怎么样画透明背景的位图？
//该函数摘自MSDN.voidDrawTransparentBitmap(HDChdc,HBITMAPhBitmap,shortxStart,shortyStart,COLORREFcTransparentColor)
{
BITMAPbm;COLORREFcColor;HBITMAPbmAndBack,bmAndObject,bmAndMem,bmSave;HBITMAPbmBackOld,bmObjectOld,bmMemOld,bmSaveOld;HDChdcMem,hdcBack,hdcObject,hdcTemp,hdcSave;POINTptSize;hdcTemp=CreateCompatibleDC(hdc);SelectObject(hdcTemp,hBitmap);//SelectthebitmapGetObject(hBitmap,sizeof(BITMAP),(LPSTR)&bm);ptSize.x=bm.bmWidth;//GetwidthofbitmapptSize.y=bm.bmHeight;//GetheightofbitmapDPtoLP(hdcTemp,&ptSize,1);//Convertfromdevice//tologicalpoints//CreatesomeDCstoholdtemporarydata.hdcBack=CreateCompatibleDC(hdc);hdcObject=CreateCompatibleDC(hdc);hdcMem=CreateCompatibleDC(hdc);hdcSave=CreateCompatibleDC(hdc);//CreateabitmapforeachDC.DCsarerequiredforanumberof//GDIfunctions.//MonochromeDCbmAndBack=CreateBitmap(ptSize.x,ptSize.y,1,1,NULL);//MonochromeDCbmAndObject=CreateBitmap(ptSize.x,ptSize.y,1,1,NULL);bmAndMem=CreateCompatibleBitmap(hdc,ptSize.x,ptSize.y);bmSave=CreateCompatibleBitmap(hdc,ptSize.x,ptSize.y);//EachDCmustselectabitmapobjecttostorepixeldata.bmBackOld=(HBITMAP)::SelectObject(hdcBack,bmAndBack);bmObjectOld=(HBITMAP)::SelectObject(hdcObject,bmAndObject);bmMemOld=(HBITMAP)::SelectObject(hdcMem,bmAndMem);bmSaveOld=(HBITMAP)::SelectObject(hdcSave,bmSave);//Setpropermappingmode.SetMapMode(hdcTemp,GetMapMode(hdc));//Savethebitmapsenthere,becauseitwillbeoverwritten.BitBlt(hdcSave,0,0,ptSize.x,ptSize.y,hdcTemp,0,0,SRCCOPY);//SetthebackgroundcolorofthesourceDCtothecolor.//containedinthepartsofthebitmapthatshouldbetransparentcColor=SetBkColor(hdcTemp,cTransparentColor);//CreatetheobjectmaskforthebitmapbyperformingaBitBlt//fromthesourcebitmaptoamonochromebitmap.BitBlt(hdcObject,0,0,ptSize.x,ptSize.y,hdcTemp,0,0,SRCCOPY);//SetthebackgroundcolorofthesourceDCbacktotheoriginal//color.SetBkColor(hdcTemp,cColor);//Createtheinverseoftheobjectmask.BitBlt(hdcBack,0,0,ptSize.x,ptSize.y,hdcObject,0,0,NOTSRCCOPY);//CopythebackgroundofthemainDCtothedestination.BitBlt(hdcMem,0,0,ptSize.x,ptSize.y,hdc,xStart,yStart,SRCCOPY);//Maskouttheplaceswherethebitmapwillbeplaced.BitBlt(hdcMem,0,0,ptSize.x,ptSize.y,hdcObject,0,0,SRCAND);//Maskoutthetransparentcoloredpixelsonthebitmap.BitBlt(hdcTemp,0,0,ptSize.x,ptSize.y,hdcBack,0,0,SRCAND);//XORthebitmapwiththebackgroundonthedestinationDC.BitBlt(hdcMem,0,0,ptSize.x,ptSize.y,hdcTemp,0,0,SRCPAINT);//Copythedestinationtothescreen.BitBlt(hdc,xStart,yStart,ptSize.x,ptSize.y,hdcMem,0,0,SRCCOPY);//Placetheoriginalbitmapbackintothebitmapsenthere.BitBlt(hdcTemp,0,0,ptSize.x,ptSize.y,hdcSave,0,0,SRCCOPY);//Deletethememorybitmaps.DeleteObject(SelectObject(hdcBack,bmBackOld));DeleteObject(SelectObject(hdcObject,bmObjectOld));DeleteObject(SelectObject(hdcMem,bmMemOld));DeleteObject(SelectObject(hdcSave,bmSaveOld));//DeletethememoryDCs.DeleteDC(hdcMem);DeleteDC(hdcBack);DeleteDC(hdcObject);DeleteDC(hdcSave);DeleteDC(hdcTemp);
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