[wxWidgets.git] / docs / latex / wx / memorydc.tex

\section{\class{wxMemoryDC}}\label{wxmemorydc}

A memory device context provides a means to draw graphics onto a bitmap.

\wxheading{Derived from}

\helpref{wxDC}{wxdc}\\
\helpref{wxObject}{wxobject}

\wxheading{Include files}

<wx/dcmemory.h>

\wxheading{Remarks}

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

\begin{verbatim}
  // Create a memory DC
  wxMemoryDC temp_dc;
  temp_dc.SelectObject(test_bitmap);

  // We can now draw into the memory DC...
  // Copy from this DC to another DC.
  old_dc.Blit(250, 50, BITMAP_WIDTH, BITMAP_HEIGHT, temp_dc, 0, 0);
\end{verbatim}

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

\wxheading{See also}

\helpref{wxBitmap}{wxbitmap}, \helpref{wxDC}{wxdc}

\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxMemoryDC::wxMemoryDC}

\func{}{wxMemoryDC}{\void}

Constructs a new memory device context.

Use the {\it Ok} member to test whether the constructor was successful
in creating a useable device context. Don't forget to select a bitmap
into the DC before drawing on it.

\membersection{wxMemoryDC::SelectObject}

\func{}{SelectObject}{\param{const wxBitmap\& }{bitmap}}

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 {\bf Blit} to copy
the bitmap to a window. For this purpose, you may find \helpref{wxDC::DrawIcon}{wxdcdrawicon}\rtfsp
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.
Commit	Line	Data
a660d684 KB	1	\section{\class{wxMemoryDC}}\label{wxmemorydc}
	2
	3	A memory device context provides a means to draw graphics onto a bitmap.
	4
	5	\wxheading{Derived from}
	6
	7	\helpref{wxDC}{wxdc}\\
	8	\helpref{wxObject}{wxobject}
	9
954b8ae6 JS	10	\wxheading{Include files}
	11
	12	<wx/dcmemory.h>
	13
a660d684 KB	14	\wxheading{Remarks}
	15
	16	A bitmap must be selected into the new memory DC before it may be used
	17	for anything. Typical usage is as follows:
	18
	19	\begin{verbatim}
	20	// Create a memory DC
	21	wxMemoryDC temp_dc;
	22	temp_dc.SelectObject(test_bitmap);
	23
	24	// We can now draw into the memory DC...
	25	// Copy from this DC to another DC.
	26	old_dc.Blit(250, 50, BITMAP_WIDTH, BITMAP_HEIGHT, temp_dc, 0, 0);
	27	\end{verbatim}
	28
	29	Note that the memory DC {\it must} be deleted (or the bitmap selected out of it) before a bitmap
	30	can be reselected into another memory DC.
	31
	32	\wxheading{See also}
	33
	34	\helpref{wxBitmap}{wxbitmap}, \helpref{wxDC}{wxdc}
	35
	36	\latexignore{\rtfignore{\wxheading{Members}}}
	37
	38	\membersection{wxMemoryDC::wxMemoryDC}
	39
	40	\func{}{wxMemoryDC}{\void}
	41
	42	Constructs a new memory device context.
	43
	44	Use the {\it Ok} member to test whether the constructor was successful
	45	in creating a useable device context. Don't forget to select a bitmap
	46	into the DC before drawing on it.
	47
	48	\membersection{wxMemoryDC::SelectObject}
	49
	50	\func{}{SelectObject}{\param{const wxBitmap\& }{bitmap}}
	51
	52	Selects the given bitmap into the device context, to use as the memory
	53	bitmap. Selecting the bitmap into a memory DC allows you to draw into
	54	the DC (and therefore the bitmap) and also to use {\bf Blit} to copy
fe604ccd	55	the bitmap to a window. For this purpose, you may find \helpref{wxDC::DrawIcon}{wxdcdrawicon}\rtfsp
a660d684 KB	56	easier to use instead.
	57
	58	If the argument is wxNullBitmap (or some other uninitialised wxBitmap) the current bitmap is selected out of the device
	59	context, and the original bitmap restored, allowing the current bitmap to
	60	be destroyed safely.
	61