由于WordPress是服务器端脚本，因此无法在上载之前检查图像。

但是，在将图像插入媒体库之前，您有不同的选项，如中所述this answer, 带筛选wp_handle_upload_prefilter.

在您的情况下，函数将过滤wp_handle_upload_prefilter 应该是这样的：

add_filter(\'wp_handle_upload_prefilter\', \'f711_image_size_prevent\');
function f711_image_size_prevent($file) {

    // get filesize of upload
    $size = $file[\'size\'];
    $size = $size / 1024; // Calculate down to KB

    // get imagetype of upload
    $type = $file[\'type\'];
    $is_image = strpos($type, \'image\');

    // set sizelimit
    $limit = 700; // Your Filesize in KB

    // set imagelimit
    $imagelimit = 7;

    // set allowed imagetype
    $imagetype = \'image/jpeg\';

    // query how many images the current user already uploaded
    global $current_user;
    $args = array(
        \'orderby\'         => \'post_date\',
        \'order\'           => \'DESC\',
        \'numberposts\'     => -1,
        \'post_type\'       => \'attachment\',
        \'author\'          => $current_user->ID,
    );
    $attachmentsbyuser = get_posts( $args );

    if ( ( $size > $limit ) && ($is_image !== false) ) { // check if the image is small enough
        $file[\'error\'] = \'Image files must be smaller than \'.$limit.\'KB\';
    } elseif ( $type != $imagetype ) { // check if image type is allowed
        $file[\'error\'] = \'Image must be \' . $imagetype . \'.\';
    } elseif ( count( $attachmentsbyuser ) >= $imagelimit ) { // check if the user has exceeded the image limit
        $file[\'error\'] = \'Image limit of \' . $imagelimit . \' is exceeded for this user.\';
    }
    return $file;

}