如何使用c++获取win32中活动窗口的句柄？

Question

[![enter image description here][1]][1]I am trying to capture the active window in Win32 using C++. With the BitBlt function I am able to capture, but once another window opens, the same window which I have already captured should only be captured. I don't want the other window which I have opened, it should be black. Can someone help with a solution?

https://www.codeproject.com/Articles/20367/Screen-Capture-Simple-Win32-Dialog-Based

void CaptureActiveWindow(void)
{
    RECT ActWndRect;

    WCHAR buf [100],buf1[20];
    int xSrc=0,ySrc=-19;
    int DepcWidth=10, DepcHeight=5;
    OutputDebugString(L"Start capture act window ");     
    HDC ActWndDC = GetDC(hWndActWnd);               //DC for the window you have clicked on 

    MemDC = CreateCompatibleDC(ActWndDC);           //Memory DC Compatible with Above DC

    GetWindowRect(hWndActWnd,&ActWndRect);          //Will Store the Windows Are in Rectangle 

    wsprintf(buf,L"x1 = %d , y1 = %d, x2 = %d y2 =%d",ActWndRect.left,ActWndRect.top,ActWndRect.right,ActWndRect.bottom);
    OutputDebugString(buf); 

    int Width = ActWndRect.right-ActWndRect.left;       //Width of the Window
    int Height =ActWndRect.bottom-ActWndRect.top;       //Hight of the Window

    if(GetWindowText(hWndActWnd,buf1,20) >0)
    {
        OutputDebugString(buf1);
    }
    if(CaptureControl)
    {
        ySrc= DepcWidth = DepcHeight = 0;
    }

    HBITMAP hBitmap = CreateCompatibleBitmap(DlgDC,Width-DepcWidth,Height-DepcHeight);//Will Create Bitmap Comatible With Our Window
    SelectObject(MemDC,hBitmap);


    BitBlt(MemDC,0,0,Width,Height,ActWndDC,xSrc,ySrc,SRCCOPY);//Will Copy the Window into MemDC
    //BitBlt(DeskDC,110,110,Width,Height,MemDC,Begpt.x,Begpt.y,SRCCOPY);


    SaveBitmap(MemDC, hBitmap,"Sample.bmp");    // will Save DC into .bmp File  
    ShowImage();                                //Will Show u the .bmp File in MSPAINT.


}

Answer 1

Hook the mouse event Before sending active message to the window. Use WindowFromPoint to get the specified window(Hwnd). Then use GetWindowRect to get the window rect area. In this area, call WindowFromPoint for all the point in the rect, compare it with Hwnd(if it is a child window or not), and get the overlap RECT. After getting the bitmap of the capture window and then overwrites the black on the covered rect.

PS: I encounter BITMAPINFO error: Run-Time Check Failure #2 - Stack around the variable was corrupted. Here provide a solution.

You can't capture the image of Chrome using BitBlt() , unless disable the Hardware Acceleration option of Chrome. But PrintWindow() works with PW_RENDERFULLCONTENT flag. When use it, the image in center will have a black border. While using PrintWindow (hWndActWnd,ActWndDC,0x00000003) align the image to the left.Then modify cx and cy of CreateCompatibleBitmap() , you can remove the border easily.