Round the values in wxDC coordinate calculations.

Make the conversion of logical coordinates to the device ones more precise by
avoiding errors due to truncation of floating point values to integer ones.

See #13284.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67961 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/src/msw/dc.cpp b/src/msw/dc.cpp
index e0e1ec6523475415acc22f3a6de4b47c28ff85d7..962054ae85524e9a6cf76deb63fa74b2afdef09c 100644 (file)
--- a/src/msw/dc.cpp
+++ b/src/msw/dc.cpp
@@ -34,6 +34,7 @@
     #include "wx/bitmap.h"
     #include "wx/dcmemory.h"
     #include "wx/log.h"
+    #include "wx/math.h"
     #include "wx/icon.h"
     #include "wx/dcprint.h"
     #include "wx/module.h"
@@ -1978,24 +1979,24 @@ void wxMSWDCImpl::RealizeScaleAndOrigin()
         logExtX, logExtY;   // Window, i.e. logical coordinate space, extents.
     if ( m_scaleX >= 1 )
     {
-        devExtX = VIEWPORT_EXTENT*m_scaleX;
+        devExtX = wxRound(VIEWPORT_EXTENT*m_scaleX);
         logExtX = m_signX*VIEWPORT_EXTENT;
     }
     else
     {
         devExtX = VIEWPORT_EXTENT;
-        logExtX = m_signX*VIEWPORT_EXTENT/m_scaleX;
+        logExtX = wxRound(m_signX*VIEWPORT_EXTENT/m_scaleX);
     }
 
     if ( m_scaleY >= 1 )
     {
-        devExtY = VIEWPORT_EXTENT*m_scaleY;
+        devExtY = wxRound(VIEWPORT_EXTENT*m_scaleY);
         logExtY = m_signY*VIEWPORT_EXTENT;
     }
     else
     {
         devExtY = VIEWPORT_EXTENT;
-        logExtY = m_signY*VIEWPORT_EXTENT/m_scaleY;
+        logExtY = wxRound(m_signY*VIEWPORT_EXTENT/m_scaleY);
     }
 
     ::SetViewportExtEx(GetHdc(), devExtX, devExtY, NULL);