Implement platform-specific coordinate conversion functions

Generic wxDC::DeviceToLogicalRel{X|Y}() and wxDC::LogicalToDeviceRel{X|Y}()
functions don't take into account scaling applied with
wxDC::SetTransformMatrix().
We need to implement in wxDCImpl and its platform-specific derivates
new conversion functions that take all applied transformations into account.

See #18923.

include/wx/dc.h

@@ -325,6 +325,8 @@ public:
     // coordinates conversions and transforms
     virtual wxPoint DeviceToLogical(wxCoord x, wxCoord y) const;
     virtual wxPoint LogicalToDevice(wxCoord x, wxCoord y) const;
+    virtual wxSize DeviceToLogicalRel(int x, int y) const;
+    virtual wxSize LogicalToDeviceRel(int x, int y) const;
 
     // bounding box
 

include/wx/dcgraph.h

@@ -124,6 +124,8 @@ public:
     // coordinates conversions and transforms
     virtual wxPoint DeviceToLogical(wxCoord x, wxCoord y) const wxOVERRIDE;
     virtual wxPoint LogicalToDevice(wxCoord x, wxCoord y) const wxOVERRIDE;
+    virtual wxSize DeviceToLogicalRel(int x, int y) const wxOVERRIDE;
+    virtual wxSize LogicalToDeviceRel(int x, int y) const wxOVERRIDE;
 
     // the true implementations
     virtual bool DoFloodFill(wxCoord x, wxCoord y, const wxColour& col,

include/wx/msw/dc.h

@@ -88,6 +88,8 @@ public:
 
     virtual wxPoint DeviceToLogical(wxCoord x, wxCoord y) const wxOVERRIDE;
     virtual wxPoint LogicalToDevice(wxCoord x, wxCoord y) const wxOVERRIDE;
+    virtual wxSize DeviceToLogicalRel(int x, int y) const wxOVERRIDE;
+    virtual wxSize LogicalToDeviceRel(int x, int y) const wxOVERRIDE;
 
 #if wxUSE_DC_TRANSFORM_MATRIX
     virtual bool CanUseTransformMatrix() const wxOVERRIDE;

src/common/dcbase.cpp

@@ -512,6 +512,16 @@ wxPoint wxDCImpl::LogicalToDevice(wxCoord x, wxCoord y) const
     return wxPoint(LogicalToDeviceX(x), LogicalToDeviceY(y));
 }
 
+wxSize wxDCImpl::DeviceToLogicalRel(int x, int y) const
+{
+    return wxSize(DeviceToLogicalXRel(x), DeviceToLogicalYRel(y));
+}
+
+wxSize wxDCImpl::LogicalToDeviceRel(int x, int y) const
+{
+    return wxSize(LogicalToDeviceXRel(x), LogicalToDeviceYRel(y));
+}
+
 void wxDCImpl::ComputeScaleAndOrigin()
 {
     m_scaleX = m_logicalScaleX * m_userScaleX;

src/common/dcgraph.cpp

@@ -613,6 +613,22 @@ wxPoint wxGCDCImpl::LogicalToDevice(wxCoord x, wxCoord y) const
     return wxPoint(wxRound(px), wxRound(py));
 }
 
+wxSize wxGCDCImpl::DeviceToLogicalRel(int x, int y) const
+{
+    wxDouble dx = x;
+    wxDouble dy = y;
+    m_matrixCurrentInv.TransformDistance(&dx, &dy);
+    return wxSize(wxRound(dx), wxRound(dy));
+}
+
+wxSize wxGCDCImpl::LogicalToDeviceRel(int x, int y) const
+{
+    wxDouble dx = x;
+    wxDouble dy = y;
+    m_matrixCurrent.TransformDistance(&dx, &dy);
+    return wxSize(wxRound(dx), wxRound(dy));
+}
+
 bool wxGCDCImpl::DoFloodFill(wxCoord WXUNUSED(x), wxCoord WXUNUSED(y),
                              const wxColour& WXUNUSED(col),
                              wxFloodFillStyle WXUNUSED(style))

src/msw/dc.cpp

@@ -2118,6 +2118,28 @@ wxPoint wxMSWDCImpl::LogicalToDevice(wxCoord x, wxCoord y) const
     return wxPoint(p[0].x, p[0].y);
 }
 
+wxSize wxMSWDCImpl::DeviceToLogicalRel(int x, int y) const
+{
+    POINT p[2];
+    p[0].x = 0;
+    p[0].y = 0;
+    p[1].x = x;
+    p[1].y = y;
+    ::DPtoLP(GetHdc(), p, WXSIZEOF(p));
+    return wxSize(p[1].x-p[0].x, p[1].y-p[0].y);
+}
+
+wxSize wxMSWDCImpl::LogicalToDeviceRel(int x, int y) const
+{
+    POINT p[2];
+    p[0].x = 0;
+    p[0].y = 0;
+    p[1].x = x;
+    p[1].y = y;
+    ::LPtoDP(GetHdc(), p, WXSIZEOF(p));
+    return wxSize(p[1].x-p[0].x, p[1].y-p[0].y);
+}
+
 // ----------------------------------------------------------------------------
 // Transform matrix
 // ----------------------------------------------------------------------------