From c4340eab04bfd4baa7bda6782c7e55dea1f5c467 Mon Sep 17 00:00:00 2001
From: czeidler <haiku@clemens-zeidler.de>
Date: Fri, 20 Jan 2012 16:47:01 +1300
Subject: [PATCH] Fix row column weight.

---
 src/libs/alm/RowColumnManager.cpp | 21 +++++++++++----------
 src/libs/alm/RowColumnManager.h   | 17 ++++++++++++++---
 2 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/src/libs/alm/RowColumnManager.cpp b/src/libs/alm/RowColumnManager.cpp
index 269909691e..ebd4e223bf 100644
--- a/src/libs/alm/RowColumnManager.cpp
+++ b/src/libs/alm/RowColumnManager.cpp
@@ -138,16 +138,16 @@ RowColumnManager::_PreferredHeight(Row* row, double& weight)
 	double pref = 0;
 	for (int32 i = 0; i < row->fAreas.CountItems(); i++) {
 		BSize prefSize = row->fAreas.ItemAt(i)->Item()->PreferredSize();
-		if (prefSize.height > 0) {
-			nAreas++;
-			pref += prefSize.height;
-		}
+		if (prefSize.height <= 0)
+			continue;
+		nAreas++;
+		pref += prefSize.height;
 		double negPen = row->fAreas.ItemAt(i)->ShrinkPenalties().height;
 		if (negPen > 0)
 			weight += negPen;
 	}
 	if (nAreas == 0) {
-		pref = 0;
+		pref = -1;
 		weight = 1;
 	} else {
 		pref /= nAreas;
@@ -165,16 +165,17 @@ RowColumnManager::_PreferredWidth(Column* column, double& weight)
 	double pref = 0;
 	for (int32 i = 0; i < column->fAreas.CountItems(); i++) {
 		BSize prefSize = column->fAreas.ItemAt(i)->Item()->PreferredSize();
-		if (prefSize.width > 0) {
-			nAreas++;
-			pref += prefSize.width;
-		}
+		if (prefSize.width <= 0)
+			continue;
+		nAreas++;
+		pref += prefSize.width;
+
 		double negPen = column->fAreas.ItemAt(i)->ShrinkPenalties().height;
 		if (negPen > 0)
 			weight += negPen;
 	}
 	if (nAreas == 0) {
-		pref = 0;
+		pref = -1;
 		weight = 1;
 	} else {
 		pref /= nAreas;
diff --git a/src/libs/alm/RowColumnManager.h b/src/libs/alm/RowColumnManager.h
index b18006e021..55a844397a 100644
--- a/src/libs/alm/RowColumnManager.h
+++ b/src/libs/alm/RowColumnManager.h
@@ -16,6 +16,20 @@
 
 namespace BALM {
 
+
+/*! The RowColumnManager groups areas with same vertical or horizontal tabs
+	into column and rows. For each row and column, a preferred size is
+	calculated from the areas in the row or column. This preferred size is used
+	to create a preferred size soft-constraint.
+	Having only one constraint for each row and column avoids the so called
+	spring effect. That is each area with a preferred size constraint is pulling
+	or pressing torwards its preferred size. For example, a row with three areas
+	pushes stronger than a row with two areas. Assuming that all areas have	the
+	same preferred size, the three-area row gets a different size than the
+	two-area row. However, one would expect that both rows have the same height.
+	The row and column approach of the RowColumnManager solves this problem.
+
+*/
 class RowColumnManager {
 public:
 								RowColumnManager(LinearSpec* spec);
@@ -26,9 +40,6 @@ public:
 
 			void				UpdateConstraints();
 			void				TabsChanged(Area* area);
-
-			Row*				CreateRow(YTab* top, YTab* bottom);
-			Column*				CreateColumn(XTab* left, XTab* right);
 private:
 			Row*				_FindRowFor(Area* area);
 			Column*				_FindColumnFor(Area* area);