win32api SendMessage 无法在 WM_CREATE 之外工作

Question

所以，我正在做一个 "larger" 项目，突然遇到了一个简单的 sendmessage 命令的奇怪问题。所以我创建了一个新项目，它只创建了一个编辑控件和一个计时器。每次计时器滴答作响时，它都应该将 "test" 输出到编辑控件。但它永远不会发生..

我试过带有消息框的定时器，它工作正常。如果我把它放在 WM_CREATE 中，sendmessage 也可以工作。这是为什么？

// 785tyughj.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "785tyughj.h"

#define MAX_LOADSTRING 100
#define ID_FLSPEED 1
#define ID_TIMER 2




// Global Variables:
HINSTANCE hInst;        // current instance
TCHAR szTitle[MAX_LOADSTRING];     // The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];   // the main window class name
HWND FLSPEED;
// Forward declarations of functions included in this code module:
ATOM    MyRegisterClass(HINSTANCE hInstance);
BOOL    InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);








int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
 UNREFERENCED_PARAMETER(hPrevInstance);
 UNREFERENCED_PARAMETER(lpCmdLine);

  // TODO: Place code here.
 MSG msg;
 HACCEL hAccelTable;
 

 // Initialize global strings
 LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
 LoadString(hInstance, IDC_MY785TYUGHJ, szWindowClass, MAX_LOADSTRING);
 MyRegisterClass(hInstance);

 // Perform application initialization:
 if (!InitInstance (hInstance, nCmdShow))
 {
  return FALSE;
 }

 hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_MY785TYUGHJ));

 // Main message loop:
 while (GetMessage(&msg, NULL, 0, 0))
 {
  if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
  {
   TranslateMessage(&msg);
   DispatchMessage(&msg);
  }
 }

 return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage are only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
 WNDCLASSEX wcex;

 wcex.cbSize = sizeof(WNDCLASSEX);

 wcex.style   = CS_HREDRAW | CS_VREDRAW;
 wcex.lpfnWndProc = WndProc;
 wcex.cbClsExtra  = 0;
 wcex.cbWndExtra  = 0;
 wcex.hInstance  = hInstance;
 wcex.hIcon   = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MY785TYUGHJ));
 wcex.hCursor  = LoadCursor(NULL, IDC_ARROW);
 wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
 wcex.lpszMenuName = MAKEINTRESOURCE(IDC_MY785TYUGHJ);
 wcex.lpszClassName = szWindowClass;
 wcex.hIconSm  = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

 return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}






//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND - process the application menu
//  WM_PAINT - Paint the main window
//  WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
 int wmId, wmEvent;
 PAINTSTRUCT ps;
 HDC hdc;
 

 switch (message)
 {
 case WM_CREATE:
  
  {
  HWND FLSPEED=CreateWindowEx(WS_EX_CLIENTEDGE,
  L"EDIT",
  L"speed",
  WS_CHILD|WS_VISIBLE|ES_MULTILINE|ES_AUTOVSCROLL|ES_AUTOHSCROLL,
  50,
  50,
  125,
  25,
  hWnd,
  (HMENU)ID_FLSPEED,
  GetModuleHandle(NULL),
  NULL);
  

  SetTimer (hWnd,ID_TIMER,1000,NULL);

  
  }

  

 case WM_TIMER:
  
  {
  SendMessageA(FLSPEED,WM_SETTEXT,NULL,(LPARAM)"test");
  


  break;
  }


 case WM_COMMAND:
  wmId    = LOWORD(wParam);
  wmEvent = HIWORD(wParam);
  // Parse the menu selections:
  switch (wmId)
  {
  case IDM_ABOUT:
   DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
   break;
  case IDM_EXIT:
   DestroyWindow(hWnd);
   break;
  default:
   return DefWindowProc(hWnd, message, wParam, lParam);
  }
  break;
 case WM_PAINT:
  hdc = BeginPaint(hWnd, &ps);
  // TODO: Add any drawing code here...
  EndPaint(hWnd, &ps);
  break;
 case WM_DESTROY:
  PostQuitMessage(0);
  break;


 

  
  


 default:
  
  return DefWindowProc(hWnd, message, wParam, lParam);
 }
 return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
 UNREFERENCED_PARAMETER(lParam);
 switch (message)
 {
 case WM_INITDIALOG:
  return (INT_PTR)TRUE;

 case WM_COMMAND:
  if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
  {
   EndDialog(hDlg, LOWORD(wParam));
   return (INT_PTR)TRUE;
  }
  break;
 }
 return (INT_PTR)FALSE;
}

Answer 1

下一行是问题所在：

HWND FLSPEED=CreateWindowEx(WS_EX_CLIENTEDGE,
L"EDIT",
L"speed",
WS_CHILD|WS_VISIBLE|ES_MULTILINE|ES_AUTOVSCROLL|ES_AUTOHSCROLL,
50,
50,
125,
25,
hWnd,
(HMENU)ID_FLSPEED,
GetModuleHandle(NULL),
NULL);

在该行中，您将创建一个新的本地 FLSPEED 来屏蔽全局 FLSPEED。要解决这个问题，请删除 HWND，这样您就不会声明新变量，而是实际上更改了全局变量的值。

FLSPEED=CreateWindowEx(WS_EX_CLIENTEDGE,
L"EDIT",
L"speed",
WS_CHILD|WS_VISIBLE|ES_MULTILINE|ES_AUTOVSCROLL|ES_AUTOHSCROLL,
50,
50,
125,
25,
hWnd,
(HMENU)ID_FLSPEED,
GetModuleHandle(NULL),
NULL);

win32api SendMessage 无法在 WM_CREATE 之外工作

win32api SendMessage wont work outside of WM_CREATE

c++

winapi

sendmessage