#程序员摸鱼速来 #C++ 窗口背景：不同格式图片转化为BMP格式

#C++ Visual Studio 各位程序员上班摸鱼时速来打小菜
C++初学升进步者，可能很多细节内容没处理到位。
一个打印窗口背景的程序，求解！

第五行将不同格式图片转为BMP格式有问题，报错：
“ATL::Clmage::Load”：2个重载中没有一个可以转换所有参数类型

代码如下：

#include 
#include <Windows.h>
#include 

//将不同格式图片转为BMP
bool convert2bmp(HBITMAP& bitmap, const std::string& url)
{
    CImage img;
    HRESULT ret = img.Load(url.c_str());
    bitmap = img.Detach();
    return true;
}

// 消息处理函数的实现  
LRESULT CALLBACK PlayerWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = ::BeginPaint(hwnd, &ps);
        HDC s_hdcMem = CreateCompatibleDC(hdc);

        HBITMAP hBitmap;
        BITMAP s_bm;
        convert2bmp(hBitmap, "./background/bg.png");//png,jpg,bmp均可            
        SelectObject(s_hdcMem, hBitmap);
        GetObject(hBitmap, sizeof(s_bm), &s_bm);// 得到位图信息

        RECT       rect;
        GetClientRect(hwnd, &rect);

        //通过SetStretchBltMode的设置能使StretchBlt在缩放图像更加清晰
        SetStretchBltMode(hdc, COLORONCOLOR);//STRETCH_HALFTONE
        StretchBlt(hdc, 0, 0, rect.right, rect.bottom, s_hdcMem, 0, 0, s_bm.bmWidth, s_bm.bmHeight, SRCCOPY);

        ::EndPaint(hwnd, &ps);
        return 0;
    }

    case WM_NCHITTEST: //实现窗口移动，与WM_LBUTTONDBLCLK冲突
    {
        UINT nHitTest;
        nHitTest = ::DefWindowProc(hwnd, uMsg, wParam, lParam);

        if (nHitTest == HTCLIENT && ::GetAsyncKeyState(MK_LBUTTON) < 0)
        {
            nHitTest = HTCAPTION;
        }

        return nHitTest;
    }

    case WM_DESTROY:
    {
        PostQuitMessage(0);
        return 0;
    }

    case WM_KEYDOWN:
        if (wParam == VK_ESCAPE)//"ECS键"退出
        {
            PostMessage(hwnd, WM_DESTROY, 0, 0);
            return 0;
        }
        break;
    }
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

//创建窗口
HWND CreateWin(double pos_x, double pos_y, double width, double height, HWND hwd, DWORD style)
{
    HINSTANCE hinstance = (HINSTANCE)GetModuleHandle(NULL);    // 得到进程实例句柄.

    WNDCLASSEXA wcex;

    wcex.cbSize = sizeof(WNDCLASSEXA);
    wcex.style = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS;
    wcex.lpfnWndProc = PlayerWndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hinstance;
    wcex.hIcon = LoadIcon(hinstance, MAKEINTRESOURCE(IDC_ICON));
    wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground = CreateSolidBrush(RGB(0, 0, 0));
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = "player";
    wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDC_ICON));

    RegisterClassExA(&wcex);

    // 创建窗口.
    HWND hwnd = CreateWindowExA(0, "player", "", style, pos_x, pos_y, width, height, hwd, NULL, hinstance, NULL);

    ShowWindow(hwnd, SW_SHOW);

    return hwnd;
}


int main(int argc, char* argv[])
{
    HWND hwnd = CreateWin(0, 0, 720, 576, NULL, WS_POPUP);

    MSG msg;
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

附带错误列表

自己也不知道怎么试，求程序员解答

想要达到的结果：程序能够正常运行

CImage 类
https://docs.microsoft.com/zh-cn/cpp/atl-mfc-shared/reference/cimage-class?view=msvc-170
声明：Load的参数类型为：LPCTSTR

// bool convert2bmp(HBITMAP &bitmap, const std::string &url)
bool convert2bmp(HBITMAP &bitmap, LPCTSTR url)
{
    CImage img;
    HRESULT ret = img.Load(url);
    bitmap = img.Detach();
    return true;
}

调用
convert2bmp(hBitmap, _T("./background/bg.png")); 


PS：
include之后加一句
#pragma comment(linker, "/subsystem:windows /entry:mainCRTStartup")
取消命令行窗口的显示

你从MSDN上找一下CImage::Load的说明

就是给的变量类型不符合Load函数要求的参数类型呗