ios/web/web_state/js/resources/context_menu.js

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview APIs used by CRWContextMenuController.
 */

goog.provide('__crWeb.contextMenu');

/** Beginning of anonymous object */
(function() {

  /**
   * Returns the url of the image or link under the selected point. Returns an
   * empty object if no links or images are found.
   * @param {number} x Horizontal center of the selected point in web view
   *                   coordinates.
   * @param {number} y Vertical center of the selected point in web view
   *                 coordinates.
   * @param {number} webViewWidth the width of web view.
   * @param {number} webViewHeight the height of web view.
   * @return {!Object} An object of the form {
   *     href,  // URL of the link under the point
   *     innerText,  // innerText of the link, if the selected element is a link
   *     src,  // src of the image, if the selected element is an image
   *     title,  // title of the image, if the selected
   *     referrerPolicy
   *   }
   *   where:
   *     <ul>
   *     <li>href, innerText are set if the selected element is a link.
   *     <li>src, title are set if the selected element is an image.
   *     <li>href is also set if the selected element is an image with a link.
   *     <li>referrerPolicy is the referrer policy to use for navigations away
   *         from the current page.
   *     </ul>
   */
  __gCrWeb['getElementFromPoint'] =
      function(x, y, webViewWidth, webViewHeight) {
        var scale = getPageWidth() / webViewWidth;
        return getElementFromPointInPageCoordinates(x * scale, y * scale)
      };

  /**
   * Suppresses the next click such that they are not handled by JS click
   * event handlers.
   * @type {void}
   */
  __gCrWeb['suppressNextClick'] = function() {
    var suppressNextClick = function(evt) {
      evt.preventDefault();
      document.removeEventListener('click', suppressNextClick, false);
    };
    document.addEventListener('click', suppressNextClick);
  };

  /**
   * Returns the url of the image or link under the selected point in page
   * coordinates. Returns an empty object if no links or images are found.
   * @param {number} x Horizontal center of the selected point in page
   *                 coordinates.
   * @param {number} y Vertical center of the selected point in page
   *                 coordinates.
   * @return {!Object} An object in the same form as
   *                   {@code getElementFromPoint} result.
   */
  var getElementFromPointInPageCoordinates = function(x, y) {
    var hitCoordinates = spiralCoordinates_(x, y);
    for (var index = 0; index < hitCoordinates.length; index++) {
      var coordinates = hitCoordinates[index];

      var element = elementFromPoint_(coordinates.x, coordinates.y);
      if (!element || !element.tagName) {
        // Nothing under the hit point. Try the next hit point.
        continue;
      }

      // Also check element's ancestors. A bound on the level is used here to
      // avoid large overhead when no links or images are found.
      var level = 0;
      while (++level < 8 && element && element != document) {
        var tagName = element.tagName;
        if (!tagName)
          continue;
        tagName = tagName.toLowerCase();

        if (tagName === 'input' || tagName === 'textarea' ||
            tagName === 'select' || tagName === 'option') {
          // If the element is a known input element, stop the spiral search and
          // return empty results.
          return {};
        }

       if (getComputedWebkitTouchCallout_(element) !== 'none') {
          if (tagName === 'a' && element.href) {
            // Found a link.
            return {
              href: element.href,
              referrerPolicy: getReferrerPolicy_(element),
              innerText: element.innerText
            };
          }

          if (tagName === 'img' && element.src) {
            // Found an image.
            var result = {
              src: element.src,
              referrerPolicy: getReferrerPolicy_()
            };
            // Copy the title, if any.
            if (element.title) {
              result.title = element.title;
            }
            // Check if the image is also a link.
            var parent = element.parentNode;
            while (parent) {
              if (parent.tagName &&
                  parent.tagName.toLowerCase() === 'a' &&
                  parent.href) {
                // This regex identifies strings like void(0),
                // void(0)  ;void(0);, ;;;;
                // which result in a NOP when executed as JavaScript.
                var regex = RegExp("^javascript:(?:(?:void\\(0\\)|;)\\s*)+$");
                if (parent.href.match(regex)) {
                  parent = parent.parentNode;
                  continue;
                }
                result.href = parent.href;
                result.referrerPolicy = getReferrerPolicy_(parent);
                break;
              }
              parent = parent.parentNode;
            }
            return result;
          }
        }
        element = element.parentNode;
      }
    }
    return {};
  };

  /**
   * Returns the margin in points around touchable elements (e.g. links for
   * custom context menu).
   * @type {number}
   */
  var getPageWidth = function() {
    var documentElement = document.documentElement;
    var documentBody = document.body;
    return Math.max(documentElement.clientWidth,
                    documentElement.scrollWidth,
                    documentElement.offsetWidth,
                    documentBody.scrollWidth,
                    documentBody.offsetWidth);
  };

  /**
   * Implementation of document.elementFromPoint that is working for iOS4 and
   * iOS5 and that also goes into frames and iframes.
   * @private
   */
  var elementFromPoint_ = function(x, y) {
    var elementFromPointIsUsingViewPortCoordinates = function(win) {
      if (win.pageYOffset > 0) {  // Page scrolled down.
        return (win.document.elementFromPoint(
            0, win.pageYOffset + win.innerHeight - 1) === null);
      }
      if (win.pageXOffset > 0) {  // Page scrolled to the right.
        return (win.document.elementFromPoint(
            win.pageXOffset + win.innerWidth - 1, 0) === null);
      }
      return false;  // No scrolling, don't care.
    };

    var newCoordinate = function(x, y) {
      var coordinates = {
          x: x, y: y,
          viewPortX: x - window.pageXOffset, viewPortY: y - window.pageYOffset,
          useViewPortCoordinates: false,
          window: window
      };
      return coordinates;
    };

    // Returns the coordinates of the upper left corner of |obj| in the
    // coordinates of the window that |obj| is in.
    var getPositionInWindow = function(obj) {
      var coord = { x: 0, y: 0 };
      while (obj.offsetParent) {
        coord.x += obj.offsetLeft;
        coord.y += obj.offsetTop;
        obj = obj.offsetParent;
      }
      return coord;
    };

    var elementsFromCoordinates = function(coordinates) {
      coordinates.useViewPortCoordinates = coordinates.useViewPortCoordinates ||
          elementFromPointIsUsingViewPortCoordinates(coordinates.window);

      var currentElement = null;
      if (coordinates.useViewPortCoordinates) {
        currentElement = coordinates.window.document.elementFromPoint(
            coordinates.viewPortX, coordinates.viewPortY);
      } else {
        currentElement = coordinates.window.document.elementFromPoint(
            coordinates.x, coordinates.y);
      }
      // We have to check for tagName, because if a selection is made by the
      // UIWebView, the element we will get won't have one.
      if (!currentElement || !currentElement.tagName) {
        return null;
      }
      if (currentElement.tagName.toLowerCase() === 'iframe' ||
          currentElement.tagName.toLowerCase() === 'frame') {
        // Check if the frame is in a different domain using only information
        // visible to the current frame (i.e. currentElement.src) to avoid
        // triggering a SecurityError in the console.
        if (!__gCrWeb.common.isSameOrigin(
            window.location.href, currentElement.src)) {
          return currentElement;
        }
        var framePosition = getPositionInWindow(currentElement);
        coordinates.viewPortX -=
            framePosition.x - coordinates.window.pageXOffset;
        coordinates.viewPortY -=
            framePosition.y - coordinates.window.pageYOffset;
        coordinates.window = currentElement.contentWindow;
        coordinates.x -= framePosition.x + coordinates.window.pageXOffset;
        coordinates.y -= framePosition.y + coordinates.window.pageYOffset;
        return elementsFromCoordinates(coordinates);
      }
      return currentElement;
    };

    return elementsFromCoordinates(newCoordinate(x, y));
  };

  /** @private */
  var spiralCoordinates_ = function(x, y) {
    var MAX_ANGLE = Math.PI * 2.0 * 3.0;
    var POINT_COUNT = 30;
    var ANGLE_STEP = MAX_ANGLE / POINT_COUNT;
    var TOUCH_MARGIN = 25;
    var SPEED = TOUCH_MARGIN / MAX_ANGLE;

    var coordinates = [];
    for (var index = 0; index < POINT_COUNT; index++) {
      var angle = ANGLE_STEP * index;
      var radius = angle * SPEED;

      coordinates.push({x: x + Math.round(Math.cos(angle) * radius),
                        y: y + Math.round(Math.sin(angle) * radius)});
    }

    return coordinates;
  };

  /** @private */
  var getComputedWebkitTouchCallout_ = function(element) {
    return window.getComputedStyle(element, null)['webkitTouchCallout'];
  };

  /**
   * Gets the referrer policy to use for navigations away from the current page.
   * If a link element is passed, and it includes a rel=noreferrer tag, that
   * will override the page setting.
   * @param {HTMLElement=} opt_linkElement The link triggering the navigation.
   * @return {string} The policy string.
   * @private
   */
  var getReferrerPolicy_ = function(opt_linkElement) {
    if (opt_linkElement) {
      var rel = opt_linkElement.getAttribute('rel');
      if (rel && rel.toLowerCase() == 'noreferrer') {
        return 'never';
      }
    }

    // Search for referrer meta tag.  WKWebView only supports a subset of values
    // for referrer meta tags.  If it parses a referrer meta tag with an
    // unsupported value, it will default to 'never'.
    var metaTags = document.getElementsByTagName('meta');
    for (var i = 0; i < metaTags.length; ++i) {
      if (metaTags[i].name.toLowerCase() == 'referrer') {
        var referrerPolicy = metaTags[i].content.toLowerCase();
        if (referrerPolicy == 'default' ||
            referrerPolicy == 'always' ||
            referrerPolicy == 'no-referrer' ||
            referrerPolicy == 'origin' ||
            referrerPolicy == 'no-referrer-when-downgrade' ||
            referrerPolicy == 'unsafe-url') {
          return referrerPolicy;
        } else {
          return 'never';
        }
      }
    }
    return 'default';
  };

}());  // End of anonymouse object