MSPaint 未接收通过 PostCommand 发送的命令答案

【问题标题】：MSPaint not receiving commands sent through PostCommandMSPaint 未接收通过 PostCommand 发送的命令
【发布时间】：2014-11-20 05:05:18
【问题描述】：

我正在尝试通过我的程序调用 Paint 并想要绘制一些东西

我所做的是 - 1.首先获取绘制窗口的句柄（我只产生了该进程），然后尝试将光标设置为中心并尝试获取该特定窗口的句柄，没有错误或警告，我已经检查了返回值和所有内容，但不知何故，事情没有被绘制出来。请参考代码

HWND    hWndPaint = NULL;
HWND    hTempWindow = NULL;


BOOL CALLBACK EnumWindowsProc(HWND hWnd, LPARAM lParam)
{
    int     textLen = 0;
    PWSTR   pszMem;

    if (!hWnd)
        return TRUE;
    if (!::IsWindowVisible(hWnd))
        return TRUE;

    textLen = GetWindowTextLength(hWnd);
    pszMem = (PWSTR)VirtualAlloc(NULL, textLen + 1, MEM_COMMIT, PAGE_READWRITE);
    GetClassName(hWnd, pszMem, textLen + 1);
    if ((_wcsicmp(pszMem, L"MSPaintApp")) == 0)
    {
        hWndPaint = hWnd;
        return TRUE;
    }
    return TRUE;
}


HWND SpawnPaintAndGetDrawHandle()
{
    int width = 0, height = 0;

    ShellExecute(0, L"open", L"C:\\Windows\\System32\\mspaint.exe", NULL, NULL, SW_SHOWNORMAL);

    Sleep(1000);
    EnumWindows(EnumWindowsProc, NULL);
    if (hWndPaint)
        BOOL res = PostMessage(hWndPaint, WM_SYSCOMMAND, SC_MAXIMIZE, 0);

    RECT rect;
    if (GetWindowRect(hWndPaint, &rect))
    {
        width = rect.right - rect.left;
        height = rect.bottom - rect.top;

        SetCursorPos(width / 2, height / 2);
    }
    POINT   currentCusrsorPoint;
    currentCusrsorPoint.x = width / 2;
    currentCusrsorPoint.y = height / 2;
    return (ChildWindowFromPoint(hWndPaint, currentCusrsorPoint));

}

DWORD MakePosition(WORD x, WORD y)
{
    return ((DWORD)y << 16 | (DWORD)x);
}

int main()
{
    HWND hDrawArea = NULL;
    hDrawArea = SpawnPaintAndGetDrawHandle();

    if (hDrawArea == NULL)
    {
        std::cout << "Could not find the draw area.. something went wrong.";
        return 0;
    }

    // draw something on DarwArea
    int         pX = 0, pY = 0;
    BOOLEAN     bFirstPoint = true;

    for (double i = 0; i < 1; i += 0.1)
    {
        double radius = 10 * 2 * 3.14 * i;
        double x = cos(radius) * 100 * i;
        double y = sin(radius) * 100 * i;

        pX = (int)x + 300;
        pY = (int)y + 300;

        if (bFirstPoint)
        {
            bool res = PostMessage(hDrawArea, WM_LBUTTONDOWN, MK_LBUTTON, MakePosition(pX, pY));
            bFirstPoint = false;
        }
        PostMessage(hDrawArea, WM_MOUSEMOVE, MK_LBUTTON, MakePosition(pX, pY));
        PostMessage(hDrawArea, WM_MOUSEMOVE, MK_LBUTTON, MakePosition(pX, pY));
        Sleep(100);
    }

    PostMessage(hDrawArea, WM_LBUTTONUP, MK_LBUTTON, MakePosition(pX, pY));


    return 0;
}

【问题讨论】：

标签： c++ winapi window postmessage

【解决方案1】：

问题在于return (ChildWindowFromPoint(hWndPaint, currentCusrsorPoint));

这个函数不能递归地工作，我认为它可以。这个函数返回的句柄不是我们实际绘制东西时应该接收点击的窗口。它是这个孩子的孩子，所以我需要自己递归，直到我没有更多的孩子窗口，并将句柄返回给那个孩子

    do
    {
        curParent = ctrlParent;
        ctrlParent = ChildWindowFromPoint(curParent, currentCusrsorPoint);
    }while(ctrlParent != curParent);

这会给我一个作用于点击消息并能够生成“绘制”结果的窗口。

【讨论】：