View Source wxBufferedDC (wx v2.4.3)
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:
This class is derived, and can use functions, from:
wxWidgets docs: wxBufferedDC
Summary
Functions
Destroys the object
Equivalent to init(This, Dc, [])
.
Initializes the object created using the default constructor.
Default constructor.
Equivalent to new(Dc, [])
.
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.
Destroys the object
-spec init(This, Dc) -> ok when This :: wxBufferedDC(), Dc :: wxDC:wxDC().
Equivalent to init(This, Dc, [])
.
-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().
Equivalent to new(Dc, [])
.
-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.