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 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* 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/. */

 /* constants for what needs to be recomputed in response to style changes */

 #ifndef nsChangeHint_h___

 #define nsChangeHint_h___

 #include "nsDebug.h"

 // Defines for various style related constants

 enum nsChangeHint {

   // change was visual only (e.g., COLOR=)

   // Invalidates all descendant frames (including following

   // placeholders to out-of-flow frames).

   nsChangeHint_RepaintFrame = 0x01,

   // For reflow, we want flags to give us arbitrary FrameNeedsReflow behavior.

   // just do a FrameNeedsReflow.

   nsChangeHint_NeedReflow = 0x02,

   // Invalidate intrinsic widths on the frame's ancestors.  Must not be set

   // without setting nsChangeHint_NeedReflow.

   nsChangeHint_ClearAncestorIntrinsics = 0x04,

   // Invalidate intrinsic widths on the frame's descendants.  Must not be set

   // without also setting nsChangeHint_ClearAncestorIntrinsics.

   nsChangeHint_ClearDescendantIntrinsics = 0x08,

   // Force unconditional reflow of all descendants.  Must not be set without

   // setting nsChangeHint_NeedReflow, but is independent of both the

   // Clear*Intrinsics flags.

   nsChangeHint_NeedDirtyReflow = 0x10,

   // change requires view to be updated, if there is one (e.g., clip:).

   // Updates all descendants (including following placeholders to out-of-flows).

   nsChangeHint_SyncFrameView = 0x20,

   // The currently shown mouse cursor needs to be updated

   nsChangeHint_UpdateCursor = 0x40,

   /**

    * Used when the computed value (a URI) of one or more of an element's

    * filter/mask/clip/etc CSS properties changes, causing the element's frame

    * to start/stop referencing (or reference different) SVG resource elements.

    * (_Not_ used to handle changes to referenced resource elements.) Using this

    * hint results in nsSVGEffects::UpdateEffects being called on the element's

    * frame.

    */

   nsChangeHint_UpdateEffects = 0x80,

   /**

    * Visual change only, but the change can be handled entirely by

    * updating the layer(s) for the frame.

    * Updates all descendants (including following placeholders to out-of-flows).

    */

   nsChangeHint_UpdateOpacityLayer = 0x100,

   /**

    * Updates all descendants. Any placeholder descendants' out-of-flows

    * are also descendants of the transformed frame, so they're updated.

    */

   nsChangeHint_UpdateTransformLayer = 0x200,

   /**

    * Change requires frame change (e.g., display:).

    * This subsumes all the above. Reconstructs all frame descendants,

    * including following placeholders to out-of-flows.

    */

   nsChangeHint_ReconstructFrame = 0x400,

   /**

    * The frame's overflow area has changed, either through a change in its

    * transform or a change in its position. Does not update any descendant

    * frames.

    */

   nsChangeHint_UpdateOverflow = 0x800,

   /**

    * The frame's overflow area has changed, through a change in its transform.

    * Does not update any descendant frames.

    */

   nsChangeHint_UpdatePostTransformOverflow = 0x1000,

   /**

    * The children-only transform of an SVG frame changed, requiring the

    * overflow rects of the frame's immediate children to be updated.

    */

   nsChangeHint_ChildrenOnlyTransform = 0x2000,

   /**

    * The frame's offsets have changed, while its dimensions might have

    * changed as well.  This hint is used for positioned frames if their

    * offset changes.  If we decide that the dimensions are likely to

    * change, this will trigger a reflow.

    *

    * Note that this should probably be used in combination with

    * nsChangeHint_UpdateOverflow in order to get the overflow areas of

    * the ancestors updated as well.

    */

   nsChangeHint_RecomputePosition = 0x4000,

   /**

    * Behaves like ReconstructFrame, but only if the frame has descendants

    * that are absolutely or fixed position. Use this hint when a style change

    * has changed whether the frame is a container for fixed-pos or abs-pos

    * elements, but reframing is otherwise not needed.

    */

   nsChangeHint_AddOrRemoveTransform = 0x8000,

   /**

    * This change hint has *no* change handling behavior.  However, it

    * exists to be a non-inherited hint, because when the border-style

    * changes, and it's inherited by a child, that might require a reflow

    * due to the border-width change on the child.

    */

   nsChangeHint_BorderStyleNoneChange = 0x10000,

   /**

    * SVG textPath needs to be recomputed because the path has changed.

    * This means that the glyph positions of the text need to be recomputed.

    */

   nsChangeHint_UpdateTextPath = 0x20000

   // IMPORTANT NOTE: When adding new hints, consider whether you need to

   // add them to NS_HintsNotHandledForDescendantsIn() below.

 };

 // Redefine these operators to return nothing. This will catch any use

 // of these operators on hints. We should not be using these operators

 // on nsChangeHints

 inline void operator<(nsChangeHint s1, nsChangeHint s2) {}

 inline void operator>(nsChangeHint s1, nsChangeHint s2) {}

 inline void operator!=(nsChangeHint s1, nsChangeHint s2) {}

 inline void operator==(nsChangeHint s1, nsChangeHint s2) {}

 inline void operator<=(nsChangeHint s1, nsChangeHint s2) {}

 inline void operator>=(nsChangeHint s1, nsChangeHint s2) {}

 // Operators on nsChangeHints

 // Merge two hints, taking the union

 inline nsChangeHint NS_CombineHint(nsChangeHint aH1, nsChangeHint aH2) {

   return (nsChangeHint)(aH1 | aH2);

 }

 // Merge two hints, taking the union

 inline nsChangeHint NS_SubtractHint(nsChangeHint aH1, nsChangeHint aH2) {

   return (nsChangeHint)(aH1 & ~aH2);

 }

 // Merge the "src" hint into the "dst" hint

 // Returns true iff the destination changed

 inline bool NS_UpdateHint(nsChangeHint& aDest, nsChangeHint aSrc) {

   nsChangeHint r = (nsChangeHint)(aDest | aSrc);

   bool changed = (int)r != (int)aDest;

   aDest = r;

   return changed;

 }

 // Returns true iff the second hint contains all the hints of the first hint

 inline bool NS_IsHintSubset(nsChangeHint aSubset, nsChangeHint aSuperSet) {

   return (aSubset & aSuperSet) == aSubset;

 }

 /**

  * We have an optimization when processing change hints which prevents

  * us from visiting the descendants of a node when a hint on that node

  * is being processed.  This optimization does not apply in some of the

  * cases where applying a hint to an element does not necessarily result

  * in the same hint being handled on the descendants.

  */

 // The most hints that NS_HintsNotHandledForDescendantsIn could possibly return:

 #define nsChangeHint_Hints_NotHandledForDescendants nsChangeHint( \

           nsChangeHint_UpdateTransformLayer | \

           nsChangeHint_UpdateEffects | \

           nsChangeHint_UpdateOpacityLayer | \

           nsChangeHint_UpdateOverflow | \

           nsChangeHint_UpdatePostTransformOverflow | \

           nsChangeHint_ChildrenOnlyTransform | \

           nsChangeHint_RecomputePosition | \

           nsChangeHint_AddOrRemoveTransform | \

           nsChangeHint_BorderStyleNoneChange | \

           nsChangeHint_NeedReflow | \

           nsChangeHint_ClearAncestorIntrinsics)

 inline nsChangeHint NS_HintsNotHandledForDescendantsIn(nsChangeHint aChangeHint) {

   nsChangeHint result = nsChangeHint(aChangeHint & (

     nsChangeHint_UpdateTransformLayer |

     nsChangeHint_UpdateEffects |

     nsChangeHint_UpdateOpacityLayer |

     nsChangeHint_UpdateOverflow |

     nsChangeHint_UpdatePostTransformOverflow |

     nsChangeHint_ChildrenOnlyTransform |

     nsChangeHint_RecomputePosition |

     nsChangeHint_AddOrRemoveTransform |

     nsChangeHint_BorderStyleNoneChange));

   if (!NS_IsHintSubset(nsChangeHint_NeedDirtyReflow, aChangeHint) &&

       NS_IsHintSubset(nsChangeHint_NeedReflow, aChangeHint)) {

     // If NeedDirtyReflow is *not* set, then NeedReflow is a

     // non-inherited hint.

     NS_UpdateHint(result, nsChangeHint_NeedReflow);

   }

   if (!NS_IsHintSubset(nsChangeHint_ClearDescendantIntrinsics, aChangeHint) &&

       NS_IsHintSubset(nsChangeHint_ClearAncestorIntrinsics, aChangeHint)) {

     // If ClearDescendantIntrinsics is *not* set, then

     // ClearAncestorIntrinsics is a non-inherited hint.

     NS_UpdateHint(result, nsChangeHint_ClearAncestorIntrinsics);

   }

   NS_ABORT_IF_FALSE(NS_IsHintSubset(result,

                                     nsChangeHint_Hints_NotHandledForDescendants),

                     "something is inconsistent");

   return result;

 }

 // Redefine the old NS_STYLE_HINT constants in terms of the new hint structure

 #define NS_STYLE_HINT_NONE \

   nsChangeHint(0)

 #define NS_STYLE_HINT_VISUAL \

   nsChangeHint(nsChangeHint_RepaintFrame | nsChangeHint_SyncFrameView)

 #define nsChangeHint_AllReflowHints                     \

   nsChangeHint(nsChangeHint_NeedReflow |                \

                nsChangeHint_ClearAncestorIntrinsics |   \

                nsChangeHint_ClearDescendantIntrinsics | \

                nsChangeHint_NeedDirtyReflow)

 #define NS_STYLE_HINT_REFLOW \

   nsChangeHint(NS_STYLE_HINT_VISUAL | nsChangeHint_AllReflowHints)

 #define NS_STYLE_HINT_FRAMECHANGE \

   nsChangeHint(NS_STYLE_HINT_REFLOW | nsChangeHint_ReconstructFrame)

 /**

  * |nsRestyleHint| is a bitfield for the result of

  * |HasStateDependentStyle| and |HasAttributeDependentStyle|.  When no

  * restyling is necessary, use |nsRestyleHint(0)|.

  */

 enum nsRestyleHint {

   eRestyle_Self = 0x1,

   eRestyle_Subtree = 0x2, /* self and descendants */

   eRestyle_LaterSiblings = 0x4 /* implies "and descendants" */

 };

 #endif /* nsChangeHint_h___ */