Now that child classes aren't overriding the various InvalidateLayout() methods, we can take advantage of some guarantees to simplify/clean/optimize the layout invalidation propagation mechanisms!

headers/os/interface/Layout.h

@@ -90,8 +90,6 @@ protected:
 private:
 			friend class BView;
 
-			bool				InvalidateLayoutsForView(BView* view);
-			bool				InvalidationLegal();
 			void				SetOwner(BView* owner);
 			void				SetTarget(BView* target);
 

src/kits/interface/Layout.cpp

@@ -299,8 +299,10 @@ BLayout::InvalidateLayout(bool children)
 	// printf("BLayout(%p)::InvalidateLayout(%i) : state %x, disabled %li\n",
 	// this, children, (unsigned int)fState, fInvalidationDisabled);
 
-	if (!InvalidationLegal())
+	if (fInvalidationDisabled > 0
+		|| (fState & B_LAYOUT_INVALIDATION_ILLEGAL) != 0) {
 		return;
+	}
 
 	fState |= B_LAYOUT_NECESSARY;
 	LayoutInvalidated(children);
@@ -310,23 +312,15 @@ BLayout::InvalidateLayout(bool children)
 			ItemAt(i)->InvalidateLayout(children);
 	}
 
-	if (fOwner && BView::Private(fOwner).MinMaxValid())
+	if (fOwner)
 		fOwner->InvalidateLayout(children);
 
 	if (BLayout* nestedIn = Layout()) {
-		if (nestedIn->InvalidationLegal())
-			nestedIn->InvalidateLayout();
+		nestedIn->InvalidateLayout();
 	} else if (fOwner) {
 		// If we weren't added as a BLayoutItem, we still have to invalidate
 		// whatever layout our owner is in.
-		BView* ownerParent = fOwner->fParent;
-		if (ownerParent) {
-			BLayout* layout = ownerParent->GetLayout();
-			if (layout && layout->fNestedLayouts.CountItems() > 0)
-				layout->InvalidateLayoutsForView(fOwner);
-			else if (BView::Private(ownerParent).MinMaxValid())
-				ownerParent->InvalidateLayout(false);
-		}
+		fOwner->_InvalidateParentLayout();
 	}
 }
 
@@ -591,31 +585,6 @@ BLayout::LayoutContext() const
 }
 
 
-bool
-BLayout::InvalidateLayoutsForView(BView* view)
-{
-	BView::Private viewPrivate(view);
-	int32 count = viewPrivate.CountLayoutItems();
-	if (count == 0)
-		return false;
-
-	for (int32 i = 0; i < count; i++) {
-		BLayout* layout = viewPrivate.LayoutItemAt(i)->Layout();
-		if (layout->InvalidationLegal())
-			layout->InvalidateLayout();
-	}
-	return true;
-}
-
-
-bool
-BLayout::InvalidationLegal()
-{
-	return fInvalidationDisabled <= 0
-		&& (fState & B_LAYOUT_INVALIDATION_ILLEGAL) == 0;
-}
-
-
 void
 BLayout::SetOwner(BView* owner)
 {

src/kits/interface/LayoutInvalidator.cpp

@@ -0,0 +1,250 @@
+/*
+ * Copyright 2011, Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#include "LayoutInvalidator.h"
+
+#include <Layout.h>
+#include <LayoutItem.h>
+#include <View.h>
+#include <ViewPrivate.h>
+
+
+/*
+	Handles propagation of layout invalidations between the various classes.
+		* keeps the propagation logic in one place
+		* lets the other classes focus on invalidation, not propagation logic
+		* along with NVI, makes it easier to ensure that we are not
+			invalidating the same objects over and over.
+
+	TODO: could be optimized further if we can be certain that encountering
+	an already invalidated object means we are done.
+
+	Note: we must be certain of this for BLayout objects, if we want to have
+	any reasonable way to invalidate from a set of BLayoutItems without
+	invalidating all of their parent objects n times.
+*/
+
+
+class LayoutInvalidator {
+public:
+
+	class Layout;
+	class View;
+	class LayoutItem;
+
+	/* Since we use templates, we don't need these in the base class,
+		but these methods are conceptually virtual.
+	virtual bool IsFinished() = 0;
+	virtual *this InvalidateChildren() = 0;
+	virtual *this DoInvalidation() = 0; // actually does the invalidation
+	virtual void Up() = 0; // propagates upwards
+	*/
+
+	template <class T>
+	static void InvalidateLayout(T from, bool deep = false)
+	{
+		if (LayoutInvalidator::For(from).IsFinished())
+			return;
+
+		if (deep) {
+			LayoutInvalidator::For(from)
+				.DoInvalidation()
+				.InvalidateChildren()
+				.Up();
+		} else {
+			LayoutInvalidator::For(from)
+				.DoInvalidation()
+				.Up();
+		}
+	}
+
+	static LayoutInvalidator::Layout For(BLayout* layout);
+	static LayoutInvalidator::View For(BView* view);
+	static LayoutInvalidator::LayoutItem For(BLayoutItem* item);
+
+	class View {
+	public:
+		View(BView* view)
+			:
+			fView(view),
+			fViewPrivate(view)
+		{
+		}
+
+		bool IsFinished()
+		{
+			return fView != NULL;
+			// TODO: test other conditions
+		}
+		
+		View& InvalidateChildren()
+		{
+			// fViewPrivate.InvalidateChildren();
+			// TODO: propagate downwards
+			return *this;
+		}
+
+		View& DoInvalidation()
+		{
+			// fViewPrivate.InvalidateLayout();
+			// BLayout::Private(fView->GetLayout()).InvalidateLayout();
+			// We don't invalidate layout items, if a BView subclass requires
+			// that behaviour, it can be implemented there.
+
+			return *this;
+		}
+		
+		View& View::Up()
+		{
+			BLayout* layout = fView->GetLayout();
+			if (layout && layout->Layout()) {
+				LayoutInvalidator::InvalidateLayout(layout->Layout());
+			} else if (fViewPrivate.CountLayoutItems() > 0) {
+				_UpThroughLayoutItems();
+			} else {
+				LayoutInvalidator::InvalidateLayout(fView->Parent());
+			}
+
+			return *this;
+		}
+
+	private:
+		void _UpThroughLayoutItems()
+		{
+			int32 count = fViewPrivate.CountLayoutItems();
+			for (int32 i = 0; i < count; i++) {
+				BLayoutItem* item = fViewPrivate.LayoutItemAt(i);
+				LayoutInvalidator::InvalidateLayout(item);
+			}
+		}
+
+		BView*				fView;
+		BView::Private		fViewPrivate;
+	};
+
+
+	class Layout {
+	public:
+		Layout(BLayout* layout)
+			:
+			fLayout(layout)
+		{
+		}
+
+		bool IsFinished()
+		{
+			// return !fLayout->LayoutIsValid();
+			return false;
+		}
+
+		Layout& InvalidateChildren()
+		{
+			/*
+			for (int32 i = fLayout->CountItems() - 1; i >= 0 i--;)
+				BLayoutItem::Private(fLayout->ItemAt(i)).InvalidateLayout(true);
+			*/
+			return *this;
+		}
+		
+		Layout& DoInvalidation()
+		{
+			BLayout::Private(fLayout).InvalidateLayout();
+			BView::Private(fLayout->Owner()).InvalidateLayout();
+
+			return *this;
+		}
+		
+		void Up()
+		{
+			if (fLayout->Layout())
+				LayoutInvalidator::InvalidateLayout(fLayout->Layout());
+			else if (fLayout->Owner())
+				LayoutInvalidator::For(fLayout->Owner()).Up();
+		}
+
+	private:
+		BLayout* fLayout;
+	};
+
+	class LayoutItem {
+	public:
+		LayoutItem(BLayoutItem* layoutItem)
+			:
+			fLayoutItem(layoutItem)
+		{
+		}
+
+		bool IsFinished()
+		{
+			return !fLayoutItem->LayoutIsValid();
+		}
+
+		LayoutItem& InvalidateChildren()
+		{
+			/* what to do here?? */
+			return *this;
+		}
+		
+		LayoutItem& DoInvalidation()
+		{
+			BLayoutItem::Private(fLayoutItem).InvalidateLayout();
+			BView::Private(fLayoutItem->View()).InvalidateLayout();
+			return *this;
+		}
+		
+		void Up()
+		{
+			if (fLayoutItem->Layout())
+				BLayoutInvalidator::_InvalidateLayout(fLayoutItem->Layout());
+			else if (fLayoutItem->View())
+				BLayoutInvalidator::For(fLayoutItem->View()).Up();
+		}
+
+	private:
+		BLayoutItem* fLayoutItem;
+	};
+
+
+};
+
+
+inline LayoutInvalidator::Layout
+LayoutInvalidator::For(BLayout* layout)
+{
+	return BLayoutInvalidator::Layout(layout);
+}
+
+inline LayoutInvalidator::View
+LayoutInvalidator::For(BView* view)
+{
+	return BLayoutInvalidator::View(view);
+}
+
+inline LayoutInvalidator::LayoutItem
+LayoutInvalidator::For(BLayoutItem* item)
+{
+	return LayoutInvalidator::LayoutItem(view);
+}
+
+
+void
+BLayoutInvalidator::InvalidateLayout(BLayout* layout, bool deep)
+{
+	LayoutInvalidator::For(layout).InvalidateLayout(deep);
+}
+
+
+void
+BLayoutInvalidator::InvalidateLayout(BLayoutItem* item, bool deep)
+{
+	LayoutInvalidator::For(item).InvalidateLayout(deep);
+}
+
+
+void
+BLayoutInvalidator::InvalidateLayout(BView* view, bool deep)
+{
+	LayoutInvalidator::For(view).InvalidateLayout(deep);
+}
+

src/kits/interface/LayoutInvalidator.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2011, Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef	_LAYOUT_INVALIDATOR_H
+#define	_LAYOUT_INVALIDATOR_H
+
+
+class BLayout;
+class BLayoutItem;
+class BView;
+
+
+struct BLayoutInvalidator {
+	static	void				InvalidateLayout(BLayout* layout, bool deep);
+	static	void				InvalidateLayout(BLayoutItem* item, bool deep);
+	static	void				InvalidateLayout(BView* view, bool deep);
+};
+
+#endif

src/kits/interface/View.cpp

@@ -4692,32 +4692,30 @@ BView::InvalidateLayout(bool descendants)
 	//	this, descendants, fLayoutData->fLayoutValid,
 	//	fLayoutData->fLayoutInProgress);
 
-	if (fLayoutData->fMinMaxValid && !fLayoutData->fLayoutInProgress
- 		&& fLayoutData->fLayoutInvalidationDisabled == 0) {
+	if (!fLayoutData->fMinMaxValid || fLayoutData->fLayoutInProgress
+ 			|| fLayoutData->fLayoutInvalidationDisabled > 0) {
+		return;
+	}
 
-		fLayoutData->fLayoutValid = false;
-		fLayoutData->fMinMaxValid = false;
-		LayoutInvalidated(descendants);
+	fLayoutData->fLayoutValid = false;
+	fLayoutData->fMinMaxValid = false;
+	LayoutInvalidated(descendants);
 
-		if (descendants) {
-			for (BView* child = fFirstChild;
-				child; child = child->fNextSibling) {
-				child->InvalidateLayout(descendants);
-			}
-		}
-
-		if (fLayoutData->fLayout && fLayoutData->fLayout->InvalidationLegal())
-			fLayoutData->fLayout->InvalidateLayout(descendants);
-		else if (!fLayoutData->fLayout && fParent) {
-			_InvalidateParentLayout();
-		}
-
-		if (fTopLevelView) {
-			// trigger layout process
-			if (fOwner)
-				fOwner->PostMessage(B_LAYOUT_WINDOW);
+	if (descendants) {
+		for (BView* child = fFirstChild;
+			child; child = child->fNextSibling) {
+			child->InvalidateLayout(descendants);
 		}
 	}
+
+	if (fLayoutData->fLayout)
+		fLayoutData->fLayout->InvalidateLayout(descendants);
+	else if (fParent) {
+		_InvalidateParentLayout();
+	}
+
+	if (fTopLevelView && fOwner)
+		fOwner->PostMessage(B_LAYOUT_WINDOW);
 }
 
 
@@ -4936,12 +4934,18 @@ BView::_LayoutLeft(BLayout* deleted)
 void
 BView::_InvalidateParentLayout()
 {
+	if (!fParent)
+		return;
+
 	BLayout* layout = fLayoutData->fLayout;
 	BLayout* layoutParent = layout ? layout->Layout() : NULL;
-	if (layoutParent && layoutParent->InvalidationLegal()) {
-		layout->Layout()->InvalidateLayout();
-	} else if (fParent && fParent->fLayoutData->fLayout) {
-		fParent->fLayoutData->fLayout->InvalidateLayoutsForView(this);
+	if (layoutParent) {
+		layoutParent->InvalidateLayout();
+	} else if (fLayoutData->fLayoutItems.CountItems() > 0) {
+		int32 count = fLayoutData->fLayoutItems.CountItems();
+		for (int32 i = 0; i < count; i++) {
+			fLayoutData->fLayoutItems.ItemAt(i)->Layout()->InvalidateLayout();
+		}
 	} else if (fParent) {
 		fParent->InvalidateLayout();
 	}