Function FBmpShrinkToWin

xdevice.cpp:507–555

// composing the source one. This is done to produce an antialiasing effect.

flag FBmpShrinkToWin(HDC hdc, HBITMAP hbmp, HDC hdcWin)
{
  Bitmap *b = &wi.bmpSmooth, *b2 = &wi.bmpWin;
  int x, y, cR, cG, cB, nR, nG, nB, x1, y1, x2, y2, sq, sq2;
  flag fRet;
  byte *pb, *pb2;

  if (us.fWriteOld) {
    // Windows can quickly do the shrinking and blending, but not as well.
    SetStretchBltMode(hdcWin, HALFTONE);
    SetBrushOrgEx(hdcWin, 0, 0, NULL);
    StretchBlt(hdcWin, 0, 0, wi.xClient, wi.yClient,
      hdc, 0, 0, wi.xClient*wi.nScaleWin, wi.yClient*wi.nScaleWin, SRCCOPY);
    return fTrue;
  }

  // First copy to or allocate internal bitmap structures to make use of.
  wi.xClient *= wi.nScaleWin; wi.yClient *= wi.nScaleWin;
  fRet = FBmpCopyFromWin(b, hdc, wi.hbmp);
  wi.xClient /= wi.nScaleWin; wi.yClient /= wi.nScaleWin;
  if (!fRet)
    return fFalse;

  if (!FAllocateBmp(b2, wi.xClient, wi.yClient))
    return fFalse;
  sq = Sq(wi.nScaleWin); sq2 = sq >> 1;

  // Loop over each pixel in the destination bitmap.
  for (y = 0; y < wi.yClient; y++) {
    pb2 = _PbXY(b2, 0, y);
    for (x = 0; x < wi.xClient; x++) {
      // Loop over the current NxN square of pixels in the source bitmap.
      cR = cG = cB = 0;
      for (y1 = y * wi.nScaleWin, y2 = y1 + wi.nScaleWin; y1 < y2; y1++) {
        pb = _PbXY(b, x * wi.nScaleWin, y1);
        for (x1 = x * wi.nScaleWin, x2 = x1 + wi.nScaleWin; x1 < x2; x1++) {
          _GetRGB(pb, &nR, &nG, &nB);
          cR += nR; cG += nG; cB += nB;
          pb += cbPixelK;
        }
      }
      _SetRGB(pb2, (cR + sq2) / sq, (cG + sq2) / sq, (cB + sq2) / sq);
      pb2 += cbPixelK;
    }
  }

  BmpCopyToWin(b2, hdcWin, 0, 0);
  return fTrue;
}
#endif
#endif // WINANY