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Diffstat (limited to 'dom/base/DirectionalityUtils.h')
| -rw-r--r-- | dom/base/DirectionalityUtils.h | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/dom/base/DirectionalityUtils.h b/dom/base/DirectionalityUtils.h new file mode 100644 index 0000000000..6dc922e95c --- /dev/null +++ b/dom/base/DirectionalityUtils.h @@ -0,0 +1,166 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef DirectionalityUtils_h___ +#define DirectionalityUtils_h___ + +#include "nscore.h" +#include "nsStringFwd.h" + +class nsIContent; +class nsINode; +class nsAttrValue; +class nsTextNode; + +namespace mozilla::dom { +class Element; +class HTMLSlotElement; +} // namespace mozilla::dom + +namespace mozilla { + +enum Directionality : uint8_t { eDir_NotSet, eDir_RTL, eDir_LTR, eDir_Auto }; + +/** + * Various methods for returning the directionality of a string using the + * first-strong algorithm defined in http://unicode.org/reports/tr9/#P2 + * + * @param[out] aFirstStrong the offset to the first character in the string with + * strong directionality, or UINT32_MAX if there is none (return + value is eDir_NotSet). + * @return the directionality of the string + */ +Directionality GetDirectionFromText(const char16_t* aText, + const uint32_t aLength, + uint32_t* aFirstStrong = nullptr); + +/** + * Set the directionality of an element according to the algorithm defined at + * http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#the-directionality, + * not including elements with auto direction. + * + * @return the directionality that the element was set to + */ +Directionality RecomputeDirectionality(mozilla::dom::Element* aElement, + bool aNotify = true); + +/** + * Set the directionality of any descendants of a node that do not themselves + * have a dir attribute. + * For performance reasons we walk down the descendant tree in the rare case + * of setting the dir attribute, rather than walking up the ancestor tree in + * the much more common case of getting the element's directionality. + */ +void SetDirectionalityOnDescendants(mozilla::dom::Element* aElement, + Directionality aDir, bool aNotify = true); + +/** + * Walk the descendants of a node in tree order and, for any text node + * descendant that determines the directionality of some element and is not a + * descendant of another descendant of the original node with dir=auto, + * redetermine that element's directionality + */ +void WalkDescendantsResetAutoDirection(mozilla::dom::Element* aElement); + +/** + * In case a slot element was added or removed it may change the directionality + * of ancestors or assigned nodes. + * + * aAllAssignedNodesChanged forces the computation of the state for all of the + * assigned descendants. + */ +void SlotStateChanged(dom::HTMLSlotElement* aSlot, + bool aAllAssignedNodesChanged = true); + +/** + * When only a single node in a slot is reassigned we can save some work + * compared to the above. + */ +void SlotAssignedNodeChanged(dom::HTMLSlotElement* aSlot, + nsIContent& aAssignedNode); + +/** + * After setting dir=auto on an element, walk its descendants in tree order. + * If the node doesn't have the NODE_ANCESTOR_HAS_DIR_AUTO flag, set the + * NODE_ANCESTOR_HAS_DIR_AUTO flag on all of its descendants. + * Resolve the directionality of the element by the "downward propagation + * algorithm" (defined in section 3 in the comments at the beginning of + * DirectionalityUtils.cpp) + */ +void WalkDescendantsSetDirAuto(mozilla::dom::Element* aElement, + bool aNotify = true); + +/** + * After unsetting dir=auto on an element, walk its descendants in tree order, + * skipping any that have dir=auto themselves, and unset the + * NODE_ANCESTOR_HAS_DIR_AUTO flag + */ +void WalkDescendantsClearAncestorDirAuto(nsIContent* aContent); + +/** + * When the contents of a text node are about to change, retrieve the current + * directionality of the text + * + * @return whether the text node affects the directionality of any element + */ +bool TextNodeWillChangeDirection(nsTextNode* aTextNode, Directionality* aOldDir, + uint32_t aOffset); + +/** + * After the contents of a text node have changed, change the directionality + * of any elements whose directionality is determined by that node + */ +void TextNodeChangedDirection(nsTextNode* aTextNode, Directionality aOldDir, + bool aNotify); + +/** + * When a text node is appended to an element, find any ancestors with dir=auto + * whose directionality will be determined by the text node + */ +void SetDirectionFromNewTextNode(nsTextNode* aTextNode); + +/** + * When a text node is removed from a document, find any ancestors whose + * directionality it determined and redetermine their directionality + * + * @param aTextNode the text node + */ +void ResetDirectionSetByTextNode(nsTextNode* aTextNode); + +/** + * Set the directionality of an element according to the directionality of the + * text in aValue + */ +void SetDirectionalityFromValue(mozilla::dom::Element* aElement, + const nsAString& aValue, bool aNotify); + +/** + * Called when setting the dir attribute on an element, immediately after + * AfterSetAttr. This is instead of using BeforeSetAttr or AfterSetAttr, because + * in AfterSetAttr we don't know the old value, so we can't identify all cases + * where we need to walk up or down the document tree and reset the direction; + * and in BeforeSetAttr we can't do the walk because this element hasn't had the + * value set yet so the results will be wrong. + */ +void OnSetDirAttr(mozilla::dom::Element* aElement, const nsAttrValue* aNewValue, + bool hadValidDir, bool hadDirAuto, bool aNotify); + +/** + * Called when binding a new element to the tree, to set the + * NodeAncestorHasDirAuto flag and set the direction of the element and its + * ancestors if necessary + */ +void SetDirOnBind(mozilla::dom::Element* aElement, nsIContent* aParent); + +/** + * Called when unbinding an element from the tree, to recompute the + * directionality of the element if it doesn't have autodirection, and to + * clean up any entries in nsTextDirectionalityMap that refer to it. + */ +void ResetDir(mozilla::dom::Element* aElement); +} // end namespace mozilla + +#endif /* DirectionalityUtils_h___ */ |