Big change deriving BLayout from BLayoutItem, and allowing viewless BLayouts.

a few highlights:
* BLayout now derives publicly from BLayoutItem
* Added BAbstractLayout class, which our layouts now derive from
* updated layout builders to avoid creating views when they don't need to
* updated layout classes
* updated AboutSystem to fix a little regression
* more details on #6407
* please tell me about any regressions, I've tried to find them all, but some
  may have slipped by.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@38207 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/interface/AbstractLayout.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2010, Haiku, Inc. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef	_ABSTRACT_LAYOUT_H
+#define	_ABSTRACT_LAYOUT_H
+
+#include <Alignment.h>
+#include <Layout.h>
+#include <Size.h>
+
+class BAbstractLayout : public BLayout {
+public:
+								BAbstractLayout();
+								BAbstractLayout(BMessage* from);
+	virtual						~BAbstractLayout();
+
+	virtual	BSize				MinSize();
+	virtual	BSize				MaxSize();
+	virtual	BSize				PreferredSize();
+	virtual	BAlignment			Alignment();
+
+	virtual	void				SetExplicitMinSize(BSize size);
+	virtual	void				SetExplicitMaxSize(BSize size);
+	virtual	void				SetExplicitPreferredSize(BSize size);
+	virtual	void				SetExplicitAlignment(BAlignment alignment);
+
+	virtual	BSize				BaseMinSize();
+	virtual	BSize				BaseMaxSize();
+	virtual	BSize				BasePreferredSize();
+	virtual	BAlignment			BaseAlignment();
+
+	virtual BRect				Frame();
+	virtual	void				SetFrame(BRect frame);	
+
+	virtual	bool				IsVisible();
+	virtual	void				SetVisible(bool visible);
+
+	virtual status_t			Archive(BMessage* into, bool deep = true) const;
+	virtual	status_t			AllUnarchived(const BMessage* from);
+
+protected:
+	virtual	void				OwnerChanged(BView* was);
+	virtual	void				AncestorVisibilityChanged(bool shown);
+
+private:
+			struct	Proxy;
+			struct	ViewProxy;
+			struct	DataProxy;
+
+			Proxy*				fExplicitData;
+};
+
+#endif	//	_ABSTRACT_LAYOUT_ITEM_H

headers/os/interface/CardLayout.h

@@ -5,10 +5,10 @@
 #ifndef	_CARD_LAYOUT_H
 #define	_CARD_LAYOUT_H
 
-#include <Layout.h>
+#include <AbstractLayout.h>
 
 
-class BCardLayout : public BLayout {
+class BCardLayout : public BAbstractLayout {
 public:
 								BCardLayout();
 								BCardLayout(BMessage* from);
@@ -19,23 +19,23 @@ public:
 			void				SetVisibleItem(int32 index);
 			void				SetVisibleItem(BLayoutItem* item);
 
-	virtual	BSize				MinSize();
-	virtual	BSize				MaxSize();
-	virtual	BSize				PreferredSize();
-	virtual	BAlignment			Alignment();
+	virtual	BSize				BaseMinSize();
+	virtual	BSize				BaseMaxSize();
+	virtual	BSize				BasePreferredSize();
+	virtual	BAlignment			BaseAlignment();
 
 	virtual	bool				HasHeightForWidth();
 	virtual	void				GetHeightForWidth(float width, float* min,
 									float* max, float* preferred);
 
-	virtual	void				InvalidateLayout();
-	virtual	void				LayoutView();
+	virtual	void				InvalidateLayout(bool children = false);
 
 	virtual status_t			Archive(BMessage* into, bool deep = true) const;
 	virtual status_t			AllUnarchived(const BMessage* from);
 	static	BArchivable*		Instantiate(BMessage* from);
 
 protected:
+	virtual	void				DerivedLayoutItems();
 	virtual	bool				ItemAdded(BLayoutItem* item, int32 atIndex);
 	virtual	void				ItemRemoved(BLayoutItem* item, int32 fromIndex);
 

headers/os/interface/GridLayoutBuilder.h

@@ -16,9 +16,9 @@ public:
 								BGridLayoutBuilder(BGridView* view);
 
 			BGridLayout*		GridLayout() const;
-			BView*				View() const;
 			BGridLayoutBuilder& GetGridLayout(BGridLayout** _layout);
-			BGridLayoutBuilder& GetView(BView** _view);
+			BView*				View() const;
+			BGridLayoutBuilder&	GetView(BView** _view);
 
 			BGridLayoutBuilder& Add(BView* view, int32 column, int32 row,
 									int32 columnCount = 1, int32 rowCount = 1);
@@ -32,7 +32,6 @@ public:
 									float bottom);
 
 								operator BGridLayout*();
-								operator BView*();
 
 private:
 			BGridLayout*		fLayout;

headers/os/interface/GroupLayoutBuilder.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006, Haiku, Inc. All rights reserved.
+ * Copyright 2006-2010, Haiku, Inc. All rights reserved.
  * Distributed under the terms of the MIT License.
  */
 #ifndef	_GROUP_LAYOUT_BUILDER_H
@@ -39,7 +39,6 @@ public:
 									float bottom);
 
 								operator BGroupLayout*();
-								operator BView*();
 
 private:
 			bool				_PushLayout(BGroupLayout* layout);

headers/os/interface/Layout.h

@@ -8,22 +8,27 @@
 
 #include <Alignment.h>
 #include <Archivable.h>
+#include <LayoutItem.h>
 #include <List.h>
 #include <Size.h>
 
 
+class BLayoutContext;
 class BLayoutItem;
 class BView;
 
 
-class BLayout : public BArchivable {
+class BLayout : public BLayoutItem {
 public:
 								BLayout();
 								BLayout(BMessage* archive);
 	virtual						~BLayout();
 
-			BView*				View() const;
+			BView*				Owner() const;
+			BView*				TargetView() const;
+	virtual	BView*				View(); // from BLayoutItem
 
+	// methods dealing with items
 	virtual	BLayoutItem*		AddView(BView* child);
 	virtual	BLayoutItem*		AddView(int32 index, BView* child);
 
@@ -39,18 +44,22 @@ public:
 			int32				IndexOfItem(const BLayoutItem* item) const;
 			int32				IndexOfView(BView* child) const;
 
-	virtual	BSize				MinSize() = 0;
-	virtual	BSize				MaxSize() = 0;
-	virtual	BSize				PreferredSize() = 0;
-	virtual	BAlignment			Alignment() = 0;
+			bool				AncestorsVisible();
 
-	virtual	bool				HasHeightForWidth() = 0;
-	virtual	void				GetHeightForWidth(float width, float* min,
-									float* max, float* preferred) = 0;
+	// Layouting related methods
 
-	virtual	void				InvalidateLayout();
+	virtual	void				InvalidateLayout(bool children = false);
+	virtual	void				Relayout(bool immediate = false);
+			void				RequireLayout();
+			bool				IsValid();
+			void				EnableLayoutInvalidation();
+			void				DisableLayoutInvalidation();
 
-	virtual	void				LayoutView() = 0;
+			void				LayoutItems(bool force = false);
+			BRect				LayoutArea();
+			BLayoutContext*		LayoutContext();
+
+	// Archiving methods
 
 	virtual status_t			Archive(BMessage* into, bool deep = true) const;
 	virtual	status_t			AllUnarchived(const BMessage* from);
@@ -59,17 +68,44 @@ public:
 									int32 index) const;
 	virtual	status_t			ItemUnarchived(const BMessage* from,
 									BLayoutItem* item, int32 index);
+
 protected:
+	// BLayout hook methods
 	virtual	bool				ItemAdded(BLayoutItem* item, int32 atIndex);
 	virtual	void				ItemRemoved(BLayoutItem* item, int32 fromIndex);
+	virtual	void				DerivedLayoutItems() = 0;
+	virtual	void				OwnerChanged(BView* was);
+
+	// BLayoutItem hook methods
+	virtual	void				AttachedToLayout();
+	virtual void				DetachedFromLayout(BLayout* layout);
+	virtual	void				AncestorVisibilityChanged(bool shown);
+
+	// To be called by sub-classes in SetVisible().
+			void				VisibilityChanged(bool show);
+	// To be called when layout data is known to be good
+			void				ResetLayoutInvalidation();
 
 private:
 			friend class BView;
 
-			void				SetView(BView* view);
+			bool				RemoveViewRecursive(BView* view);
+			bool				InvalidateLayoutsForView(BView* view);
+			bool				InvalidationLegal();
+			void				SetOwner(BView* owner);
+			void				SetTarget(BView* target);
 
-			BView*				fView;
+			void				_LayoutWithinContext(bool force,
+									BLayoutContext* context);
+
+			uint32				fState;
+			bool				fAncestorsVisible;
+			int32				fInvalidationDisabled;
+			BLayoutContext*		fContext;
+			BView*				fOwner;
+			BView*				fTarget;
 			BList				fItems;
+			BList				fNestedLayouts;
 };
 
 

headers/os/interface/LayoutBuilder.h

@@ -33,7 +33,6 @@ protected:
 public:
 	inline	void				SetParent(ParentBuilder* parent);
 		// conceptually private
-
 	inline	ParentBuilder&		End();
 
 protected:
@@ -71,11 +70,23 @@ public:
 
 	inline	GroupBuilder		AddGroup(enum orientation orientation,
 									float spacing = 0.0f, float weight = 1.0f);
+	inline	GroupBuilder		AddGroup(BGroupView* groupView,
+									float weight = 1.0f);
+	inline	GroupBuilder		AddGroup(BGroupLayout* groupLayout,
+									float weight = 1.0f);
+
 	inline	GridBuilder			AddGrid(float horizontalSpacing = 0.0f,
 									float verticalSpacing = 0.0f,
 									float weight = 1.0f);
+	inline	GridBuilder			AddGrid(BGridLayout* gridLayout,
+									float weight = 1.0f);
+	inline	GridBuilder			AddGrid(BGridView* gridView,
+									float weight = 1.0f);
+
 	inline	SplitBuilder		AddSplit(enum orientation orientation,
 									float spacing = 0.0f, float weight = 1.0f);
+	inline	SplitBuilder		AddSplit(BSplitView* splitView,
+									float weight = 1.0f);
 
 	inline	ThisBuilder&		AddGlue(float weight = 1.0f);
 	inline	ThisBuilder&		AddStrut(float size);
@@ -84,7 +95,6 @@ public:
 									float bottom);
 
 	inline						operator BGroupLayout*();
-	inline						operator BView*();
 
 private:
 			BGroupLayout*		fLayout;
@@ -131,13 +141,30 @@ public:
 	inline	GroupBuilder		AddGroup(enum orientation orientation,
 									float spacing, int32 column, int32 row,
 									int32 columnCount = 1, int32 rowCount = 1);
+	inline	GroupBuilder		AddGroup(BGroupView* groupView,	int32 column,
+									int32 row, int32 columnCount = 1,
+									int32 rowCount = 1);
+	inline	GroupBuilder		AddGroup(BGroupLayout* groupLayout, 
+									int32 column, int32 row,
+									int32 columnCount = 1, int32 rowCount = 1);
+
 	inline	GridBuilder			AddGrid(float horizontalSpacing,
 									float verticalSpacing, int32 column,
 									int32 row, int32 columnCount = 1,
 									int32 rowCount = 1);
+	inline	GridBuilder			AddGrid(BGridLayout* gridLayout,
+									int32 column, int32 row,
+									int32 columnCount = 1, int32 rowCount = 1);
+	inline	GridBuilder			AddGrid(BGridView* gridView,
+									int32 column, int32 row,
+									int32 columnCount = 1, int32 rowCount = 1);
+
 	inline	SplitBuilder		AddSplit(enum orientation orientation,
 									float spacing, int32 column, int32 row,
 									int32 columnCount = 1, int32 rowCount = 1);
+	inline	SplitBuilder		AddSplit(BSplitView* splitView, int32 column,
+									int32 row, int32 columnCount = 1,
+									int32 rowCount = 1);
 
 	inline	ThisBuilder&		SetColumnWeight(int32 column, float weight);
 	inline	ThisBuilder&		SetRowWeight(int32 row, float weight);
@@ -146,7 +173,6 @@ public:
 									float bottom);
 
 	inline						operator BGridLayout*();
-	inline						operator BView*();
 
 private:
 			BGridLayout*		fLayout;
@@ -168,7 +194,8 @@ public:
 	inline						Split(BSplitView* view);
 
 	inline	BSplitView*			View() const;
-	inline	ThisBuilder&		GetView(BSplitView** _view);
+	inline	ThisBuilder&		GetView(BView** _view);
+	inline	ThisBuilder&		GetSplitView(BSplitView** _view);
 
 	inline	ThisBuilder&		Add(BView* view);
 	inline	ThisBuilder&		Add(BView* view, float weight);
@@ -177,11 +204,23 @@ public:
 
 	inline	GroupBuilder		AddGroup(enum orientation orientation,
 									float spacing = 0.0f, float weight = 1.0f);
+	inline	GroupBuilder		AddGroup(BGroupView* groupView,
+									float weight = 1.0f);
+	inline	GroupBuilder		AddGroup(BGroupLayout* groupLayout,
+									float weight = 1.0f);
+
 	inline	GridBuilder			AddGrid(float horizontalSpacing = 0.0f,
 									float verticalSpacing = 0.0f,
 									float weight = 1.0f);
+	inline	GridBuilder			AddGrid(BGridView* gridView,
+									float weight = 1.0f);
+	inline	GridBuilder			AddGrid(BGridLayout* gridLayout,
+									float weight = 1.0f);
+
 	inline	SplitBuilder		AddSplit(enum orientation orientation,
 									float spacing = 0.0f, float weight = 1.0f);
+	inline	SplitBuilder		AddSplit(BSplitView* splitView,
+									float weight = 1.0f);
 
 	inline	ThisBuilder&		SetCollapsible(bool collapsible);
 	inline	ThisBuilder&		SetCollapsible(int32 index, bool collapsible);
@@ -244,7 +283,7 @@ Group<ParentBuilder>::Group(BWindow* window, enum orientation orientation,
 {
 	window->SetLayout(fLayout);
 
-	fLayout->View()->SetViewColor(ui_color(B_PANEL_BACKGROUND_COLOR));
+	fLayout->Owner()->SetViewColor(ui_color(B_PANEL_BACKGROUND_COLOR));
 		// TODO: we get a white background if we don't do this
 }
 
@@ -277,7 +316,7 @@ template<typename ParentBuilder>
 BView*
 Group<ParentBuilder>::View() const
 {
-	return fLayout->View();
+	return fLayout->Owner();
 }
 
 
@@ -294,7 +333,7 @@ template<typename ParentBuilder>
 typename Group<ParentBuilder>::ThisBuilder&
 Group<ParentBuilder>::GetView(BView** _view)
 {
-	*_view = fLayout->View();
+	*_view = fLayout->Owner();
 	return *this;
 }
 
@@ -340,21 +379,65 @@ typename Group<ParentBuilder>::GroupBuilder
 Group<ParentBuilder>::AddGroup(enum orientation orientation, float spacing,
 	float weight)
 {
-	GroupBuilder builder(orientation, spacing);
+	GroupBuilder builder(new BGroupLayout(orientation, spacing));
 	builder.SetParent(this);
-	fLayout->AddView(builder.View(), weight);
+	fLayout->AddItem(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Group<ParentBuilder>::GroupBuilder
+Group<ParentBuilder>::AddGroup(BGroupView* groupView, float weight)
+{
+	GroupBuilder builder(groupView);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Group<ParentBuilder>::GroupBuilder
+Group<ParentBuilder>::AddGroup(BGroupLayout* groupLayout, float weight)
+{
+	GroupBuilder builder(groupLayout);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), weight);
 	return builder;
 }
 
 
 template<typename ParentBuilder>
 typename Group<ParentBuilder>::GridBuilder
-Group<ParentBuilder>::AddGrid(float horizontalSpacing, float verticalSpacing,
-	float weight)
+Group<ParentBuilder>::AddGrid(float horizontalSpacing,
+	float verticalSpacing, float weight)
 {
-	GridBuilder builder(horizontalSpacing, verticalSpacing);
+	GridBuilder builder(new BGridLayout(horizontalSpacing, verticalSpacing));
 	builder.SetParent(this);
-	fLayout->AddView(builder.View(), weight);
+	fLayout->AddItem(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Group<ParentBuilder>::GridBuilder
+Group<ParentBuilder>::AddGrid(BGridLayout* gridLayout, float weight)
+{
+	GridBuilder builder(gridLayout);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Group<ParentBuilder>::GridBuilder
+Group<ParentBuilder>::AddGrid(BGridView* gridView, float weight)
+{
+	GridBuilder builder(gridView);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), weight);
 	return builder;
 }
 
@@ -371,6 +454,17 @@ Group<ParentBuilder>::AddSplit(enum orientation orientation, float spacing,
 }
 
 
+template<typename ParentBuilder>
+typename Group<ParentBuilder>::SplitBuilder
+Group<ParentBuilder>::AddSplit(BSplitView* splitView, float weight)
+{
+	SplitBuilder builder(splitView);
+	builder.SetParent(this);
+	fLayout->AddView(builder.View(), weight);
+	return builder;
+}
+
+
 template<typename ParentBuilder>
 typename Group<ParentBuilder>::ThisBuilder&
 Group<ParentBuilder>::AddGlue(float weight)
@@ -410,13 +504,6 @@ Group<ParentBuilder>::operator BGroupLayout*()
 }
 
 
-template<typename ParentBuilder>
-Group<ParentBuilder>::operator BView*()
-{
-	return fLayout->View();
-}
-
-
 // #pragma mark - Grid
 
 
@@ -436,7 +523,7 @@ Grid<ParentBuilder>::Grid(BWindow* window, float horizontalSpacing,
 {
 	window->SetLayout(fLayout);
 
-	fLayout->View()->SetViewColor(ui_color(B_PANEL_BACKGROUND_COLOR));
+	fLayout->Owner()->SetViewColor(ui_color(B_PANEL_BACKGROUND_COLOR));
 		// TODO: we get a white background if we don't do this
 }
 
@@ -469,7 +556,7 @@ template<typename ParentBuilder>
 BView*
 Grid<ParentBuilder>::View() const
 {
-	return fLayout->View();
+	return fLayout->Owner();
 }
 
 
@@ -486,7 +573,7 @@ template<typename ParentBuilder>
 typename Grid<ParentBuilder>::ThisBuilder&
 Grid<ParentBuilder>::GetView(BView** _view)
 {
-	*_view = fLayout->View();
+	*_view = fLayout->Owner();
 	return *this;
 }
 
@@ -546,9 +633,33 @@ typename Grid<ParentBuilder>::GroupBuilder
 Grid<ParentBuilder>::AddGroup(enum orientation orientation, float spacing,
 	int32 column, int32 row, int32 columnCount, int32 rowCount)
 {
-	GroupBuilder builder(orientation, spacing);
+	GroupBuilder builder(new BGroupLayout(orientation, spacing));
 	builder.SetParent(this);
-	fLayout->AddView(builder.View(), column, row, columnCount, rowCount);
+	fLayout->AddItem(builder.Layout(), column, row, columnCount, rowCount);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Grid<ParentBuilder>::GroupBuilder
+Grid<ParentBuilder>::AddGroup(BGroupView* groupView, int32 column, int32 row,
+	int32 columnCount, int32 rowCount)
+{
+	GroupBuilder builder(groupView);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), column, row, columnCount, rowCount);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Grid<ParentBuilder>::GroupBuilder
+Grid<ParentBuilder>::AddGroup(BGroupLayout* groupLayout, int32 column,
+	int32 row, int32 columnCount, int32 rowCount)
+{
+	GroupBuilder builder(groupLayout);
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), column, row, columnCount, rowCount);
 	return builder;
 }
 
@@ -558,7 +669,19 @@ typename Grid<ParentBuilder>::GridBuilder
 Grid<ParentBuilder>::AddGrid(float horizontalSpacing, float verticalSpacing,
 	int32 column, int32 row, int32 columnCount, int32 rowCount)
 {
-	GridBuilder builder(horizontalSpacing, verticalSpacing);
+	GridBuilder builder(new BGridLayout(horizontalSpacing, verticalSpacing));
+	builder.SetParent(this);
+	fLayout->AddItem(builder.Layout(), column, row, columnCount, rowCount);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Grid<ParentBuilder>::GridBuilder
+Grid<ParentBuilder>::AddGrid(BGridView* gridView, int32 column, int32 row,
+	int32 columnCount, int32 rowCount)
+{
+	GridBuilder builder(gridView);
 	builder.SetParent(this);
 	fLayout->AddView(builder.View(), column, row, columnCount, rowCount);
 	return builder;
@@ -574,7 +697,19 @@ Grid<ParentBuilder>::AddSplit(enum orientation orientation, float spacing,
 	builder.SetParent(this);
 	fLayout->AddView(builder.View(), column, row, columnCount, rowCount);
 	return builder;
-}
+} 
+
+
+template<typename ParentBuilder>
+typename Grid<ParentBuilder>::SplitBuilder
+Grid<ParentBuilder>::AddSplit(BSplitView* splitView, int32 column, int32 row,
+	int32 columnCount, int32 rowCount)
+{
+	SplitBuilder builder(splitView);
+	builder.SetParent(this);
+	fLayout->AddView(builder.View(), column, row, columnCount, rowCount);
+	return builder;
+} 
 
 
 template<typename ParentBuilder>
@@ -612,13 +747,6 @@ Grid<ParentBuilder>::operator BGridLayout*()
 }
 
 
-template<typename ParentBuilder>
-Grid<ParentBuilder>::operator BView*()
-{
-	return fLayout->View();
-}
-
-
 // #pragma mark - Split
 
 
@@ -648,7 +776,16 @@ Split<ParentBuilder>::View() const
 
 template<typename ParentBuilder>
 typename Split<ParentBuilder>::ThisBuilder&
-Split<ParentBuilder>::GetView(BSplitView** _view)
+Split<ParentBuilder>::GetView(BView** _view)
+{
+	*_view = fView;
+	return *this;
+}
+
+
+template<typename ParentBuilder>
+typename Split<ParentBuilder>::ThisBuilder&
+Split<ParentBuilder>::GetSplitView(BSplitView** _view)
 {
 	*_view = fView;
 	return *this;
@@ -696,9 +833,31 @@ typename Split<ParentBuilder>::GroupBuilder
 Split<ParentBuilder>::AddGroup(enum orientation orientation, float spacing,
 	float weight)
 {
-	GroupBuilder builder(orientation, spacing);
+	GroupBuilder builder(new BGroupLayout(orientation, spacing));
 	builder.SetParent(this);
-	fView->AddChild(builder.View(), weight);
+	fView->AddChild(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Split<ParentBuilder>::GroupBuilder
+Split<ParentBuilder>::AddGroup(BGroupView* groupView, float weight)
+{
+	GroupBuilder builder(groupView);
+	builder.SetParent(this);
+	fView->AddChild(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Split<ParentBuilder>::GroupBuilder
+Split<ParentBuilder>::AddGroup(BGroupLayout* groupLayout, float weight)
+{
+	GroupBuilder builder(groupLayout);
+	builder.SetParent(this);
+	fView->AddChild(builder.Layout(), weight);
 	return builder;
 }
 
@@ -708,9 +867,31 @@ typename Split<ParentBuilder>::GridBuilder
 Split<ParentBuilder>::AddGrid(float horizontalSpacing, float verticalSpacing,
 	float weight)
 {
-	GridBuilder builder(horizontalSpacing, verticalSpacing);
+	GridBuilder builder(new BGridLayout(horizontalSpacing, verticalSpacing));
 	builder.SetParent(this);
-	fView->AddChild(builder.View(), weight);
+	fView->AddChild(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Split<ParentBuilder>::GridBuilder
+Split<ParentBuilder>::AddGrid(BGridView* gridView, float weight)
+{
+	GridBuilder builder(gridView);
+	builder.SetParent(this);
+	fView->AddChild(builder.Layout(), weight);
+	return builder;
+}
+
+
+template<typename ParentBuilder>
+typename Split<ParentBuilder>::GridBuilder
+Split<ParentBuilder>::AddGrid(BGridLayout* layout, float weight)
+{
+	GridBuilder builder(layout);
+	builder.SetParent(this);
+	fView->AddChild(builder.Layout(), weight);
 	return builder;
 }
 

headers/os/interface/LayoutItem.h

@@ -16,7 +16,7 @@ class BLayout;
 class BView;
 
 
-class BLayoutItem: public BArchivable {
+class BLayoutItem : public BArchivable {
 public:
 								BLayoutItem();
 								BLayoutItem(BMessage* from);
@@ -46,7 +46,8 @@ public:
 
 	virtual	BView*				View();
 
-	virtual	void				InvalidateLayout();
+	virtual	void				InvalidateLayout(bool children = false);
+	virtual	void				Relayout(bool immediate = false);
 
 			void*				LayoutData() const;
 			void				SetLayoutData(void* data);
@@ -57,11 +58,19 @@ public:
 	virtual status_t			AllArchived(BMessage* into) const;
 	virtual	status_t			AllUnarchived(const BMessage* from);
 
-private:
-			friend class BLayout;
+protected:
 
 			void				SetLayout(BLayout* layout);
 
+	// hook methods
+	virtual	void				AttachedToLayout();
+	virtual	void				DetachedFromLayout(BLayout* layout);
+
+	virtual void				AncestorVisibilityChanged(bool shown);
+
+private:
+			friend class BLayout;
+
 			BLayout*			fLayout;
 			void*				fLayoutData;
 };

headers/os/interface/TwoDimensionalLayout.h

@@ -6,12 +6,12 @@
 #define	_TWO_DIMENSIONAL_LAYOUT_H
 
 
-#include <Layout.h>
+#include <AbstractLayout.h>
 
 class BLayoutContext;
 
 
-class BTwoDimensionalLayout : public BLayout {
+class BTwoDimensionalLayout : public BAbstractLayout {
 public:
 								BTwoDimensionalLayout();
 								BTwoDimensionalLayout(BMessage* from);
@@ -25,18 +25,18 @@ public:
 			void				AlignLayoutWith(BTwoDimensionalLayout* other,
 									enum orientation orientation);
 
-	virtual	BSize				MinSize();
-	virtual	BSize				MaxSize();
-	virtual	BSize				PreferredSize();
-	virtual	BAlignment			Alignment();
+	virtual	BSize				BaseMinSize();
+	virtual	BSize				BaseMaxSize();
+	virtual	BSize				BasePreferredSize();
+	virtual	BAlignment			BaseAlignment();
 
 	virtual	bool				HasHeightForWidth();
 	virtual	void				GetHeightForWidth(float width, float* min,
 									float* max, float* preferred);
 
-	virtual	void				InvalidateLayout();
+	virtual	void				SetFrame(BRect frame);
 
-	virtual	void				LayoutView();
+	virtual	void				InvalidateLayout(bool children = false);
 
 	virtual status_t			Archive(BMessage* into, bool deep = true) const;
 	virtual status_t			AllArchived(BMessage* into) const;
@@ -56,6 +56,8 @@ protected:
 				int32	height;
 			};
 
+	virtual	void				DerivedLayoutItems();
+
 			BSize				AddInsets(BSize size);
 			void				AddInsets(float* minHeight, float* maxHeight,
 									float* preferredHeight);
@@ -82,7 +84,6 @@ private:
 			friend class LocalLayouter;
 
 			void				_ValidateMinMax();
-			BLayoutContext*		_CurrentLayoutContext();
 
 protected:
 			float				fLeftInset;

headers/os/interface/View.h

@@ -562,6 +562,8 @@ public:
 			void				Layout(bool force);
 			void				Relayout();
 
+	class Private;
+
 protected:
 	virtual	void				DoLayout();
 
@@ -580,6 +582,8 @@ protected:
 
 private:
 			void				_Layout(bool force, BLayoutContext* context);
+			void				_LayoutLeft(BLayout* deleted);
+			void				_InvalidateParentLayout();
 
 private:
 	// FBC padding and forbidden methods
@@ -595,6 +599,7 @@ private:
 private:
 	struct LayoutData;
 
+	friend class Private;
 	friend class BBitmap;
 	friend class BLayout;
 	friend class BPrintJob;

headers/os/interface/Window.h

@@ -103,6 +103,7 @@ public:
 			void				Close() { Quit(); }
 
 			void				AddChild(BView* child, BView* before = NULL);
+			void				AddChild(BLayoutItem* child);
 			bool				RemoveChild(BView* child);
 			int32				CountChildren() const;
 			BView*				ChildAt(int32 index) const;