Function to add an avatar...

bp-custom.php

<?php
/**
 * Must used functions
 *
 * Functions that will always be loaded
 */

// Exit if accessed directly
defined( 'ABSPATH' ) or die;

class Sven_Attachment {

	public $result = false;

	public function __construct( $item_id = 0, $object = '', $file = false ) {
		if ( empty( $item_id ) || empty( $object ) ) {
			return;
		}

		$this->item_id = (int) $item_id;
		$this->object  = sanitize_key( $object );

		// Defaults to user
		$this->component = 'xprofile';

		// might be improvable!
		if ( 'user' !== $this->object ) {
			$this->component = $this->object . 's';
		}

		// It's a new upload
		if ( is_array( $file ) ) {
			$this->upload( $file );

		// it's an absolute path to a previously uploaded image file
		} elseif ( ! empty( $file ) ) {
			$this->crop( $file );
		}
	}

	public function upload( $file = array() ) {
		$bp = buddypress();
		if ( ! isset( $bp->avatar_admin ) ) {
			$bp->avatar_admin = new StdClass;
		}

		// Skip the test form
		add_filter( 'bp_attachment_upload_overrides', array( $this, 'upload_overrides' ), 10, 1 );

		$uploaded = bp_core_avatar_handle_upload( $file, array( $this, 'upload_dir_filter' ) );

		// Restore the test form
		remove_filter( 'bp_attachment_upload_overrides', array( $this, 'upload_overrides' ), 10, 1 );

		if ( empty( $uploaded ) || ! isset( $bp->avatar_admin->image->dir ) ) {
			$this->result = false;
			return $this->result;
		}

		$this->crop( $bp->avatar_admin->image->dir );
	}

	public function crop( $image_file = '' ) {
		$avatar_dir      = sprintf( '%s-avatars', $this->object );
		$upload_path     = bp_core_avatar_upload_path();
		$avatar_dir_path = $upload_path . '/' . $avatar_dir . '/' . $this->item_id;

		if ( file_exists( $image_file ) ) {
			$image = basename( $image_file );

			// It's not a regular upload, we may need to create this folder
			if( ! is_dir( $avatar_dir_path ) ) {
				if ( ! wp_mkdir_p( $avatar_dir_path ) ) {
					return false;
				}
			}
			copy( $image_file, $avatar_dir_path . '/' . $image );
			$image_file = '/' . $avatar_dir . '/' . $this->item_id . '/' . $image;
		}

		if ( ! file_exists( $upload_path . $image_file ) ) {
			$this->result = false;
			return $this->result;
		}

		$cropped = bp_core_avatar_handle_crop( array(
			'object'        => $this->object,
			'avatar_dir'    => sprintf( '%s-avatars', $this->object ),
			'item_id'       => $this->item_id,
			'original_file' => $image_file,
			'crop_x'        => 0,
			'crop_y'        => 0
		) );

		if ( ! $cropped ) {
			$this->result = false;
		} else {
			$this->result = true;
		}
	}

	public function upload_overrides( $overrides = array() ) {
		$overrides = array_merge( $overrides, array( 'test_form' => false ) );
		return $overrides;
	}

	public function upload_dir_filter() {
		$callback = $this->component . '_avatar_upload_dir';

		if ( is_callable( $this->component . '_avatar_upload_dir' ) ) {
			return call_user_func_array( $this->component . '_avatar_upload_dir', array( $this->item_id ) );
		// return an error
		} else {
			return array( 'error' => 'dang!' );
		}
	}
}

/**
 * Add an avatar to a BuddyPress object
 *
 * @param  int           $item_id  the ID of the user or group
 * @param  string        $object  the item type (user or group)
 * @param  string|array  $file    the absolute path to a previously uploaded image or $_FILES
 * @return bool          true if the image was set as the avatar for the item it,
 *                       false otherwise
 */
function svn_add_avatar_by_item_id( $item_id = 0, $object = '', $file ) {
	$default_upload_crop = new Sven_Attachment( $item_id, $object, $file );
	return $default_upload_crop->result;
}