nanogui: How to draw images in Microwindows/Nano-X
Subject:
How to draw images in Microwindows/Nano-X
From:
Greg Haerr ####@####.####
Date:
25 Jan 2000 23:36:09 -0000
Message-Id: <C1962B36D9BBD311B0F80060083DFEFB0419CA@SYS.CenSoft.COM>
On Tuesday, January 25, 2000 2:33 PM, Kyle Harris wrote:
: Speaking of all this image handling and optimizations.....
:
: What is the preferred method (i.e., fastest) for putting an image on the
: screen? Do I draw to a memory psd first, followed by GdBlit(), or some
: other procedure?
:
: Thanks, Kyle.
In Microwindows:
DrawImage(PIMAGEHDR image,HDC hdc,...)
This will draw a pre-defined image structure (color palette
and pixels) onto a memory or physical screen. In the
case of 8bpp display, it automatically enlarges the physical
palette.
In Nano-X there are two options: Monochrome bitmaps
are displayed with GrBitmap(), and color bitmaps with
GrArea(). In Nano-X, bitmaps are less sophisticated,
merely packed pixels, never with any color information
associated with them. Palette reorganization is the applications'
problem.
Drawing to memory and then blitting to screen is always slower,
but is required if to avoid flickering in some circumstances.
To draw to offscreen memory in Microwindows:
memdc = CreateCompatibleDC(NULL); // create memdc
hbmp = CreateCompatibleBitmap( hdc, x, y);
SelectObject(memdc, hbmp);
// draw into memdc
// blit to screen
BitBlit(ScreenDC, x, y, w, h, memdc, 0, 0, SCR_COPY);
Currently, Nano-X doesn't support off-screen drawing, but it's coming.
Regards,
Greg
