element-web/src/components/views/elements/AccessibleButton.js

/*
 Copyright 2016 Jani Mustonen

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

import React from 'react';
import PropTypes from 'prop-types';

import {Key} from '../../../Keyboard';

/**
 * AccessibleButton is a generic wrapper for any element that should be treated
 * as a button.  Identifies the element as a button, setting proper tab
 * indexing and keyboard activation behavior.
 *
 * @param {Object} props  react element properties
 * @returns {Object} rendered react
 */
export default function AccessibleButton(props) {
    const {element, onClick, children, kind, disabled, ...restProps} = props;

    if (!disabled) {
        restProps.onClick = onClick;
        // We need to consume enter onKeyDown and space onKeyUp
        // otherwise we are risking also activating other keyboard focusable elements
        // that might receive focus as a result of the AccessibleButtonClick action
        // It's because we are using html buttons at a few places e.g. inside dialogs
        // And divs which we report as role button to assistive technologies.
        // Browsers handle space and enter keypresses differently and we are only adjusting to the
        // inconsistencies here
        restProps.onKeyDown = function(e) {
            if (e.key === Key.ENTER) {
                e.stopPropagation();
                e.preventDefault();
                return onClick(e);
            }
            if (e.key === Key.SPACE) {
                e.stopPropagation();
                e.preventDefault();
            }
        };
        restProps.onKeyUp = function(e) {
            if (e.key === Key.SPACE) {
                e.stopPropagation();
                e.preventDefault();
                return onClick(e);
            }
            if (e.key === Key.ENTER) {
                e.stopPropagation();
                e.preventDefault();
            }
        };
    }

    // Pass through the ref - used for keyboard shortcut access to some buttons
    restProps.ref = restProps.inputRef;
    delete restProps.inputRef;

    restProps.className = (restProps.className ? restProps.className + " " : "") + "mx_AccessibleButton";

    if (kind) {
        // We apply a hasKind class to maintain backwards compatibility with
        // buttons which might not know about kind and break
        restProps.className += " mx_AccessibleButton_hasKind mx_AccessibleButton_kind_" + kind;
    }

    if (disabled) {
        restProps.className += " mx_AccessibleButton_disabled";
        restProps["aria-disabled"] = true;
    }

    return React.createElement(element, restProps, children);
}

/**
 * children: React's magic prop. Represents all children given to the element.
 * element:  (optional) The base element type. "div" by default.
 * onClick:  (required) Event handler for button activation. Should be
 *           implemented exactly like a normal onClick handler.
 */
AccessibleButton.propTypes = {
    children: PropTypes.node,
    inputRef: PropTypes.oneOfType([
        // Either a function
        PropTypes.func,
        // Or the instance of a DOM native element
        PropTypes.shape({ current: PropTypes.instanceOf(Element) }),
    ]),
    element: PropTypes.string,
    onClick: PropTypes.func.isRequired,

    // The kind of button, similar to how Bootstrap works.
    // See available classes for AccessibleButton for options.
    kind: PropTypes.string,
    // The ARIA role
    role: PropTypes.string,
    // The tabIndex
    tabIndex: PropTypes.oneOfType([PropTypes.number, PropTypes.string]),

    disabled: PropTypes.bool,
};

AccessibleButton.defaultProps = {
    element: 'div',
    role: 'button',
    tabIndex: "0",
};

AccessibleButton.displayName = "AccessibleButton";