How can I make add_image_size() crop from the top?

Question

I have a series of posts, all with featured images, but I need to be able to customise the crop top right corner. In this instance, I need them to be cropped from top right, but it would be useful to also know how to position that point myself.

At present, the add_image_size() function is taking its crop from the centre of the image. Not always pretty!!

Answer 1

Intermediate image generation is extremely rigid. image_resize() keeps it close to code and completely lacks hooks.

Pretty much only option for this is to hook into wp_generate_attachment_metadata and overwrite WP-generated image with your own (which will need bit of a image_resize() fork).

I need this for work so I might be able to share some code later.

Ok, here is rough, but working example. Note that setting up crop in this way requires understanding of imagecopyresampled().

add_filter('wp_generate_attachment_metadata', 'custom_crop');

function custom_crop($metadata) {

    $uploads = wp_upload_dir();
    $file = path_join( $uploads['basedir'], $metadata['file'] ); // original image file
    list( $year, $month ) = explode( '/', $metadata['file'] );
    $target = path_join( $uploads['basedir'], "{$year}/{$month}/".$metadata['sizes']['medium']['file'] ); // intermediate size file
    $image = imagecreatefromjpeg($file); // original image resource
    $image_target = wp_imagecreatetruecolor( 44, 44 ); // blank image to fill
    imagecopyresampled($image_target, $image, 0, 0, 25, 15, 44, 44, 170, 170); // crop original
    imagejpeg($image_target, $target, apply_filters( 'jpeg_quality', 90, 'image_resize' )); // write cropped to file

    return $metadata;
}

Answer 2

Wordpress codex has the answer, its below.

Set the image size by cropping the image and defining a crop position:

add_image_size( 'custom-size', 220, 220, array( 'left', 'top' ) ); // Hard crop left top

When setting a crop position, the first value in the array is the x axis crop position, the second is the y axis crop position.

x_crop_position accepts 'left' 'center', or 'right'. y_crop_position accepts 'top', 'center', or 'bottom'. By default, these values default to 'center' when using hard crop mode.

And also codex references a page which shows how crop positions acts.

http://havecamerawilltravel.com/photographer/wordpress-thumbnail-crop

Answer 3

I have developed a solution to this problem that does not require hacking the core: http://bradt.ca/archives/image-crop-position-in-wordpress/

I have also submitted a patch to core: http://core.trac.wordpress.org/ticket/19393

Add yourself as a Cc on the ticket to show your support for it to be added to core.

Answer 4

You can use the plugin Thumbnail Crop Position to select the crop position of your thumbnails.

Answer 5

Alternative solution here: http://pixert.com/blog/cropping-post-featured-thumbnails-from-top-instead-of-center-in-wordpress-with-native-cropping-tool/

Just add this code to functions.php, then use "Regenerate Thumbnails" plugin (https://wordpress.org/plugins/regenerate-thumbnails/):

function px_image_resize_dimensions( $payload, $orig_w, $orig_h, $dest_w, $dest_h, $crop ){

// Change this to a conditional that decides whether you want to override the defaults for this image or not.
if( false )
return $payload;

if ( $crop ) {
// crop the largest possible portion of the original image that we can size to $dest_w x $dest_h
$aspect_ratio = $orig_w / $orig_h;
$new_w = min($dest_w, $orig_w);
$new_h = min($dest_h, $orig_h);

if ( !$new_w ) {
$new_w = intval($new_h * $aspect_ratio);
}

if ( !$new_h ) {
$new_h = intval($new_w / $aspect_ratio);
}

$size_ratio = max($new_w / $orig_w, $new_h / $orig_h);

$crop_w = round($new_w / $size_ratio);
$crop_h = round($new_h / $size_ratio);

$s_x = 0; // [[ formerly ]] ==> floor( ($orig_w - $crop_w) / 2 );
$s_y = 0; // [[ formerly ]] ==> floor( ($orig_h - $crop_h) / 2 );
} else {
// don't crop, just resize using $dest_w x $dest_h as a maximum bounding box
$crop_w = $orig_w;
$crop_h = $orig_h;

$s_x = 0;
$s_y = 0;

list( $new_w, $new_h ) = wp_constrain_dimensions( $orig_w, $orig_h, $dest_w, $dest_h );
}

// if the resulting image would be the same size or larger we don't want to resize it
if ( $new_w >= $orig_w && $new_h >= $orig_h )
return false;

// the return array matches the parameters to imagecopyresampled()
// int dst_x, int dst_y, int src_x, int src_y, int dst_w, int dst_h, int src_w, int src_h
return array( 0, 0, (int) $s_x, (int) $s_y, (int) $new_w, (int) $new_h, (int) $crop_w, (int) $crop_h );

}
add_filter( 'image_resize_dimensions', 'px_image_resize_dimensions', 10, 6 );