GDI实现透明菜单位图

case WM_CONTEXTMENU:
        {
            m_hMenu = CreatePopupMenu();
            g_BitMap = (HBITMAP)LoadImage(NULL, L"1.bmp", IMAGE_BITMAP, 16, 16, LR_LOADFROMFILE | LR_CREATEDIBSECTION);
            InsertMenu(m_hMenu, 1, MF_BYPOSITION | MF_POPUP, NULL, L"Windows");
            MENUITEMINFO mii = { sizeof(MENUITEMINFO) };
            mii.fMask = MIIM_BITMAP;
            mii.hbmpItem = g_BitMap;
            SetMenuItemInfo(m_hMenu, 0, true, &mii);
            TrackPopupMenu(m_hMenu, TPM_TOPALIGN | TPM_LEFTALIGN | TPM_HORPOSANIMATION, GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam), 0, hWnd, NULL);

        }
        break;

注意在LoadImage中添加 LR_CREATEDIBSECTION ，这是实现背景透明的关键