关于 MaskBlt 中掩模图 的问题

[jinyt]

void CTabtestDlg::OnPaint()
{
CPaintDC dc(this);


HBITMAP bitmap1,OldBitmap1;
HBITMAP bitmap2,OldBitmap2;
HBITMAP bitmap3,OldBitmap3;


CDC MemDCs;
MemDCs.CreateCompatibleDC(&dc);
bitmap1=(HBITMAP)LoadImage(AfxGetInstanceHandle(),
"d:\\aa.bmp",//this is background picture
IMAGE_BITMAP,0,0,LR_LOADFROMFILE|LR_CREATEDIBSECTION);
OldBitmap1=(HBITMAP)MemDCs.SelectObject(bitmap1);

dc.BitBlt(0,0 ,500,500,&MemDCs,0,0,SRCCOPY);


CDC MemDCd;
MemDCd.CreateCompatibleDC(&dc);
bitmap2=(HBITMAP)LoadImage(AfxGetInstanceHandle(),
"d:\\mark2400.bmp",//this is foreground picture
IMAGE_BITMAP,0,0,LR_LOADFROMFILE|LR_CREATEDIBSECTION);
OldBitmap2=(HBITMAP)MemDCd.SelectObject(bitmap2);


CDC MemDCm;
MemDCm.CreateCompatibleDC(&dc);
bitmap3=(HBITMAP)LoadImage(AfxGetInstanceHandle(),
"d:\\j_mark2400.bmp",//this is MAKE picture
IMAGE_BITMAP,128,128,LR_LOADFROMFILE|LR_MONOCHROME);
OldBitmap3=(HBITMAP)MemDCm.SelectObject(bitmap3);

CBitmap pic;
/* Code 1*/
pic.CreateCompatibleBitmap(&MemDCm,128,128);
/* Code 2*/
// pic.LoadBitmap (IDB_BITMAP1);

dc.MaskBlt(10,10,128,128,&MemDCd,0,0,pic,0,0,MAKEROP4(SRCCOPY,SRCAND));

CDialog::OnPaint();

}
掩模图 是单色的
IDB_BITMAP1 是该掩模图直接导入的资源

当我使用Code 2的代码时，所得的结果是正确的；
而使用Code 1的代码时，确是错误的。

aa.bmp室一蓝色底图
mark2400.bmp 是白色背景的一个图标，比如中间是个月亮
j_mark2400.bmp是掩模图，月亮部分是白色，背景部分是黑色

结果应该是
蓝色底图上有一个月亮
但是
当我使用Code 1的代码时
月亮变成了黑或蓝的抖动图
但形状是对的

请问，我该如何直接使用*.bmp的文件来作为我的掩模图。
而是结果是正确的


谢谢

[用户 昵称]

希望有帮助

绘制“透明”位图是指绘制某一位图中除指定颜色外的其余部分，我们称这种颜色为“透明色”。通过将位图的背景色指定为“透明色”，在绘制时，不绘制这部分背景，而仅绘制图像，这样就可以将位图中图像透明地绘制到窗口上。

绘制“透明”位图的关键是创建一个“掩码”位图(mask bitmap)，“掩码”位图是一个单色位图，它是位图中图像的一个单色剪影。

在Windows编程中，绘图都要用到设备描述表，我们需创建两个内存设备描述表：位图设备描述表(image DC)和“掩码”位图设备描述表(mask DC)。位图设备描述表用来装入位图，而“掩码”位图设备描述表用来装入“掩码”位图。在“掩码”位图设备描述表中制作“掩码”位图的方式是：先创建一个单色的Bitmap，装入mask DC，然后，以“SRCCOPY”的方式将装有位图的位图设备描述表绘制(BitBlt)到mask DC上。这样，mask DC的显示平面中的位图即是“掩码”位图。

绘制“透明”位图的实际操作步骤：

1.将位图设备描述表以“SRCINVERT”的方式绘制(BitBlt)到显示设备描述表上；

2.将“掩码”位图设备描述表以“SRCAND”的方式绘制(BitBlt)到显示设备描述表上；

3.再将位图设备描述表以“SRCINVERT”的方式绘制(BitBlt)到显示设备描述表上。这样除“透明色”外的其余位图部分(图像部分)就被绘制到窗口上了。

实现代码如下:

void DrawTransparent(CDC ＊ pDC, int x, int y, COLORREF crColour)

{ COLORREF crOldBack=pDC－〉SetBkColor(RGB(255,255,255));

COLORREF crOldText=pDC－〉SetTextColor(RGB(0,0,0));

CDC dcImage, dcMask;

CBitmap bmp;

bmp.LoadBitmap(IDB—TRANS);

//IDB—TRANS是待显示位图的资源ID

BITMAP bm;bmp.GetBitmap(＆bm);

int nWidth=bm.bmWidth,nHeight=bm.bmHeight;

//为图像及mask各创建一个DC

dcImage.CreateCompatibleDC(pDC);

dcMask.CreateCompatibleDC(pDC);

//把图像装入image DC

CBitmap＊ pOldBitmapImage=dcImage.SelectObject(＆bmp);

//为“掩码”位图创建一个单色bitmap

CBitmap bitmapMask;

bitmapMask.CreateBitmap(nWidth, nHeight, 1, 1, NULL); //把mask位图装入mask DC

CBitmap＊ pOldBitmapMask = dcMask.SelectObject(＆bitmapMask); //用透明色创建“掩码”位图

dcImage.SetBkColor(crColour);//crColor是位图中的透明色

dcMask.BitBlt(0, 0, nWidth, nHeight, ＆dcImage, 0, 0, SRCCOPY);//分3步进行实际的绘制

pDC－〉BitBlt(x, y, nWidth, nHeight, ＆dcImage, 0, 0, SRCINVERT);

pDC－〉BitBlt(x, y, nWidth, nHeight, ＆dcMask, 0, 0, SRCAND);

pDC－〉BitBlt(x, y, nWidth, nHeight, ＆dcImage, 0, 0, SRCINVERT); //恢复原先设置

dcImage.SelectObject(pOldBitmapImage);

dcMask.SelectObject(pOldBitmapMask);

pDC－〉SetBkColor(crOldBack);

pDC－〉SetTextColor(crOldText);}

以上这种“透明”位图的绘制方法，还可以用到动画技术中，如绘制在某场景中不断移动的人物或动物，就可以通过将人物或动物位图“透明”地绘制到背景中实现。

[dyw]

clever

[rockroll]

我记得我以前做的是把原先的位图给翻转了
就是把颜色给翻过来了

然后异或操作

[hurry2002]

mark

[jinyt]

BOOL DrawTransparentBmp(HDC hdc, HBITMAP hbmp, RECT &rect, COLORREF colorTrans)
{
HDC dcImage, dcTrans, dcImage24;
HBITMAP holdbmp24, hbmp24;
HBITMAP holdbmp;
HBITMAP hbmpTrans, holdbmpTrans;

_BITMAP bmp;

dcImage = CreateCompatibleDC(hdc);
dcTrans = CreateCompatibleDC(hdc);
dcImage24 = CreateCompatibleDC(hdc);

if (dcImage == NULL || dcTrans == NULL || dcImage24 == NULL)
// Error: can't create compatible dc
return FALSE;

GetObject(hbmp, sizeof(bmp), &bmp);


holdbmp = (HBITMAP)SelectObject(dcImage, hbmp);


LPBITMAPINFO lpBmpInfo;

lpBmpInfo = (BITMAPINFO*) new BYTE[sizeof(BITMAPINFOHEADER)];

lpBmpInfo->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
lpBmpInfo->bmiHeader.biPlanes = 1;
lpBmpInfo->bmiHeader.biBitCount = 24/*nBitCount*/;
lpBmpInfo->bmiHeader.biCompression = BI_RGB;
lpBmpInfo->bmiHeader.biSizeImage = 0;
lpBmpInfo->bmiHeader.biClrUsed = 0;

lpBmpInfo->bmiHeader.biWidth = bmp.bmWidth;
lpBmpInfo->bmiHeader.biHeight = bmp.bmHeight;

HDC dc = CreateCompatibleDC(NULL);


LPVOID lpBits;
hbmp24 =::CreateDIBSection(dc,lpBmpInfo,DIB_RGB_COLORS,
&lpBits,NULL,0);

DeleteDC(dc);
delete lpBmpInfo;

if (hbmp24 == NULL)
// Error
return FALSE;

holdbmp24 = (HBITMAP)SelectObject(dcImage24, hbmp24);


BitBlt(dcImage24, 0, 0, bmp.bmWidth, bmp.bmHeight, dcImage, 0, 0, SRCCOPY);


hbmpTrans = CreateBitmap(bmp.bmWidth, bmp.bmHeight, 1, 1, NULL);
if (hbmpTrans == NULL)
// Error
return FALSE;


holdbmpTrans = (HBITMAP)SelectObject(dcTrans, hbmpTrans);


COLORREF oldbkcolor = SetBkColor(dcImage24, colorTrans);
BitBlt(dcTrans, 0, 0, bmp.bmWidth, bmp.bmHeight, dcImage24, 0, 0, SRCCOPY);

SetBkColor(dcImage24, RGB(0,0,0));
COLORREF oldtextcolor = SetTextColor(dcImage24, RGB(255,255,255));
BitBlt(dcImage24, 0, 0, bmp.bmWidth, bmp.bmHeight, dcTrans, 0, 0, SRCAND);


COLORREF crOldBack, crOldText;
crOldBack = SetBkColor(hdc, RGB(255,255,255));
crOldText = SetTextColor(hdc, RGB(0,0,0));


StretchBlt(hdc, rect.left, rect.top, rect.right - rect.left,rect.bottom - rect.top,
dcTrans, 0, 0, bmp.bmWidth, bmp.bmHeight, SRCAND);
StretchBlt(hdc, rect.left, rect.top, rect.right - rect.left,rect.bottom - rect.top,
dcImage24, 0, 0, bmp.bmWidth, bmp.bmHeight, SRCPAINT);


SelectObject(dcImage, holdbmp);

SelectObject(dcImage24, holdbmp24);
SelectObject(dcTrans, holdbmpTrans);

DeleteObject(hbmp24);
DeleteObject(hbmpTrans);

SetBkColor(hdc, crOldBack);
SetTextColor(hdc, crOldText);

SetBkColor(dcImage24, oldbkcolor);
SetTextColor(dcImage24, oldtextcolor);

DeleteDC(dcImage);
DeleteDC(dcImage24);
DeleteDC(dcTrans);

return TRUE;
}

我终于找到了答案

：）

[用户 昵称]

#define FORE_ROP3(ROP4) (0x00FFFFFF&(ROP4))
#define BACK_ROP3(ROP4) (ROP3FromIndex(SwapROP3_SrcDst(BYTE((ROP4)>>24))))
#define DSTCOPY 0x00AA0029
#define DSTERASE 0x00220326 // dest = dest & (~src) : DSna

BOOL WINAPI MyMaskBlt(HDC hdcDest, int nXDest, int nYDest, int nWidth, int nHeight,
HDC hdcSrc, int nXSrc, int nYSrc,
HBITMAP hbmMask, int xMask, int yMask,
DWORD dwRop
)
{
if ( hbmMask == NULL )
return BitBlt(hdcDest, nXDest, nYDest, nWidth, nHeight, hdcSrc,
nXSrc, nYSrc, FORE_ROP3(dwRop));

// 1. make mask bitmap's dc
HDC hDCMask = ::CreateCompatibleDC(hdcDest);
HBITMAP hOldMaskBitmap = (HBITMAP)::SelectObject(hDCMask, hbmMask);
ASSERT ( hOldMaskBitmap );

// 2. make masked Background bitmap

// 2.1 make bitmap
HDC hDC1 = ::CreateCompatibleDC(hdcDest);
ASSERT ( hDC1 );
HBITMAP hBitmap2 = ::CreateCompatibleBitmap(hdcDest, nWidth, nHeight);
HBITMAP hOldBitmap2 = (HBITMAP)::SelectObject(hDC1, hBitmap2);
ASSERT ( hOldBitmap2 );

// 2.2 draw dest bitmap and mask
DWORD dwRop3 = BACK_ROP3(dwRop);
::BitBlt(hDC1, 0, 0, nWidth, nHeight, hdcSrc, nXSrc, nYSrc, SRCCOPY);
::BitBlt(hDC1, 0, 0, nWidth, nHeight, hdcDest, nXDest, nYDest, dwRop3);
::BitBlt(hDC1, 0, 0, nWidth, nHeight, hDCMask, xMask, yMask, DSTERASE);

// 3. make masked Foreground bitmap

// 3.1 make bitmap
HDC hDC2 = ::CreateCompatibleDC(hdcDest);
ASSERT ( hDC2 );
HBITMAP hBitmap3 = ::CreateCompatibleBitmap(hdcDest, nWidth, nHeight);
HBITMAP hOldBitmap3 = (HBITMAP)::SelectObject(hDC2, hBitmap3);
ASSERT ( hOldBitmap3 );

// 3.2 draw src bitmap and mask
dwRop3 = FORE_ROP3(dwRop);
::BitBlt(hDC2, 0, 0, nWidth, nHeight, hdcDest, nXDest, nYDest, SRCCOPY);
::BitBlt(hDC2, 0, 0, nWidth, nHeight, hdcSrc, nXSrc, nYSrc, dwRop3);
::BitBlt(hDC2, 0, 0, nWidth, nHeight, hDCMask, xMask, yMask, SRCAND);

// 4. combine two bitmap and copy it to hdcDest
::BitBlt(hDC1, 0, 0, nWidth, nHeight, hDC2, 0, 0, SRCPAINT);
::BitBlt(hdcDest, nXDest, nYDest, nWidth, nHeight, hDC1, 0, 0, SRCCOPY);

// 5. restore all object
::SelectObject(hDCMask, hOldMaskBitmap);
::SelectObject(hDC1, hOldBitmap2);
::SelectObject(hDC2, hOldBitmap3);

// 6. delete all temp object
DeleteObject(hBitmap2);
DeleteObject(hBitmap3);

DeleteDC(hDC1);
DeleteDC(hDC2);
DeleteDC(hDCMask);

return TRUE;
}