Applications must inform DIVE of the state of the physical palette upon initialization and whenever the physical palette changes. At application initialization, and in response to a WM_REALIZEPALETTE message, the application calls the following sequence:
BYTE pbPal[1024]; /* Query the physical palette from PM */ GpiQueryRealColors( hps, 0, 0, 256, (PLONG)pbPal); /* Pass it to DIVE */ DiveSetDestinationPalette( hDive, (PBYTE)pbPal);
If the application itself is using palettes, these palettes must also be communicated to DIVE through the DiveSetSourcePalette function. For example, if the application is using DIVE to blit 256-color palettized images to the screen, the application must send the image palette with a call to DiveSetSourcePalette. If a sequence of images is being used for animation and the palette remains constant through the series, it is necessary to call DiveSetSourcePalette only once before blitting the first image in the series.
DIVE provides high-speed screen updates by bypassing PM. In order to maintain the integrity of the PM desktop, DIVE applications must notify DIVE whenever the visible region of the application window changes so that output may be clipped accordingly.
Every DIVE application will request visible region notification at window initialization time with the following call:
WinSetVisibleRegionNotify( hwnd, TRUE);
The first parameter is the handle of the window where the graphics operations will appear, and the second parameter turns on notification for that window. (A corresponding WinSetVisibleRegionNotify(hwnd, FALSE) call should be made to turn notification off at window termination time.)
Whenever the window's visible region begins to change, either because the window is being moved or sized or another window or icon overlaying the window is being moved or sized, the window will receive a WM_VRNDISABLED message. In response to this message, the DIVE application will call DiveSetupBlitter (hDiveInst, 0). Once the movement is complete, the window will receive a WM_VRNENABLED message. In response to this message, the DIVE application will query the new visible region, using WinQueryVisibleRegion as follows:
hps = WinGetPS( hwnd ); hrgn = GpiCreateRegion( hps, 0, NULL); WinQueryVisibleRegion( hwnd, hrgn);
Whenever the visible region, source color format, or image source or destination size changes, the DIVE application must pass the changes to DIVE with a call to DiveSetupBlitter. Note that it is necessary to pass the rectangles for the region in window coordinates and the position of the window in desktop coordinates. First, get the rectangles and window coordinates:
RECTL rctls[50]; /* Rectangles for visible rgn */
RGNRECT rgnCtl; /* Region control struct */
SETUP_BLITTER SetupBlitter; /* DiveSetupBlitter struct */
POINTL pointl;
SWP swp;
HPS hps;
HRGN hrgn;
rgnCtl.ircStart = 0; /* Enumerate rectangles */
rgnCtl.crc = 50; /* Starting with first */
rgnCtl.ulDirection = RECTDIR_LFRT_TOPBOT;
/* Get rectangles for the visible region */
GpiQueryRegionRects( hps, hrgn, NULL, &rgnCtl, rctls);
/* Find the window position relative to its parent. */
WinQueryWindowPos( hwnd, &swp );
/* Map window position to the desktop. */
pointl.x = swp.x;
pointl.y = swp.y;
WinMapWindowPoints( WinQueryWindow( hwnd, QW_PARENT ),
HWND_DESKTOP, &pointl, 1);
Then, pass the information to DIVE:
/* Tell DIVE about the new settings. */ SIZEL sizlSrcImg; /* Size of source image */ FOURCC fccSrcColors; /* Source image format */ SetupBlitter.ulStructLen = sizeof ( SETUP_BLITTER ); SetupBlitter.fInvert = 0; SetupBlitter.fccSrcColorFormat = fccSrcColors; SetupBlitter.ulSrcLineSizeBytes = ulScanLineBytes; SetupBlitter.ulSrcWidth = sizlSrcImg.cx; SetupBlitter.ulSrcHeight = sizlSrcImg.cy; SetupBlitter.ulSrcPosX = 0; SetupBlitter.ulSrcPosY = 0; SetupBlitter.fccDstColorFormat = FOURCC_SCRN; SetupBlitter.ulDstLineSizeBytes = 0; SetupBlitter.ulDstWidth = swp.cx; SetupBlitter.ulDstHeight = swp.cy; SetupBlitter.ulDstPosX = 0; SetupBlitter.ulDstPosY = 0; SetupBlitter.lScreenPosX = pointl.x; SetupBlitter.lScreenPosY = pointl.y; SetupBlitter.ulNumDstRects = rgnCtl.crcReturned; SetupBlitter.pVisDstRects = rctls; DiveSetupBlitter ( hDive, &SetupBlitter );
The color format of the source image is described by fccSrcColors.
Note that, in this example, the DIVE blitter is set up to blit to the screen, but that need not be the case. DIVE could also be used to perform color conversion and/or stretch blitting to a destination image. The destination color-encoding format would be indicated in fccDstColorFormat; ulDstWidth and ulDstHeight would be set to the size of the destination image; ulNumDstRects would be set to 1; and pVisDstRects would point to a single rectangle with xLeft=yBottom=0 xRight=ulDstWidth and yTop=ulDstHeight.