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// Copyright 2006 The Closure Library Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//      http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS-IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/**
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 * @fileoverview Anchored viewport positioning class.
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 *
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 * @author [email protected] (Emil A Eklund)
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 */
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goog.provide('goog.positioning.AnchoredViewportPosition');
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goog.require('goog.positioning');
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goog.require('goog.positioning.AnchoredPosition');
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goog.require('goog.positioning.Overflow');
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goog.require('goog.positioning.OverflowStatus');
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/**
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 * Encapsulates a popup position where the popup is anchored at a corner of
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 * an element. The corners are swapped if dictated by the viewport. For instance
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 * if a popup is anchored with its top left corner to the bottom left corner of
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 * the anchor the popup is either displayed below the anchor (as specified) or
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 * above it if there's not enough room to display it below.
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 *
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 * When using this positioning object it's recommended that the movable element
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 * be absolutely positioned.
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 *
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 * @param {Element} anchorElement Element the movable element should be
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 *     anchored against.
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 * @param {goog.positioning.Corner} corner Corner of anchored element the
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 *     movable element should be positioned at.
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 * @param {boolean=} opt_adjust Whether the positioning should be adjusted until
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 *     the element fits inside the viewport even if that means that the anchored
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 *     corners are ignored.
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 * @param {goog.math.Box=} opt_overflowConstraint Box object describing the
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 *     dimensions in which the movable element could be shown.
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 * @constructor
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 * @extends {goog.positioning.AnchoredPosition}
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 */
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goog.positioning.AnchoredViewportPosition = function(
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    anchorElement, corner, opt_adjust, opt_overflowConstraint) {
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  goog.positioning.AnchoredPosition.call(this, anchorElement, corner);
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  /**
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   * The last resort algorithm to use if the algorithm can't fit inside
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   * the viewport.
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   *
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   * IGNORE = do nothing, just display at the preferred position.
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   *
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   * ADJUST_X | ADJUST_Y = Adjust until the element fits, even if that means
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   * that the anchored corners are ignored.
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   *
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   * @type {number}
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   * @private
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   */
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  this.lastResortOverflow_ = opt_adjust ? (goog.positioning.Overflow.ADJUST_X |
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                                           goog.positioning.Overflow.ADJUST_Y) :
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                                          goog.positioning.Overflow.IGNORE;
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  /**
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   * The dimensions in which the movable element could be shown.
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   * @type {goog.math.Box|undefined}
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   * @private
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   */
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  this.overflowConstraint_ = opt_overflowConstraint || undefined;
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};
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goog.inherits(
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    goog.positioning.AnchoredViewportPosition,
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    goog.positioning.AnchoredPosition);
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/**
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 * @return {goog.math.Box|undefined} The box object describing the
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 *     dimensions in which the movable element will be shown.
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 */
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goog.positioning.AnchoredViewportPosition.prototype.getOverflowConstraint =
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    function() {
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  return this.overflowConstraint_;
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};
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/**
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 * @param {goog.math.Box|undefined} overflowConstraint Box object describing the
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 *     dimensions in which the movable element could be shown.
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 */
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goog.positioning.AnchoredViewportPosition.prototype.setOverflowConstraint =
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    function(overflowConstraint) {
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  this.overflowConstraint_ = overflowConstraint;
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};
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/**
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 * @return {number} A bitmask for the "last resort" overflow.
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 */
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goog.positioning.AnchoredViewportPosition.prototype.getLastResortOverflow =
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    function() {
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  return this.lastResortOverflow_;
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};
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/**
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 * @param {number} lastResortOverflow A bitmask for the "last resort" overflow,
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 *     if we fail to fit the element on-screen.
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 */
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goog.positioning.AnchoredViewportPosition.prototype.setLastResortOverflow =
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    function(lastResortOverflow) {
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  this.lastResortOverflow_ = lastResortOverflow;
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};
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/**
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 * Repositions the movable element.
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 *
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 * @param {Element} movableElement Element to position.
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 * @param {goog.positioning.Corner} movableCorner Corner of the movable element
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 *     that should be positioned adjacent to the anchored element.
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 * @param {goog.math.Box=} opt_margin A margin specified in pixels.
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 * @param {goog.math.Size=} opt_preferredSize The preferred size of the
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 *     movableElement.
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 * @override
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 */
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goog.positioning.AnchoredViewportPosition.prototype.reposition = function(
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    movableElement, movableCorner, opt_margin, opt_preferredSize) {
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  var status = goog.positioning.positionAtAnchor(
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      this.element, this.corner, movableElement, movableCorner, null,
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      opt_margin,
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      goog.positioning.Overflow.FAIL_X | goog.positioning.Overflow.FAIL_Y,
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      opt_preferredSize, this.overflowConstraint_);
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  // If the desired position is outside the viewport try mirroring the corners
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  // horizontally or vertically.
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  if (status & goog.positioning.OverflowStatus.FAILED) {
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    var cornerFallback = this.adjustCorner(status, this.corner);
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    var movableCornerFallback = this.adjustCorner(status, movableCorner);
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    status = goog.positioning.positionAtAnchor(
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        this.element, cornerFallback, movableElement, movableCornerFallback,
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        null, opt_margin,
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        goog.positioning.Overflow.FAIL_X | goog.positioning.Overflow.FAIL_Y,
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        opt_preferredSize, this.overflowConstraint_);
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    if (status & goog.positioning.OverflowStatus.FAILED) {
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      // If that also fails, pick the best corner from the two tries,
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      // and adjust the position until it fits.
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      cornerFallback = this.adjustCorner(status, cornerFallback);
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      movableCornerFallback = this.adjustCorner(status, movableCornerFallback);
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      goog.positioning.positionAtAnchor(
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          this.element, cornerFallback, movableElement, movableCornerFallback,
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          null, opt_margin, this.getLastResortOverflow(), opt_preferredSize,
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          this.overflowConstraint_);
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    }
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  }
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};
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/**
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 * Adjusts the corner if X or Y positioning failed.
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 * @param {number} status The status of the last positionAtAnchor call.
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 * @param {goog.positioning.Corner} corner The corner to adjust.
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 * @return {goog.positioning.Corner} The adjusted corner.
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 * @protected
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 */
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goog.positioning.AnchoredViewportPosition.prototype.adjustCorner = function(
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    status, corner) {
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  if (status & goog.positioning.OverflowStatus.FAILED_HORIZONTAL) {
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    corner = goog.positioning.flipCornerHorizontal(corner);
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  }
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  if (status & goog.positioning.OverflowStatus.FAILED_VERTICAL) {
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    corner = goog.positioning.flipCornerVertical(corner);
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  }
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  return corner;
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};
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