Direct2D:WM_RESIZE开关案例中的未处理异常 [英] Direct2D : Unhandled Exception In WM_RESIZE switch case

问题描述

我正在创建.

I am creating a Simple Direct2D Application. Unfortunately it is giving an unhandled exception. The function where it is taking place:

    void DemoApp::OnResize(UINT width, UINT height)
{
    if (m_pRenderTarget) <----|****The exception occurs here.....****
    {
        // Note: This method can fail, but it's okay to ignore the
        // error here, because the error will be returned again
        // the next time EndDraw is called.
        m_pRenderTarget->Resize(D2D1::SizeU(width, height));
    }
}

And the code snippet calling OnResize() is:

DemoApp *pDemoApp = reinterpret_cast<DemoApp *>(static_cast<LONG_PTR>(
            ::GetWindowLongPtrW(
                hwnd,
                GWLP_USERDATA
            )));

        bool wasHandled = false;

        if (pDemoApp)
        {
            switch (message)
            {
            case WM_SIZE:
            {
                UINT width = LOWORD(lParam);
                UINT height = HIWORD(lParam);
                pDemoApp->OnResize(width, height);
            }
            result = 0;
            wasHandled = true;
            break;
/*rest of switch case*/
       }

The exception says: Unhandled exception at 0x00007FF6BE402CCA in Simple Direct2D application.exe: 0xC000041D: An unhandled exception was encountered during a user callback. occurred

Exception screenshot:

As soon as I start to debug, the program, it gives the exception.I even copied the program word by word from the site.As I am new to the world of DirectX, I am clueless about the exception. What should I do?

解决方案

I've compiled that sample. It works in 32-bit builds, crashes in 64-bit builds.

The error is in Microsoft's sample code and is unrelated to Direct2D.

They pass this into SetWindowLongPtr, in combination with PtrToUlong macro for type conversion. In 64-bit builds, this is 8-bytes long, SetWindowLongPtr also accepts 8 bytes, however PtrToUlong macro converts to unsigned long which is only 4 bytes. So PtrToUlong macro drops higher 4 bytes from this pointer, and the app fails spectacularly.

You can fix by replacing PtrToUlong( pDemoApp ) with (LONG_PTR)pDemoApp

P.S. I think the root cause is, MS pretends very hard Win32 platform is obsolete, pushes developers to UWP instead. That’s why in their DirectX and Direct2D samples, they don’t use their own ATL, because it’s desktop-only library. Using ATL would dramatically simplify these samples: CComPtr for interface pointers, CWindowImpl for windows creation and message handling, and lots more.

Update: here's a better sample.

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