wxMemoryDC - Functions for wxMemoryDC class

wxMemoryDC() = wx:wx_object()

       A  memory  device  context  provides  a  means to draw graphics onto a bitmap. When drawing in to a mono-
       bitmap, using wxWHITE, wxWHITE_PEN and wxWHITE_BRUSH will draw the background colour (i.e. 0) whereas all
       other colours will draw the foreground colour (i.e. 1).

       A bitmap must be selected into the new memory DC before it may be used for anything. Typical usage is  as
       follows:

       Note  that  the  memory  DC  must  be  deleted  (or the bitmap selected out of it) before a bitmap can be
       reselected into another memory DC.

       And, before performing any other operations on the bitmap data, the bitmap must be selected  out  of  the
       memory DC:

       This happens automatically when wxMemoryDC object goes out of scope.

       See: wxBitmap, wxDC

       This class is derived (and can use functions) from: wxDC

       wxWidgets docs: wxMemoryDC

new()->wxMemoryDC()

              Constructs a new memory device context.

              Use  the  wxDC:isOk/1  member  to test whether the constructor was successful in creating a usable
              device context. Don't forget to select a bitmap into the DC before drawing on it.

       new(Dc)->wxMemoryDC()

              Types:

                 Dc = wxDC:wxDC() | wxBitmap:wxBitmap()

              Constructs a new memory device context having the  same  characteristics  as  the  given  existing
              device context.

              This  constructor  creates  a  memory  device context compatible with dc in wxMSW, the argument is
              ignored in the other ports. If dc is NULL, a device context compatible with the screen is created,
              just as with the default constructor.

       selectObject(This,Bitmap)->ok

              Types:

                 This = wxMemoryDC()
                 Bitmap = wxBitmap:wxBitmap()

              Works exactly like selectObjectAsSource/2 but this is the function you should use when you  select
              a bitmap because you want to modify it, e.g.

              drawing on this DC.

              Using selectObjectAsSource/2 when modifying the bitmap may incur some problems related to wxBitmap
              being a reference counted object (see overview_refcount).

              Before  using  the  updated  bitmap  data,  make  sure to select it out of context first either by
              selecting ?wxNullBitmap into the device context or destroying the device context entirely.

              If the bitmap is already selected in this device context, nothing is done. If it  is  selected  in
              another context, the function asserts and drawing on the bitmap won't work correctly.

              See: wxDC:drawBitmap/4selectObjectAsSource(This,Bitmap)->ok

              Types:

                 This = wxMemoryDC()
                 Bitmap = wxBitmap:wxBitmap()

              Selects the given bitmap into the device context, to use as the memory bitmap.

              Selecting  the  bitmap  into a memory DC allows you to draw into the DC (and therefore the bitmap)
              and also to use wxDC:blit/6 to copy the bitmap to  a  window.  For  this  purpose,  you  may  find
              wxDC:drawIcon/3 easier to use instead.

              If  the  argument  is  ?wxNullBitmap  (or some other uninitialised wxBitmap) the current bitmap is
              selected out of the device context, and the original bitmap restored, allowing the current  bitmap
              to be destroyed safely.

       destroy(This::wxMemoryDC())->ok

              Destroys the object.

wxWidgets team.                                     wx 2.1.1                                    wxMemoryDC(3erl)

       wxMemoryDC - Functions for wxMemoryDC class