From 2b826c43d9094cbe5baff98c950fa1d04c6b8a58 Mon Sep 17 00:00:00 2001
From: zeljko <zeljko@lazarus-ide.org>
Date: Mon, 28 Apr 2014 07:10:35 +0000
Subject: [PATCH] Qt: return correct size of QScrollBar when widget isn't
 mapped yet.issue #26084

git-svn-id: trunk@44831 -
---
 lcl/interfaces/qt/qtwinapi.inc | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/lcl/interfaces/qt/qtwinapi.inc b/lcl/interfaces/qt/qtwinapi.inc
index 3adf4c2aaf..00cfa05b11 100644
--- a/lcl/interfaces/qt/qtwinapi.inc
+++ b/lcl/interfaces/qt/qtwinapi.inc
@@ -3430,6 +3430,7 @@ function TQtWidgetSet.GetScrollBarSize(Handle: HWND; BarKind: Integer): integer;
 var
   w: TQtWidget;
   ScrollBar: TQtScrollBar;
+  ASize: TSize;
 begin
 	{$ifdef VerboseQtWinAPI}
   writeln('Trace:> [WinAPI GetScrollBarSize] Handle: ' + dbghex(Handle),' BarKind: ',BarKind);
@@ -3439,14 +3440,13 @@ begin
 
   w := TQtWidget(Handle);
 
-  {TODO: find out what to do with TCustomForm descendants }
   {$IFDEF QTSCROLLABLEFORMS}
   if (w is TQtMainWindow) and Assigned(TQtMainWindow(w).ScrollArea) then
     w := TQtMainWindow(w).ScrollArea;
   {$ENDIF}
   if w is TQtAbstractScrollArea then
   begin
-    if BarKind in [SM_CXVSCROLL, SM_CYVSCROLL] then
+    if BarKind in [SB_VERT, SM_CXVSCROLL, SM_CYVSCROLL] then
       ScrollBar := TQtAbstractScrollArea(w).verticalScrollBar
     else
       ScrollBar := TQtAbstractScrollArea(w).horizontalScrollBar;
@@ -3457,10 +3457,23 @@ begin
     ScrollBar := nil;
   if ScrollBar <> nil then
   begin
-    if BarKind in [SM_CXHSCROLL, SM_CYVSCROLL] then
-      Result := ScrollBar.getWidth
-    else
-      Result := ScrollBar.getHeight;
+    if ScrollBar.getOrientation = QtVertical then
+    begin
+      if not ScrollBar.testAttribute(QtWA_Mapped) then
+      begin
+        ScrollBar.sizeHint(@ASize);
+        Result := ASize.cx;
+      end else
+        Result := ScrollBar.getWidth;
+    end else
+    begin
+      if not ScrollBar.testAttribute(QtWA_Mapped) then
+      begin
+        ScrollBar.sizeHint(@ASize);
+        Result := ASize.cy;
+      end else
+        Result := ScrollBar.getHeight;
+    end;
   end;
 end;