本文使用QT+opencv来实现对指定窗体画面录制，并保存为avi文件。
（1）获取窗体界面QScreen类有一个grabWindow函数，可以用来获取窗体的画面，这个函数使用很简单，就是传入窗体句柄和要截取的坐标。但是这个函数有一个缺陷，它是通过截取桌面画面的方式，而不是通过
窗体获取界面，所以当你的窗体被其他窗体遮挡时，就无法截取完整的窗体界面，如果你是要录制整个桌面画面，那用这个函数就可以了，下面的方法调用GDI函数来实现，即使窗体被遮挡时仍然能够获取到完整界面，但是窗体最小化时也一样无法获取。
/*
* 函数功能：获取窗体指定窗体图像
* 参 数：hd:窗体句柄
* pm:保存获取到的图片
* x:截取的起始x坐标，
* y:截取的起始y坐标，
* w:截取的宽度
* h:截取的高度
*/
bool GetGDIBitmap(HWND hd,QPixmap &pm, int x, int y, int w, int h)
{
if(hd==NULL)
return false;
HDC hDC;
hDC=GetDCEx(hd,NULL,DCX_PARENTCLIP );
HDC hMemDC; //内存缓冲设备环境
HBITMAP hbmMem,hbmOld; //内存缓冲设备环境中的位图
RECT rc;
rc.left=x;
rc.top=y;
rc.right=x+w;
rc.bottom=y+h;
//判断边境值
RECT clientrc;
::GetClientRect(hd,&clientrc);
int xc =0;
int cx =0;
int cy =0;
if(rc.bottom>clientrc.bottom || rc.bottom<0)
rc.bottom=clientrc.bottom;
if(rc.right>clientrc.right || rc.right<0)
rc.right=clientrc.right;
// 24位图的BITMAPINFO
BITMAPINFO *pBITMAPINFO = (BITMAPINFO*)malloc(sizeof(BITMAPINFOHEADER));
memset(pBITMAPINFO, 0, sizeof(BITMAPINFOHEADER));
BITMAPINFOHEADER *pInfo_Header = (BITMAPINFOHEADER *)pBITMAPINFO;
pInfo_Header->biSize = sizeof(BITMAPINFOHEADER);
pInfo_Header->biWidth = rc.right - rc.left;
pInfo_Header->biHeight = (rc.bottom - rc.top);
pInfo_Header->biPlanes = 1;
pInfo_Header->biBitCount = 24;
pInfo_Header->biCompression = BI_RGB;
hMemDC=CreateCompatibleDC(hDC); //创建内存兼容设备环境
//创建内存兼容位图
hbmMem=CreateCompatibleBitmap(hDC,pInfo_Header->biWidth,pInfo_Header->biHeight);
hbmOld=(HBITMAP)SelectObject(hMemDC,hbmMem);
//将内存设备环境中的内容绘制到物理设备环境 hDC
BitBlt(hMemDC,0,0,pInfo_Header->biWidth,pInfo_Header->biHeight,hDC,cx+rc.left,xc+cy+rc.top,CAPTUREBLT|SRCCOPY);
HBITMAP hBitmap=(HBITMAP)SelectObject(hMemDC,hbmOld);
// 获得数据buf
DWORD bufSize=(pInfo_Header->biWidth * 3 + 3) / 4 * 4 * pInfo_Header->biHeight;
BYTE * pBuffer = new BYTE[bufSize];
int aHeight=pInfo_Header->biHeight;
if(::GetDIBits(hMemDC, hBitmap, 0, aHeight, pBuffer,pBITMAPINFO, DIB_RGB_COLORS) == 0)
{
return false;
}
bool bret=BitmapToPixmap(hBitmap,pm);
ReleaseDC(hd,hDC);
//释放资源
DeleteObject(hbmMem);
DeleteObject(hbmOld);
DeleteDC(hMemDC);
free(pBITMAPINFO);
::DeleteObject(hBitmap);
delete [] pBuffer;
return bret;
}
/*
* 函数功能：将bitmap转为QPixmap
*/
bool BitmapToPixmap(HBITMAP hBitmap, QPixmap &pm)
{
HDC hDC;
//设备描述表
int iBits;
//当前显示分辨率下每个像素所占字节数
WORD wBitCount;
//位图中每个像素所占字节数
//定义调色板大小， 位图中像素字节大小 ， 位图文件大小 ， 写入文件字节数
DWORD dwPaletteSize=0,dwBmBitsSize,dwDIBSize;
BITMAP Bitmap;
//位图属性结构
BITMAPFILEHEADER bmfHdr;
//位图文件头结构
BITMAPINFOHEADER bi;
//位图信息头结构
LPBITMAPINFOHEADER lpbi;
//指向位图信息头结构
HANDLE hDib, hPal;
HPALETTE hOldPal=NULL;
//定义文件，分配内存句柄，调色板句柄
//计算位图文件每个像素所占字节数
hDC = CreateDC(L"DISPLAY",NULL,NULL,NULL);
iBits = GetDeviceCaps(hDC, BITSPIXEL) * GetDeviceCaps(hDC, PLANES);
DeleteDC(hDC);
if (iBits <= 1)
wBitCount = 1;
else if (iBits <= 4)
wBitCount = 4;
else if (iBits <= 8)
wBitCount = 8;
else if (iBits <= 24)
wBitCount = 24;
else
wBitCount = 24;
//计算调色板大小
if (wBitCount <= 8)
dwPaletteSize=(1<<wBitCount)*sizeof(RGBQUAD);
//设置位图信息头结构
GetObject(hBitmap, sizeof(BITMAP), (LPSTR)&Bitmap);
bi.biSize = sizeof(BITMAPINFOHEADER);
bi.biWidth = Bitmap.bmWidth;
bi.biHeight = Bitmap.bmHeight;
bi.biPlanes = 1;
bi.biBitCount = wBitCount;
bi.biCompression = BI_RGB;
bi.biSizeImage = 0;
bi.biXPelsPerMeter = 0;
bi.biYPelsPerMeter = 0;
bi.biClrUsed = 0;
bi.biClrImportant = 0;
dwBmBitsSize = ((Bitmap.bmWidth*wBitCount+31)/32)*4*Bitmap.bmHeight;
//为位图内容分配内存
hDib = GlobalAlloc(GHND,dwBmBitsSize+dwPaletteSize+sizeof(BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;
// 处理调色板
hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
hDC = ::GetDC(NULL);
hOldPal=SelectPalette(hDC,(HPALETTE)hPal,FALSE);
RealizePalette(hDC);
}
// 获取该调色板下新的像素值
GetDIBits(hDC,hBitmap,0,(UINT)Bitmap.bmHeight,(LPSTR)lpbi+sizeof(BITMAPINFOHEADER)+dwPaletteSize, (BITMAPINFO *)lpbi,DIB_RGB_COLORS);
//恢复调色板
if (hOldPal)
{
SelectPalette(hDC, hOldPal, TRUE);
RealizePalette(hDC);
::ReleaseDC(NULL, hDC);
}
// 设置位图文件头
bmfHdr.bfType = 0x4D42; // "BM"
dwDIBSize=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+dwPaletteSize+dwBmBitsSize;
bmfHdr.bfSize = dwDIBSize;
bmfHdr.bfReserved1 = 0;
bmfHdr.bfReserved2 = 0;
bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER)+(DWORD)sizeof(BITMAPINFOHEADER)+dwPaletteSize;
std::vector<uchar>buffer;
uchar *p=(uchar*)&bmfHdr;
// 写入位图文件头
buffer.insert(buffer.end(),p,p+sizeof(BITMAPFILEHEADER));
// 写入位图文件其余内容
p=(uchar*)lpbi;
buffer.insert(buffer.end(),p,p+sizeof(BITMAPINFOHEADER)+dwPaletteSize+dwBmBitsSize);
//清除
GlobalUnlock(hDib);
GlobalFree(hDib);
pm=QPixmap::fromImage(QImage::fromData(buffer.data(),buffer.size()));
return true;
}
（2）录制画面
bool g_needstop =false;void Record()
{
RECT rect;
//获取窗体位置大小
GetWindowRect(hd,&rect);
cv::Size frameSize;
frameSize.width=rect.right-rect.left;
frameSize.height=rect.bottom-rect.top;
cv::VideoWriter VideoWriter;
if(!VideoWriter.open("d:\\1.avi",CV_FOURCC('M', 'J', 'P', 'G'),40,frameSize))
return;
while(!g_needstop)
{
QPixmap pm;
GetGDIBitmap(hd,pm,0,0,frameSize.width,frameSize.height);
VideoWriter.write(ImageToMat(pm.toImage()));
} VideoWriter.release();
}
Mat ImageToMat(QImage img,QString imgFormat)
{
if(img.isNull())
return Mat();
QByteArray ba;
QBuffer buffer(&ba);
buffer.open(QIODevice::WriteOnly);
img.save(&buffer,imgFormat.toLatin1().data());
_InputArray arrSrc(ba.data(), ba.size());
Mat mat = cv::imdecode(arrSrc, CV_LOAD_IMAGE_COLOR);
return mat;
}
(3) 播放视频
void Play()
{
cv::VideoCapture Capture;
if(!Capture.open("d:\\1.avi"))
return;
Mat frame;
//逐帧读取画面
while(Capture.read(frame))
{
//转成QImage格式用于显示
QImage img = MatToImage(frame);
emit Frame(img);
QThread::msleep(40);
}
Capture.release();
emit PlayFinsh();
}
QImage MatToImage(Mat mat)
{
if(mat.type() == CV_8UC1)
{
QImage image(mat.cols, mat.rows, QImage::Format_Indexed8);
// Set the color table (used to translate colour indexes to qRgb values)
image.setColorCount(256);
for(int i = 0; i < 256; i++)
{
image.setColor(i, qRgb(i, i, i));
}
// Copy input Mat
uchar *pSrc = mat.data;
for(int row = 0; row < mat.rows; row ++)
{
uchar *pDest = image.scanLine(row);
memcpy(pDest, pSrc, mat.cols);
pSrc += mat.step;
}
return image;
}
// 8-bits unsigned, NO. OF CHANNELS = 3
else if(mat.type() == CV_8UC3)
{
// Copy input Mat
const uchar *pSrc = (const uchar*)mat.data;
// Create QImage with same dimensions as input Mat
QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_RGB888);
return image.rgbSwapped();
}
else if(mat.type() == CV_8UC4)
{
qDebug() << "CV_8UC4";
// Copy input Mat
const uchar *pSrc = (const uchar*)mat.data;
// Create QImage with same dimensions as input Mat
QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);
return image.copy();
}
else
{
qDebug() << "ERROR: Mat could not be converted to QImage.";
return QImage();
}
}
