//  FILE:  PIXEL.CPP
//  Provides 16 Bit Put Pixel, Locking, and Unlocking Methods.
//  By Sam Christiansen  (schristi@cs.utexas.edu)

#include "pixel.h"

                
static BOOL locked = FALSE;
static LPVOID lockedSurf = NULL;
static int lockedWidth = 0;
static int lockedHeight = 0;


//Must run this proc to fill the RGB16 struct with the information needed to plot a pixel

BOOL GetRGB16 ( LPDIRECTDRAWSURFACE Surface, RGB16 *rgb16)
{
    DDSURFACEDESC   ddsd;
    BYTE shiftcount;
    //get a surface description
    ddsd.dwSize = sizeof( ddsd );
    ddsd.dwFlags = DDSD_PIXELFORMAT;
    if (Surface->GetSurfaceDesc ( &ddsd ) != DD_OK )
        return FALSE;
    //get red
    shiftcount = 0;


	char rc=0, gc=0, bc=0;
	for(int n = 1; n<65536; n<<=1) { 
     if(ddsd.ddpfPixelFormat.dwRBitMask & n) ++rc;
     if(ddsd.ddpfPixelFormat.dwGBitMask & n) ++gc;
     if(ddsd.ddpfPixelFormat.dwBBitMask & n) ++bc;
	}


    rgb16->dwRBitMask = ddsd.ddpfPixelFormat.dwRBitMask;
    rgb16->Position.rgbRed = gc + bc;

    rgb16->dwGBitMask = ddsd.ddpfPixelFormat.dwGBitMask;
    rgb16->Position.rgbGreen = bc;

    rgb16->dwBBitMask = ddsd.ddpfPixelFormat.dwBBitMask;
    rgb16->Position.rgbBlue = 0;

    return TRUE;
}//GetRBG16





// Must have the surface locked, pass the surface description 
// that gets returned from the lock call
void PlotPixel(int x, int y, int r, int g, int b, DDSURFACEDESC *ddsd, RGB16 *rgb16)
{
 WORD Pixel;
   Pixel = (r << rgb16->Position.rgbRed) |
           (g << rgb16->Position.rgbGreen) |
           (b);// << rgb16->Position.rgbBlue);
 WORD *pixels = (WORD *)ddsd->lpSurface;
 DWORD pitch = ddsd->dwWidth;
 pixels[y*pitch + x] = Pixel; 
}



//  lock direct draw surface
BOOL Lock(DDSURFACEDESC* ddsd)
{
        HRESULT ddrval;

        
        // VERY IMPORTANT - the next two steps are crucial!
        memset( ddsd, 0, sizeof( *ddsd ));
        ddsd->dwSize = sizeof( *ddsd );

        // attempt to Lock the surface
        ddrval = g_lpDDSBack->Lock(NULL, ddsd, DDLOCK_WAIT, NULL);

        // Always, always check for errors with DirectX!
        if( ddrval == DD_OK )
        {
                locked = TRUE;
                lockedSurf = ddsd->lpSurface;
                lockedWidth = ddsd->lPitch;
                lockedHeight = ddsd->dwHeight;
        }
        else
        {
                locked = FALSE;
                lockedSurf = NULL;
                lockedWidth = 0;
                return FALSE;
        }

	return TRUE;
}

// unlock direct draw surface
BOOL UnLock(void)
{
        if (DD_OK != g_lpDDSBack->Unlock(lockedSurf))
                return FALSE;
                
        locked = FALSE;
        lockedSurf = NULL;
        lockedWidth = 0;
        lockedHeight = 0;
	  return TRUE;
}