Using WordPress ‘attachment_max_dims’ PHP filter

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The attachment_max_dims WordPress PHP filter allows you to modify the maximum dimensions for an uploaded attachment.

Usage

add_filter('attachment_max_dims', 'custom_attachment_max_dims', 10, 3);

function custom_attachment_max_dims($max_dims, $width, $height) {
    // your custom code here
    return $max_dims;
}

Parameters

  • $max_dims (array): An array containing the maximum width and height for the attachment in the format array($width, $height).
  • $width (int): The original width of the attachment.
  • $height (int): The original height of the attachment.

More information

See WordPress Developer Resources: attachment_max_dims

Examples

Limit attachment dimensions to 800×600

This example sets the maximum dimensions for an uploaded attachment to 800 pixels wide and 600 pixels tall.

add_filter('attachment_max_dims', 'limit_attachment_dimensions', 10, 3);

function limit_attachment_dimensions($max_dims, $width, $height) {
    $max_dims = array(800, 600);
    return $max_dims;
}

Scale dimensions proportionally

This example scales the attachment dimensions proportionally to fit within a maximum width of 1200 pixels.

add_filter('attachment_max_dims', 'scale_attachment_dimensions', 10, 3);

function scale_attachment_dimensions($max_dims, $width, $height) {
    $max_width = 1200;

    if ($width > $max_width) {
        $ratio = $max_width / $width;
        $width = $max_width;
        $height = $height * $ratio;
    }

    $max_dims = array($width, $height);
    return $max_dims;
}

Set dimensions based on orientation

This example sets the maximum dimensions based on the attachment’s orientation (portrait or landscape).

add_filter('attachment_max_dims', 'orientation_based_dimensions', 10, 3);

function orientation_based_dimensions($max_dims, $width, $height) {
    if ($width > $height) {
        // Landscape
        $max_dims = array(1200, 800);
    } else {
        // Portrait
        $max_dims = array(800, 1200);
    }
    return $max_dims;
}

Prevent large attachments

This example prevents attachments larger than 1600×1200 pixels from being uploaded.

add_filter('attachment_max_dims', 'prevent_large_attachments', 10, 3);

function prevent_large_attachments($max_dims, $width, $height) {
    if ($width > 1600 || $height > 1200) {
        return false;
    }
    return $max_dims;
}

Enforce square attachments

This example enforces that all uploaded attachments must be square.

add_filter('attachment_max_dims', 'enforce_square_attachments', 10, 3);

function enforce_square_attachments($max_dims, $width, $height) {
    if ($width !== $height) {
        return false;
    }
    return $max_dims;
}