如何在VC中显示透明背景位图

简单的调用系统API。

Windows NT/2000/XP: Included in Windows 2000 and later.
Windows 95/98/Me: Included in Windows 98 and later.
Header: Declared in Wingdi.h; include Windows.h.
Library: Use Msimg32.lib.

void CTransparentBltTestDlg::OnPaint()
{
    CPaintDC dc(this); // device context for painting
   
    CDialog::OnPaint();
    COLORREF crMask = RGB(0x00,0x00,0xff); // Mask color of bitmap
    BITMAP bm;
    m_bmp.GetBitmap(&bm);
    int nWidth = bm.bmWidth;
    int nHeight = bm.bmHeight;
    CDC ImageDC;
    ImageDC.CreateCompatibleDC(&dc);
    CBitmap *pOldImageBMP = ImageDC.SelectObject(&m_bmp);
    ::TransparentBlt(dc.m_hDC,50,40,nWidth,nHeight,ImageDC.m_hDC,0,0,nWidth,nHeight,crMask);
    ImageDC.SelectObject(pOldImageBMP);
    }
}

TransparentBlt

The TransparentBlt function performs a bit-block transfer of the color data corresponding to a rectangle of pixels from the specified source device context into a destination device context.

BOOL TransparentBlt(
  HDC hdcDest,        // handle to destination DC
  int nXOriginDest,   // x-coord of destination upper-left corner
  int nYOriginDest,   // y-coord of destination upper-left corner
  int nWidthDest,     // width of destination rectangle
  int hHeightDest,    // height of destination rectangle
  HDC hdcSrc,         // handle to source DC
  int nXOriginSrc,    // x-coord of source upper-left corner
  int nYOriginSrc,    // y-coord of source upper-left corner
  int nWidthSrc,      // width of source rectangle
  int nHeightSrc,     // height of source rectangle
  UINT crTransparent  // color to make transparent
);

Parameters

hdcDest

[in] Handle to the destination device context.

nXOriginDest

[in] Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nYOriginDest

[in] Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.

nWidthDest

[in] Specifies the width, in logical units, of the destination rectangle.

hHeightDest

[in] Handle to the height, in logical units, of the destination rectangle.

hdcSrc

[in] Handle to the source device context.

nXOriginSrc

[in] Specifies the x-coordinate, in logical units, of the source rectangle.

nYOriginSrc

[in] Specifies the y-coordinate, in logical units, of the source rectangle.

nWidthSrc

[in] Specifies the width, in logical units, of the source rectangle.

nHeightSrc

[in] Specifies the height, in logical units, of the source rectangle.

crTransparent

[in] The RGB color in the source bitmap to treat as transparent.

Return Values

If the function succeeds, the return value is TRUE.

If the function fails, the return value is FALSE.

Windows NT/2000/XP: To get extended error information, call GetLastError.