Make BALMLayout::BasePreferredSize() useful again.

src/libs/alm/ALMLayout.cpp

@@ -851,8 +851,11 @@ BALMLayout::BaseMaxSize()
 BSize
 BALMLayout::BasePreferredSize()
 {
-	fSolver->ValidateMinSize();
-	return fMinSize;
+	ResultType result = fSolver->ValidatePreferredSize();
+	if (result != kOptimal)
+		fBadLayoutPolicy->OnBadLayout(this, result, NULL);
+
+	return fPreferredSize;
 }
 
 

src/libs/alm/SharedSolver.cpp

@@ -91,11 +91,33 @@ struct SharedSolver::MaxSizeValidator : LayoutOperation {
 };
 
 
+struct SharedSolver::PreferredSizeValidator : LayoutOperation {
+	PreferredSizeValidator(BObjectList<BALMLayout>* layouts)
+		:
+		LayoutOperation(layouts)
+	{
+	}
+
+	void CallSolverMethod(LinearSpec* spec, VariableList* vars)
+	{
+		spec->Solve();
+	}
+
+	void Finalize(BALMLayout* layout, SharedSolver* solver)
+	{
+		float width = layout->Right()->Value() - layout->Left()->Value();
+		float height = layout->Top()->Value() - layout->Bottom()->Value();
+		solver->SetPreferredSize(layout, BSize(width, height));
+	}
+};
+
+
 SharedSolver::SharedSolver()
 	:
 	fConstraintsValid(false),
 	fMinValid(false),
 	fMaxValid(false),
+	fPreferredValid(false),
 	fLayoutValid(false),
 	fLayoutContext(NULL)
 {
@@ -127,6 +149,7 @@ SharedSolver::Invalidate(bool children)
 	fConstraintsValid = false;
 	fMinValid = false;
 	fMaxValid = false;
+	fPreferredValid = false;
 	fLayoutValid = false;
 
 	_SetContext(NULL);
@@ -191,6 +214,26 @@ SharedSolver::ValidateMaxSize()
 }
 
 
+ResultType
+SharedSolver::ValidatePreferredSize()
+{
+	if (fPreferredValid)
+		return fPreferredResult;
+
+	_ValidateConstraints();
+
+	PreferredSizeValidator validator(&fLayouts);
+	validator.Validate(this);
+
+	fPreferredResult = fLinearSpec.Result();
+
+	fPreferredValid = true;
+	fLayoutValid = false;
+
+	return fPreferredResult;
+}
+
+
 ResultType
 SharedSolver::ValidateLayout(BLayoutContext* context)
 {
@@ -227,6 +270,13 @@ SharedSolver::SetMinSize(BALMLayout* layout, const BSize& min)
 }
 
 
+void
+SharedSolver::SetPreferredSize(BALMLayout* layout, const BSize& preferred)
+{
+	layout->fPreferredSize = preferred;
+}
+
+
 void
 SharedSolver::LayoutContextLeft(BLayoutContext* context)
 {

src/libs/alm/SharedSolver.h

@@ -37,18 +37,23 @@ public:
 
 			ResultType			ValidateMinSize();
 			ResultType			ValidateMaxSize();
+			ResultType			ValidatePreferredSize();
 			ResultType			ValidateLayout(BLayoutContext* context);
 private:
 			struct MinSizeValidator;
 			struct MaxSizeValidator;
+			struct PreferredSizeValidator;
 
 			friend struct MinSizeValidator;
 			friend struct MaxSizeValidator;
+			friend struct PreferredSizeValidator;
 
 			void				SetMaxSize(BALM::BALMLayout* layout,
 									const BSize& max);
 			void				SetMinSize(BALM::BALMLayout* layout,
 									const BSize& min);
+			void				SetPreferredSize(BALM::BALMLayout* layout,
+									const BSize& preferred);
 
 	virtual	void				LayoutContextLeft(BLayoutContext* context);
 
@@ -61,6 +66,7 @@ private:
 			bool				fConstraintsValid;
 			bool				fMinValid;
 			bool				fMaxValid;
+			bool				fPreferredValid;
 			bool				fLayoutValid;
 
 			BLayoutContext*		fLayoutContext;
@@ -69,6 +75,7 @@ private:
 
 			ResultType			fMinResult;
 			ResultType			fMaxResult;
+			ResultType			fPreferredResult;
 			ResultType			fLayoutResult;
 };