DIrectSUrface用 双线性插值

# define FILENAME "main.png"
# define MOD_SHIFT_ 11
# define MOD_MAPPER_ ( (1 << MOD_SHIFT_))/* MOD_MAPPER is 2^n*/
# define MOD_SHIFT_MUL_ (MOD_MAPPER_*MOD_MAPPER_)

DWORD AlphaRGB32_S (DWORD RGB32, DWORD max, DWORD cur)  {
  DWORD D0 = RGB32 & 0xFF;
  DWORD D1 = RGB32 & 0xFF00;
  DWORD D2 = RGB32 & 0xFF0000;
  D0 >>= 0;
  D1 >>= 8;
  D2 >>= 16;
  D0 *= cur;
  D1 *= cur;
  D2 *= cur;
  D0 /= max;
  D1 /= max;
  D2 /= max;
  D0 &= 0xFF;
  D1 &= 0xFF;
  D2 &= 0xFF;
  D0 <<= 0;
  D1 <<= 8;
  D2 <<= 16;
  return (D0 | D1 | D2);
}

DWORD SuratADD (DWORD U, DWORD V)  {
  DWORD U0 = U & 0xFF;
  DWORD U1 = U & 0xFF00;
  DWORD U2 = U & 0xFF0000;
  DWORD V0 = V & 0xFF;
  DWORD V1 = V & 0xFF00;
  DWORD V2 = V & 0xFF0000;
  U0 += V0;
  U1 += V1;
  U2 += V2;
  if (U0 > 0xFF) U0 = 0xFF;
  if (U1 > 0xFF00) U1 = 0xFF00;
  if (U2 > 0xFF0000) U2 = 0xFF0000;
  return (U0 | U1 | U2);
}

#  if  1
void Bilinear (DWORD *pDstVPTR, DWORD dwDstPitch,
               DWORD *pSrcVPTR, DWORD dwSrcPitch,
               DWORD dwDstWidth, DWORD dwDstHeight,
               DWORD dwSrcWidth, DWORD dwSrcHeight)
{
  DWORD dwMapX = (DWORD) (  ((float)MOD_MAPPER_) * (( (float) dwSrcWidth) / ( (float) dwDstWidth) )); // 2->3
  DWORD dwMapY = (DWORD) (  ((float)MOD_MAPPER_) * (( (float) dwSrcHeight) / ( (float) dwDstHeight))); // 2->3
  DWORD dwPosInSrcY = 0;
  DWORD dwPosInSrcX = 0;
  DWORD dwRTInSrcY;
  DWORD dwRTInSrcX;
  DWORD dwsPit = dwSrcPitch >> 2;
  DWORD dwdPit = dwDstPitch >> 2;
  DWORD dwMapTotal_X = 0;
  DWORD dwMapTotal_Y = 0;
  DWORD dwRVADst = dwDstPitch - dwDstWidth *4;
  DWORD dwCahceScanLine_Y = 0;
  DWORD dwCahceScanLine_Y2 = 0;
  for (DWORD dwScanY = 0; dwScanY != dwDstHeight; dwScanY++)  {
    dwMapTotal_Y += dwMapY;
    dwPosInSrcY = dwMapTotal_Y >> MOD_SHIFT_;
    dwRTInSrcY = dwMapTotal_Y & (MOD_MAPPER_ - 1);
    dwMapTotal_X = 0;
    dwCahceScanLine_Y = dwsPit*dwPosInSrcY;
    dwCahceScanLine_Y2 = dwdPit*dwScanY;
    for (DWORD dwScanX = 0; dwScanX != dwDstWidth; dwScanX++)  {
      //  fetch  top-left, top-right, botton-left, bottom-right
      //  source sample .
      dwMapTotal_X += dwMapX;
      dwPosInSrcX = dwMapTotal_X >> MOD_SHIFT_;
      dwRTInSrcX = dwMapTotal_X & (MOD_MAPPER_ - 1);

      const DWORD temp = dwCahceScanLine_Y+dwPosInSrcX;

      DWORD cpTopLeft = pSrcVPTR[temp];
      DWORD cpTopRight = pSrcVPTR[temp+1];
      DWORD cpBottomLeft = pSrcVPTR[temp+dwsPit];
      DWORD cpBottomRight = pSrcVPTR[temp+dwsPit+1];

      //  Get X, Y ratio .
      DWORD apLeft = dwRTInSrcX;
      DWORD apRight = MOD_MAPPER_ - apLeft;
      DWORD apTop = dwRTInSrcY;
      DWORD apBottom = MOD_MAPPER_ - apTop;
      // Get Weighted ratio
      DWORD wtTopLeft =   apRight * apBottom;
      DWORD wtTopRight =     apLeft * apBottom;
      DWORD wtBottomLeft = apRight * apTop;
      DWORD wtBottomRight =  apLeft * apTop;
      // Get RGB percent. Write Into Buffer.
      DWORD dbTopLeft = AlphaRGB32_S (cpTopLeft, MOD_SHIFT_MUL_, wtTopLeft);
      DWORD dbTopRight = AlphaRGB32_S (cpTopRight, MOD_SHIFT_MUL_, wtTopRight);
      DWORD dbBottomLeft = AlphaRGB32_S (cpBottomLeft, MOD_SHIFT_MUL_, wtBottomLeft);
      DWORD dbBottomRight = AlphaRGB32_S (cpBottomRight, MOD_SHIFT_MUL_, wtBottomRight);
      DWORD dbTopMix = SuratADD  (  dbTopLeft,  dbTopRight);
      DWORD dbBottomMix = SuratADD  (  dbBottomLeft,  dbBottomRight);
      DWORD dbOutputMix = SuratADD ( dbTopMix, dbBottomMix);

      pDstVPTR[dwCahceScanLine_Y2+dwScanX] = dbOutputMix;
    }
  }
}