NAME

       wxMemoryDC - Functions for wxMemoryDC class

DESCRIPTION

       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

DATA TYPES

       wxMemoryDC() = wx:wx_object()

EXPORTS

       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/4

       selectObjectAsSource(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.