Im sure this question is so easy for all you experts, but I am new to C++ and trying to add a comboBox to a "Option" Dialog in my program, I have done the following, but still can't see any item in Combo box can you please tell me what I am missing here.
in Resourse.h : #define IDD_TRIGGER_MODE 201
in Project.rc : COMBOBOX IDD_TRIGGER_MODE, 64,22,68,14,WS_TABSTOP | WS_VSCROLL | CBS_DROPDOWN
any in the .cpp file I have the folliwng codes :
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam){
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
switch (message)
{
case WM_COMMAND:
///Other codes///
case IDM_OPTIONS:
g_hToolbar = CreateDialog(hInst, MAKEINTRESOURCE(IDD_OPTION_BOX), hWnd, ToolDlgProc);
if(g_hToolbar != NULL)
{
ShowWindow(g_hToolbar, SW_SHOW);
}
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
///Other codes///
}
the ToolDlgProc function :
INT_PTR CALLBACK ToolDlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
HWND fgModes;
switch (message)
{
case WM_INITDIALOG:
fgModes = ::GetDlgItem(hDlg, IDD_TRIGGER_MODE);
fgModes = GetDlgItem(hDlg, IDD_TRIGGER_MODE);
if(fgModes!=NULL){
if(SendMessage(fgModes,CB_ADDSTRING,0, reinterpret_cast<LPARAM (_T("FreeRun")))==NULL){
return (INT_PTR)FALSE ;
}
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 appricate it for any idea to solve this problem, Thank you
thank you so much for your help. but I notice I didnt have problem in my code, simply the size of the ComboBox in .rc file was quite small (because of my lack of experiance in c++ API), so I change it to 42 now I can see my items. here is the edited code :
COMBOBOX IDD_TRIGGER_MODE, 64,22,69,42,WS_CHILD|WS_VISIBLE|CBS_DROPDOWNLIST
Change:
SendMessage(fgModes,CB_ADDSTRING,0, reinterpret_cast<LPARAM>("FreeRun"));
To:
SendMessage(fgModes,CB_ADDSTRING,0, reinterpret_cast<LPARAM>(_T("FreeRun")));
Also is there a good reason you are mixing CreateWindow/Ex and resources? I am assuming CreateWindow/Ex because I see you are using a WndProc for the first cpp, not a DialogProc.
Related
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 try to change standart WndProc function. I have this code:
HWND btn = CreateWindowEx(WS_EX_TRANSPARENT | WS_EX_CLIENTEDGE, L"BUTTON", L"Window title", WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON
, 50, 50, 50, 50, (HWND)XApplicationMainWindow->window->_wnd, (HMENU)123,
(HINSTANCE)GetWindowLongPtr(XApplicationMainWindow->window->_wnd, GWLP_HINSTANCE), NULL);
SetWindowLongPtrW(btn, GWLP_WNDPROC, (LONG_PTR)SubclassWindowProc);
I can use L"BUTTON" class name, but when I change WndProc function I'll have a problem.
On this picture, you can see the blank square and normal button. If I try to create new WNDCLASS or WNDCLASSEX, I'll have nothing... Why?
How can I change the standart WndProc function, if I use L"BUTTON" class name?
It's my second WndProc:
LRESULT CALLBACK SubclassWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
case WM_CREATE:
break;
case WM_COMMAND:
//Event click
switch (LOWORD(wParam))
{
case 123:
OutputDebugStringA("Subclass click2");
break;
default:
break;
}
break;
default:
return DefWindowProc(hWnd, uMsg, wParam, lParam);
}
return 0;
}
DefWindowProc() is the wrong window procedure for your SubclassWindowProc() to be calling.
You need to call the previous window procedure that you are replacing - the window procedure that handles all of the button's default behaviors (like drawing the button so it actually looks like a button, and responding to user input like a button, etc). SetWindowLongPtr() returns a pointer to that procedure to you, but you are currently ignoring it.
See Subclassing Controls on MSDN for more details.
Try this instead:
WNDPROC btnWndProc;
LRESULT CALLBACK SubclassWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
case WM_COMMAND:
//Event click
switch (LOWORD(wParam))
{
case 123:
OutputDebugStringA("Subclass click2");
break;
}
break;
}
return CallWindowProc(hWnd, btnWndProc, uMsg, wParam, lParam);
}
...
HWND btn = CreateWindowEx(...);
btnWndProc = (WNDPROC) SetWindowLongPtrW(btn, GWLP_WNDPROC, (LONG_PTR)SubclassWindowProc);
Alternatively, using SetWindowSubclass(), which is safer than using SetWindowsLongPtr(), eg:
LRESULT CALLBACK SubclassWindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData) {
switch (uMsg) {
case WM_NCDESTROY:
RemoveWindowSubclass(hWnd, SubclassWindowProc, uIdSubclass);
break;
case WM_COMMAND:
//Event click
switch (LOWORD(wParam))
{
case 123:
OutputDebugStringA("Subclass click2");
break;
}
break;
}
return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}
...
HWND btn = CreateWindowEx(...);
SetWindowSubclass(btn, SubclassWindowProc, 1, 0);
Now, that being said, your subclass will never call OutputDebugStringA(), because it will never receive the WM_COMMAND message you are expecting. When a button is clicked, a WM_COMMAND message is not sent to the button itself. The button posts a WM_COMMAND message to the button's parent window instead (in this case, to XApplicationMainWindow->window->_wnd). So, you need to handle the WM_COMMAND message in the window procedure of the parent window, not in the window procedure of the button itself.
Otherwise, if you still want to subclass the button itself, you will have to handle the WM_LBUTTON(DOWN|UP) and WM_KEY(DOWN|UP)/WM_CHAR messages that the button receives and then subsequently translates into a WM_COMMAND message for its parent window.
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{ HDC hdc;
int count=1; int xs,ys,xe,ye;
switch (message)
{
case WM_LBUTTONDOWN
hdc=GetDC(hwnd);
if(count%2!=1){
xs=GET_X_LPARAM(lParam);
ys=GET_Y_LPARAM(lParam);}
else{
xe=GET_X_LPARAM(lParam);
ye=GET_Y_LPARAM(lParam);
drawline(hdc,xs,ys,xe,ye);
}
ReleaseDC(hwnd,hdc);
count++;
break;
case WM_DESTROY:
PostQuitMessage (0);
break;
default:
return DefWindowProc (hwnd, message, wParam, lParam);
}
I've tried , but there's something wrong with this code.
Use
if(count%2 == 1)
insted of
if(count%2 != 1)
Might work then.
I've created a formview using the Visual Studio resource editor but I can't get it to show.
The procedure to handle it's messages is this:
BOOL CALLBACK DlgProc(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
switch(message)
{
case WM_INITDIALOG:
return TRUE;
case WM_COMMAND:
switch (LOWORD (wParam))
{
case IDC_BUTTONCancel:
EndDialog(hDlg,0);
return TRUE;
}
break;
}
return FALSE;
}
When a button is pressed in the main window I call:
DialogBox(hInst, MAKEINTRESOURCE(IDD_FORMVIEW), hwnd, (DLGPROC)DlgProc);
The main window freezes, but there is no dialog shown.
I'd appreciate some help. Thanks in advance.
I am trying to Subclass the Listbox and the Edit Control of a Combobox for some customasing reasons. Below is the code work . Subclassing for Edit Control is working perfect but Listbox is not getting the messeage of MouseDown.
void Subclass(HWND hComboBox)
{
HWND hEdit=FindWindowEx(hComboBox, NULL, WC_EDIT, NULL);
HWND hCombo=FindWindowEx(hComboBox, NULL, WC_LISTBOX, NULL);
SetProp(hEdit, TEXT("Wprc"), (HANDLE)GetWindowLongPtr(hEdit, GWL_WNDPROC));
SubclassWindow(hEdit, ComboBox_Proc);
SetProp(hCombo, TEXT("Wprc1"), (HANDLE)GetWindowLongPtr(hCombo, GWL_WNDPROC));
SubclassWindow(hCombo, ComboBox_Proc1);
}
static LRESULT CALLBACK ComboBox_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_CHAR:
break;
case WM_KEYDOWN:
break;
case WM_DESTROY:
SetWindowLongPtr(hwnd, GWLP_WNDPROC, (DWORD)GetProp(hwnd, TEXT("Wprc")));
RemoveProp(hwnd, TEXT("Wprc"));
break;
default:
return CallWindowProc((WNDPROC)GetProp(hwnd, TEXT("Wprc")), hwnd, msg, wParam, lParam);
}
return FALSE;
}
static LRESULT CALLBACK ComboBox_Proc1(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
case WM_LBUTTONDOWN:
//PROBLEM IS HERE
break;
case WM_DESTROY:
SetWindowLongPtr(hwnd, GWLP_WNDPROC, (DWORD)GetProp(hwnd, TEXT("Wprc1")));
RemoveProp(hwnd, TEXT("Wprc1"));
break;
default:
return CallWindowProc((WNDPROC)GetProp(hwnd, TEXT("Wprc1")), hwnd, msg, wParam, lParam);
}
return FALSE;
}
The ListBox part of a ComboBox is of type COMBOLBOX (with L).
The ComboLBox window is not a child of the ComboBox window.
The only way I found to subclass the COMBOLBOX control is as follows.
Windows sends the WM_CTLCOLORLISTBOX message to the COMBOBOX (no L) before the listbox is drawn. The lParam of this message contains the handle of the listbox.
case WM_CTLCOLORLISTBOX:
{
if ( !hSubclassedListBox )
{
hSubclassedListBox = (HWND)lParam;
SubclassWindow(hSubclassedListBox , MyLBProc);
}
}
Alsoo see this link for more information
For those who are using Visual Studio with WINVER set to 0500 or higher (Windows XP or later), you can use the GetComboBoxInfo function (passing the handle to the ComboBox), which will return (in a COMBOBOXINFO structure) the handles to both the Edit box and the ComboLBox (ListBox). The handles can then be used to get the CWnd-derived objects they represent.