| | 1 | \section{\class{wxMemoryDC}}\label{wxmemorydc} |
| | 2 | |
| | 3 | A memory device context provides a means to draw graphics onto a bitmap. When |
| | 4 | drawing in to a mono-bitmap, using {\tt wxWHITE}, {\tt wxWHITE\_PEN} and |
| | 5 | {\tt wxWHITE\_BRUSH} |
| | 6 | will draw the background colour (i.e. 0) whereas all other colours will draw the |
| | 7 | foreground colour (i.e. 1). |
| | 8 | |
| | 9 | \wxheading{Derived from} |
| | 10 | |
| | 11 | \helpref{wxDC}{wxdc}\\ |
| | 12 | \helpref{wxObject}{wxobject} |
| | 13 | |
| | 14 | \wxheading{Include files} |
| | 15 | |
| | 16 | <wx/dcmemory.h> |
| | 17 | |
| | 18 | \wxheading{Remarks} |
| | 19 | |
| | 20 | A bitmap must be selected into the new memory DC before it may be used |
| | 21 | for anything. Typical usage is as follows: |
| | 22 | |
| | 23 | \begin{verbatim} |
| | 24 | // Create a memory DC |
| | 25 | wxMemoryDC temp_dc; |
| | 26 | temp_dc.SelectObject(test_bitmap); |
| | 27 | |
| | 28 | // We can now draw into the memory DC... |
| | 29 | // Copy from this DC to another DC. |
| | 30 | old_dc.Blit(250, 50, BITMAP_WIDTH, BITMAP_HEIGHT, temp_dc, 0, 0); |
| | 31 | \end{verbatim} |
| | 32 | |
| | 33 | Note that the memory DC {\it must} be deleted (or the bitmap selected out of it) before a bitmap |
| | 34 | can be reselected into another memory DC. |
| | 35 | |
| | 36 | \wxheading{See also} |
| | 37 | |
| | 38 | \helpref{wxBitmap}{wxbitmap}, \helpref{wxDC}{wxdc} |
| | 39 | |
| | 40 | \latexignore{\rtfignore{\wxheading{Members}}} |
| | 41 | |
| | 42 | \membersection{wxMemoryDC::wxMemoryDC} |
| | 43 | |
| | 44 | \func{}{wxMemoryDC}{\void} |
| | 45 | |
| | 46 | Constructs a new memory device context. |
| | 47 | |
| | 48 | Use the {\it Ok} member to test whether the constructor was successful |
| | 49 | in creating a useable device context. Don't forget to select a bitmap |
| | 50 | into the DC before drawing on it. |
| | 51 | |
| | 52 | \membersection{wxMemoryDC::SelectObject} |
| | 53 | |
| | 54 | \func{}{SelectObject}{\param{const wxBitmap\& }{bitmap}} |
| | 55 | |
| | 56 | Selects the given bitmap into the device context, to use as the memory |
| | 57 | bitmap. Selecting the bitmap into a memory DC allows you to draw into |
| | 58 | the DC (and therefore the bitmap) and also to use {\bf Blit} to copy |
| | 59 | the bitmap to a window. For this purpose, you may find \helpref{wxDC::DrawIcon}{wxdcdrawicon}\rtfsp |
| | 60 | easier to use instead. |
| | 61 | |
| | 62 | If the argument is wxNullBitmap (or some other uninitialised wxBitmap) the current bitmap is selected out of the device |
| | 63 | context, and the original bitmap restored, allowing the current bitmap to |
| | 64 | be destroyed safely. |
| | 65 | |
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