Overview

You can use the square_crop() function to automatically resize and trim virtually any JPEG, GIF, or PNG image. The function accepts up to four parameters, but only requires two. If the file extension of the destination file is different from the source file, the image will automatically be converted to the appropriate format.

This function requires the PHP GD library.

Parameters

Return Values

This function returns true on success, false otherwise.

The Code

<?php

function square_crop($src_image, $dest_image, $thumb_size = 64, $jpg_quality = 90) {

    // Get dimensions of existing image
    $image = getimagesize($src_image);

    // Check for valid dimensions
    if( $image[0] <= 0 || $image[1] <= 0 ) return false;

    // Determine format from MIME-Type
    $image['format'] = strtolower(preg_replace('/^.*?\//', '', $image['mime']));

    // Import image
    switch( $image['format'] ) {
        case 'jpg':
        case 'jpeg':
            $image_data = imagecreatefromjpeg($src_image);
        break;
        case 'png':
            $image_data = imagecreatefrompng($src_image);
        break;
        case 'gif':
            $image_data = imagecreatefromgif($src_image);
        break;
        default:
            // Unsupported format
            return false;
        break;
    }

    // Verify import
    if( $image_data == false ) return false;

    // Calculate measurements
    if( $image[0] &gt; $image[1] ) {
        // For landscape images
        $x_offset = ($image[0] - $image[1]) / 2;
        $y_offset = 0;
        $square_size = $image[0] - ($x_offset * 2);
    } else {
        // For portrait and square images
        $x_offset = 0;
        $y_offset = ($image[1] - $image[0]) / 2;
        $square_size = $image[1] - ($y_offset * 2);
    }

    // Resize and crop
    $canvas = imagecreatetruecolor($thumb_size, $thumb_size);
    if( imagecopyresampled(
        $canvas,
        $image_data,
        0,
        0,
        $x_offset,
        $y_offset,
        $thumb_size,
        $thumb_size,
        $square_size,
        $square_size
    )) {

        // Create thumbnail
        switch( strtolower(preg_replace('/^.*\./', '', $dest_image)) ) {
            case 'jpg':
            case 'jpeg':
                return imagejpeg($canvas, $dest_image, $jpg_quality);
            break;
            case 'png':
                return imagepng($canvas, $dest_image);
            break;
            case 'gif':
                return imagegif($canvas, $dest_image);
            break;
            default:
                // Unsupported format
                return false;
            break;
        }

    } else {
        return false;
    }

}

?>

Example

In its simplest form, you can produce a 64×64 pixel square thumbnail using the following code:

square_crop('full.jpg', 'thumb.jpg');

You can specify any size for thumbnails by passing a third argument. This will generate a 100×100 pixel thumbnail:

square_crop('full.jpg', 'thumb.jpg', 100);

You can also convert between different image formats. The following will produce a JPEG thumbnail from a GIF image:

square_crop('full.gif', 'thumb.jpg');

Sample Outputs

The image will be resized with its edges trimmed into a square: