为什么LoadImage载入bmp图片需要ps中添加alpha通道才能在list control中显示出来？,report风格，重绘的

weping 2013-04-02 11:30:38

在做一个仿QQ好友列表那样的效果。用的list control控件， report风格。重载DrawItem. 现在能显示特定的bmp格式图标，有的bmp显示不出来。经过试验发现只要给bmp图片在photoshop中添加一个alpha通道，就可以显示了。因为程序运行后要从文件中载入图片。不能从资源中获取。所以这些bmp图片不可能我每一张都手动去ps里处理。想问问这是为什么？为什么需要添加alpha通道才能在重绘后的list control显示出来。是我重绘代码写错了吗？







void COrangeListCtrl::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)

{





// TODO:  添加您的代码以绘制指定项

 CBitmap *bmp=new CBitmap;

  CString strText;

 int  wz = 0;

 TCHAR lpBuffer[256];

 LV_COLUMN lvc, lvcprev ;

 ::ZeroMemory(&lvc, sizeof(lvc));

 lvc.mask = LVCF_WIDTH | LVCF_FMT;

 long hight = 0;

  CDC* pDC;

  pDC = CDC::FromHandle(lpDrawItemStruct->hDC);

 for ( int nCol=0; GetColumn(nCol, &lvc); nCol++)

 {

  lpDrawItemStruct->rcItem.left += hight ;

  lpDrawItemStruct->rcItem.right += hight ;

  hight = lvc.cx ;

  LV_ITEM lvi;

  ::ZeroMemory(&lvi, sizeof(lvi));

  lvi.iItem = lpDrawItemStruct->itemID;

  lvi.mask = LVIF_TEXT | LVIF_PARAM;

  lvi.iSubItem = nCol;

  lvi.pszText = lpBuffer;

  lvi.cchTextMax = sizeof(lpBuffer);

  VERIFY(GetItem(&lvi));

 

  if ( lpDrawItemStruct->itemState & ODS_SELECTED )

  {

   pDC->FillSolidRect(&lpDrawItemStruct->rcItem,RGB(231, 243, 229)) ;

   pDC->SetTextColor(RGB(255, 0, 0)) ;

  }

 }



//载入图片

m_imagelist.Create(ICON_SHOW_SIZE, ICON_SHOW_SIZE,ILC_COLORDDB|ILC_COLOR32 | ILC_MASK, 5, 5);  

  bmp->m_hObject=(HBITMAP)LoadImage(AfxGetInstanceHandle(), _T("qqface\\a12.bmp"), IMAGE_BITMAP, ICON_SHOW_SIZE, ICON_SHOW_SIZE, LR_LOADFROMFILE|LR_CREATEDIBSECTION);

	

  m_imagelist.Add(bmp, RGB(255,255, 255));	





 strText = lpBuffer;

 

 CRect lrect = lpDrawItemStruct->rcItem;

 CDC ldc;

 ldc.CreateCompatibleDC(pDC);

 CBitmap lbmp;

 lbmp.CreateCompatibleBitmap(pDC, ICON_SHOW_SIZE, ICON_SHOW_SIZE);

 ldc.SelectObject(lbmp);



 m_imagelist.Draw(&ldc, lpDrawItemStruct->itemID % 2, CPoint(0, 0), ILD_TRANSPARENT);

 BLENDFUNCTION ab;

 ab.BlendOp = AC_SRC_OVER;

 ab.BlendFlags = 0;

 ab.SourceConstantAlpha = 0xFF;

 ab.AlphaFormat = AC_SRC_ALPHA;

 AlphaBlend(pDC->GetSafeHdc(), lrect.left, lrect.top, ICON_SHOW_SIZE, ICON_SHOW_SIZE, ldc.GetSafeHdc(), 0, 0, ICON_SHOW_SIZE, ICON_SHOW_SIZE, ab);





 CFont lfont;

 lfont.CreateFont(12, 0, 0, 0, FW_BOLD ,0, 1, 0, GB2312_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, DEFAULT_PITCH ,L"宋体");

 CFont* pold = pDC->SelectObject(&lfont);



 wz = ICON_SHOW_SIZE + 10;

 lrect.DeflateRect( wz, 6, 0, 0);

 pDC->DrawText(strText, lrect, DT_LEFT | DT_TOP | DT_SINGLELINE);

 pDC->SelectObject(pold);

 pDC->SetTextColor(RGB(223, 0, 0));

	

}