Keep the preferred size ratio into account. This make layout behaviour much more intuitive when resizing a window. Thanks Christof.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@39641 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/libs/alm/ALMLayout.h

@@ -151,6 +151,9 @@ private:
 			float				fSpacing;
 
 			Area*				fCurrentArea;
+
+			Variable*			fScaleWidth;
+			Variable*			fScaleHeight;
 };
 
 }	// namespace BALM

headers/libs/alm/Area.h

@@ -107,8 +107,12 @@ private:
 								Area(BLayoutItem* item);
 
 			void				_Init(LinearSpec* ls, XTab* left, YTab* top,
-									XTab* right, YTab* bottom);
-			void				_Init(LinearSpec* ls, Row* row, Column* column);
+									XTab* right, YTab* bottom,
+									Variable* scaleWidth,
+									Variable* scaleHeight);
+			void				_Init(LinearSpec* ls, Row* row, Column* column,
+									Variable* scaleWidth,
+									Variable* scaleHeight);
 
 			void				_DoLayout();
 
@@ -145,6 +149,9 @@ private:
 			double				fContentAspectRatio;
 			Constraint*			fContentAspectRatioC;
 
+			Variable*			fScaleWidth;
+			Variable*			fScaleHeight;
+
 public:
 	friend class		BALMLayout;
 

src/libs/alm/ALMLayout.cpp

@@ -52,12 +52,16 @@ BALMLayout::BALMLayout(float spacing, BALMLayout* friendLayout)
 	fPreferredSize = kUnsetSize;
 
 	fPerformancePath = NULL;
+
+	fScaleWidth = fSolver->AddVariable();
+	fScaleHeight = fSolver->AddVariable();
 }
 
 
 BALMLayout::~BALMLayout()
 {
-	
+	delete fScaleWidth;
+	delete fScaleHeight;
 }
 
 
@@ -479,7 +483,7 @@ BALMLayout::AddItem(BLayoutItem* item, XTab* left, YTab* top, XTab* right,
 		return NULL;
 	fCurrentArea = area;
 
-	area->_Init(fSolver, left, top, right, bottom);
+	area->_Init(fSolver, left, top, right, bottom, fScaleWidth, fScaleHeight);
 	return area;
 }
 
@@ -494,7 +498,7 @@ BALMLayout::AddItem(BLayoutItem* item, Row* row, Column* column)
 		return NULL;
 	fCurrentArea = area;
 
-	area->_Init(fSolver, row, column);
+	area->_Init(fSolver, row, column, fScaleWidth, fScaleHeight);
 	return area;
 }
 

src/libs/alm/Area.cpp

@@ -593,7 +593,8 @@ Area::Area(BLayoutItem* item)
  * Initialize variables.
  */
 void
-Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom)
+Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom,
+	Variable* scaleWidth, Variable* scaleHeight)
 {
 	fLS = ls;
 	fLeft = left;
@@ -601,6 +602,9 @@ Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom)
 	fTop = top;
 	fBottom = bottom;
 
+	fScaleWidth = scaleWidth;
+	fScaleHeight = scaleHeight;
+
 	// adds the two essential constraints of the area that make sure that the
 	// left x-tab is really to the left of the right x-tab, and the top y-tab
 	// really above the bottom y-tab
@@ -612,11 +616,12 @@ Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom)
 	fConstraints.AddItem(fMinContentWidth);
 	fConstraints.AddItem(fMinContentHeight);
 
-	fPreferredContentWidth = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight,
-		OperatorType(EQ), 0, fShrinkPenalties.Height(), fGrowPenalties.Width());
+	fPreferredContentWidth = fLS->AddConstraint(-1.0, fLeft, 1.0, fRight, -1.0,
+		fScaleWidth, OperatorType(EQ), 0, fShrinkPenalties.Height(),
+		fGrowPenalties.Width());
 
-	fPreferredContentHeight = fLS->AddConstraint(-1.0, fTop, 1.0, fBottom,
-		OperatorType(EQ), 0, fShrinkPenalties.Height(),
+	fPreferredContentHeight = fLS->AddConstraint(-1.0, fTop, 1.0, fBottom, -1.0,
+		fScaleHeight, OperatorType(EQ), 0, fShrinkPenalties.Height(),
 		fGrowPenalties.Height());
 
 	fConstraints.AddItem(fPreferredContentWidth);
@@ -625,9 +630,11 @@ Area::_Init(LinearSpec* ls, XTab* left, YTab* top, XTab* right, YTab* bottom)
 
 
 void
-Area::_Init(LinearSpec* ls, Row* row, Column* column)
+Area::_Init(LinearSpec* ls, Row* row, Column* column, Variable* scaleWidth,
+	Variable* scaleHeight)
 {
-	_Init(ls, column->Left(), row->Top(), column->Right(), row->Bottom());
+	_Init(ls, column->Left(), row->Top(), column->Right(), row->Bottom(),
+		scaleWidth, scaleHeight);
 	fRow = row;
 	fColumn = column;
 }
@@ -718,6 +725,9 @@ Area::_UpdatePreferredConstraint(BSize preferred)
 	if (preferred.height > 0)
 		height = preferred.Height() + TopInset() + BottomInset();
 
-	fPreferredContentWidth->SetRightSide(width);
-	fPreferredContentHeight->SetRightSide(height);
+	fPreferredContentWidth->SetLeftSide(-1.0, fLeft, 1.0, fRight, -width,
+		fScaleWidth);
+
+	fPreferredContentHeight->SetLeftSide(-1.0, fTop, 1.0, fBottom, -height,
+		fScaleHeight);
 }