Decorator: Introduce Scroll bar size call

Change-Id: I07f08c2893d832e431c29ae753e0a93d6e619701
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3892
Reviewed-by: Adrien Destugues <[email protected]>
Reviewed-by: X512 <[email protected]>

headers/os/interface/ControlLook.h

@@ -426,10 +426,11 @@ public:
 									BRect rect, const BRect& updateRect,
 									const rgb_color& base, uint32 flags,
 									orientation orientation) = 0;
+	virtual float				GetScrollBarWidth(
+									orientation orientation = B_VERTICAL);
 
 private:
 	// FBC padding
-	virtual	void				_ReservedControlLook5();
 	virtual	void				_ReservedControlLook6();
 	virtual	void				_ReservedControlLook7();
 	virtual	void				_ReservedControlLook8();

headers/private/interface/HaikuControlLook.h

@@ -339,6 +339,8 @@ public:
 									uint32 flags = 0,
 									uint32 borders = B_ALL_BORDERS,
 									orientation orientation = B_HORIZONTAL);
+	virtual float				GetScrollBarWidth(
+									orientation orientation = B_VERTICAL);
 
 protected:
 			void				_DrawButtonFrame(BView* view, BRect& rect,

src/kits/interface/ControlLook.cpp

@@ -71,6 +71,15 @@ BControlLook::GetInsets(frame_type frameType, background_type backgroundType,
 }
 
 
+float
+BControlLook::GetScrollBarWidth(orientation orientation)
+{
+	// this matches HaikuControlLook.cpp currently
+	if (be_plain_font->Size() <= 12.0f) { return 14.0f; }
+	return be_plain_font->Size() / 12.0f * 14.0f;
+}
+
+
 void
 BControlLook::SetBackgroundInfo(const BMessage& backgroundInfo)
 {
@@ -127,7 +136,15 @@ B_IF_GCC_2(_ReservedControlLook4__Q28BPrivate12BControlLook,
 }
 
 
-void BControlLook::_ReservedControlLook5() {}
+extern "C" float
+B_IF_GCC_2(_ReservedControlLook5__Q28BPrivate12BControlLook,
+		_ZN8BPrivate12BControlLook21_ReservedControlLook5Ev)(
+	BControlLook* controlLook, orientation orientation)
+{
+	return controlLook->GetScrollBarWidth(orientation);
+}
+
+
 void BControlLook::_ReservedControlLook6() {}
 void BControlLook::_ReservedControlLook7() {}
 void BControlLook::_ReservedControlLook8() {}

src/kits/interface/HaikuControlLook.cpp

@@ -3832,6 +3832,16 @@ HaikuControlLook::_FillGlossyGradient(BView* view, const BRect& rect,
 }
 
 
+float
+HaikuControlLook::GetScrollBarWidth(orientation orientation)
+{
+	// HaikuControlLook does not make a distinction between the
+	// width and height of the scrollbar, but other controllooks may
+	if (be_plain_font->Size() <= 12.0f) { return 14.0f; }
+	return be_plain_font->Size() / 12.0f * 14.0f;
+}
+
+
 void
 HaikuControlLook::_MakeGradient(BGradientLinear& gradient, const BRect& rect,
 	const rgb_color& base, float topTint, float bottomTint,

src/kits/interface/ScrollBar.cpp

@@ -995,10 +995,9 @@ BScrollBar::SetBorderHighlighted(bool highlight)
 void
 BScrollBar::GetPreferredSize(float* _width, float* _height)
 {
-	const float scale = std::max(be_plain_font->Size() / 12.0f, 1.0f);
 	if (fOrientation == B_VERTICAL) {
 		if (_width)
-			*_width = B_V_SCROLL_BAR_WIDTH * scale;
+			*_width = be_control_look->GetScrollBarWidth(B_VERTICAL);
 
 		if (_height)
 			*_height = _MinSize().Height();
@@ -1007,7 +1006,7 @@ BScrollBar::GetPreferredSize(float* _width, float* _height)
 			*_width = _MinSize().Width();
 
 		if (_height)
-			*_height = B_H_SCROLL_BAR_HEIGHT * scale;
+			*_height = be_control_look->GetScrollBarWidth(B_HORIZONTAL);
 	}
 }