OpenEuphoria

Re: windows graphics engine

• Posted by mic _ <stabmaster_ at HOTMAIL.COM> Dec 20, 2000
• 612 views

>Where do I get Windows GDI?

The GDI (Graphics Device Interface (?) ) is a standard component of Windows.
You can import the routines from gdi32.dll.

Here's an example of how to use the gdi function StretchDIBits() (note that
StretchDIBits isn't the fastest function available).
(note 2: this code is for 8-bit bitmaps)



--STRUCT BITMAPINFOHEADER
global constant biSize          = 0,
                biWidth         = 4,
                biHeight        = 8,
                biPlanes        = 12,
                biBitCount      = 14,
                biCompression   = 16,
                biSizeImage     = 20,
                biXPelsPerMeter = 24,
                biYPelsPerMeter = 28,
                biClrUsed       = 32,
                biClrImportant  = 36,
                SIZE_OF_BITMAPINFOHEADER = 40
--END STRUCT


--STRUCT RGBQUAD
global constant rgbBlue         = 0,
                rgbGreen        = 1,
                rgbRed          = 2,
                rgbReserved     = 3,
                SIZE_OF_RGBQUAD = 4
--END STRUCT


--### STRUCT RECT ###
global constant rect_left       = 0,
                rect_top        = 4,
                rect_right      = 8,
                rect_bottom     = 12,
                SIZE_OF_RECT    = 16
--### END STRUCT ###


--### Color component compression ###
global constant BI_RGB          = 0,
                BI_RLE8         = 1,
                BI_RLE4         = 2,
                BI_BITFIELDS    = 3

global constant DIB_PAL_COLORS  = 1,
                DIB_RGB_COLORS  = 0


--### Raster operations ###
global constant SRCINVERT       = #660046,
                SRCAND          = #8800C6,
                MERGEPAINT      = #BB0226,
                MERGECOPY       = #C000CA,
                SRCCOPY         = #CC0020,
                SRCPAINT        = #EE0086


--STRUCT BITMAPINFO
global constant BITMAPINFOHEADER = 0,
                RGBQUAD          = 40,
                SIZE_OF_BITMAPINFO = SIZE_OF_BITMAPINFOHEADER + SIZE_OF_RGBQUAD
--END STRUCT



-- make room for one BITMAPINFOHEADER + 256 RGBQUAD structs
bi = allocate(SIZE_OF_BITMAPINFOHEADER + 1024)

constant rect = allocate(SIZE_OF_RECT)

constant Width = ???,
         Height = ???,
         Pointer = allocate(Width*Height)

-- 'Pointer' is your bitmap, this is where you keep your graphics.

atom dc



--### Here's how to set the palette ###
--### R, G & B should be 0-255      ###
procedure set_windows_palette(sequence pal)
for i=0 to 255 do
  poke(bi + RGBQUAD + (i*4),pal[i+1][3])
  poke(bi + RGBQUAD + (i*4)+1,pal[i+1][2])
  poke(bi + RGBQUAD + (i*4)+2,pal[i+1][1])
  poke(bi + RGBQUAD + (i*4)+3,0)
end for
end procedure


--### Do this once at init ###

mem_set(bi, 0, SIZE_OF_BITMAPINFOHEADER)



--### Do this whenever you repaint your window ###

poke4(bi + BITMAPINFOHEADER + biSize, SIZE_OF_BITMAPINFOHEADER)
poke4(bi + BITMAPINFOHEADER + biWidth, Width)
poke4(bi + BITMAPINFOHEADER + biHeight, Height)
poke_word(bi + BITMAPINFOHEADER + biPlanes, 1)
poke_word(bi + BITMAPINFOHEADER + biBitCount, 8)
-- the RGBQUAD entries contains explicit RGB values (actually BGRX..)
poke4(bi + BITMAPINFOHEADER + biCompression, BI_RGB)

dc = GetDC(hwnd)
if GetClientRect(hwnd,rect) then end if

-- this is it - StretchDIBits copies a memory block to a window's device
context
-- syntax is as follows:
-- StretchDIBits({
--    atom  hdc,                handle of device context
--    atom  XDest,              x-coordinate of upper-left corner of dest. rect.
--    atom  YDest,              y-coordinate of upper-left corner of dest. rect.
--    atom  nDestWidth, width of destination rectangle
--    atom  nDestHeight,        height of destination rectangle
--    atom  XSrc,               x-coordinate of upper-left corner of source
rect.
--    atom  YSrc,               y-coordinate of upper-left corner of source
rect.
--    atom  nSrcWidth,          width of source rectangle
--    atom  nSrcHeight, height of source rectangle
--    atom  lpBits,             address of bitmap bits
--    atom  lpBitsInfo, address of bitmap data
--    atom  iUsage,             usage
--    atom  dwRop               raster operation code
--   })
StretchDIBits({dc,0,0,peek4s(rect + rect_right),peek4s(rect + rect_bottom),
                0,0,Width,Height,Pointer,bi,DIB_RGB_COLORS,SRCCOPY})

if ReleaseDC(hwnd,dc) then end if

--### The End ###



If this just confused you, I've written some programs that actually use this
stuff, and not only for 8-bit graphics. Try searching for "windows
animation" at the Euphoria site and my program should pop up at the top..

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