_keyDownHandler: function NavBarContainer_keyDownHandler()

in src/Clients/Web/winjs/js/winjs.js [75088:75208]

• 98 lines of code
• 32 McCabe index (conditional complexity)

                _keyDownHandler: function NavBarContainer_keyDownHandler(ev) {
                    var keyCode = ev.keyCode;
                    if (!ev.altKey && (keyCode === Key.pageUp || keyCode === Key.pageDown)) {
                        var srcElement = ev.target;
                        if (_ElementUtilities._matchesSelector(srcElement, ".win-interactive, .win-interactive *")) {
                            return;
                        }

                        var index = this._keyboardBehavior.currentIndex;
                        this._measure();

                        var sizes = this._sizes;
                        var page = Math.floor(index / (sizes.columnsPerPage * sizes.rowsPerPage));

                        var scrollPositionTarget = null;
                        if (keyCode === Key.pageUp) {
                            if (this.layout === _UI.Orientation.horizontal) {
                                var indexOfFirstItemOnPage = page * sizes.columnsPerPage * sizes.rowsPerPage;
                                if (index === indexOfFirstItemOnPage && this._surfaceEl.children[index].winControl._buttonEl === _Global.document.activeElement) {
                                    // First item on page so go back 1 page.
                                    index = index - sizes.columnsPerPage * sizes.rowsPerPage;
                                } else {
                                    // Not first item on page so go to the first item on page.
                                    index = indexOfFirstItemOnPage;
                                }
                            } else {
                                var currentItem = this._surfaceEl.children[index];
                                var top = currentItem.offsetTop;
                                var bottom = top + currentItem.offsetHeight;
                                var scrollPosition = this._zooming ? this._zoomPosition : this._scrollPosition;

                                if (top >= scrollPosition && bottom < scrollPosition + sizes.viewportOffsetHeight) {
                                    // current item is fully on screen.
                                    while (index > 0 &&
                                        this._surfaceEl.children[index - 1].offsetTop > scrollPosition) {
                                        index--;
                                    }
                                }

                                if (this._keyboardBehavior.currentIndex === index) {
                                    var scrollPositionForOnePageAboveItem = bottom - sizes.viewportOffsetHeight;
                                    index = Math.max(0, index - 1);
                                    while (index > 0 &&
                                        this._surfaceEl.children[index - 1].offsetTop > scrollPositionForOnePageAboveItem) {
                                        index--;
                                    }
                                    if (index > 0) {
                                        scrollPositionTarget = this._surfaceEl.children[index].offsetTop - this._sizes.itemMarginTop;
                                    } else {
                                        scrollPositionTarget = 0;
                                    }
                                }
                            }

                            index = Math.max(index, 0);
                            this._keyboardBehavior.currentIndex = index;

                            var element = this._surfaceEl.children[index].winControl._buttonEl;

                            if (scrollPositionTarget !== null) {
                                this._scrollTo(scrollPositionTarget);
                            }

                            _ElementUtilities._setActive(element, this._viewportEl);
                        } else {
                            if (this.layout === _UI.Orientation.horizontal) {
                                var indexOfLastItemOnPage = (page + 1) * sizes.columnsPerPage * sizes.rowsPerPage - 1;

                                if (index === indexOfLastItemOnPage) {
                                    // Last item on page so go forward 1 page.
                                    index = index + sizes.columnsPerPage * sizes.rowsPerPage;
                                } else {
                                    // Not Last item on page so go to last item on page.
                                    index = indexOfLastItemOnPage;
                                }
                            } else {
                                var currentItem = this._surfaceEl.children[this._keyboardBehavior.currentIndex];
                                var top = currentItem.offsetTop;
                                var bottom = top + currentItem.offsetHeight;
                                var scrollPosition = this._zooming ? this._zoomPosition : this._scrollPosition;

                                if (top >= scrollPosition && bottom < scrollPosition + sizes.viewportOffsetHeight) {
                                    // current item is fully on screen.
                                    while (index < this._surfaceEl.children.length - 1 &&
                                        this._surfaceEl.children[index + 1].offsetTop + this._surfaceEl.children[index + 1].offsetHeight < scrollPosition + sizes.viewportOffsetHeight) {
                                        index++;
                                    }
                                }

                                if (index === this._keyboardBehavior.currentIndex) {
                                    var scrollPositionForOnePageBelowItem = top + sizes.viewportOffsetHeight;
                                    index = Math.min(this._surfaceEl.children.length - 1, index + 1);
                                    while (index < this._surfaceEl.children.length - 1 &&
                                        this._surfaceEl.children[index + 1].offsetTop + this._surfaceEl.children[index + 1].offsetHeight < scrollPositionForOnePageBelowItem) {
                                        index++;
                                    }

                                    if (index < this._surfaceEl.children.length - 1) {
                                        scrollPositionTarget = this._surfaceEl.children[index + 1].offsetTop - this._sizes.viewportOffsetHeight;
                                    } else {
                                        scrollPositionTarget = this._scrollLength - this._sizes.viewportOffsetHeight;
                                    }
                                }
                            }

                            index = Math.min(index, this._surfaceEl.children.length - 1);
                            this._keyboardBehavior.currentIndex = index;

                            var element = this._surfaceEl.children[index].winControl._buttonEl;

                            if (scrollPositionTarget !== null) {
                                this._scrollTo(scrollPositionTarget);
                            }

                            try {
                                _ElementUtilities._setActive(element, this._viewportEl);
                            } catch (e) {
                            }
                        }
                    }
                },