devextreme/dist/transpiled/core/utils/resize_callbacks.js

HTML5 JavaScript Component Suite for Responsive Web Development

"use strict";

var windowUtils = require("./window"),
    domAdapter = require("../dom_adapter"),
    Callbacks = require("./callbacks"),
    readyCallbacks = require("./ready_callbacks"),
    callOnce = require("./call_once");

var resizeCallbacks = function () {
    var prevSize,
        callbacks = Callbacks(),
        originalCallbacksAdd = callbacks.add,
        originalCallbacksRemove = callbacks.remove;

    if (!windowUtils.hasWindow()) {
        return callbacks;
    }

    var formatSize = function formatSize() {
        var documentElement = domAdapter.getDocumentElement();
        return {
            width: documentElement.clientWidth,
            height: documentElement.clientHeight
        };
    };

    var handleResize = function handleResize() {
        var now = formatSize();
        if (now.width === prevSize.width && now.height === prevSize.height) {
            return;
        }

        var changedDimension;
        if (now.width === prevSize.width) {
            changedDimension = 'height';
        }
        if (now.height === prevSize.height) {
            changedDimension = 'width';
        }

        prevSize = now;

        callbacks.fire(changedDimension);
    };

    var setPrevSize = callOnce(function () {
        prevSize = formatSize();
    });

    var removeListener;

    callbacks.add = function () {
        var result = originalCallbacksAdd.apply(callbacks, arguments);

        setPrevSize();

        readyCallbacks.add(function () {
            if (!removeListener && callbacks.has()) {
                removeListener = domAdapter.listen(windowUtils.getWindow(), "resize", handleResize);
            }
        });

        return result;
    };

    callbacks.remove = function () {
        var result = originalCallbacksRemove.apply(callbacks, arguments);

        if (!callbacks.has() && removeListener) {
            removeListener();
            removeListener = undefined;
        }
        return result;
    };

    return callbacks;
}();

module.exports = resizeCallbacks;