改變bitmap大小的函數

BOOL TranslateBitmapSize(<br /> IN HDC hCurScreemDC,//當前螢幕DC，可通過GetDC獲得<br /> IN HBITMAP hBmpSrc,//原BITMAP控制代碼<br /> IN int nSrcWidth,//原BITMAP的寬度<br /> IN int nSrcHeight,//原BITMAP的高度<br /> OUT HBITMAP &hBmpDst,//改變大小後的BITMAP的控制代碼<br /> IN int nDstWidth,//改變大小後的BITMAP的寬度<br /> IN int nDstHeight//改變大小後的BITMAP的高度<br /> )<br />{<br />if (hBmpSrc == NULL || hCurScreemDC == NULL)<br />{<br />return FALSE;<br />}<br />if (hBmpDst != NULL)<br />{<br />DeleteObject(hBmpDst);<br />}<br />HDC hOldSrcDC = NULL;<br />HDC hOldDstDC = NULL;<br />HDC hSrcDC = CreateCompatibleDC(hCurScreemDC);<br />HDC hDstDC = CreateCompatibleDC(hCurScreemDC);<br />hBmpDst = CreateCompatibleBitmap(hCurScreemDC,nDstWidth,nDstHeight);<br />hOldSrcDC = (HDC)SelectObject(hSrcDC,hBmpSrc);<br />hOldDstDC = (HDC)SelectObject(hDstDC,hBmpDst);<br />StretchBlt(hDstDC,0,0,nDstWidth,nDstHeight,hSrcDC,0,0,nSrcWidth,nSrcHeight,SRCCOPY);<br />SelectObject(hSrcDC,hOldSrcDC);<br />SelectObject(hDstDC,hOldDstDC);<br />DeleteObject(hSrcDC);<br />DeleteObject(hDstDC);<br />return TRUE;<br />}

 

原理：

 

建立兩個與當前螢幕DC相容的DC，建立一個與當前螢幕相容的位元影像控制代碼，把兩個位元影像控制代碼分別選入兩個相容DC，然後通過StretchBlt函數進行DC拷貝，目的位元影像控制代碼就獲得了改變後的位元影像。