I used the MSVC++ wizard to create a win32 application. I added a new menu resource and added the typical 'File'->'Exit' etc.. Then I added it to the main dialog under the properties in msvc++. When I run the form it shows the menu on the form but if I click on File it doesn't even do the hover and it doesn't show the popup of Exit. Its almost like it's disabled. I really didn't think I needed to add any code. Any help is appreciated. Thanks.
#include "stdafx.h"
#define MAX_LOADSTRING 100
struct _globals {
HINSTANCE hInst;
HWND hWnd;
} g;
LRESULT CALLBACK DialogProc(HWND, UINT, WPARAM, LPARAM);
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
InitCommonControls();
g.hInst = hInstance;
g.hWnd = CreateDialog(hInstance, MAKEINTRESOURCE(IDD_MAIN), NULL, (DLGPROC)DialogProc);
if (g.hWnd == NULL) {
GetLastError();
return FALSE;
}
ShowWindow(g.hWnd, nCmdShow);
UpdateWindow(g.hWnd);
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_ACCELLS));
MSG msg;
while (GetMessage(&msg, NULL, 0, 0)) {
if (TranslateAccelerator(g.hWnd, hAccelTable, &msg))
continue;
if (IsDialogMessage(g.hWnd, &msg))
continue;
// process message
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return 0;
}
LRESULT CALLBACK DialogProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_INITDIALOG:
break;
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
switch (wmId)
{
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
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;
}
Your DialogProc function looks more like a window procedure than a dialog procedure. Unlike window procedures, dalog procedures do not return LRESULT values, they return BOOL values, and they do not call DefWindowProc. There are some other differences as well.
Related
Having such supers simple Win app:
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow) {
...
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance(hInstance, nCmdShow)) {
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_GL1WIN));
MSG msg;
// Main message loop:
while (GetMessage(&msg, nullptr, 0, 0)) {
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int)msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
switch (message) {
case WM_COMMAND: {
int wmId = LOWORD(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_CLOSE:
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
When the WM_CLOSE case is disabled (commented out) everything works OK - when i click the X button the window closes but when the WM_CLOSE case is enabled like in the above code the app seems to freeze - doesn't react when clicking the X button and i have to kill it from the task manager.
On WM_CLOSE the window should normally be destroyed with DestroyWindow, like:
case WM_CLOSE:
DestroyWindow(hWnd);
break;
In your case you just return without doing anything with that window, so it simple 'freezes'.
Without WM_CLOSE case, the message is passed to DefWindowProc that reacts to it by destroying the window. With WM_CLOSE case, you handle the message and don't pass it to DefWindowProc - then it's your responsibility to do something in response to that message.
This question already has answers here:
Read access violation using m_pRenderTarget with winapi due to non-NULL pointer
(2 answers)
Closed 2 years ago.
I am trying to learn the win32 api using the Microsoft documentation. I have gotten to chapter 4, and I seem to have run into an issue that I am struggling to debug. The dialogue box triggered by the about button throws an exception:
Exception thrown at 0x773BDCFF (ntdll.dll) in practice.exe: 0xC0000005: Access violation reading location 0x00905A4C.
Here is the declaration of the WndProc and About callbacks:
static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam);
Here is the code for the implementation of the WndProc and About callbacks:
LRESULT CALLBACK App::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
App* pApp;
if (message == WM_CREATE)
{
LPCREATESTRUCT pcs = (LPCREATESTRUCT)lParam;
pApp = (App*)pcs->lpCreateParams;
::SetWindowLongPtrW(hWnd, GWLP_USERDATA, PtrToUlong(pApp));
return TRUE;
}
else
{
pApp = reinterpret_cast<App*>(static_cast<LONG_PTR>(::GetWindowLongPtrW(hWnd, GWLP_USERDATA)));
if (!pApp)
return DefWindowProc(hWnd, message, wParam, lParam);
}
int wmld, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
switch (message)
{
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(pApp->getInstance(), MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code that uses hdc 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 App::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;
I hope the error is within these snippets. If not, I would be happy to provide more code. I have done research, and I truly have very little idea what the problem is. I know that the callback for the about function must be static, which I believe it is. Apart from that, I don't know what would cause it to throw an exception. Thank you for any help you can give me.
Fail to reproduce this issue using your presented code. The following is an example based on your code piece and it works for me. You can refer to.
App.h
class App
{
public:
App(HINSTANCE hInstance, CONST WCHAR* clsName);
private:
static LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
static INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam);
ATOM MyRegisterClass(HINSTANCE hInstance, CONST WCHAR* clsName);
};
App.cpp
#include "App.h"
App::App(HINSTANCE hInstance, CONST WCHAR* clsName)
{
App::MyRegisterClass(hInstance, clsName);
}
ATOM App::MyRegisterClass(HINSTANCE hInstance, CONST WCHAR* clsName)
{
WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = App::WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_DIALOGBOXEXCEPTION));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_DIALOGBOXEXCEPTION);
wcex.lpszClassName = clsName;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
LRESULT CALLBACK App::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
App* pApp;
if (message == WM_CREATE)
{
LPCREATESTRUCT pcs = (LPCREATESTRUCT)lParam;
pApp = (App*)pcs->lpCreateParams;
::SetWindowLongPtrW(hWnd, GWLP_USERDATA, (LONG_PTR)pApp);
return TRUE;
}
else
{
pApp = reinterpret_cast<App*>(static_cast<LONG_PTR>(::GetWindowLongPtrW(hWnd, GWLP_USERDATA)));
if (!pApp)
return DefWindowProc(hWnd, message, wParam, lParam);
}
switch (message)
{
case WM_COMMAND:
{
int wmId = LOWORD(wParam);
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(NULL, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, pApp->About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
break;
case WM_PAINT:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code that uses hdc 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 App::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;
}
Create the main window:
App pApp = App(hInst, szWindowClass);
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, &pApp);
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
I'm having trouble utilizing Win API's DwmDefWindowProc. It always returning false, even when DWM is enabled.
I'm sending a WM_NCHITTEST message to the window procedure to detect the action of the mouse position but it's not giving me accurate results (due to DWM being enabled and me needing to call DwmDefWindowProc beforehand).
I'm using a Windows 10 (Ver. 2004) machine and I have tested the same behavior on my Windows 7 virtual machine. If I change the combability of the executable to launch as Windows XP (Disabling DWM, I'm getting the expected behavior).
Otherwise, the information I'm getting back from WM_NCHITTEST is incorrect as the right side of the maximize button returns the expected HTMAXBUTTON while the left side of it returns HTREDUCE.
Reproducing the issue with the Windows Desktop Application template (found below). If you have DWM enabled (Most Windows 10 users would), the maximize button no longer works properly. If run the program in Visual Studio and select the Output tab, you'll see that when you hover to the left (green border in the picture below) of the maximize button you will get a HTMINBUTTON message while if you hover to the right (red border in the picture below) you will get the expected HTMAXBUTTON message.
Here's the sample code
// SimpleWindow.cpp : Defines the entry point for the application.
//
#include "framework.h"
#include "SimpleWindow.h"
#define MAX_LOADSTRING 100
// Global Variables:
HINSTANCE hInst; // current instance
WCHAR szTitle[MAX_LOADSTRING]; // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name
// 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);
/* New Stuff */
#include <dwmapi.h>
#pragma comment(lib, "Dwmapi.lib")
void DWMExample(HWND hWnd, unsigned int msg, unsigned int wParam, int lParam);
LRESULT ProcessNCHitTest(HWND hWnd, int lParam);
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: Place code here.
// Initialize global strings
LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadStringW(hInstance, IDC_SIMPLEWINDOW, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance(hInstance, nCmdShow)) {
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_SIMPLEWINDOW));
MSG msg;
// Main message loop:
while (GetMessage(&msg, nullptr, 0, 0)) {
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg)) {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int)msg.wParam;
}
//
// FUNCTION: MyRegisterClass()
//
// PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW 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_SIMPLEWINDOW));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_SIMPLEWINDOW);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&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)
{
hInst = hInstance; // Store instance handle in our global variable
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
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)
{
switch (message) {
case WM_COMMAND:
{
int wmId = LOWORD(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:
{
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code that uses hdc here...
EndPaint(hWnd, &ps);
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
}
/* New Stuff */
if (message == WM_NCHITTEST) {
return ProcessNCHitTest(hWnd, lParam);
}
DWMExample(hWnd, message, wParam, lParam);
return DefWindowProc(hWnd, message, wParam, lParam);
}
void DWMExample(const HWND hWnd, const unsigned int msg, const unsigned int wParam, const int lParam)
{
switch (msg) {
case WM_NCMOUSEMOVE:
case WM_MOUSEMOVE:
{
const auto ht = SendMessageA(hWnd, WM_NCHITTEST, wParam, lParam);
switch (ht) {
case HTBORDER:
OutputDebugStringA("HTBORDER\n");
break;
case HTBOTTOM:
OutputDebugStringA("HTBOTTOM\n");
break;
case HTBOTTOMLEFT:
OutputDebugStringA("HTBOTTOMLEFT\n");
break;
case HTBOTTOMRIGHT:
OutputDebugStringA("HTBOTTOMRIGHT\n");
break;
case HTCAPTION:
OutputDebugStringA("HTCAPTION\n");
break;
case HTCLIENT:
OutputDebugStringA("HTCLIENT\n");
break;
case HTCLOSE:
OutputDebugStringA("HTCLOSE\n");
break;
case HTERROR:
OutputDebugStringA("HTERROR\n");
break;
case HTGROWBOX:
OutputDebugStringA("HTGROWBOX\n");
break;
case HTHELP:
OutputDebugStringA("HTHELP\n");
break;
case HTHSCROLL:
OutputDebugStringA("HTHSCROLL\n");
break;
case HTLEFT:
OutputDebugStringA("HTLEFT\n");
break;
case HTMENU:
OutputDebugStringA("HTMENU\n");
break;
case HTMAXBUTTON:
OutputDebugStringA("HTMAXBUTTON\n");
break;
case HTMINBUTTON:
OutputDebugStringA("HTMINBUTTON\n");
break;
case HTNOWHERE:
OutputDebugStringA("HTNOWHERE\n");
break;
// case HTREDUCE:
// OutputDebugStringA("HTREDUCE\n");
// break;
case HTRIGHT:
OutputDebugStringA("HTRIGHT\n");
break;
// case HTSIZE:
// OutputDebugStringA("HTSIZE\n");
// break;
case HTSYSMENU:
OutputDebugStringA("HTSYSMENU\n");
break;
case HTTOP:
OutputDebugStringA("HTTOP\n");
break;
case HTTOPLEFT:
OutputDebugStringA("HTTOPLEFT\n");
break;
case HTTOPRIGHT:
OutputDebugStringA("HTTOPRIGHT\n");
break;
case HTTRANSPARENT:
OutputDebugStringA("HTTRANSPARENT\n");
break;
case HTVSCROLL:
OutputDebugStringA("HTVSCROLL\n");
break;
// case HTZOOM:
// OutputDebugStringA("HTZOOM\n");
// break;
}
}
break;
}
}
LRESULT ProcessNCHitTest(const HWND hWnd, const int lParam)
{
BOOL isDWMEnabled = false;
if (FAILED(DwmIsCompositionEnabled(&isDWMEnabled))) {
return DefWindowProcA(hWnd, WM_NCHITTEST, 0, lParam);
}
if (!isDWMEnabled) {
return DefWindowProcA(hWnd, WM_NCHITTEST, 0, lParam);
}
LRESULT result = 0;
if (!DwmDefWindowProc(hWnd, WM_NCHITTEST, 0, lParam, &result)) {
return DefWindowProcA(hWnd, WM_NCHITTEST, 0, lParam);
}
return result;
}
// 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;
}
Any idea where I'm going wrong? Any help would be appreciated!
I'm learning win32 Programming. In order to better comprehend the concepts of the programming in win32 framework, So that I am going to write a simple calculator. I design its view but now I want when a user click on a button, for example button 1, Its number shows on a static label. I used SetDlgItemText, But it doesn't work. I put the picture of the program in the following:
I have 12 button with IDs IDC_Button01 to IDC_Button12 and I have a static label element with IDC_Display ID. I put my code in the following section.
#include <windows.h>
#include <tchar.h>
#include "resource.h"
#pragma comment(linker, \
"\"/manifestdependency:type='Win32' "\
"name='Microsoft.Windows.Common-Controls' "\
"version='6.0.0.0' "\
"processorArchitecture='*' "\
"publicKeyToken='6595b64144ccf1df' "\
"language='*'\"")
#pragma comment(lib, "ComCtl32.lib")
// Step 4: the Window Procedure
INT_PTR CALLBACK DialogProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam);
const char g_szClassName[] = "myWindowClass";
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
HWND hDlg;
BOOL ret;
MSG msg;
hDlg = CreateDialogParam(hInstance, MAKEINTRESOURCE(IDD_MainWindow), 0, DialogProc, 0);
ShowWindow(hDlg, nCmdShow);
// Step 3: The Message Loop
while ((ret = GetMessage(&msg, 0, 0, 0)) != 0) {
if (ret == -1) /* error found */
return -1;
if (!IsDialogMessage(hDlg, &msg)) {
TranslateMessage(&msg); /* translate virtual-key messages */
DispatchMessage(&msg); /* send it to dialog procedure */
}
}
return msg.wParam;
}
// Step 4: the Window Procedure
INT_PTR CALLBACK DialogProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDCANCEL:
SendMessage(hDlg, WM_CLOSE, 0, 0);
return TRUE;
case IDOK:
MessageBox(hDlg, TEXT("Program will quit."), TEXT("Message"), MB_ICONQUESTION);
PostQuitMessage(0);
return TRUE;
}
break;
case IDC_BUTTON1:
SetDlgItemText(hDlg, IDC_Display, TEXT("1"));
case WM_CLOSE:
if (MessageBox(hDlg, TEXT("Close the program?"), TEXT("Close"), MB_ICONQUESTION | MB_YESNO) == IDYES)
{
DestroyWindow(hDlg);
}
return TRUE;
case WM_DESTROY:
PostQuitMessage(0);
return TRUE;
}
return FALSE;
}
The resource ID is not a valid Windows message, the WM_COMMAND is used to send a notification to a parent window
INT_PTR CALLBACK DialogProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
..
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDC_BUTTON1: {
SetDlgItemText(hDlg, IDC_Display, TEXT("1"));
return TRUE;
} break;
break;
wParam is set to the control identifier.
If I create a child window (In this case window "About") to the main window, the dialog box for some reason is not called. If you do not the child window is a dialog box called normal and works fine. GetLastError returns the error number 1812 (The specified image file did not contain a resource section.). But from a resource file everything is fine. And as I said, if you do not create a child window then everything works fine. What's the problem?
#include <windows.h>
#include "resource.h"
LONG WINAPI WndProc(HWND, UINT, WPARAM,LPARAM);
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam);
LRESULT CALLBACK PointsProc(HWND hPoints, UINT message, WPARAM wParam,LPARAM lParam);
HINSTANCE hInst;
HWND hPoints;
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
hInst = hInstance;
HWND hwnd;
MSG msg;
WNDCLASS w;
memset(&w,0,sizeof(WNDCLASS));
w.style = CS_HREDRAW | CS_VREDRAW;
w.lpfnWndProc = WndProc;
w.hInstance = hInstance;
w.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
w.lpszClassName = L"My Class";
RegisterClass(&w);
hwnd = CreateWindow(L"My Class", L"My title", WS_OVERLAPPEDWINDOW,
300, 200, 200, 180, NULL, NULL, hInstance, NULL);
HMENU main_menu = CreateMenu();
AppendMenu(main_menu, MF_STRING, 1111, L"Box");
WNDCLASS w2;
memset(&w2, 0, sizeof(WNDCLASS));
w2.lpfnWndProc = (WNDPROC)PointsProc;
w2.hInstance = hInst;
w2.lpszClassName = L"About";
w2.hCursor = LoadCursor(NULL, IDC_ARROW);
w2.hbrBackground = (HBRUSH)CreateSolidBrush(RGB(111, 111, 111));
RegisterClass(&w2);
hPoints = CreateWindowEx(0, L"About", (LPCTSTR) NULL,
WS_CHILD | WS_BORDER | WS_VISIBLE | WS_DISABLED, 10, 10,
100, 100, hwnd, (HMENU)1112, hInst, NULL);
ShowWindow(hPoints,SW_NORMAL);
UpdateWindow(hPoints);
SetMenu(hwnd, main_menu);
ShowWindow(hwnd,nCmdShow);
UpdateWindow(hwnd);
while(GetMessage(&msg,NULL,0,0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LONG WINAPI WndProc(HWND hwnd, UINT Message, WPARAM wparam, LPARAM lparam)
{
switch (Message)
{
case WM_COMMAND:
switch(LOWORD(wparam))
{
case 1111:
DialogBox(hInst, MAKEINTRESOURCE(IDD_DIALOG1), hwnd, About);
return 0;
}
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, Message, wparam, lparam);
}
return 0;
}
LRESULT CALLBACK PointsProc(HWND hPoints, UINT message, WPARAM wParam,LPARAM lParam)
{
switch(message)
{
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_PAINT:
break;
default:
return DefWindowProc(hPoints, message, wParam, lParam);
}
return 0;
}
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) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}
The dialog box is called, only it takes a long time because PointsProc() is looping...
The problem was the break; while handling WM_PAINT in PointsProc() -- it then skips calling DefWindowProc(), so the window keeps getting WM_PAINT messages because the window remains invalid.
// case WM_PAINT:
// break;