RestyleTracker.h
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* Contributor(s):
* Boris Zbarsky <bzbarsky@mit.edu> (original author)
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/**
* A class which manages pending restyles. This handles keeping track
* of what nodes restyles need to happen on and so forth.
*/
#ifndef mozilla_css_RestyleTracker_h
#define mozilla_css_RestyleTracker_h
#include "mozilla/dom/Element.h"
#include "nsDataHashtable.h"
#include "nsIFrame.h"
class nsCSSFrameConstructor;
namespace mozilla {
namespace css {
class RestyleTracker {
public:
typedef mozilla::dom::Element Element;
RestyleTracker(PRUint32 aRestyleBits,
nsCSSFrameConstructor* aFrameConstructor) :
mRestyleBits(aRestyleBits), mFrameConstructor(aFrameConstructor),
mHaveLaterSiblingRestyles(PR_FALSE)
{
NS_PRECONDITION((mRestyleBits & ~ELEMENT_ALL_RESTYLE_FLAGS) == 0,
"Why do we have these bits set?");
NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
"Must have a restyle flag");
NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) !=
ELEMENT_PENDING_RESTYLE_FLAGS,
"Shouldn't have both restyle flags set");
NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
"Must have root flag");
NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) !=
(ELEMENT_ALL_RESTYLE_FLAGS & ~ELEMENT_PENDING_RESTYLE_FLAGS),
"Shouldn't have both root flags");
}
PRBool Init() {
return mPendingRestyles.Init();
}
PRUint32 Count() const {
return mPendingRestyles.Count();
}
/**
* Add a restyle for the given element to the tracker. Returns true
* if the element already had eRestyle_LaterSiblings set on it.
*/
PRBool AddPendingRestyle(Element* aElement, nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint);
/**
* Process the restyles we've been tracking.
*/
void ProcessRestyles();
// Return our ELEMENT_HAS_PENDING_(ANIMATION_)RESTYLE bit
PRUint32 RestyleBit() const {
return mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS;
}
// Return our ELEMENT_IS_POTENTIAL_(ANIMATION_)RESTYLE_ROOT bit
PRUint32 RootBit() const {
return mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS;
}
struct RestyleData {
nsRestyleHint mRestyleHint; // What we want to restyle
nsChangeHint mChangeHint; // The minimal change hint for "self"
};
/**
* If the given Element has a restyle pending for it, return the
* relevant restyle data. This function will clear everything other
* than a possible eRestyle_LaterSiblings hint for aElement out of
* our hashtable. The returned aData will never have an
* eRestyle_LaterSiblings hint in it.
*
* The return value indicates whether any restyle data was found for
* the element. If false is returned, then the state of *aData is
* undefined.
*/
PRBool GetRestyleData(Element* aElement, RestyleData* aData);
/**
* The document we're associated with.
*/
inline nsIDocument* Document() const;
struct RestyleEnumerateData : public RestyleData {
nsRefPtr<Element> mElement;
};
private:
/**
* Handle a single mPendingRestyles entry. aRestyleHint must not
* include eRestyle_LaterSiblings; that needs to be dealt with
* before calling this function.
*/
inline void ProcessOneRestyle(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aChangeHint);
typedef nsDataHashtable<nsISupportsHashKey, RestyleData> PendingRestyleTable;
typedef nsAutoTArray< nsRefPtr<Element>, 32> RestyleRootArray;
// Our restyle bits. These will be a subset of ELEMENT_ALL_RESTYLE_FLAGS, and
// will include one flag from ELEMENT_PENDING_RESTYLE_FLAGS and one flag
// that's not in ELEMENT_PENDING_RESTYLE_FLAGS.
PRUint32 mRestyleBits;
nsCSSFrameConstructor* mFrameConstructor; // Owns us
// A hashtable that maps elements to RestyleData structs. The
// values only make sense if the element's current document is our
// document and it has our RestyleBit() flag set. In particular,
// said bit might not be set if the element had a restyle posted and
// then was moved around in the DOM.
PendingRestyleTable mPendingRestyles;
// An array that keeps track of our possible restyle roots. This
// maintains the invariant that if A and B are both restyle roots
// and A is an ancestor of B then A will come after B in the array.
// We maintain this invariant by checking whether an element has an
// ancestor with the restyle root bit set before appending it to the
// array.
RestyleRootArray mRestyleRoots;
// True if we have some entries with the eRestyle_LaterSiblings
// flag. We need this to avoid enumerating the hashtable looking
// for such entries when we can't possibly have any.
PRBool mHaveLaterSiblingRestyles;
};
inline PRBool RestyleTracker::AddPendingRestyle(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint)
{
RestyleData existingData;
existingData.mRestyleHint = nsRestyleHint(0);
existingData.mChangeHint = NS_STYLE_HINT_NONE;
// Check the RestyleBit() flag before doing the hashtable Get, since
// it's possible that the data in the hashtable isn't actually
// relevant anymore (if the flag is not set).
if (aElement->HasFlag(RestyleBit())) {
mPendingRestyles.Get(aElement, &existingData);
} else {
aElement->SetFlags(RestyleBit());
}
PRBool hadRestyleLaterSiblings =
(existingData.mRestyleHint & eRestyle_LaterSiblings) != 0;
existingData.mRestyleHint =
nsRestyleHint(existingData.mRestyleHint | aRestyleHint);
NS_UpdateHint(existingData.mChangeHint, aMinChangeHint);
mPendingRestyles.Put(aElement, existingData);
// We can only treat this element as a restyle root if we would
// actually restyle its descendants (so either call
// ReResolveStyleContext on it or just reframe it).
if ((aRestyleHint & (eRestyle_Self | eRestyle_Subtree)) ||
(aMinChangeHint & nsChangeHint_ReconstructFrame)) {
for (const Element* cur = aElement; !cur->HasFlag(RootBit()); ) {
nsIContent* parent = cur->GetFlattenedTreeParent();
// Stop if we have no parent or the parent is not an element or
// we're part of the viewport scrollbars (because those are not
// frametree descendants of the primary frame of the root
// element).
// XXXbz maybe the primary frame of the root should be the root scrollframe?
if (!parent || !parent->IsElement() ||
// If we've hit the root via a native anonymous kid and that
// this native anonymous kid is not obviously a descendant
// of the root's primary frame, assume we're under the root
// scrollbars. Since those don't get reresolved when
// reresolving the root, we need to make sure to add the
// element to mRestyleRoots.
(cur->IsInNativeAnonymousSubtree() && !parent->GetParent() &&
cur->GetPrimaryFrame() &&
cur->GetPrimaryFrame()->GetParent() != parent->GetPrimaryFrame())) {
mRestyleRoots.AppendElement(aElement);
break;
}
cur = parent->AsElement();
}
// At this point some ancestor of aElement (possibly aElement
// itself) is in mRestyleRoots. Set the root bit on aElement, to
// speed up searching for an existing root on its descendants.
aElement->SetFlags(RootBit());
}
mHaveLaterSiblingRestyles =
mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
return hadRestyleLaterSiblings;
}
} // namespace css
} // namespace mozilla
#endif /* mozilla_css_RestyleTracker_h */
