layout/base/nsFrameTraversal.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef NSFRAMETRAVERSAL_H
   8 #define NSFRAMETRAVERSAL_H
   9
  10 #include <cstdint>
  11 #include "mozilla/Attributes.h"
  12
  13 class nsIFrame;
  14 class nsPresContext;
  15
  16 class MOZ_STACK_CLASS nsFrameIterator final {
  17  public:
  18   void First();
  19   void Next();
  20   nsIFrame* CurrentItem();
  21   bool IsDone();
  22
  23   void Last();
  24   void Prev();
  25
  26   inline nsIFrame* Traverse(bool aForward) {
  27     if (aForward) {
  28       Next();
  29     } else {
  30       Prev();
  31     }
  32     return CurrentItem();
  33   };
  34
  35   enum class Type : uint8_t {
  36     // only leaf nodes
  37     Leaf,
  38     // "open tag" order
  39     PreOrder,
  40     // "close tag" order
  41     PostOrder,
  42   };
  43   nsFrameIterator(nsPresContext* aPresContext, nsIFrame* aStart, Type aType,
  44                   bool aVisual, bool aLockInScrollView, bool aFollowOOFs,
  45                   bool aSkipPopupChecks, nsIFrame* aLimiter = nullptr);
  46   ~nsFrameIterator() = default;
  47
  48  protected:
  49   void SetCurrent(nsIFrame* aFrame) { mCurrent = aFrame; }
  50   nsIFrame* GetCurrent() { return mCurrent; }
  51   nsIFrame* GetStart() { return mStart; }
  52   nsIFrame* GetLast() { return mLast; }
  53   void SetLast(nsIFrame* aFrame) { mLast = aFrame; }
  54   int8_t GetOffEdge() { return mOffEdge; }
  55   void SetOffEdge(int8_t aOffEdge) { mOffEdge = aOffEdge; }
  56
  57   /*
  58    Our own versions of the standard frame tree navigation
  59    methods, which, if the iterator is following out-of-flows,
  60    apply the following rules for placeholder frames:
  61
  62    - If a frame HAS a placeholder frame, getting its parent
  63    gets the placeholder's parent.
  64
  65    - If a frame's first child or next/prev sibling IS a
  66    placeholder frame, then we instead return the real frame.
  67
  68    - If a frame HAS a placeholder frame, getting its next/prev
  69    sibling gets the placeholder frame's next/prev sibling.
  70
  71    These are all applied recursively to support multiple levels of
  72    placeholders.
  73    */
  74
  75   nsIFrame* GetParentFrame(nsIFrame* aFrame);
  76   // like GetParentFrame but returns null once a popup frame is reached
  77   nsIFrame* GetParentFrameNotPopup(nsIFrame* aFrame);
  78
  79   nsIFrame* GetFirstChild(nsIFrame* aFrame);
  80   nsIFrame* GetLastChild(nsIFrame* aFrame);
  81
  82   nsIFrame* GetNextSibling(nsIFrame* aFrame);
  83   nsIFrame* GetPrevSibling(nsIFrame* aFrame);
  84
  85   /*
  86    These methods are overridden by the bidi visual iterator to have the
  87    semantics of "get first child in visual order", "get last child in visual
  88    order", "get next sibling in visual order" and "get previous sibling in
  89    visual order".
  90   */
  91
  92   nsIFrame* GetFirstChildInner(nsIFrame* aFrame);
  93   nsIFrame* GetLastChildInner(nsIFrame* aFrame);
  94
  95   nsIFrame* GetNextSiblingInner(nsIFrame* aFrame);
  96   nsIFrame* GetPrevSiblingInner(nsIFrame* aFrame);
  97
  98   /**
  99    * Return the placeholder frame for aFrame if it has one, otherwise return
 100    * aFrame itself.
 101    */
 102   nsIFrame* GetPlaceholderFrame(nsIFrame* aFrame);
 103   bool IsPopupFrame(nsIFrame* aFrame);
 104
 105   bool IsInvokerOpenPopoverFrame(nsIFrame* aFrame);
 106
 107   nsPresContext* const mPresContext;
 108   const bool mLockScroll;
 109   const bool mFollowOOFs;
 110   const bool mSkipPopupChecks;
 111   const bool mVisual;
 112   const Type mType;
 113
 114  private:
 115   nsIFrame* const mStart;
 116   nsIFrame* mCurrent;
 117   nsIFrame* mLast;  // the last one that was in current;
 118   nsIFrame* mLimiter;
 119   int8_t mOffEdge;  // 0= no -1 to far prev, 1 to far next;
 120 };
 121
 122 #endif  // NSFRAMETRAVERSAL_H