CImage类的使用介绍!
链接参考:http://www.cnblogs.com/juncheng/articles/1600730.html
CImage是MFC和ATL共享的新类,它能从外部磁盘中调入一个JPEG、GIF、BMP和PNG格式的图像文件加以显示,而且这些文件格式可以相互转换。例如通过简单的几句,就可以实现CImage类和CBitmap类实例的转换:
HBITMAP hBitmap=image.Detach();
CBitmap bmp;
bmp.Attach(hBitmap);
这样一来,就又回归到以前操纵CBitmap的方式了.CImage本身封装了DIB(设备无关位图)的功能,因而能够处理每个位图像素。
它具有下列最酷特性:
1、AlphaBlend支持像素级的颜色混合,从而实现透明和半透明的效果。
2、PlgBlt能使一个矩形区域的位图映射到一个平行四边形区域中,而且还可能使用位屏蔽操作。
3、TransparentBlt在目标区域中产生透明图像,SetTransparentColor用来设置某种颜色是透明色。
4、MaskBlt在目标区域中产生源位图与屏蔽位图合成的效果。
由于CImage在不同的Windows操作系统中其某些性能是不一样的,因此在使用时要特别注意。例如,CImage::PlgBlt和CImage::MaskBlt只能在 Windows NT 4.0 或更高版本中使用,但不能运行在Windows 95/98 应用程序中。CImage::AlphaBlend和CImage::TransparentBlt也只能在 Windows 2000/98或其更高版本中使用。即使在Windows 2000运行程序还必须将stdafx.h文件中的WINVER和_WIN32_WINNT的预定义修改成0x0500才能正常使用。
(1):MFC中显示图像的类CImage:
我使用的函数:
void CAviTestDlg::showCimage(CImage &image) { //CImage image; //创建图片类 //image.Load(rphoto); //根据图片路径加载图片 CRect rect;//定义矩形类 int cx = image.GetWidth();//获取图片宽度 int cy = image.GetHeight();//获取图片高度 GetDlgItem(IDC_SHOWPIC)->GetWindowRect(&rect);//将窗口矩形选中到picture控件上 ScreenToClient(&rect);//将客户区选中到Picture控件表示的矩形区域内 GetDlgItem(IDC_SHOWPIC)->MoveWindow(rect.left, rect.top, cx, cy, TRUE);//将窗口移动到Picture控 CWnd *pWnd=GetDlgItem(IDC_SHOWPIC);//获得pictrue控件窗口的句柄 pWnd->GetClientRect(&rect);//获得pictrue控件所在的矩形区域 CDC *pDC=pWnd->GetDC();//获得pictrue控件的DC image.Draw(pDC->m_hDC, rect); //将图片画到Picture控件表示的矩形区域 ReleaseDC(pDC);//释放picture控件的DC }
(2):CImage(MFC) 加载剪贴板图像数据
CView *cv=this; CImage* m_image; OpenClipboard(NULL); HANDLE h=::GetClipboardData(CF_BITMAP); if(h==0) { CloseClipboard(); return; } BITMAP bm; GetObject(h,sizeof(bm),&bm); if(m_image!=NULL) { delete m_image; m_image=NULL; } m_image=new CImage(); m_image->Create(bm.bmWidth,bm.bmHeight,32,0); HDC hdc=m_image->GetDC(); CDC imgDC; imgDC.Attach(hdc); CBitmap *pBmp=new CBitmap; pBmp->Attach(h); CClientDC dc(cv); CDC memDC; memDC.CreateCompatibleDC(&dc); CBitmap *pOldBitmap=memDC.SelectObject(pBmp); imgDC.BitBlt(0,0,bm.bmWidth,bm.bmHeight,&memDC,0,0,SRCCOPY); memDC.SelectObject(pOldBitmap); pBmp->Detach(); delete pBmp; imgDC.Detach(); m_image->ReleaseDC();
(3):微软官方说明:http://technet.microsoft.com/zh-cn/magazine/k826sz5e(en-us,VS.80).aspx
类的使用:http://msdn.microsoft.com/zh-cn/library/bwea7by5(v=vs.80)
Creates a CImage bitmap and attach it to the previously constructed CImage object.
BOOL Create( int nWidth, int nHeight, int nBPP, DWORD dwFlags = 0 ) throw( );
Parameters
- nWidth
-
The width of the CImage bitmap, in pixels.
- nHeight
-
The height of the CImage bitmap, in pixels. If nHeight is positive, the bitmap is a bottom-up DIB and its origin is the lower left corner. If nHeight is negative, the bitmap is a top-down DIB and its origin is the upper left corner.
- nBPP
-
The numbers of bits per pixel in the bitmap. Usually 4, 8, 16, 24, or 32. Can be 1 for monochrome bitmaps or masks.
- dwFlags
-
Specifies if the bitmap object has an alpha channel. Can be a combination of zero or more of the following values:
-
createAlphaChannel Can only be used if nBPP is 32, and eCompression is BI_RGB. If specified, the created image has an alpha (transparency) value for each pixel, stored in the 4th byte of each pixel (unused in a non-alpha 32-bit image). This alpha channel is automatically used when callingCImage::AlphaBlend.
-