layout/generic/SelectionMovementUtils.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 mozilla_SelectionMovementUtils_h
   8 #define mozilla_SelectionMovementUtils_h
   9
  10 #include "mozilla/intl/BidiEmbeddingLevel.h"
  11 #include "mozilla/Attributes.h"
  12 #include "mozilla/EnumSet.h"
  13 #include "mozilla/Result.h"
  14 #include "nsIFrame.h"
  15
  16 struct nsPrevNextBidiLevels;
  17
  18 namespace mozilla {
  19
  20 class PresShell;
  21 enum class PeekOffsetOption : uint16_t;
  22
  23 namespace intl {
  24 class BidiEmbeddingLevel;
  25 }
  26
  27 struct MOZ_STACK_CLASS PrimaryFrameData {
  28   // The frame which should be used to layout the caret.
  29   nsIFrame* mFrame = nullptr;
  30   // The offset in content of mFrame.  This is valid only when mFrame is not
  31   // nullptr.
  32   uint32_t mOffsetInFrameContent = 0;
  33   // Whether the caret should be put before or after the point. This is valid
  34   // only when mFrame is not nullptr.
  35   CaretAssociationHint mHint{0};  // Before
  36 };
  37
  38 struct MOZ_STACK_CLASS CaretFrameData : public PrimaryFrameData {
  39   // The frame which is found only from a DOM point.  This frame becomes
  40   // different from mFrame when the point is around end of a line or
  41   // at a bidi text boundary.
  42   nsIFrame* mUnadjustedFrame = nullptr;
  43 };
  44
  45 enum class ForceEditableRegion : bool { No, Yes };
  46
  47 class SelectionMovementUtils final {
  48  public:
  49   using PeekOffsetOptions = EnumSet<PeekOffsetOption>;
  50
  51   /**
  52    * Given a node and its child offset, return the nsIFrame and the offset into
  53    * that frame.
  54    *
  55    * @param aNode input parameter for the node to look at
  56    *              TODO: Make this `const nsIContent*` for `ContentEventHandler`.
  57    * @param aOffset offset into above node.
  58    * @param aReturnOffset will contain offset into frame.
  59    */
  60   static nsIFrame* GetFrameForNodeOffset(nsIContent* aNode, uint32_t aOffset,
  61                                          CaretAssociationHint aHint,
  62                                          uint32_t* aReturnOffset = nullptr);
  63
  64   /**
  65    * GetPrevNextBidiLevels will return the frames and associated Bidi levels of
  66    * the characters logically before and after a (collapsed) selection.
  67    *
  68    * @param aNode is the node containing the selection
  69    * @param aContentOffset is the offset of the selection in the node
  70    * @param aJumpLines
  71    *   If true, look across line boundaries.
  72    *   If false, behave as if there were base-level frames at line edges.
  73    *
  74    * @return A struct holding the before/after frame and the before/after
  75    * level.
  76    *
  77    * At the beginning and end of each line there is assumed to be a frame with
  78    * Bidi level equal to the paragraph embedding level.
  79    *
  80    * In these cases the before frame and after frame respectively will be
  81    * nullptr.
  82    */
  83   static nsPrevNextBidiLevels GetPrevNextBidiLevels(nsIContent* aNode,
  84                                                     uint32_t aContentOffset,
  85                                                     CaretAssociationHint aHint,
  86                                                     bool aJumpLines);
  87
  88   /**
  89    * PeekOffsetForCaretMove() only peek offset for caret move from the specified
  90    * point of the normal selection.  I.e., won't change selection ranges nor
  91    * bidi information.
  92    */
  93   static Result<PeekOffsetStruct, nsresult> PeekOffsetForCaretMove(
  94       nsIContent* aContent, uint32_t aOffset, nsDirection aDirection,
  95       CaretAssociationHint aHint, intl::BidiEmbeddingLevel aCaretBidiLevel,
  96       const nsSelectionAmount aAmount, const nsPoint& aDesiredCaretPos,
  97       PeekOffsetOptions aOptions);
  98
  99   /**
 100    * IsIntraLineCaretMove() is a helper method for PeekOffsetForCaretMove()
 101    * and CreateRangeExtendedToSomwhereFromNormalSelection().  This returns
 102    * whether aAmount is intra line move or is crossing hard line break.
 103    * This returns error if aMount is not supported by the methods.
 104    */
 105   static Result<bool, nsresult> IsIntraLineCaretMove(
 106       nsSelectionAmount aAmount) {
 107     switch (aAmount) {
 108       case eSelectCharacter:
 109       case eSelectCluster:
 110       case eSelectWord:
 111       case eSelectWordNoSpace:
 112       case eSelectBeginLine:
 113       case eSelectEndLine:
 114         return true;
 115       case eSelectLine:
 116         return false;
 117       default:
 118         return Err(NS_ERROR_FAILURE);
 119     }
 120   }
 121
 122   /**
 123    * Return a frame for considering caret geometry.
 124    *
 125    * @param aFrameSelection     [optional] If this is specified and selection in
 126    *                            aContent is not managed by the specified
 127    *                            instance, return nullptr.
 128    * @param aContentNode        The content node where selection is collapsed.
 129    * @param aOffset             Collapsed position in aContentNode
 130    * @param aFrameHint          Caret association hint.
 131    * @param aBidiLevel
 132    * @param aForceEditableRegion    Whether selection should be limited in
 133    *                                editable region or not.
 134    */
 135   static CaretFrameData GetCaretFrameForNodeOffset(
 136       const nsFrameSelection* aFrameSelection, nsIContent* aContentNode,
 137       uint32_t aOffset, CaretAssociationHint aFrameHint,
 138       intl::BidiEmbeddingLevel aBidiLevel,
 139       ForceEditableRegion aForceEditableRegion);
 140
 141   static bool AdjustFrameForLineStart(nsIFrame*& aFrame,
 142                                       uint32_t& aFrameOffset);
 143
 144   /**
 145    * Get primary frame and some other data for putting caret or extending
 146    * selection at the point.
 147    */
 148   static PrimaryFrameData GetPrimaryFrameForCaret(
 149       nsIContent* aContent, uint32_t aOffset, bool aVisual,
 150       CaretAssociationHint aHint, intl::BidiEmbeddingLevel aCaretBidiLevel);
 151
 152  private:
 153   /**
 154    * GetFrameFromLevel will scan in a given direction
 155    * until it finds a frame with a Bidi level less than or equal to a given
 156    * level. It will return the last frame before this.
 157    *
 158    * @param aPresContext is the context to use
 159    * @param aFrameIn is the frame to start from
 160    * @param aDirection is the direction to scan
 161    * @param aBidiLevel is the level to search for
 162    */
 163   static Result<nsIFrame*, nsresult> GetFrameFromLevel(
 164       nsIFrame* aFrameIn, nsDirection aDirection,
 165       intl::BidiEmbeddingLevel aBidiLevel);
 166
 167   // This is helper method for GetPrimaryFrameForCaret.
 168   // If aVisual is true, this returns caret frame.
 169   // If false, this returns primary frame.
 170   static PrimaryFrameData GetPrimaryOrCaretFrameForNodeOffset(
 171       nsIContent* aContent, uint32_t aOffset, bool aVisual,
 172       CaretAssociationHint aHint, intl::BidiEmbeddingLevel aCaretBidiLevel);
 173 };
 174
 175 }  // namespace mozilla
 176
 177 #endif  // #ifndef mozilla_SelectionMovementUtils_h