First round of BSlider fixes to be more layout friendly:

* Improve the minimum size calculation and cache it.
* Invalidate the layout on various property changes that require it.

Vertical BSliders are very broken... that's up next.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26441 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/interface/Slider.h

@@ -145,6 +145,12 @@ class BSlider : public BControl {
 
 		virtual void		SetLimits(int32 minimum, int32 maximum);
 
+		virtual	void		InvalidateLayout(bool descendants = false);
+
+		virtual	BSize		MinSize();
+		virtual	BSize		MaxSize();
+		virtual	BSize		PreferredSize();
+
 	private:
 				void		_DrawBlockThumb();
 				void		_DrawTriangleThumb();
@@ -156,6 +162,8 @@ class BSlider : public BControl {
 				float		_MaxPosition() const;
 				bool		_ConstrainPoint(BPoint& point, BPoint compare) const;
 
+				BSize		_ValidateMinSize();
+
 		virtual	void		_ReservedSlider5();
 		virtual	void		_ReservedSlider6();
 		virtual	void		_ReservedSlider7();
@@ -201,10 +209,12 @@ class BSlider : public BControl {
 		orientation			fOrientation;
 		float				fBarThickness;
 
+		BSize				fMinSize;
+
 #if USE_OFF_SCREEN_VIEW
-		uint32				_reserved[7];
+		uint32				_reserved[5];
 #else
-		uint32				_reserved[9];
+		uint32				_reserved[7];
 #endif
 };