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Diffstat (limited to 'layout/base/nsChangeHint.h')
| -rw-r--r-- | layout/base/nsChangeHint.h | 513 |
1 files changed, 513 insertions, 0 deletions
diff --git a/layout/base/nsChangeHint.h b/layout/base/nsChangeHint.h new file mode 100644 index 0000000000..5806abfd84 --- /dev/null +++ b/layout/base/nsChangeHint.h @@ -0,0 +1,513 @@ +/* -*- 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/. */ + +/* constants for what needs to be recomputed in response to style changes */ + +#ifndef nsChangeHint_h___ +#define nsChangeHint_h___ + +#include "mozilla/Types.h" +#include "mozilla/Assertions.h" + +// Defines for various style related constants + +enum nsChangeHint : uint32_t { + nsChangeHint_Empty = 0, + + // change was visual only (e.g., COLOR=) + // Invalidates all descendant frames (including following + // placeholders to out-of-flow frames). + nsChangeHint_RepaintFrame = 1 << 0, + + // For reflow, we want flags to give us arbitrary FrameNeedsReflow behavior. + // just do a FrameNeedsReflow. + nsChangeHint_NeedReflow = 1 << 1, + + // Invalidate intrinsic widths on the frame's ancestors. Must not be set + // without setting nsChangeHint_NeedReflow. + nsChangeHint_ClearAncestorIntrinsics = 1 << 2, + + // Invalidate intrinsic widths on the frame's descendants. Must not be set + // without also setting nsChangeHint_ClearAncestorIntrinsics, + // nsChangeHint_NeedDirtyReflow and nsChangeHint_NeedReflow. + nsChangeHint_ClearDescendantIntrinsics = 1 << 3, + + // Force unconditional reflow of all descendants. Must not be set without + // setting nsChangeHint_NeedReflow, but can be set regardless of whether the + // Clear*Intrinsics flags are set. + nsChangeHint_NeedDirtyReflow = 1 << 4, + + // The currently shown mouse cursor needs to be updated + nsChangeHint_UpdateCursor = 1 << 5, + + /** + * 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 SVGObserverUtils::UpdateEffects being called on the + * element's frame. + */ + nsChangeHint_UpdateEffects = 1 << 6, + + /** + * 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 = 1 << 7, + /** + * Updates all descendants. Any placeholder descendants' out-of-flows + * are also descendants of the transformed frame, so they're updated. + */ + nsChangeHint_UpdateTransformLayer = 1 << 8, + + /** + * Change requires frame change (e.g., display:). + * Reconstructs all frame descendants, including following placeholders + * to out-of-flows. + * + * Note that this subsumes all the other change hints. (see + * RestyleManager::ProcessRestyledFrames for details). + */ + nsChangeHint_ReconstructFrame = 1 << 9, + + /** + * The frame's overflow area has changed. Does not update any descendant + * frames. + */ + nsChangeHint_UpdateOverflow = 1 << 10, + + /** + * The overflow area of the frame and all of its descendants has changed. This + * can happen through a text-decoration change. + */ + nsChangeHint_UpdateSubtreeOverflow = 1 << 11, + + /** + * The frame's overflow area has changed, through a change in its transform. + * In other words, the frame's pre-transform overflow is unchanged, but + * its post-transform overflow has changed, and thus its effect on its + * parent's overflow has changed. If the pre-transform overflow has + * changed, see nsChangeHint_UpdateOverflow. + * Does not update any descendant frames. + */ + nsChangeHint_UpdatePostTransformOverflow = 1 << 12, + + /** + * This frame's effect on its parent's overflow area has changed. + * (But neither its pre-transform nor post-transform overflow have + * changed; if those are the case, see + * nsChangeHint_UpdatePostTransformOverflow.) + */ + nsChangeHint_UpdateParentOverflow = 1 << 13, + + /** + * The children-only transform of an SVG frame changed, requiring overflows to + * be updated. + */ + nsChangeHint_ChildrenOnlyTransform = 1 << 14, + + /** + * 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 = 1 << 15, + + /** + * 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. + * + * Note that ComputedStyle::CalcStyleDifference adjusts results + * returned by style struct CalcDifference methods to return this hint + * only if there was a change to whether the element's overall style + * indicates that it establishes a containing block. + */ + nsChangeHint_UpdateContainingBlock = 1 << 16, + + /** + * 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 = 1 << 17, + + /** + * This will schedule an invalidating paint. This is useful if something + * has changed which will be invalidated by DLBI. + */ + nsChangeHint_SchedulePaint = 1 << 18, + + /** + * A hint reflecting that style data changed with no change handling + * behavior. We need to return this, rather than nsChangeHint(0), + * so that certain optimizations that manipulate the style tree are + * correct. + * + * nsChangeHint_NeutralChange must be returned by CalcDifference on a given + * style struct if the data in the style structs are meaningfully different + * and if no other change hints are returned. If any other change hints are + * set, then nsChangeHint_NeutralChange need not also be included, but it is + * safe to do so. (An example of style structs having non-meaningfully + * different data would be cached information that would be re-calculated + * to the same values, such as nsStyleBorder::mSubImages.) + */ + nsChangeHint_NeutralChange = 1 << 19, + + /** + * This will cause rendering observers to be invalidated. + */ + nsChangeHint_InvalidateRenderingObservers = 1 << 20, + + /** + * Indicates that the reflow changes the size or position of the + * element, and thus the reflow must start from at least the frame's + * parent. Must be not be set without also setting nsChangeHint_NeedReflow. + * And consider adding nsChangeHint_ClearAncestorIntrinsics if needed. + */ + nsChangeHint_ReflowChangesSizeOrPosition = 1 << 21, + + /** + * Indicates that the style changes the computed BSize --- e.g. 'height'. + * Must not be set without also setting nsChangeHint_NeedReflow. + */ + nsChangeHint_UpdateComputedBSize = 1 << 22, + + /** + * Indicates that the 'opacity' property changed between 1 and non-1. + * + * Used as extra data for handling UpdateOpacityLayer hints. + * + * Note that we do not send this hint if the non-1 value was 0.99 or + * greater, since in that case we send a RepaintFrame hint instead. + */ + nsChangeHint_UpdateUsesOpacity = 1 << 23, + + /** + * Indicates that the 'background-position' property changed. + * Regular frames can invalidate these changes using DLBI, but + * for some frame types we need to repaint the whole frame because + * the frame does not build individual background image display items + * for each background layer. + */ + nsChangeHint_UpdateBackgroundPosition = 1 << 24, + + /** + * Indicates that a frame has changed to or from having the CSS + * transform property set. + */ + nsChangeHint_AddOrRemoveTransform = 1 << 25, + + /** + * Indicates that the presence of scrollbars might have changed. + * + * This happens when at least one of overflow-{x,y} properties changed. + * + * In most cases, this is equivalent to nsChangeHint_ReconstructFrame. But + * in some special cases where the change is really targeting the viewport's + * scrollframe, this is instead equivalent to nsChangeHint_AllReflowHints + * (because the viewport always has an associated scrollframe). + */ + nsChangeHint_ScrollbarChange = 1 << 26, + + /** + * Indicates that there has been a colspan or rowspan attribute change + * on the cells of a table. + */ + nsChangeHint_UpdateTableCellSpans = 1 << 27, + + /** + * Indicates that the visiblity property changed. + * This change hint is used for skip restyling for animations on + * visibility:hidden elements in the case where the elements have no visible + * descendants. + */ + nsChangeHint_VisibilityChange = 1u << 28, + + // IMPORTANT NOTE: When adding a new hint, you will need to add it to + // one of: + // + // * nsChangeHint_Hints_NeverHandledForDescendants + // * nsChangeHint_Hints_AlwaysHandledForDescendants + // * nsChangeHint_Hints_SometimesHandledForDescendants + // + // and you also may need to handle it in NS_HintsNotHandledForDescendantsIn. + // + // Please also add it to RestyleManager::ChangeHintToString and + // modify nsChangeHint_AllHints below accordingly. + + /** + * Dummy hint value for all hints. It exists for compile time check. + */ + nsChangeHint_AllHints = uint32_t((1ull << 29) - 1), +}; + +// 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 + +// 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; +} + +// The functions below need an integral type to cast to to avoid +// infinite recursion. +typedef decltype(nsChangeHint(0) + nsChangeHint(0)) nsChangeHint_size_t; + +inline nsChangeHint constexpr operator|(nsChangeHint aLeft, + nsChangeHint aRight) { + return nsChangeHint(nsChangeHint_size_t(aLeft) | nsChangeHint_size_t(aRight)); +} + +inline nsChangeHint constexpr operator&(nsChangeHint aLeft, + nsChangeHint aRight) { + return nsChangeHint(nsChangeHint_size_t(aLeft) & nsChangeHint_size_t(aRight)); +} + +inline nsChangeHint& operator|=(nsChangeHint& aLeft, nsChangeHint aRight) { + return aLeft = aLeft | aRight; +} + +inline nsChangeHint& operator&=(nsChangeHint& aLeft, nsChangeHint aRight) { + return aLeft = aLeft & aRight; +} + +inline nsChangeHint constexpr operator~(nsChangeHint aArg) { + return nsChangeHint(~nsChangeHint_size_t(aArg)); +} + +inline nsChangeHint constexpr operator^(nsChangeHint aLeft, + nsChangeHint aRight) { + return nsChangeHint(nsChangeHint_size_t(aLeft) ^ nsChangeHint_size_t(aRight)); +} + +inline nsChangeHint operator^=(nsChangeHint& aLeft, nsChangeHint aRight) { + return aLeft = aLeft ^ aRight; +} + +/** + * 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 change hints that are always handled for descendants. +#define nsChangeHint_Hints_AlwaysHandledForDescendants \ + (nsChangeHint_ClearDescendantIntrinsics | nsChangeHint_NeedDirtyReflow | \ + nsChangeHint_NeutralChange | nsChangeHint_ReconstructFrame | \ + nsChangeHint_RepaintFrame | nsChangeHint_SchedulePaint | \ + nsChangeHint_UpdateCursor | nsChangeHint_UpdateSubtreeOverflow | \ + nsChangeHint_VisibilityChange) + +// The change hints that are never handled for descendants. +#define nsChangeHint_Hints_NeverHandledForDescendants \ + (nsChangeHint_BorderStyleNoneChange | nsChangeHint_ChildrenOnlyTransform | \ + nsChangeHint_ScrollbarChange | nsChangeHint_InvalidateRenderingObservers | \ + nsChangeHint_RecomputePosition | nsChangeHint_UpdateBackgroundPosition | \ + nsChangeHint_UpdateComputedBSize | nsChangeHint_UpdateContainingBlock | \ + nsChangeHint_UpdateEffects | nsChangeHint_UpdateOpacityLayer | \ + nsChangeHint_UpdateOverflow | nsChangeHint_UpdateParentOverflow | \ + nsChangeHint_UpdatePostTransformOverflow | \ + nsChangeHint_UpdateTableCellSpans | nsChangeHint_UpdateTransformLayer | \ + nsChangeHint_UpdateUsesOpacity | nsChangeHint_AddOrRemoveTransform) + +// The change hints that are sometimes considered to be handled for descendants. +#define nsChangeHint_Hints_SometimesHandledForDescendants \ + (nsChangeHint_ClearAncestorIntrinsics | nsChangeHint_NeedReflow | \ + nsChangeHint_ReflowChangesSizeOrPosition) + +static_assert(!(nsChangeHint_Hints_AlwaysHandledForDescendants & + nsChangeHint_Hints_NeverHandledForDescendants) && + !(nsChangeHint_Hints_AlwaysHandledForDescendants & + nsChangeHint_Hints_SometimesHandledForDescendants) && + !(nsChangeHint_Hints_NeverHandledForDescendants & + nsChangeHint_Hints_SometimesHandledForDescendants) && + !(nsChangeHint_AllHints ^ + nsChangeHint_Hints_AlwaysHandledForDescendants ^ + nsChangeHint_Hints_NeverHandledForDescendants ^ + nsChangeHint_Hints_SometimesHandledForDescendants), + "change hints must be present in exactly one of " + "nsChangeHint_Hints_{Always,Never,Sometimes}" + "HandledForDescendants"); + +// The most hints that NS_HintsNotHandledForDescendantsIn could possibly return: +#define nsChangeHint_Hints_NotHandledForDescendants \ + (nsChangeHint_Hints_NeverHandledForDescendants | \ + nsChangeHint_Hints_SometimesHandledForDescendants) + +// Redefine the old NS_STYLE_HINT constants in terms of the new hint structure +#define NS_STYLE_HINT_VISUAL \ + nsChangeHint(nsChangeHint_RepaintFrame | nsChangeHint_SchedulePaint) +#define nsChangeHint_AllReflowHints \ + nsChangeHint( \ + nsChangeHint_NeedReflow | nsChangeHint_ReflowChangesSizeOrPosition | \ + nsChangeHint_ClearAncestorIntrinsics | \ + nsChangeHint_ClearDescendantIntrinsics | nsChangeHint_NeedDirtyReflow) + +// Below are the change hints that we send for ISize & BSize changes. +// Each is similar to nsChangeHint_AllReflowHints with a few changes. + +// * For an ISize change, we send nsChangeHint_AllReflowHints, with two bits +// excluded: nsChangeHint_ClearDescendantIntrinsics (because an ancestor's +// inline-size change can't affect descendant intrinsic sizes), and +// nsChangeHint_NeedDirtyReflow (because ISize changes don't need to *force* +// all descendants to reflow). +#define nsChangeHint_ReflowHintsForISizeChange \ + nsChangeHint(nsChangeHint_AllReflowHints & \ + ~(nsChangeHint_ClearDescendantIntrinsics | \ + nsChangeHint_NeedDirtyReflow)) + +// * For a BSize change, we send almost the same hints as for ISize changes, +// with one extra: nsChangeHint_UpdateComputedBSize. We need this hint because +// BSize changes CAN affect descendant intrinsic sizes, due to replaced +// elements with percentage BSizes in descendants which also have percentage +// BSizes. nsChangeHint_UpdateComputedBSize clears intrinsic sizes for frames +// that have such replaced elements. (We could instead send +// nsChangeHint_ClearDescendantIntrinsics, but that's broader than we need.) +// +// NOTE: You might think that BSize changes could exclude +// nsChangeHint_ClearAncestorIntrinsics (which is inline-axis specific), but we +// do need to send it, to clear cached results from CSS Flex measuring reflows. +#define nsChangeHint_ReflowHintsForBSizeChange \ + nsChangeHint( \ + (nsChangeHint_AllReflowHints | nsChangeHint_UpdateComputedBSize) & \ + ~(nsChangeHint_ClearDescendantIntrinsics | \ + nsChangeHint_NeedDirtyReflow)) + +// For a change in whether a scrollframe displays or not scrollbars. +// +// When requesting this reflow, we send the exact same change hints that "width" +// and "height" would send (since conceptually, adding/removing scrollbars is +// like changing the available space). +// +// FIXME(emilio): Seems we could be a bit more efficient here, as adding or +// removing scrollbars doesn't change the size of the element itself, so maybe +// ClearAncestorIntrinsics or ReflowChangesSizeOrPosition are not needed... I +// think this ideally should be just nsChangehint_NeedReflow. +#define nsChangeHint_ReflowHintsForScrollbarChange \ + nsChangeHint(nsChangeHint_ReflowHintsForBSizeChange | \ + nsChangeHint_ReflowHintsForISizeChange) + +// * For changes to the float area of an already-floated element, we need all +// reflow hints, but not the ones that apply to descendants. +// Our descendants aren't impacted when our float area only changes +// placement but not size/shape. (e.g. if we change which side we float to). +// But our ancestors/siblings are potentially impacted, so we need to send +// the non-descendant reflow hints. +#define nsChangeHint_ReflowHintsForFloatAreaChange \ + nsChangeHint(nsChangeHint_AllReflowHints & \ + ~(nsChangeHint_ClearDescendantIntrinsics | \ + nsChangeHint_NeedDirtyReflow)) + +#define NS_STYLE_HINT_REFLOW \ + nsChangeHint(NS_STYLE_HINT_VISUAL | nsChangeHint_AllReflowHints) + +// Change hints for added or removed transform style. +// +// If we've added or removed the transform property, we need to reconstruct the +// frame to add or remove the view object, and also to handle abs-pos and +// fixed-pos containers. +// +// We do not need to apply nsChangeHint_UpdateTransformLayer since +// nsChangeHint_RepaintFrame will forcibly invalidate the frame area and +// ensure layers are rebuilt (or removed). +#define nsChangeHint_ComprehensiveAddOrRemoveTransform \ + nsChangeHint(nsChangeHint_UpdateContainingBlock | \ + nsChangeHint_AddOrRemoveTransform | \ + nsChangeHint_UpdateOverflow | nsChangeHint_RepaintFrame) + +// NB: Once we drop support for the old style system, this logic should be +// inlined in the Servo style system to eliminate the FFI call. +inline nsChangeHint NS_HintsNotHandledForDescendantsIn( + nsChangeHint aChangeHint) { + nsChangeHint result = + aChangeHint & nsChangeHint_Hints_NeverHandledForDescendants; + + if (!(aChangeHint & nsChangeHint_NeedDirtyReflow)) { + if (aChangeHint & nsChangeHint_NeedReflow) { + // If NeedDirtyReflow is *not* set, then NeedReflow is a + // non-inherited hint. + result |= nsChangeHint_NeedReflow; + } + + if (aChangeHint & nsChangeHint_ReflowChangesSizeOrPosition) { + // If NeedDirtyReflow is *not* set, then ReflowChangesSizeOrPosition is a + // non-inherited hint. + result |= nsChangeHint_ReflowChangesSizeOrPosition; + } + } + + if (!(aChangeHint & nsChangeHint_ClearDescendantIntrinsics) && + (aChangeHint & nsChangeHint_ClearAncestorIntrinsics)) { + // If ClearDescendantIntrinsics is *not* set, then + // ClearAncestorIntrinsics is a non-inherited hint. + result |= nsChangeHint_ClearAncestorIntrinsics; + } + + MOZ_ASSERT( + NS_IsHintSubset(result, nsChangeHint_Hints_NotHandledForDescendants), + "something is inconsistent"); + + return result; +} + +inline nsChangeHint NS_HintsHandledForDescendantsIn(nsChangeHint aChangeHint) { + return aChangeHint & ~NS_HintsNotHandledForDescendantsIn(aChangeHint); +} + +// Returns the change hints in aOurChange that are not subsumed by those +// in aHintsHandled (which are hints that have been handled by an ancestor). +inline nsChangeHint NS_RemoveSubsumedHints(nsChangeHint aOurChange, + nsChangeHint aHintsHandled) { + nsChangeHint result = + aOurChange & ~NS_HintsHandledForDescendantsIn(aHintsHandled); + + if (result & + (nsChangeHint_ClearAncestorIntrinsics | + nsChangeHint_ClearDescendantIntrinsics | nsChangeHint_NeedDirtyReflow | + nsChangeHint_ReflowChangesSizeOrPosition | + nsChangeHint_UpdateComputedBSize)) { + result |= nsChangeHint_NeedReflow; + } + + if (result & (nsChangeHint_ClearDescendantIntrinsics)) { + MOZ_ASSERT(result & nsChangeHint_ClearAncestorIntrinsics); + result |= // nsChangeHint_ClearAncestorIntrinsics | + nsChangeHint_NeedDirtyReflow; + } + + return result; +} + +namespace mozilla { + +struct StyleRestyleHint; + +using RestyleHint = StyleRestyleHint; + +} // namespace mozilla + +#endif /* nsChangeHint_h___ */ |