# Yahoo! UI Library

### dom 3.0.0b1

Yahoo! UI Library > dom > dom-region.js (source view)
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    (function(Y) {
    var TOP = 'top',
        RIGHT = 'right',
        BOTTOM = 'bottom',
        LEFT = 'left',

        getOffsets = function(r1, r2) {
            var t = Math.max(r1[TOP], r2[TOP]),
                r = Math.min(r1[RIGHT], r2[RIGHT]),
                b = Math.min(r1[BOTTOM], r2[BOTTOM]),
                l = Math.max(r1[LEFT], r2[LEFT]),
                ret = {};

            ret[TOP] = t;
            ret[RIGHT] = r;
            ret[BOTTOM] = b;
            ret[LEFT] = l;
            return ret;
        },

        DOM = Y.DOM;

    Y.mix(DOM, {
        /**
         * Returns an Object literal containing the following about this element: (top, right, bottom, left)
         * @method region
         * @param {HTMLElement} element The DOM element.
         @return {Object} Object literal containing the following about this element: (top, right, bottom, left)
         */
        region: function(node) {
            var xy = DOM.getXY(node),
                ret = false;

            if (node && xy) {
                ret = DOM._getRegion(
                    xy[1], // top
                    xy[0] + node.offsetWidth, // right
                    xy[1] + node.offsetHeight, // bottom
                    xy[0] // left
                );
            }

            return ret;
        },

        /**
         * Find the intersect information for the passes nodes.
         * @method intersect
         * @param {HTMLElement} element The first element
         * @param {HTMLElement | Object} element2 The element or region to check the interect with
         * @param {Object} altRegion An object literal containing the region for the first element if we already have the data (for performance i.e. DragDrop)
         @return {Object} Object literal containing the following intersection data: (top, right, bottom, left, area, yoff, xoff, inRegion)
         */
        intersect: function(node, node2, altRegion) {
            var r = altRegion || DOM.region(node), region = {},
                n = node2,
                off;

            if (n.tagName) {
                region = DOM.region(n);
            } else if (Y.Lang.isObject(node2)) {
                region = node2;
            } else {
                return false;
            }

            off = getOffsets(region, r);
            return {
                top: off[TOP],
                right: off[RIGHT],
                bottom: off[BOTTOM],
                left: off[LEFT],
                area: ((off[BOTTOM] - off[TOP]) * (off[RIGHT] - off[LEFT])),
                yoff: ((off[BOTTOM] - off[TOP])),
                xoff: (off[RIGHT] - off[LEFT]),
                inRegion: DOM.inRegion(node, node2, false, altRegion)
            };

        },
        /**
         * Check if any part of this node is in the passed region
         * @method inRegion
         * @param {Object} node2 The node to get the region from or an Object literal of the region
         * $param {Boolean} all Should all of the node be inside the region
         * @param {Object} altRegion An object literal containing the region for this node if we already have the data (for performance i.e. DragDrop)
         * @return {Boolean} True if in region, false if not.
         */
        inRegion: function(node, node2, all, altRegion) {
            var region = {},
                r = altRegion || DOM.region(node),
                n = node2,
                off;

            if (n.tagName) {
                region = DOM.region(n);
            } else if (Y.Lang.isObject(node2)) {
                region = node2;
            } else {
                return false;
            }

            if (all) {
                return (
                    r[LEFT]   >= region[LEFT]   &&
                    r[RIGHT]  <= region[RIGHT]  &&
                    r[TOP]    >= region[TOP]    &&
                    r[BOTTOM] <= region[BOTTOM]  );
            } else {
                off = getOffsets(region, r);
                if (off[BOTTOM] >= off[TOP] && off[RIGHT] >= off[LEFT]) {
                    return true;
                } else {
                    return false;
                }

            }
        },

        /**
         * Check if any part of this element is in the viewport
         * @method inViewportRegion
         * @param {HTMLElement} element The DOM element.
         * @param {Boolean} all Should all of the node be inside the region
         * @param {Object} altRegion An object literal containing the region for this node if we already have the data (for performance i.e. DragDrop)
         * @return {Boolean} True if in region, false if not.
         */
        inViewportRegion: function(node, all, altRegion) {
            return DOM.inRegion(node, DOM.viewportRegion(node), all, altRegion);

        },

        _getRegion: function(t, r, b, l) {
            var region = {};

            region[TOP] = region[1] = t;
            region[LEFT] = region[0] = l;
            region[BOTTOM] = b;
            region[RIGHT] = r;
            region.width = region[RIGHT] - region[LEFT];
            region.height = region[BOTTOM] - region[TOP];

            return region;
        },

        /**
         * Returns an Object literal containing the following about the visible region of viewport: (top, right, bottom, left)
         * @method viewportRegion
         @return {Object} Object literal containing the following about the visible region of the viewport: (top, right, bottom, left)
         */
        viewportRegion: function(node) {
            node = node || Y.config.doc.documentElement;
            var ret = false,
                scrollX,
                scrollY;

            if (node) {
                scrollX = DOM.docScrollX(node);
                scrollY = DOM.docScrollY(node);

                ret = DOM._getRegion(scrollY, // top
                    DOM.winWidth(node) + scrollX, // right
                    scrollY + DOM.winHeight(node), // bottom
                    scrollX); // left
            }

            return ret;
        }
    });
    })(Y);

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