c++ - 将调整大小的位图文件设置为 MFC 优化校准

Question

有没有比这更简单的方法，如果这是唯一的方法，这里是否有任何潜在的内存泄漏？

    CImage img1;
            int dimx = 100, dimy = 100;
    img1.Load(filename);
    //filename = path on local system to the bitmap

    CDC *screenDC = GetDC();
    CDC *pMDC = new CDC;
    pMDC->CreateCompatibleDC(screenDC);

    CBitmap *pb = new CBitmap;
    pb->CreateCompatibleBitmap(screenDC, dimx, dimy);

    CBitmap *pob = pMDC->SelectObject(pb);
    pMDC->SetStretchBltMode(HALFTONE);
    img1.StretchBlt(pMDC->m_hDC,0, 0, dimx, dimy, 0, 0, img1.GetWidth(), img1.GetHeight(), SRCCOPY);
    pMDC->SelectObject(pob);

    CImage new_image;
    new_image.Attach((HBITMAP)(*pb));
    //
    m_pictureCtrl.SetBitmap(new_image.Detach());
    ReleaseDC(screenDC);

Answer 1

我认为不需要 CImage new_image(因为 SetBitmap 需要一个你已经通过 pb 拥有的 HBITMAP)并且必须删除 pb 和 pMDC(在分离 HBITMAP 之后)，但其余部分似乎是正确的。

CImage img1;
int dimx = 100, dimy = 100;
img1.Load(filename);
//filename = path on local system to the bitmap

CDC *screenDC = GetDC();
CDC mDC;
mDC.CreateCompatibleDC(screenDC);
CBitmap b;
b.CreateCompatibleBitmap(screenDC, dimx, dimy);

CBitmap *pob = mDC.SelectObject(&b);
mDC.SetStretchBltMode(HALFTONE);
img1.StretchBlt(mDC.m_hDC, 0, 0, dimx, dimy, 0, 0, img1.GetWidth(), img1.GetHeight(), SRCCOPY);
mDC.SelectObject(pob);

m_pictureCtrl.SetBitmap((HBITMAP)b.Detach());
ReleaseDC(screenDC);

当然，我会将 CImage/CBitmap 的缩放放到一个单独的函数中(使其可重用)。