tdf#107792 vcl/win/gdi: introduce ScopedHRGN

Change-Id: I3d103dcb6ebb81d50bb8a10371dba7feb92c421d
Reviewed-on: https://gerrit.libreoffice.org/65924
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

vcl/win/gdi/gdiimpl.cxx

@@ -296,9 +296,8 @@ void MakeInvisibleArea(const RECT& rSrcRect,
         rhInvalidateRgn = CreateRectRgnIndirect(&rSrcRect);
     }
 
-    HRGN hTempRgn = CreateRectRgn(nLeft, nTop, nRight, nBottom);
-    CombineRgn(rhInvalidateRgn, rhInvalidateRgn, hTempRgn, RGN_DIFF);
-    DeleteRegion(hTempRgn);
+    ScopedHRGN hTempRgn(CreateRectRgn(nLeft, nTop, nRight, nBottom));
+    CombineRgn(rhInvalidateRgn, rhInvalidateRgn, hTempRgn.get(), RGN_DIFF);
 }
 
 void ImplCalcOutSideRgn( const RECT& rSrcRect,
@@ -1259,9 +1258,8 @@ bool WinSalGraphicsImpl::setClipRegion( const vcl::Region& i_rClip )
 
                     for( sal_uLong n = 1; n < pHeader.nCount; n++, pRect++ )
                     {
-                        HRGN hRgn = CreateRectRgn( pRect->left, pRect->top, pRect->right, pRect->bottom );
-                        CombineRgn( mrParent.mhRegion, mrParent.mhRegion, hRgn, RGN_OR );
-                        DeleteRegion( hRgn );
+                        ScopedHRGN hRgn(CreateRectRgn(pRect->left, pRect->top, pRect->right, pRect->bottom));
+                        CombineRgn( mrParent.mhRegion, mrParent.mhRegion, hRgn.get(), RGN_OR );
                     }
                 }
             }

vcl/win/gdi/scoped_gdi.hxx

@@ -21,7 +21,14 @@ struct HBRUSHDeleter
     void operator()(HBRUSH hBrush) { DeleteBrush(hBrush); }
 };
 
+struct HRGNDeleter
+{
+    using pointer = HRGN;
+    void operator()(HRGN hRgn) { DeleteRegion(hRgn); }
+};
+
 using ScopedHBRUSH = std::unique_ptr<HBRUSH, HBRUSHDeleter>;
+using ScopedHRGN = std::unique_ptr<HRGN, HRGNDeleter>;
 
 #endif // INCLUDED_VCL_WIN_GDI_SCOPED_GDI_HXX