maskedbitmap.cpp

这是MFC Windows程序设计（第2版）

// MaskedBitmap.cpp: implementation of the CMaskedBitmap class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "BitmapDemo.h"
#include "MaskedBitmap.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

void CMaskedBitmap::Draw(CDC *pDC, int x, int y)
{
    BITMAP bm;
    GetBitmap (&bm);
    CPoint size (bm.bmWidth, bm.bmHeight);
    pDC->DPtoLP (&size);

    CPoint org (0, 0);
    pDC->DPtoLP (&org);

    CDC dcMem;
    dcMem.CreateCompatibleDC (pDC);
    CBitmap* pOldBitmap = dcMem.SelectObject (this);
    dcMem.SetMapMode (pDC->GetMapMode ());

    pDC->BitBlt (x, y, size.x, size.y, &dcMem, org.x, org.y, SRCCOPY);

    dcMem.SelectObject (pOldBitmap);
}

void CMaskedBitmap::DrawTransparent(CDC *pDC, int x, int y,
	COLORREF clrTransparency)
{
    BITMAP bm;
    GetBitmap (&bm);
    CPoint size (bm.bmWidth, bm.bmHeight);
    pDC->DPtoLP (&size);

    CPoint org (0, 0);
    pDC->DPtoLP (&org);

	//
    // Create a memory DC (dcImage) and select the bitmap into it.
	//
    CDC dcImage;
    dcImage.CreateCompatibleDC (pDC);
    CBitmap* pOldBitmapImage = dcImage.SelectObject (this);
    dcImage.SetMapMode (pDC->GetMapMode ());

	//
    // Create a second memory DC (dcAnd) and in it create an AND mask.
	//
    CDC dcAnd;
    dcAnd.CreateCompatibleDC (pDC);
    dcAnd.SetMapMode (pDC->GetMapMode ());

    CBitmap bitmapAnd;
    bitmapAnd.CreateBitmap (bm.bmWidth, bm.bmHeight, 1, 1, NULL);
    CBitmap* pOldBitmapAnd = dcAnd.SelectObject (&bitmapAnd);

    dcImage.SetBkColor (clrTransparency);
    dcAnd.BitBlt (org.x, org.y, size.x, size.y, &dcImage, org.x, org.y,
        SRCCOPY);

	//
    // Create a third memory DC (dcXor) and in it create an XOR mask.
	//
    CDC dcXor;
    dcXor.CreateCompatibleDC (pDC);
    dcXor.SetMapMode (pDC->GetMapMode ());

    CBitmap bitmapXor;
    bitmapXor.CreateCompatibleBitmap (&dcImage, bm.bmWidth, bm.bmHeight);
    CBitmap* pOldBitmapXor = dcXor.SelectObject (&bitmapXor);

    dcXor.BitBlt (org.x, org.y, size.x, size.y, &dcImage, org.x, org.y,
        SRCCOPY);

    dcXor.BitBlt (org.x, org.y, size.x, size.y, &dcAnd, org.x, org.y,
        0x220326);

	//
    // Copy the pixels in the destination rectangle to a temporary
    // memory DC (dcTemp).
	//
    CDC dcTemp;
    dcTemp.CreateCompatibleDC (pDC);
    dcTemp.SetMapMode (pDC->GetMapMode ());

    CBitmap bitmapTemp;
    bitmapTemp.CreateCompatibleBitmap (&dcImage, bm.bmWidth, bm.bmHeight);
    CBitmap* pOldBitmapTemp = dcTemp.SelectObject (&bitmapTemp);

    dcTemp.BitBlt (org.x, org.y, size.x, size.y, pDC, x, y, SRCCOPY);

	//
    // Generate the final image by applying the AND and XOR masks to
    // the image in the temporary memory DC.
	//
    dcTemp.BitBlt (org.x, org.y, size.x, size.y, &dcAnd, org.x, org.y,
        SRCAND);

    dcTemp.BitBlt (org.x, org.y, size.x, size.y, &dcXor, org.x, org.y,
        SRCINVERT);

	//
    // Blit the resulting image to the screen.
	//
    pDC->BitBlt (x, y, size.x, size.y, &dcTemp, org.x, org.y, SRCCOPY);

	//
    // Restore the default bitmaps.
	//
    dcTemp.SelectObject (pOldBitmapTemp);
    dcXor.SelectObject (pOldBitmapXor);
    dcAnd.SelectObject (pOldBitmapAnd);
    dcImage.SelectObject (pOldBitmapImage);
}