c++ - 反射(reflect) SendMessage 的 Windows API 编辑框

Question

我正在尝试学习 Windows API。我设法创建了一个带有按钮和编辑框的窗口。我想尝试在单击按钮时更改编辑框中的文本。

这是主循环:

while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

这里是windows回调

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_CREATE:
        {


            HWND hWndEdit   = CreateWindowEx(WS_EX_CLIENTEDGE,
                                    "EDIT","",
                                    WS_CHILD|WS_VISIBLE|ES_MULTILINE|ES_AUTOVSCROLL|ES_AUTOHSCROLL,
                                    50,100,200,100,hwnd,
                                    (HMENU) IDC_EDITBOX,
                                    GetModuleHandle(NULL),
                                    NULL);

            HWND hWndButton = CreateWindowEx(NULL,
                                "BUTTON",
                                "OK",
                                WS_TABSTOP|WS_VISIBLE|WS_CHILD|BS_DEFPUSHBUTTON,
                                50, 220, 100, 24, hwnd,
                                (HMENU)IDC_BUTTON,
                                GetModuleHandle(NULL),
                                NULL);

        }
        break;
    case WM_COMMAND:
        switch(LOWORD(wParam))
        {
        case IDC_BUTTON:
            {
                SendMessage(hWndEdit,WM_SETTEXT,NULL,(LPARAM)"BUTTON");
            }
            break;
        case IDC_EDITBOX:
        {
            MessageBox(NULL,"EDIT","editbox", MB_ICONINFORMATION|MB_OK);

        }
        break;
        default:
            MessageBox(NULL,"default","Command",MB_ICONINFORMATION|MB_OK);
            break;

        }
        break;

    case WM_SETTEXT:
        {
                MessageBox(NULL,"SetTEXT","BOX",MB_ICONINFORMATION|MB_OK);

        }
            break;
    case WM_CLOSE:
            DestroyWindow(hwnd);
            break;
    case WM_DESTROY:
            PostQuitMessage(0);
            break;
    default:

        return DefWindowProc(hwnd,msg,wParam,lParam);
    }
    return 0;
}

当我单击按钮时，我调用了 SendMessage(...)，那么它不应该在我的主循环中被提取并发送到 WndProc() 吗？如果是这样，那为什么我的开关盒没有捕捉到它？如果没有，我该如何为这个编辑框设置回调函数？

编辑:完整代码

#include <windows.h>


#define IDC_BUTTON 101
#define IDC_EDITBOX 102

HWND hWndEdit;

const char g_szClassName[] = "myWindowClass";

//Step 4: the Window Proc
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_CREATE:
        {


            HWND hWndEdit   = CreateWindowEx(WS_EX_CLIENTEDGE,
                                    "EDIT","",
                                    WS_CHILD|WS_VISIBLE|ES_MULTILINE|ES_AUTOVSCROLL|ES_AUTOHSCROLL,
                                    50,100,200,100,hwnd,
                                    (HMENU) IDC_EDITBOX,
                                    GetModuleHandle(NULL),
                                    NULL);

            HWND hWndButton = CreateWindowEx(NULL,
                                "BUTTON",
                                "OK",
                                WS_TABSTOP|WS_VISIBLE|WS_CHILD|BS_DEFPUSHBUTTON,
                                50, 220, 100, 24, hwnd,
                                (HMENU)IDC_BUTTON,
                                GetModuleHandle(NULL),
                                NULL);

        }
        break;
    case WM_COMMAND:
        switch(LOWORD(wParam))
        {
        case IDC_BUTTON:
            {
                //MessageBox(NULL,"EDIT","editbox", MB_ICONINFORMATION|MB_OK);
                SendMessage(hWndEdit,WM_SETTEXT,NULL,(LPARAM)"BUTTON");
            }
            break;
        case IDC_EDITBOX:
        {
            MessageBox(NULL,"EDIT","editbox", MB_ICONINFORMATION|MB_OK);

        }
        break;
        default:
            MessageBox(NULL,"default","Command",MB_ICONINFORMATION|MB_OK);
            break;

        }
        break;

    case WM_SETTEXT:
        {
                MessageBox(NULL,"SetTEXT","BOX",MB_ICONINFORMATION|MB_OK);

        }
            break;
    case WM_CLOSE:
            DestroyWindow(hwnd);
            break;
    case WM_DESTROY:
            PostQuitMessage(0);
            break;
    default:

        return DefWindowProc(hwnd,msg,wParam,lParam);
    }
    return 0;
}


int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, 
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;

    //Registering the Window Class
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = CS_HREDRAW|CS_VREDRAW;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH) (COLOR_WINDOW);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL,IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!", MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    //Creating the Window
    hwnd = CreateWindowEx(
        0,
        //WS_EX_CLIENTEDGE,
        g_szClassName,
        "Inventory",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 400, 300,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    // Step 3: The Message Loop
    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }

    return Msg.wParam;
}

Answer 1

您对 CreateWindowEx() 的调用将返回的 HWND 分配给 局部变量，当 WM_CREATE 已完成处理。您的 WM_COMMAND 处理程序正在使用来自不同范围的 hWndEdit 变量，但该变量从未使用编辑控件的 HWND 进行初始化。这就是为什么您的文字永远不会出现。

关于 WM_SETTEXT，您的主窗口将不会收到该消息。它直接发送到编辑控件，它没有分配给它的自定义 WndProc()，因此发送给它的所有消息都将通过 DefWindowProc()。您可以将 WM_SETTEXT 发送到编辑控件，它将按预期更新(通过 DefWindowProc())，但是您的 MessageBox() 将没出现。编辑控件确实会向其父窗口发送 WM_COMMAND 消息以获取各种 EN_... 通知，例如 EN_CHANGE，因此您的主窗口 WndProc() 将为与 IDC_EDITBOX 相关的 WM_COMMAND 消息调用 MessageBox()。