怎么了?它与指针有关吗?

时间:2013-03-15 21:20:51

标签: c++ windows winapi pointers

我的WinMain就是这样开始的:

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR lpCmdLine, int nShowCmd)
{
    if(SUCCEEDED(CoInitialize(NULL)))
    {
        {
            HRESULT hr = S_OK;

            Game game;

            D2DResources d2DResources;

            game.SetPointer(d2DResources);
            hr = d2DResources.Initialize(hInst);

我的编译器将在打破未发送的异常之前执行上面显示的行。我知道它不会更进一步,因为我在hr = d2DResources.Initialize(hInst)之前添加了一个MessageBox命令,之后又添加了另一个,只有第一个出现。

所以,D2DResources :: Initialisize(HINSTANCE)看起来像这样:

HRESULT D2DResources::Initialize(HINSTANCE hInst)
{
    HRESULT hr;

    // Create factory
    hr = D2D1CreateFactory(D2D1_FACTORY_TYPE_SINGLE_THREADED, &pD2DFactory);

    // Create WIC factory
    if(SUCCEEDED(hr))
    {
        hr = CoCreateInstance(
            CLSID_WICImagingFactory,
            NULL,
            CLSCTX_INPROC_SERVER,
            IID_PPV_ARGS(&pIWICIF)
            );
    }

    // Create a window class
    WNDCLASSEX wClass;
    ZeroMemory(&wClass,sizeof(WNDCLASSEX));
    wClass.cbClsExtra=NULL;
    wClass.cbSize=sizeof(WNDCLASSEX);
    wClass.cbWndExtra=NULL;
    wClass.hbrBackground=(HBRUSH)COLOR_WINDOW;
    wClass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wClass.hIcon=NULL;
    wClass.hIconSm=NULL;
    wClass.hInstance=hInst;
    wClass.lpfnWndProc=WinProc;
    wClass.lpszClassName="Window Class";
    wClass.lpszMenuName=NULL;
    wClass.style=CS_HREDRAW|CS_VREDRAW;

    if(!RegisterClassEx(&wClass))
    {
        int nResult=GetLastError();

        MessageBox(NULL,"Failed to register window class","Window Class Failed",MB_ICONERROR);
    }

    m_hWnd=CreateWindowEx(NULL,
            "Window Class",
            "Game", // Replace with gameName
            WS_OVERLAPPEDWINDOW|WS_MAXIMIZE,
            CW_USEDEFAULT,
            CW_USEDEFAULT,
            CW_USEDEFAULT,
            CW_USEDEFAULT,
            NULL,
            NULL,
            hInst,
            this);

    if(!m_hWnd)
    {
        int nResult=GetLastError();

        MessageBox(NULL,"Window class creation failed","Window Class Failed",MB_ICONERROR);
    }

    RECT rc;
    GetClientRect(m_hWnd,&rc);

    // Creates render target
    if(SUCCEEDED(hr))
    {
        pD2DFactory->CreateHwndRenderTarget(
            D2D1::RenderTargetProperties(),
            D2D1::HwndRenderTargetProperties(
                m_hWnd,
                D2D1::SizeU(
                    rc.right - rc.left,
                    rc.bottom - rc.top)),
                &pRT);
    }

    D2D1_SIZE_F pRTSize = pRT->GetSize();
    RECT rect = {50, (long)pRTSize.height-(LogLineSize*5), (long)pRTSize.width, (long)pRTSize.height};
    logArea = rect;

    if(SUCCEEDED(hr))
    {
        pRT->CreateSolidColorBrush(
            D2D1::ColorF(D2D1::ColorF::White),
            &pWhiteBrush
            );
    }

    if(SUCCEEDED(hr))
    {
        hr = DWriteCreateFactory(
            DWRITE_FACTORY_TYPE_SHARED,
            __uuidof(pWF),
            reinterpret_cast<IUnknown**>(&pWF)
            );
    }

    if(SUCCEEDED(hr))
    {
        hr = pWF->CreateTextFormat(
            L"Verdana",
            NULL,
            DWRITE_FONT_WEIGHT_NORMAL,
            DWRITE_FONT_STYLE_NORMAL,
            DWRITE_FONT_STRETCH_NORMAL,
            14.0f,
            L"",
            &pTextFormat
            );
    }

    return hr;
}

重载的Game :: SetPointer在使用D2DResources对象调用时看起来像这样:

void Game::SetPointer(D2DResources& p)
{
    pD2DResources=&p;
}

pD2DResources是D2DResources *。

当WM_SIZE消息发送到我的WinProc时,问题发生在D2DResources :: Initialization(HINSTANCE)期间。所以,有一些我的WinProc:

LRESULT CALLBACK WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    if(msg==WM_CREATE)
    {
        LPCREATESTRUCT pcs = (LPCREATESTRUCT)lParam;
            Game* pGame = (Game*)pcs->lpCreateParams;

            ::SetWindowLongPtrW(
                hWnd,
                GWLP_USERDATA,
                PtrToUlong(pGame)
                );
    }
    else
    {
        Game* pGame = reinterpret_cast<Game*>(static_cast<LONG_PTR>(
            ::GetWindowLongPtrW(
                hWnd,
                GWLP_USERDATA
                )));

        switch(msg)
        {

        case WM_SIZE:
            {
                UINT width = LOWORD(lParam);
                UINT height = HIWORD(lParam);
                pGame->pD2DResources->OnResize(width, height);
            }
            break;

调用OnResize时,会出现问题。

void D2DResources::OnResize(UINT width, UINT height)
{
    if(pRT)
    {
        HRESULT hr = pRT->Resize(D2D1::SizeU(width, height));
        if(hr!=0) MessageBox(NULL,"Render target could not be resized","ID2D1HwndRenterTarget Error",MB_ICONERROR);
    }
}

编译器中断并且有一个黄色箭头指向if(pRT)(pRT是指向渲染目标的指针)行。

有趣的是,在调试过程中查看autos会显示出来。

  • 这个0x00000000 {log = 0x00000000 nLogLines = ??? logArea = {...} ...} D2DResources * const
  • log 0x00000000 wchar_t [511]     nLogLines CXX0030:错误:无法计算表达式
  • logArea {top = ???底= ???左= ??? right = ???} tagRECT     m_hWnd CXX0017:错误:找不到符号“”     pD2DFactory CXX0017:错误:未找到符号“”     pIWICIF CXX0017:错误:找不到符号“”     pWF CXX0017:错误:找不到符号“”     pRT CXX0030:错误:表达式无法评估
        pCurrentScreen CXX0017:错误:找不到符号“”     pWhiteBrush CXX0017:错误:找不到符号“”     pTextFormat CXX0017:错误:符号“”未找到

那么,问题是什么,解决方案是什么?

2 个答案:

答案 0 :(得分:3)

当调用WinProc时,您在WinMain中声明的D2DResources对象已超出范围,但您仍然持有指向它的指针。当您通过指针调用方法时,它正在针对堆栈中不再指向D2DResources对象的位置执行(注意 - 您的MessageBox会误导您 - 它实际上超出了范围。)

解决此问题的最简单方法是更改​​

D2DResources d2DResources;

在WinMain中

D2DResources& d2DResources = *(new D2DResources());

将把相同的对象放在堆上。

虽然我不会发誓这是你代码的唯一问题......

答案 1 :(得分:2)

您将错误的指针传递给您的窗口。您正在D2DResources::Initialize创建窗口并将this作为lpParam传递,但在窗口过程中,您将其转换为Game*