PHP - Simple script for image compression with pngquant - php

Question

:) i found this 1 line of code in another post which successfully compresses the image using pngquant. the thing is, it outputs the optimised image with a different name (obviously to preserve the original).
im trying to find a way to:
a) add a minimum quality parameter of 60
b) use an if/else statement to to allow the user to choose to overwrite the existing file or output a new optimised image (of a user specified name)
thank you! ntlri - not to long read it
<?php system('pngquant --quality=85 image.png'); ?>
so what i have tried is the following.. for some reason the single quotes need to be double quotes to parse the variables correctly..
<?php
$min_quality = 60; $max_quality = 85;
$keep_original = 'dont_keep';
if ($keep_original == 'keep') {
$image_name = 'image.png';
$path_to_image = 'images/' . $image_name;
$new_file = 'image2.png';
$path_to_new_image = 'images/' . $new_file;
// don't know how to output to specified $new_file name
system("pngquant --quality=$min_quality-$max_quality $path_to_image");
} else {
$image_name = 'image.png';
$path_to_image = 'images/' . $image_name;
// don't know if you can overwrite file by same name as additional parameter
system("pngquant --quality=$min_quality-$max_quality $path_to_image");
// dont't know how you get the name of the new optimised image
$optimised_image = 'images/' . $whatever_the_optimised_image_is_called;
rename($optimised_image, $image_name);
unlink($optimised_image);
}
?>

Answer 1

from the docs of this program :
The output filename is the same as the input name except that\n\ it
ends in \"-fs8.png\", \"-or8.png\" or your custom extension
so , for this question:
// don't know how to output to specified $new_file name
system("pngquant --quality=$min_quality-$max_quality $path_to_image");
to choose a new name, assume you are compress image name.png :
--ext=_x.png
this will create new image called name_x.png
so , your $new_file would be just a suffix ,
$new_file = '_x.png'; // to choose new file name name_x.png
// don't know if you can overwrite file by same name as additional
parameter
as mentioned in the program docs , the new file name will be suffixed by either -fs8.png or -or8.png , so you may rename the file which will produced with this suffix , OR simply set the --ext option to : .png and this will append to the original file
--ext=.png
for more details, check the repository

Answer 2

i spoke to pornel whos the chappie that developed pngquant. its actually a lot simpler than all that i wrote that before...
! important - it is very important to use escapeshellarg() else people can take over your server by uploading a file with a special filename apparently.
$image_name = 'image.png';
$target_file = 'images/' . $image_name;
$existing_image = 'image.png'; // image already on server if applicable
$keep = 'keep';
$target_escaped = escapeshellarg($target_file);
if ($keep == 'keep') {
// process/change output file to image_compressed.png keeping both images
system("pngquant --force --quality=70 $target_escaped --ext=_compressed.png");
$remove_ext = substr($newFileName, 0 , (strrpos($newFileName, ".")));
// $new_image is just the name (image_compressed.png) if you need it
$new_image = $remove_ext . '_compressed.png';
// remove old file if different name
if ($existing_image != $newFileName) {
$removeOld = '../images/' . $existing_image;
unlink($removeOld);
} // comment out if you want to keep existing file
} else {
// overwrite if file has the same name
system("pngquant --force --quality=70 $target_escaped --ext=.png");
// remove old file if different name
if ($existing_image != $newFileName) {
$removeOld = '../images/' . $existing_image;
unlink($removeOld);
}
$new_image = $newFileName;
}

Answer 3

to override same name use this command
pngquant.exe --ext=.png --force input.png
so the output name will remain input.png