /><br />";
echo "The Error Message output for this upload is: $fileErrorMsg";
?>
ak_php_img_lib_1.0.php
<?php
// Function for resizing jpg, gif, or png image files
function ak_img_resize($target, $newcopy, $w, $h, $ext) {
list($w_orig, $h_orig) = getimagesize($target);
$scale_ratio = $w_orig / $h_orig;
if (($w / $h) > $scale_ratio) {
$w = $h * $scale_ratio;
} else {
$h = $w / $scale_ratio;
}
$img = "";
$ext = strtolower($ext);
if ($ext == "gif"){
$img = imagecreatefromgif($target);
} else if($ext =="png"){
$img = imagecreatefrompng($target);
} else {
$img = imagecreatefromjpeg($target);
}
$tci = imagecreatetruecolor($w, $h);
// imagecopyresampled(dst_img, src_img, dst_x, dst_y, src_x, src_y, dst_w, dst_h, src_w, src_h)
imagecopyresampled($tci, $img, 0, 0, 0, 0, $w, $h, $w_orig, $h_orig);
imagejpeg($tci, $newcopy, 80);
}
?>