View Source wxBufferedDC (wx v2.4.2)
Functions for wxBufferedDC class
This class provides a simple way to avoid flicker: when drawing on it,
everything is in fact first drawn on an in-memory buffer (a wxBitmap
) and
then copied to the screen, using the associated wxDC
, only once, when this
object is destroyed. wxBufferedDC
itself is typically associated with
wxClientDC
, if you want to use it in your EVT_PAINT
handler, you should
look at wxBufferedPaintDC
instead.
When used like this, a valid DC
must be specified in the constructor while the
buffer
bitmap doesn't have to be explicitly provided, by default this class
will allocate the bitmap of required size itself. However using a dedicated
bitmap can speed up the redrawing process by eliminating the repeated creation
and destruction of a possibly big bitmap. Otherwise, wxBufferedDC
can be
used in the same way as any other device context.
Another possible use for wxBufferedDC
is to use it to maintain a backing
store for the window contents. In this case, the associated DC
may be NULL but
a valid backing store bitmap should be specified.
Finally, please note that GTK+ 2.0 as well as macOS provide double buffering
themselves natively. You can either use wxWindow:isDoubleBuffered/1
to
determine whether you need to use buffering or not, or use
wxAutoBufferedPaintDC
(not implemented in wx) to avoid needless double
buffering on the systems which already do it automatically.
See: wxDC
, wxMemoryDC
, wxBufferedPaintDC
, wxAutoBufferedPaintDC
(not implemented in wx)
This class is derived (and can use functions) from: wxMemoryDC
wxDC
wxWidgets docs: wxBufferedDC
Summary
Functions
Copies everything drawn on the DC so far to the underlying DC associated with this object, if any.
Initializes the object created using the default constructor.
Default constructor.
Creates a buffer for the provided dc.
Creates a buffer for the provided dc
.
Types
-type wxBufferedDC() :: wx:wx_object().
Functions
-spec destroy(This :: wxBufferedDC()) -> ok.
Copies everything drawn on the DC so far to the underlying DC associated with this object, if any.
-spec init(This, Dc) -> ok when This :: wxBufferedDC(), Dc :: wxDC:wxDC().
-spec init(This, Dc, Area) -> ok when This :: wxBufferedDC(), Dc :: wxDC:wxDC(), Area :: {W :: integer(), H :: integer()}; (This, Dc, [Option]) -> ok when This :: wxBufferedDC(), Dc :: wxDC:wxDC(), Option :: {buffer, wxBitmap:wxBitmap()} | {style, integer()}.
-spec init(This, Dc, Area, [Option]) -> ok when This :: wxBufferedDC(), Dc :: wxDC:wxDC(), Area :: {W :: integer(), H :: integer()}, Option :: {style, integer()}.
Initializes the object created using the default constructor.
Please see the constructors for parameter details.
-spec new() -> wxBufferedDC().
Default constructor.
You must call one of the init/4
methods later in order to use the device
context.
-spec new(Dc) -> wxBufferedDC() when Dc :: wxDC:wxDC().
-spec new(Dc, Area) -> wxBufferedDC() when Dc :: wxDC:wxDC(), Area :: {W :: integer(), H :: integer()}; (Dc, [Option]) -> wxBufferedDC() when Dc :: wxDC:wxDC(), Option :: {buffer, wxBitmap:wxBitmap()} | {style, integer()}.
Creates a buffer for the provided dc.
init/4
must not be called when using this constructor.
-spec new(Dc, Area, [Option]) -> wxBufferedDC() when Dc :: wxDC:wxDC(), Area :: {W :: integer(), H :: integer()}, Option :: {style, integer()}.
Creates a buffer for the provided dc
.
init/4
must not be called when using this constructor.