编程技巧20法之七：建立灰度级图标

作者：徐景周　来源：赛迪网　

15.如何建立一个灰度级图标

HICON CreateGrayscaleIcon(HICON hIcon)
{
  HICON       hGrayIcon = NULL;
  HDC         hMainDC = NULL, 
              hMemDC1 = NULL, 
              hMemDC2 = NULL;
  BITMAP      bmp;
  HBITMAP     hOldBmp1 = NULL,
              hOldBmp2 = NULL;
  ICONINFO    csII, csGrayII;
  BOOL        bRetValue = FALSE;

  bRetValue = ::GetIconInfo(hIcon, &csII);
  if (bRetValue == FALSE) return NULL;
  hMainDC = ::GetDC(m_hWnd);
  hMemDC1 = ::CreateCompatibleDC(hMainDC);
  hMemDC2 = ::CreateCompatibleDC(hMainDC);
  if (hMainDC == NULL || 
    hMemDC1 == NULL ||
    hMemDC2 == NULL) 
      return NULL;
  if (::GetObject(csII.hbmColor, 
                sizeof(BITMAP), &
                amp;bmp))
  {
    csGrayII.hbmColor = 
         ::CreateBitmap(csII.xHotspot*2,
                        csII.yHotspot*2, 
                        bmp.bmPlanes, 
                        bmp.bmBitsPixel, 
                        NULL);
    if (csGrayII.hbmColor)
    {
      hOldBmp1 =
         (HBITMAP)::SelectObject(hMemDC1,
                                 csII.hbmColor);
      hOldBmp2 = 
         (HBITMAP)::SelectObject(hMemDC2,
                                 csGrayII.hbmColor);

      ::BitBlt(hMemDC2, 0, 0, csII.xHotspot*2,
               csII.yHotspot*2, hMemDC1, 0, 0,
               SRCCOPY);

      DWORD    dwLoopY = 0, dwLoopX = 0;
      COLORREF crPixel = 0;
      BYTE     byNewPixel = 0;

      for (dwLoopY = 0; dwLoopY < csII.yHotspot*2; dwLoopY++)
      {
        for (dwLoopX = 0; dwLoopX < csII.xHotspot*2; dwLoopX++)
        {
          crPixel = ::GetPixel(hMemDC2, dwLoopX, dwLoopY);

          byNewPixel = (BYTE)((GetRValue(crPixel) * 0.299) +
               (GetGValue(crPixel) * 0.587) +
               (GetBValue(crPixel) * 0.114));
          if (crPixel) ::SetPixel(hMemDC2,
                                  dwLoopX,
                                  dwLoopY,
                                  RGB(byNewPixel,
                                  byNewPixel,
                                  byNewPixel));
        } // for
      } // for

      ::SelectObject(hMemDC1, hOldBmp1);
      ::SelectObject(hMemDC2, hOldBmp2);

      csGrayII.hbmMask = csII.hbmMask;

      csGrayII.fIcon = TRUE;
      hGrayIcon = ::CreateIconIndirect(&#38;csGrayII);
    } // if

    ::DeleteObject(csGrayII.hbmColor);
    //::DeleteObject(csGrayII.hbmMask);
  } // if

  ::DeleteObject(csII.hbmColor);
  ::DeleteObject(csII.hbmMask);
  ::DeleteDC(hMemDC1);
  ::DeleteDC(hMemDC2);
  ::ReleaseDC(m_hWnd, hMainDC);

  return hGrayIcon;
}

16.如何按指定角度旋转显示内存位图(用法和BitBlt类似)

void RotBlt(HDC destDC, int srcx1, int srcy1, int srcx2, int srcy2,
  HDC srcDC , int destx1, int desty1 ,int thetaInDegrees ,DWORD mode)
{
  double theta = thetaInDegrees * (3.14159/180);

  //原图像原始大小
  int width = srcx2 - srcx1;
  int height = srcy2 - srcy1;

  //原图像中心点
  int centreX = int(float(srcx2 + srcx1)/2);
  int centreY = int(float(srcy2 + srcy1)/2);

  //判断出图像可以沿任意方向旋转的矩形框
  if(width>height)height = width;
  else
    width = height;
  HDC memDC = CreateCompatibleDC(destDC);
  HBITMAP memBmp = CreateCompatibleBitmap(destDC, width, height);
  HBITMAP obmp = (HBITMAP) SelectObject(memDC, memBmp);
  //内存DC新在中心点
  int newCentre = int(float(width)/2);
  //开始旋转
  for(int x = srcx1; x<=srcx2; x++)
    for(int y = srcy1; y<=srcy2; y++)
    {
      COLORREF col = GetPixel(srcDC,x,y);
      int newX = int((x-centreX)*sin(theta)+(y-centreY)*cos(theta));
      int newY = int((x-centreX)*cos(theta)-(y-centreY)*sin(theta));
      SetPixel(memDC , newX + newCentre, newY + newCentre, col);
    }

  //复制到目标DC上
  BitBlt(destDC, destx1, desty1, width, height, memDC, 0,0,mode);
  //释放内存
  SelectObject(memDC, obmp);
  DeleteDC(memDC);
  DeleteObject(memBmp);
}

用法：

RotBlt(dc, 0,0,150,150,memDC,200,0, 45, SRCCOPY);