wxDC::LogicalToDevice{Rel}() now return unmirrored coordinates in RTL under wxMSW

Ditto for wxDC::DeviceToLogical{Rel}() functions.

In RTL layout, these functions always return unmirrored coordinates under wxGTK3
and wxQt. This is now the case under wxMSW too for consistency and also to fix
double-mirroring problem when passing the transformed coordinates to GDI drawing
functions. See wxGrid::Render() for example.

include/wx/msw/private/dc.h

@@ -141,6 +141,34 @@ private:
     wxDECLARE_NO_COPY_CLASS(wxBkModeChanger);
 };
 
+// ----------------------------------------------------------------------------
+// Class to temporarily disable RTL layout if already set on the device context
+// ----------------------------------------------------------------------------
+
+// For consistency with wxGTK and wxQt, wxDC::LogicalToDevice{Rel}() and
+// DeviceToLogical{Rel}() functions should return unmirrored coordinates
+// in RTL layout to avoid double-mirroring when their results are passed
+// to GDI drawing functions.
+class wxScopedRTLDisabler
+{
+public:
+    explicit wxScopedRTLDisabler(HDC hdc)
+        : m_hdc(hdc), m_oldLayoutDir(::SetLayout(hdc, 0))
+    {
+    }
+
+    ~wxScopedRTLDisabler()
+    {
+        ::SetLayout(m_hdc, m_oldLayoutDir);
+    }
+
+private:
+    HDC m_hdc;
+    const DWORD m_oldLayoutDir;
+
+    wxDECLARE_NO_COPY_CLASS(wxScopedRTLDisabler);
+};
+
 } // namespace wxMSWImpl
 
 #endif // _MSW_PRIVATE_DC_H_

src/msw/dc.cpp

@@ -1969,6 +1969,8 @@ void wxMSWDCImpl::SetDeviceOrigin(wxCoord x, wxCoord y)
 
 wxPoint wxMSWDCImpl::DeviceToLogical(wxCoord x, wxCoord y) const
 {
+    wxScopedRTLDisabler disableRTL(GetHdc());
+
     POINT p;
     p.x = x;
     p.y = y;
@@ -2015,6 +2017,8 @@ wxPoint wxMSWDCImpl::DeviceToLogical(wxCoord x, wxCoord y) const
 
 wxPoint wxMSWDCImpl::LogicalToDevice(wxCoord x, wxCoord y) const
 {
+    wxScopedRTLDisabler disableRTL(GetHdc());
+
     POINT p;
     p.x = x;
     p.y = y;
@@ -2024,6 +2028,8 @@ wxPoint wxMSWDCImpl::LogicalToDevice(wxCoord x, wxCoord y) const
 
 wxSize wxMSWDCImpl::DeviceToLogicalRel(int x, int y) const
 {
+    wxScopedRTLDisabler disableRTL(GetHdc());
+
     POINT p[2];
     p[0].x = 0;
     p[0].y = 0;
@@ -2035,6 +2041,8 @@ wxSize wxMSWDCImpl::DeviceToLogicalRel(int x, int y) const
 
 wxSize wxMSWDCImpl::LogicalToDeviceRel(int x, int y) const
 {
+    wxScopedRTLDisabler disableRTL(GetHdc());
+
     POINT p[2];
     p[0].x = 0;
     p[0].y = 0;