“Why the hell am I writing articles in a blog?”  That’s literally what I asked myself the other day.  “Self,” I replied, “I want to help the world understand PHP and concepts of education better with the hopes making everyones lives better.”

“Liar,” I shot back… to myself, “You’re just getting old and want some place to put things you’ve figured out so you don’t forget them.”

Sigh.

So, in this episode of “Crap I Don’t Want To Figure Out Again”, I found myself in need of taking an image and resizing it using PHP.  This isn’t a very common task for PHP, as developers usually have static images and service them in a typical fashion, so this took a bit of research.

I did, however, have a level of difficulty…  These were ID badge photos coming out of a BLOB object in an Oracle database, all of which were different sizes and I needed a 100×100 image.  The nice thing is that, since these were ID badge photographs, I could generally depend on the face being fairly centered in the image.  The whole, “Getting a binary image out of a database to use” will be a different article, but this will handle taking an image and resizing it.

//Here's some sample image data.
$data = 'iVBORw0KGgoAAAANSUhEUgAAABwAAAASCAMAAAB/2U7WAAAABl'
. 'BMVEUAAAD///+l2Z/dAAAASUlEQVR4XqWQUQoAIAxC2/0vXZDr'
. 'EX4IJTRkb7lobNUStXsB0jIXIAMSsQnWlsV+wULF4Avk9fLq2r'
. '8a5HSE35Q3eO2XP1A1wQkZSgETvDtKdQAAAABJRU5ErkJggg==';

//Create the image from the string.
$img = imagecreatefromstring(base64_decode($data));

//Set the desired height and width.
$thumb_width = 100;
$thumb_height = 100;

//Measure what we have.
$width = imagesx($img);
$height = imagesy($img);

//Do some calculations.
$original_aspect = $width / $height;
$thumb_aspect = $thumb_width / $thumb_height;

//Figure out the dimensions we need.
if ($original_aspect >= $thumb_aspect)
{
    // If image is wider than thumbnail (in aspect ratio sense)
    $new_height = $thumb_height;
    $new_width = $width / ($height / $thumb_height);
}
else
{
    // If the thumbnail is wider than the image
    $new_width = $thumb_width;
    $new_height = $height / ($width / $thumb_width);
}

//Create the image template.
$thumb = imagecreatetruecolor($thumb_width, $thumb_height);

//Resize down and crop from the center.
imagecopyresampled($thumb,
$img,
0 - ($new_width - $thumb_width) / 2, // Center the image horizontally
0 - ($new_height - $thumb_height) / 2, // Center the image vertically
0, 0,
$new_width, $new_height,
$width, $height);

//Save the finished product at 100% quality to a file.
imagejpeg($thumb, "photos/imagefile.jpg", 100);

//Free up the resources.
imagedestroy($img);
imagedestroy($thumb);

That’s the short and skinny of it. It’s more of a syntax and aspect ratio puzzle rather than anything hugely difficult.