text: // Copyright 2006 The Closure Library Authors. All Rights Reserved.
  //
  // 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.
  
  /**
   * @fileoverview Common positioning code.
   *
   * @author eae@google.com (Emil A Eklund)
   */
  
  goog.provide('goog.positioning');
  goog.provide('goog.positioning.Corner');
  goog.provide('goog.positioning.CornerBit');
  goog.provide('goog.positioning.Overflow');
  goog.provide('goog.positioning.OverflowStatus');
  
  goog.require('goog.asserts');
  goog.require('goog.dom');
  goog.require('goog.dom.TagName');
  goog.require('goog.math.Coordinate');
  goog.require('goog.math.Rect');
  goog.require('goog.math.Size');
  goog.require('goog.style');
  goog.require('goog.style.bidi');
  
  
  /**
   * Enum for representing an element corner for positioning the popup.
   *
   * The START constants map to LEFT if element directionality is left
   * to right and RIGHT if the directionality is right to left.
   * Likewise END maps to RIGHT or LEFT depending on the directionality.
   *
   * @enum {number}
   */
  goog.positioning.Corner = {
    TOP_LEFT: 0,
    TOP_RIGHT: 2,
    BOTTOM_LEFT: 1,
    BOTTOM_RIGHT: 3,
    TOP_START: 4,
    TOP_END: 6,
    BOTTOM_START: 5,
    BOTTOM_END: 7
  };
  
  
  /**
   * Enum for bits in the {@see goog.positioning.Corner) bitmap.
   *
   * @enum {number}
   */
  goog.positioning.CornerBit = {
    BOTTOM: 1,
    RIGHT: 2,
    FLIP_RTL: 4
  };
  
  
  /**
   * Enum for representing position handling in cases where the element would be
   * positioned outside the viewport.
   *
   * @enum {number}
   */
  goog.positioning.Overflow = {
    /** Ignore overflow */
    IGNORE: 0,
  
    /** Try to fit horizontally in the viewport at all costs. */
    ADJUST_X: 1,
  
    /** If the element can't fit horizontally, report positioning failure. */
    FAIL_X: 2,
  
    /** Try to fit vertically in the viewport at all costs. */
    ADJUST_Y: 4,
  
    /** If the element can't fit vertically, report positioning failure. */
    FAIL_Y: 8,
  
    /** Resize the element's width to fit in the viewport. */
    RESIZE_WIDTH: 16,
  
    /** Resize the element's height to fit in the viewport. */
    RESIZE_HEIGHT: 32,
  
    /**
     * If the anchor goes off-screen in the x-direction, position the movable
     * element off-screen. Otherwise, try to fit horizontally in the viewport.
     */
    ADJUST_X_EXCEPT_OFFSCREEN: 64 | 1,
  
    /**
     * If the anchor goes off-screen in the y-direction, position the movable
     * element off-screen. Otherwise, try to fit vertically in the viewport.
     */
    ADJUST_Y_EXCEPT_OFFSCREEN: 128 | 4
  };
  
  
  /**
   * Enum for representing the outcome of a positioning call.
   *
   * @enum {number}
   */
  goog.positioning.OverflowStatus = {
    NONE: 0,
    ADJUSTED_X: 1,
    ADJUSTED_Y: 2,
    WIDTH_ADJUSTED: 4,
    HEIGHT_ADJUSTED: 8,
    FAILED_LEFT: 16,
    FAILED_RIGHT: 32,
    FAILED_TOP: 64,
    FAILED_BOTTOM: 128,
    FAILED_OUTSIDE_VIEWPORT: 256
  };
  
  
  /**
   * Shorthand to check if a status code contains any fail code.
   * @type {number}
   */
  goog.positioning.OverflowStatus.FAILED =
      goog.positioning.OverflowStatus.FAILED_LEFT |
      goog.positioning.OverflowStatus.FAILED_RIGHT |
      goog.positioning.OverflowStatus.FAILED_TOP |
      goog.positioning.OverflowStatus.FAILED_BOTTOM |
      goog.positioning.OverflowStatus.FAILED_OUTSIDE_VIEWPORT;
  
  
  /**
   * Shorthand to check if horizontal positioning failed.
   * @type {number}
   */
  goog.positioning.OverflowStatus.FAILED_HORIZONTAL =
      goog.positioning.OverflowStatus.FAILED_LEFT |
      goog.positioning.OverflowStatus.FAILED_RIGHT;
  
  
  /**
   * Shorthand to check if vertical positioning failed.
   * @type {number}
   */
  goog.positioning.OverflowStatus.FAILED_VERTICAL =
      goog.positioning.OverflowStatus.FAILED_TOP |
      goog.positioning.OverflowStatus.FAILED_BOTTOM;
  
  
  /**
   * Positions a movable element relative to an anchor element. The caller
   * specifies the corners that should touch. This functions then moves the
   * movable element accordingly.
   *
   * @param {Element} anchorElement The element that is the anchor for where
   *    the movable element should position itself.
   * @param {goog.positioning.Corner} anchorElementCorner The corner of the
   *     anchorElement for positioning the movable element.
   * @param {Element} movableElement The element to move.
   * @param {goog.positioning.Corner} movableElementCorner The corner of the
   *     movableElement that that should be positioned adjacent to the anchor
   *     element.
   * @param {goog.math.Coordinate=} opt_offset An offset specified in pixels.
   *    After the normal positioning algorithm is applied, the offset is then
   *    applied. Positive coordinates move the popup closer to the center of the
   *    anchor element. Negative coordinates move the popup away from the center
   *    of the anchor element.
   * @param {goog.math.Box=} opt_margin A margin specified in pixels.
   *    After the normal positioning algorithm is applied and any offset, the
   *    margin is then applied. Positive coordinates move the popup away from the
   *    spot it was positioned towards its center. Negative coordinates move it
   *    towards the spot it was positioned away from its center.
   * @param {?number=} opt_overflow Overflow handling mode. Defaults to IGNORE if
   *     not specified. Bitmap, {@see goog.positioning.Overflow}.
   * @param {goog.math.Size=} opt_preferredSize The preferred size of the
   *     movableElement.
   * @param {goog.math.Box=} opt_viewport Box object describing the dimensions of
   *     the viewport. The viewport is specified relative to offsetParent of
   *     {@code movableElement}. In other words, the viewport can be thought of as
   *     describing a "position: absolute" element contained in the offsetParent.
   *     It defaults to visible area of nearest scrollable ancestor of
   *     {@code movableElement} (see {@code goog.style.getVisibleRectForElement}).
   * @return {goog.positioning.OverflowStatus} Status bitmap,
   *     {@see goog.positioning.OverflowStatus}.
   */
  goog.positioning.positionAtAnchor = function(anchorElement,
                                               anchorElementCorner,
                                               movableElement,
                                               movableElementCorner,
                                               opt_offset,
                                               opt_margin,
                                               opt_overflow,
                                               opt_preferredSize,
                                               opt_viewport) {
  
    goog.asserts.assert(movableElement);
    var movableParentTopLeft =
        goog.positioning.getOffsetParentPageOffset(movableElement);
  
    // Get the visible part of the anchor element.  anchorRect is
    // relative to anchorElement's page.
    var anchorRect = goog.positioning.getVisiblePart_(anchorElement);
  
    // Translate anchorRect to be relative to movableElement's page.
    goog.style.translateRectForAnotherFrame(
        anchorRect,
        goog.dom.getDomHelper(anchorElement),
        goog.dom.getDomHelper(movableElement));
  
    // Offset based on which corner of the element we want to position against.
    var corner = goog.positioning.getEffectiveCorner(anchorElement,
                                                     anchorElementCorner);
    // absolutePos is a candidate position relative to the
    // movableElement's window.
    var absolutePos = new goog.math.Coordinate(
        corner & goog.positioning.CornerBit.RIGHT ?
            anchorRect.left + anchorRect.width : anchorRect.left,
        corner & goog.positioning.CornerBit.BOTTOM ?
            anchorRect.top + anchorRect.height : anchorRect.top);
  
    // Translate absolutePos to be relative to the offsetParent.
    absolutePos =
        goog.math.Coordinate.difference(absolutePos, movableParentTopLeft);
  
    // Apply offset, if specified
    if (opt_offset) {
      absolutePos.x += (corner & goog.positioning.CornerBit.RIGHT ? -1 : 1) *
          opt_offset.x;
      absolutePos.y += (corner & goog.positioning.CornerBit.BOTTOM ? -1 : 1) *
          opt_offset.y;
    }
  
    // Determine dimension of viewport.
    var viewport;
    if (opt_overflow) {
      if (opt_viewport) {
        viewport = opt_viewport;
      } else {
        viewport = goog.style.getVisibleRectForElement(movableElement);
        if (viewport) {
          viewport.top -= movableParentTopLeft.y;
          viewport.right -= movableParentTopLeft.x;
          viewport.bottom -= movableParentTopLeft.y;
          viewport.left -= movableParentTopLeft.x;
        }
      }
    }
  
    return goog.positioning.positionAtCoordinate(absolutePos,
                                                 movableElement,
                                                 movableElementCorner,
                                                 opt_margin,
                                                 viewport,
                                                 opt_overflow,
                                                 opt_preferredSize);
  };
  
  
  /**
   * Calculates the page offset of the given element's
   * offsetParent. This value can be used to translate any x- and
   * y-offset relative to the page to an offset relative to the
   * offsetParent, which can then be used directly with as position
   * coordinate for {@code positionWithCoordinate}.
   * @param {!Element} movableElement The element to calculate.
   * @return {!goog.math.Coordinate} The page offset, may be (0, 0).
   */
  goog.positioning.getOffsetParentPageOffset = function(movableElement) {
    // Ignore offset for the BODY element unless its position is non-static.
    // For cases where the offset parent is HTML rather than the BODY (such as in
    // IE strict mode) there's no need to get the position of the BODY as it
    // doesn't affect the page offset.
    var movableParentTopLeft;
    var parent = movableElement.offsetParent;
    if (parent) {
      var isBody = parent.tagName == goog.dom.TagName.HTML ||
          parent.tagName == goog.dom.TagName.BODY;
      if (!isBody ||
          goog.style.getComputedPosition(parent) != 'static') {
        // Get the top-left corner of the parent, in page coordinates.
        movableParentTopLeft = goog.style.getPageOffset(parent);
  
        if (!isBody) {
          movableParentTopLeft = goog.math.Coordinate.difference(
              movableParentTopLeft,
              new goog.math.Coordinate(goog.style.bidi.getScrollLeft(parent),
                  parent.scrollTop));
        }
      }
    }
  
    return movableParentTopLeft || new goog.math.Coordinate();
  };
  
  
  /**
   * Returns intersection of the specified element and
   * goog.style.getVisibleRectForElement for it.
   *
   * @param {Element} el The target element.
   * @return {!goog.math.Rect} Intersection of getVisibleRectForElement
   *     and the current bounding rectangle of the element.  If the
   *     intersection is empty, returns the bounding rectangle.
   * @private
   */
  goog.positioning.getVisiblePart_ = function(el) {
    var rect = goog.style.getBounds(el);
    var visibleBox = goog.style.getVisibleRectForElement(el);
    if (visibleBox) {
      rect.intersection(goog.math.Rect.createFromBox(visibleBox));
    }
    return rect;
  };
  
  
  /**
   * Positions the specified corner of the movable element at the
   * specified coordinate.
   *
   * @param {goog.math.Coordinate} absolutePos The coordinate to position the
   *     element at.
   * @param {Element} movableElement The element to be positioned.
   * @param {goog.positioning.Corner} movableElementCorner The corner of the
   *     movableElement that that should be positioned.
   * @param {goog.math.Box=} opt_margin A margin specified in pixels.
   *    After the normal positioning algorithm is applied and any offset, the
   *    margin is then applied. Positive coordinates move the popup away from the
   *    spot it was positioned towards its center. Negative coordinates move it
   *    towards the spot it was positioned away from its center.
   * @param {goog.math.Box=} opt_viewport Box object describing the dimensions of
   *     the viewport. Required if opt_overflow is specified.
   * @param {?number=} opt_overflow Overflow handling mode. Defaults to IGNORE if
   *     not specified, {@see goog.positioning.Overflow}.
   * @param {goog.math.Size=} opt_preferredSize The preferred size of the
   *     movableElement. Defaults to the current size.
   * @return {goog.positioning.OverflowStatus} Status bitmap.
   */
  goog.positioning.positionAtCoordinate = function(absolutePos,
                                                   movableElement,
                                                   movableElementCorner,
                                                   opt_margin,
                                                   opt_viewport,
                                                   opt_overflow,
                                                   opt_preferredSize) {
    absolutePos = absolutePos.clone();
    var status = goog.positioning.OverflowStatus.NONE;
  
    // Offset based on attached corner and desired margin.
    var corner = goog.positioning.getEffectiveCorner(movableElement,
                                                     movableElementCorner);
    var elementSize = goog.style.getSize(movableElement);
    var size = opt_preferredSize ? opt_preferredSize.clone() :
        elementSize.clone();
  
    var positionResult = goog.positioning.getPositionAtCoordinate(absolutePos,
        size, corner, opt_margin, opt_viewport, opt_overflow);
  
    if (positionResult.status & goog.positioning.OverflowStatus.FAILED) {
      return positionResult.status;
    }
  
    goog.style.setPosition(movableElement, positionResult.rect.getTopLeft());
    size = positionResult.rect.getSize();
    if (!goog.math.Size.equals(elementSize, size)) {
      goog.style.setBorderBoxSize(movableElement, size);
    }
  
    return positionResult.status;
  };
  
  
  /**
   * Computes the position for an element to be placed on-screen at the
   * specified coordinates. Returns an object containing both the resulting
   * rectangle, and the overflow status bitmap.
   *
   * @param {!goog.math.Coordinate} absolutePos The coordinate to position the
   *     element at.
   * @param {!goog.math.Size} elementSize The size of the element to be
   *     positioned.
   * @param {goog.positioning.Corner} elementCorner The corner of the
   *     movableElement that that should be positioned.
   * @param {goog.math.Box=} opt_margin A margin specified in pixels.
   *    After the normal positioning algorithm is applied and any offset, the
   *    margin is then applied. Positive coordinates move the popup away from the
   *    spot it was positioned towards its center. Negative coordinates move it
   *    towards the spot it was positioned away from its center.
   * @param {goog.math.Box=} opt_viewport Box object describing the dimensions of
   *     the viewport. Required if opt_overflow is specified.
   * @param {?number=} opt_overflow Overflow handling mode. Defaults to IGNORE
   *     if not specified, {@see goog.positioning.Overflow}.
   * @return {{rect:!goog.math.Rect, status:goog.positioning.OverflowStatus}}
   *     Object containing the computed position and status bitmap.
   */
  goog.positioning.getPositionAtCoordinate = function(
      absolutePos,
      elementSize,
      elementCorner,
      opt_margin,
      opt_viewport,
      opt_overflow) {
    absolutePos = absolutePos.clone();
    elementSize = elementSize.clone();
    var status = goog.positioning.OverflowStatus.NONE;
  
    if (opt_margin || elementCorner != goog.positioning.Corner.TOP_LEFT) {
      if (elementCorner & goog.positioning.CornerBit.RIGHT) {
        absolutePos.x -= elementSize.width + (opt_margin ? opt_margin.right : 0);
      } else if (opt_margin) {
        absolutePos.x += opt_margin.left;
      }
      if (elementCorner & goog.positioning.CornerBit.BOTTOM) {
        absolutePos.y -= elementSize.height +
            (opt_margin ? opt_margin.bottom : 0);
      } else if (opt_margin) {
        absolutePos.y += opt_margin.top;
      }
    }
  
    // Adjust position to fit inside viewport.
    if (opt_overflow) {
      status = opt_viewport ?
          goog.positioning.adjustForViewport_(
              absolutePos, elementSize, opt_viewport, opt_overflow) :
          goog.positioning.OverflowStatus.FAILED_OUTSIDE_VIEWPORT;
    }
  
    var rect = new goog.math.Rect(0, 0, 0, 0);
    rect.left = absolutePos.x;
    rect.top = absolutePos.y;
    rect.width = elementSize.width;
    rect.height = elementSize.height;
    return {rect: rect, status: status};
  };
  
  
  /**
   * Adjusts the position and/or size of an element, identified by its position
   * and size, to fit inside the viewport. If the position or size of the element
   * is adjusted the pos or size objects, respectively, are modified.
   *
   * @param {goog.math.Coordinate} pos Position of element, updated if the
   *     position is adjusted.
   * @param {goog.math.Size} size Size of element, updated if the size is
   *     adjusted.
   * @param {goog.math.Box} viewport Bounding box describing the viewport.
   * @param {number} overflow Overflow handling mode,
   *     {@see goog.positioning.Overflow}.
   * @return {goog.positioning.OverflowStatus} Status bitmap,
   *     {@see goog.positioning.OverflowStatus}.
   * @private
   */
  goog.positioning.adjustForViewport_ = function(pos, size, viewport, overflow) {
    var status = goog.positioning.OverflowStatus.NONE;
  
    var ADJUST_X_EXCEPT_OFFSCREEN =
        goog.positioning.Overflow.ADJUST_X_EXCEPT_OFFSCREEN;
    var ADJUST_Y_EXCEPT_OFFSCREEN =
        goog.positioning.Overflow.ADJUST_Y_EXCEPT_OFFSCREEN;
    if ((overflow & ADJUST_X_EXCEPT_OFFSCREEN) == ADJUST_X_EXCEPT_OFFSCREEN &&
        (pos.x < viewport.left || pos.x >= viewport.right)) {
      overflow &= ~goog.positioning.Overflow.ADJUST_X;
    }
    if ((overflow & ADJUST_Y_EXCEPT_OFFSCREEN) == ADJUST_Y_EXCEPT_OFFSCREEN &&
        (pos.y < viewport.top || pos.y >= viewport.bottom)) {
      overflow &= ~goog.positioning.Overflow.ADJUST_Y;
    }
  
    // Left edge outside viewport, try to move it.
    if (pos.x < viewport.left && overflow & goog.positioning.Overflow.ADJUST_X) {
      pos.x = viewport.left;
      status |= goog.positioning.OverflowStatus.ADJUSTED_X;
    }
  
    // Left edge inside and right edge outside viewport, try to resize it.
    if (pos.x < viewport.left &&
        pos.x + size.width > viewport.right &&
        overflow & goog.positioning.Overflow.RESIZE_WIDTH) {
      size.width = Math.max(
          size.width - ((pos.x + size.width) - viewport.right), 0);
      status |= goog.positioning.OverflowStatus.WIDTH_ADJUSTED;
    }
  
    // Right edge outside viewport, try to move it.
    if (pos.x + size.width > viewport.right &&
        overflow & goog.positioning.Overflow.ADJUST_X) {
      pos.x = Math.max(viewport.right - size.width, viewport.left);
      status |= goog.positioning.OverflowStatus.ADJUSTED_X;
    }
  
    // Left or right edge still outside viewport, fail if the FAIL_X option was
    // specified, ignore it otherwise.
    if (overflow & goog.positioning.Overflow.FAIL_X) {
      status |= (pos.x < viewport.left ?
                     goog.positioning.OverflowStatus.FAILED_LEFT : 0) |
                (pos.x + size.width > viewport.right ?
                     goog.positioning.OverflowStatus.FAILED_RIGHT : 0);
    }
  
    // Top edge outside viewport, try to move it.
    if (pos.y < viewport.top && overflow & goog.positioning.Overflow.ADJUST_Y) {
      pos.y = viewport.top;
      status |= goog.positioning.OverflowStatus.ADJUSTED_Y;
    }
  
    // Bottom edge inside and top edge outside viewport, try to resize it.
    if (pos.y <= viewport.top &&
        pos.y + size.height < viewport.bottom &&
        overflow & goog.positioning.Overflow.RESIZE_HEIGHT) {
      size.height = Math.max(size.height - (viewport.top - pos.y), 0);
      pos.y = viewport.top;
      status |= goog.positioning.OverflowStatus.HEIGHT_ADJUSTED;
    }
  
    // Top edge inside and bottom edge outside viewport, try to resize it.
    if (pos.y >= viewport.top &&
        pos.y + size.height > viewport.bottom &&
        overflow & goog.positioning.Overflow.RESIZE_HEIGHT) {
      size.height = Math.max(
          size.height - ((pos.y + size.height) - viewport.bottom), 0);
      status |= goog.positioning.OverflowStatus.HEIGHT_ADJUSTED;
    }
  
    // Bottom edge outside viewport, try to move it.
    if (pos.y + size.height > viewport.bottom &&
        overflow & goog.positioning.Overflow.ADJUST_Y) {
      pos.y = Math.max(viewport.bottom - size.height, viewport.top);
      status |= goog.positioning.OverflowStatus.ADJUSTED_Y;
    }
  
    // Top or bottom edge still outside viewport, fail if the FAIL_Y option was
    // specified, ignore it otherwise.
    if (overflow & goog.positioning.Overflow.FAIL_Y) {
      status |= (pos.y < viewport.top ?
                     goog.positioning.OverflowStatus.FAILED_TOP : 0) |
                (pos.y + size.height > viewport.bottom ?
                     goog.positioning.OverflowStatus.FAILED_BOTTOM : 0);
    }
  
    return status;
  };
  
  
  /**
   * Returns an absolute corner (top/bottom left/right) given an absolute
   * or relative (top/bottom start/end) corner and the direction of an element.
   * Absolute corners remain unchanged.
   * @param {Element} element DOM element to test for RTL direction.
   * @param {goog.positioning.Corner} corner The popup corner used for
   *     positioning.
   * @return {goog.positioning.Corner} Effective corner.
   */
  goog.positioning.getEffectiveCorner = function(element, corner) {
    return /** @type {goog.positioning.Corner} */ (
        (corner & goog.positioning.CornerBit.FLIP_RTL &&
            goog.style.isRightToLeft(element) ?
            corner ^ goog.positioning.CornerBit.RIGHT :
            corner
        ) & ~goog.positioning.CornerBit.FLIP_RTL);
  };
  
  
  /**
   * Returns the corner opposite the given one horizontally.
   * @param {goog.positioning.Corner} corner The popup corner used to flip.
   * @return {goog.positioning.Corner} The opposite corner horizontally.
   */
  goog.positioning.flipCornerHorizontal = function(corner) {
    return /** @type {goog.positioning.Corner} */ (corner ^
        goog.positioning.CornerBit.RIGHT);
  };
  
  
  /**
   * Returns the corner opposite the given one vertically.
   * @param {goog.positioning.Corner} corner The popup corner used to flip.
   * @return {goog.positioning.Corner} The opposite corner vertically.
   */
  goog.positioning.flipCornerVertical = function(corner) {
    return /** @type {goog.positioning.Corner} */ (corner ^
        goog.positioning.CornerBit.BOTTOM);
  };
  
  
  /**
   * Returns the corner opposite the given one horizontally and vertically.
   * @param {goog.positioning.Corner} corner The popup corner used to flip.
   * @return {goog.positioning.Corner} The opposite corner horizontally and
   *     vertically.
   */
  goog.positioning.flipCorner = function(corner) {
    return /** @type {goog.positioning.Corner} */ (corner ^
        goog.positioning.CornerBit.BOTTOM ^
        goog.positioning.CornerBit.RIGHT);
  };
  
  