Add paper-menu-button and its dependencies to third_party/polymer

third_party/polymer/v1_0/components-chromium/iron-dropdown/iron-dropdown-scroll-manager-extracted.js

+
+  (function() {
+    'use strict';
+
+    /**
+     * The IronDropdownScrollManager is intended to provide a central source
+     * of authority and control over which elements in a document are currently
+     * allowed to scroll.
+     */
+
+    Polymer.IronDropdownScrollManager = {
+
+      /**
+       * The current element that defines the DOM boundaries of the
+       * scroll lock. This is always the most recently locking element.
+       */
+      get currentLockingElement() {
+        return this._lockingElements[this._lockingElements.length - 1];
+      },
+
+
+      /**
+       * Returns true if the provided element is "scroll locked," which is to
+       * say that it cannot be scrolled via pointer or keyboard interactions.
+       *
+       * @param {HTMLElement} element An HTML element instance which may or may
+       * not be scroll locked.
+       */
+      elementIsScrollLocked: function(element) {
+        var currentLockingElement = this.currentLockingElement;
+        var scrollLocked;
+
+        if (this._hasCachedLockedElement(element)) {
+          return true;
+        }
+
+        if (this._hasCachedUnlockedElement(element)) {
+          return false;
+        }
+
+        scrollLocked = !!currentLockingElement &&
+          currentLockingElement !== element &&
+          !this._composedTreeContains(currentLockingElement, element);
+
+        if (scrollLocked) {
+          this._lockedElementCache.push(element);
+        } else {
+          this._unlockedElementCache.push(element);
+        }
+
+        return scrollLocked;
+      },
+
+      /**
+       * Push an element onto the current scroll lock stack. The most recently
+       * pushed element and its children will be considered scrollable. All
+       * other elements will not be scrollable.
+       *
+       * Scroll locking is implemented as a stack so that cases such as
+       * dropdowns within dropdowns are handled well.
+       *
+       * @param {HTMLElement} element The element that should lock scroll.
+       */
+      pushScrollLock: function(element) {
+        if (this._lockingElements.length === 0) {
+          this._lockScrollInteractions();
+        }
+
+        this._lockingElements.push(element);
+
+        this._lockedElementCache = [];
+        this._unlockedElementCache = [];
+      },
+
+      /**
+       * Remove an element from the scroll lock stack. The element being
+       * removed does not need to be the most recently pushed element. However,
+       * the scroll lock constraints only change when the most recently pushed
+       * element is removed.
+       *
+       * @param {HTMLElement} element The element to remove from the scroll
+       * lock stack.
+       */
+      removeScrollLock: function(element) {
+        var index = this._lockingElements.indexOf(element);
+
+        if (index === -1) {
+          return;
+        }
+
+        this._lockingElements.splice(index, 1);
+
+        this._lockedElementCache = [];
+        this._unlockedElementCache = [];
+
+        if (this._lockingElements.length === 0) {
+          this._unlockScrollInteractions();
+        }
+      },
+
+      _lockingElements: [],
+
+      _lockedElementCache: null,
+
+      _unlockedElementCache: null,
+
+      _originalBodyStyles: {},
+
+      _isScrollingKeypress: function(event) {
+        return Polymer.IronA11yKeysBehavior.keyboardEventMatchesKeys(
+          event, 'pageup pagedown home end up left down right');
+      },
+
+      _hasCachedLockedElement: function(element) {
+        return this._lockedElementCache.indexOf(element) > -1;
+      },
+
+      _hasCachedUnlockedElement: function(element) {
+        return this._unlockedElementCache.indexOf(element) > -1;
+      },
+
+      _composedTreeContains: function(element, child) {
+        // NOTE(cdata): This method iterates over content elements and their
+        // corresponding distributed nodes to implement a contains-like method
+        // that pierces through the composed tree of the ShadowDOM. Results of
+        // this operation are cached (elsewhere) on a per-scroll-lock basis, to
+        // guard against potentially expensive lookups happening repeatedly as
+        // a user scrolls / touchmoves.
+        var contentElements;
+        var distributedNodes;
+        var contentIndex;
+        var nodeIndex;
+
+        if (element.contains(child)) {
+          return true;
+        }
+
+        contentElements = Polymer.dom(element).querySelectorAll('content');
+
+        for (contentIndex = 0; contentIndex < contentElements.length; ++contentIndex) {
+
+          distributedNodes = Polymer.dom(contentElements[contentIndex]).getDistributedNodes();
+
+          for (nodeIndex = 0; nodeIndex < distributedNodes.length; ++nodeIndex) {
+
+            if (this._composedTreeContains(distributedNodes[nodeIndex], child)) {
+              return true;
+            }
+          }
+        }
+
+        return false;
+      },
+
+      _scrollInteractionHandler: function(event) {
+        if (Polymer
+              .IronDropdownScrollManager
+              .elementIsScrollLocked(event.target)) {
+          if (event.type === 'keydown' &&
+              !Polymer.IronDropdownScrollManager._isScrollingKeypress(event)) {
+            return;
+          }
+
+          event.preventDefault();
+        }
+      },
+
+      _lockScrollInteractions: function() {
+        // Memoize body inline styles:
+        this._originalBodyStyles.overflow = document.body.style.overflow;
+        this._originalBodyStyles.overflowX = document.body.style.overflowX;
+        this._originalBodyStyles.overflowY = document.body.style.overflowY;
+
+        // Disable overflow scrolling on body:
+        // TODO(cdata): It is technically not sufficient to hide overflow on
+        // body alone. A better solution might be to traverse all ancestors of
+        // the current scroll locking element and hide overflow on them. This
+        // becomes expensive, though, as it would have to be redone every time
+        // a new scroll locking element is added.
+        document.body.style.overflow = 'hidden';
+        document.body.style.overflowX = 'hidden';
+        document.body.style.overflowY = 'hidden';
+
+        // Modern `wheel` event for mouse wheel scrolling:
+        window.addEventListener('wheel', this._scrollInteractionHandler, true);
+        // Older, non-standard `mousewheel` event for some FF:
+        window.addEventListener('mousewheel', this._scrollInteractionHandler, true);
+        // IE:
+        window.addEventListener('DOMMouseScroll', this._scrollInteractionHandler, true);
+        // Mobile devices can scroll on touch move:
+        window.addEventListener('touchmove', this._scrollInteractionHandler, true);
+        // Capture keydown to prevent scrolling keys (pageup, pagedown etc.)
+        document.addEventListener('keydown', this._scrollInteractionHandler, true);
+      },
+
+      _unlockScrollInteractions: function() {
+        document.body.style.overflow = this._originalBodyStyles.overflow;
+        document.body.style.overflowX = this._originalBodyStyles.overflowX;
+        document.body.style.overflowY = this._originalBodyStyles.overflowY;
+
+        window.removeEventListener('wheel', this._scrollInteractionHandler, true);
+        window.removeEventListener('mousewheel', this._scrollInteractionHandler, true);
+        window.removeEventListener('DOMMouseScroll', this._scrollInteractionHandler, true);
+        window.removeEventListener('touchmove', this._scrollInteractionHandler, true);
+        document.removeEventListener('keydown', this._scrollInteractionHandler, true);
+      }
+    };
+  })();