DirectShow 视频上画线和输出文字

 

为了方便，就直接在视频上显示了，而没有动态的输出文字和用鼠标移动画线，不过是一样的原理，只是动态就要捕获鼠标状态的消息

LONG cx, cy;
	HRESULT hr;
	hr = pWC->GetNativeVideoSize(&cx, &cy, NULL, NULL);
	if (FAILED(hr))
	{
		Msg(TEXT("GetNativeVideoSize FAILED!  hr=0x%x\r\n"), hr);
		return hr;
	}

	HDC hdc = GetDC(hwndApp);
	HDC hdcBmp = CreateCompatibleDC(hdc);
	g_hFont=CreateFont(30, 10,0,0, 10, FALSE,FALSE,FALSE,DEFAULT_CHARSET,OUT_DEFAULT_PRECIS,
		CLIP_DEFAULT_PRECIS,DEFAULT_QUALITY,DEFAULT_PITCH,_T("宋体"));
	HFONT hOldFont = (HFONT) SelectObject(hdcBmp, g_hFont);

	HPEN hPen=CreatePen(PS_SOLID,1,RGB(255,0,0));
	HPEN hOldPen = (HPEN) SelectObject(hdcBmp, hPen);

	int nLength, nTextBmpWidth, nTextBmpHeight;
	SIZE sz={0};
	nLength = (int) _tcslen(szNewText);
	GetTextExtentPoint32(hdcBmp, szNewText, nLength, &sz);
	nTextBmpHeight = sz.cy;
	nTextBmpWidth  = 400/*sz.cx*/;

	HBITMAP hbm = CreateCompatibleBitmap(hdc, nTextBmpWidth, nTextBmpHeight);
	ReleaseDC(hwndApp, hdc);

	BITMAP bm;
	HBITMAP hbmOld;
	GetObject(hbm, sizeof(bm), &bm);
	hbmOld = (HBITMAP)SelectObject(hdcBmp, hbm);

	RECT rcText;
	SetRect(&rcText, 0, 0, nTextBmpWidth, nTextBmpHeight);
	SetBkMode(hdcBmp,TRANSPARENT);            //设置透明背景
	SetTextColor(hdcBmp, g_rgbColors);      // 文字颜色
	HBRUSH hBrush=((HBRUSH)GetStockObject(NULL_BRUSH));
    SelectObject(hdcBmp, hBrush);
	// 在位图上画图
	//输出文字
	//TextOut(hdcBmp, 0, 0, szNewText, nLength);
	DrawText(hdcBmp,szNewText,sizeof(szNewText),&rcText,DT_RIGHT);
	//画线
	MoveToEx(hdcBmp,10,10,NULL);
	LineTo(hdcBmp,200,10);
	//Ellipse(hdcBmp,0,0,100,nTextBmpHeight);

	// Configure the VMR's bitmap structure
	VMRALPHABITMAP bmpInfo;
	ZeroMemory(&bmpInfo, sizeof(bmpInfo) );
	bmpInfo.dwFlags = VMRBITMAP_HDC;
	bmpInfo.hdc = hdcBmp;  
	g_nImageWidth = bm.bmWidth;
	g_fBitmapCompWidth = (float)g_nImageWidth / (float)cx;

	bmpInfo.rDest.left  = 0.0f + X_EDGE_BUFFER;
	bmpInfo.rDest.right = 1.0f - X_EDGE_BUFFER;
	bmpInfo.rDest.top = (float)(cy - bm.bmHeight) / (float)cy - Y_EDGE_BUFFER;
	bmpInfo.rDest.bottom = 1.0f - Y_EDGE_BUFFER;
	bmpInfo.rSrc = rcText;


	bmpInfo.fAlpha = TRANSPARENCY_VALUE;
	SetColorRef(bmpInfo);

	hr = pBMP->SetAlphaBitmap(&bmpInfo);
	if (FAILED(hr))
		Msg(TEXT("SetAlphaBitmap FAILED!  hr=0x%x\r\n\r\n%s\0"), hr,
		STR_VMR_DISPLAY_WARNING);

	// Select the initial objects back into our device context
	DeleteObject(SelectObject(hdcBmp, hbmOld));
	DeleteObject(SelectObject(hdcBmp, hOldPen));
	SelectObject(hdc, hOldFont);
	DeleteObject(hbm);
	DeleteDC(hdcBmp);
	return hr;