如何保留更改？

Question

I have MainScreen.cpp

void MainScreen::Show(D2DResources* pD2DResources)
{
    HRESULT hr = S_OK;

    ID2D1Bitmap* pBitmap=pD2DResources->GetpCurrentScreen();

    hr = pD2DResources->LoadBitmapFromFile(
        pD2DResources->GetpRT(),
        pD2DResources->GetpIWICIF(),
        L".\\Images\\MainScreen.jpg",
        0,
        0,
        &pBitmap
        );

    if(SUCCEEDED(hr))pD2DResources->DrawScreen();
}

and at some point the MainScreen::Show() function is called like this

MainScreen->Show(&d2DResources);

However, it seems that as pD2DResources calls DrawScreen() in the MainScreen::Show() function, whatever was stored into &pBitmap didn't save. Actually, I get an unhandled exception and as it happens, pCurrentScreen, which should have received pBitmap's value, is 0x00000000.

What should I do?

Answer 1

As you know, LoadBitmapFromFile function failed
So you should check LoadBitmapFromFile function's arguments

However why did you assign pD2DResources->GetpCurrentScreen() to pBitmap??
Next line, pBitmap will be assigned with LoadBitmapFromFile function again.

Additionally, If MainScreen's Show function called every frames, that is not efficient.
Because you don't have to load bitmap every frames.
And d2d bitmap should be released.