I need to get the current WndProc with its messages and configuration and add my own code to it. Why do I need this? Because I'm working under an IDE that defines a window (and its children controls) with a WndProc, and I need to modify it because It contains all the actions related with every control. If I point a control to a custom WndProc the control loses all the actions and configuration set by the IDE. Suggestions?
Scheme:
HWND button; //My Button
LONG_PTR wndProc = GetWindowLongPtr(button, GWL_WNDPROC); //Getting the WndProc
wndProc -> Get this `WndProc` source code
LRESULT CALLBACK WndProcedure(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam){
wndProc (all the data);
+ my messages
}
You can't get source code of "old" WndProc of course, but you can call it using CallWindowProc() in your new wnd proc. Check out this article:
When you subclass a window, it's the original window procedure of the window you subclass you have to call when you want to call the original window procedure
Quote:
... your subclass function should go something like this:
wndProcOrig =
(WNDPROC)SetWindowLongPtr(hwndButton, GWLP_WNDPROC, (LONG_PTR)SubclassWndProc);
LRESULT CALLBACK SubclassWndProc(HWND hwnd, UINT wm, WPARAM wParam, LPARAM lParam)
{
switch (wm) {
...
default:
return CallWindowProc(wndprocOrig, hwnd, wm, wParam, lParam);
}
}
Related
I need to redraw NC area of the window and set custom text in there. So with redrawing I'm okay, but I don't know what should I use to set my own text in caption of the window. I tried to use DefWindowProc function, but it suddenly draws default windows title bar, which is unnecessarily. Using SetWindowText also is inappropriate, because it causes WM_SETTEXT message once again. So help me, please, I need just to customize caption of window without any drawing default title bar.
LRESULT SkinWindow::WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM
lParam)
{
...
case WM_SETTEXT:
OnSetText(hWnd, wParam, lParam);
break;
...
}
void SkinWindow::OnSetText(HWND hWnd, WPARAM wParam, LPARAM lParam)
{
DefWindowProc(hWnd, WM_SETTEXT, wParam, lParam);
OnNcPaint(hWnd, wParam, lParam);
}
You must fully handle the two gettext messages:
case WM_GETTEXT:
lstrcpyn((LPTSTR)lParam, "Booga!", (int)wParam);
return lstrlen((LPTSTR)lParam);
case WM_GETTEXTLENGTH:
return 7; // lstrlen("Booga!") + null
If you want WM_SETTEXT to work correctly you must store the text in you own buffer and use that buffer when queried for the text. Never pass these to DefWindowProc because DefWindowProc stores/retrieves the text internally in the HWND.
Note: External applications will still read it incorrectly if they use GetWindowText because it reads from the hidden internal storage when sent cross-process.
Okay, I have a ListView and I've just worked out how to manually set it's Callback procedure:
// Sets the list view procedure
listproc = (D_ListView *) LocalAlloc(LMEM_FIXED, sizeof(D_ListView));
listproc->oldproc = (WNDPROC)SetWindowLongPtr(g_hList, GWL_WNDPROC, (LONG)&ListViewProc);
SetWindowLongPtr(g_hList, GWL_USERDATA, (LONG)&listproc);
I used a code example I found - D_ListView is just a struct with a WNDPROC variable called oldproc.
Anyhow, I'm sending messages to my ListView to add items. But I don't want to handle the ADD messages manually, I want to pass them onto the ListView's default procedure, and only handle messages that I need to over-ride the functionality for.
LRESULT CALLBACK ListViewProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch(msg)
{
// Just a test - we're getting this message so it worked
case LVM_INSERTCOLUMN:
{
cout << "CREATED" << endl;
}
}
WNDPROC* wp;
wp = (WNDPROC*)(::GetWindowLongPtr(hwnd, GWL_WNDPROC));
return ::CallWindowProc(*wp, hwnd, msg, wParam, lParam);
}
In the above, I don't want to deal withe LVM_INSERTCOLUMN: I just want to pass it on.
Any one able to help?
Thanks,
Rob
use getWindowLongPtr (...GWL_USERDATA) to get the pointer to your D_ListView instance and then forward any unwanted messages to oldproc
::CallWindowProc(*listproc->oldproc, hwnd, msg, wParam, lParam);
I'll go ahead and give a summary to this, how can I use a dialog procedure that is a member of a class? I am creating a window wrapper class, but CreateDialogParam needs a global dialog procedure, so I tried this workaround:
I have done a bit of searching on this topic. I am making a Dialog class which I am subclassing to make a CMainWnd and then instantiating that. In the Dialog class I have a member function defined as INT_PTR CALLBACK Dialog::cb_proc(HWND,UINT,WPARAM,LPARAM). Now, I know that windows must have a global function as a callback procedure.
So I made a std::map<HWND,Dialog*> DlgProcs map to associate the dialogs window handle with its Dialog class pointer.
And a INT_PTR CALLBACK DlgMainProc(HWND,UINT,WPARAM,LPARAM) so I could pass that to CreateDialogParam(). In the body of DlgMainProc(...) I search the map for using the hWnd parameter to find the Dialog* and return its cb_proc(..) member.
My problem is that none of the messages get processed, this is because the member procedure in my Dialog class never gets called. Even though when I put a MessageBox() in DlgMainProc inside a if (DlgProcs.find(hWnd) != DlgProcs.end()) { statement, the messagebox is displayed, over and over again until I have to abort the program from Visual Studio 2008. Which tells me that it is finding the hWnd in my map. The weird thing is it also does this if I put it in the else statement after that, which contradictingly tells me it is NOT finding the hWnd in the map.
If I put a messagebox in the cb_proc member function it does not get displayed at all. But during this I never get any compiler, linker, or runtime errors. When I remove the messagebox from it (as to not have to abort the program, it was just for debugging purposes) the program runs but no messages get processed, the X button does not close the program, button clicks do nothing.
Here is the PasteBin code: http://pastebin.com/GsGUBpZU
Btw, I have no problem subclassing this, my window is created fine, just no messages are processed, cb_proc just never gets called.
EDIT: Here is the relevant parts of the code
map<HWND,Dialog*> g_DlgProcs;
INT_PTR CALLBACK g_MainDlgProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
if (g_DlgProcs.find(hWnd) != g_DlgProcs.end()) {
Alert("blah"); // Gets executed repeatedly
return g_DlgProcs[hWnd]->cb_proc(hWnd, msg, wParam, lParam);
} else {
Alert("blah"); // Removing the above alert, this gets
// executed repeatedly, erm, as well.. O.o strange
return FALSE;
}
}
Dialog::Dialog(int id, HWND parent /* = HWND_DESKTOP */) {
_id = id;
_parent = parent;
// Tried this before CreateDialogParam
g_DlgProcs.insert(make_pair(_handle, this));
_handle = CreateDialogParam(
(HINSTANCE)GetModuleHandle(NULL),
MAKEINTRESOURCE(id), _parent,
(DLGPROC)g_MainDlgProc, NULL
);
// Then tried it after CreateDialogParam
g_DlgProcs.insert(make_pair(_handle, this));
}
INT_PTR CALLBACK Dialog::cb_proc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
Alert("blah"); // Never gets executed
bool handled = true;
switch (msg)
{
case WM_INITDIALOG:
OnInitialize();
break;
case WM_COMMAND:
if (HIWORD(wParam) == 0 || HIWORD(wParam) == 1) {
OnMenuCommand((HIWORD(wParam) == 1), (int)LOWORD(wParam));
} else {
OnCtrlCommand((int)HIWORD(wParam), (int)LOWORD(wParam), (HWND)lParam);
}
break;
case WM_NOTIFY:
{
LPNMHDR head = (LPNMHDR)lParam;
OnNotification(head->code, head->idFrom, head->hwndFrom);
}
break;
case WM_CLOSE:
OnClose(); // DestroyWindow(_handle)
break;
case WM_DESTROY:
OnDestroy(); // PostQuitMessage(0)
default:
handled = ProcessMsg(msg, wParam, lParam);
}
// Convert bool to Windows BOOL enum
return ((handled == true) ? TRUE : FALSE);
}
Does anybody know why it never gets called? Or maybe just guide me to another way to use a member function as a DLGPROC?
The standard solution is to pass your this pointer as the last parameter to Create,DialogParam, stash it in DWLP_USER in your WM_INITDIALOG handler, and retrieve it from DWLP_USER thereafter. Basically you use DWLP_USER as your map.
I tried your code and it worked: cb_proc gets called. You will miss any messages (e.g. WM_INITDIALOG) that get sent before CreateDialogParam returns.
You can fix the latter problem by adding the window handle and the object to the map in g_MainDlgProc. If you get a message for an unknown window, you know it belongs to the window you're creating; put the object in a global and you can add the handle/object to the map.
I'm just adding this here in case someone finds it useful; using the magic of C++11 lambdas and templates you can have a simple wrapper template that means you don't have to continually rewrite the boiler-plate code for saving and loading userdata in window and dialog box procedures.
Here's an example for the DialogBoxParam function, but the same technique can be applied to CreateDialogParam and CreateWindowEx as well.
template <typename T, INT_PTR (T::*P)(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)>
INT_PTR DialogBoxThis(T* pThis, HINSTANCE hInstance, LPCWSTR lpTemplateName, HWND hWndParent)
{
return ::DialogBoxParam(hInstance, lpTemplateName, hWndParent, [](HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) -> INT_PTR {
if (uMsg == WM_INITDIALOG) SetWindowLongPtr(hWnd, DWLP_USER, lParam);
T* pThis = reinterpret_cast<T*>(GetWindowLongPtr(hWnd, DWLP_USER));
return pThis ? (pThis->*P)(hWnd, uMsg, wParam, lParam) : FALSE;
}, reinterpret_cast<LPARAM>(pThis));
}
You would use it like this:
class MyClass
{
INT_PTR MyDlgProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
};
// from inside MyClass, we can show a dialog that uses member function MyDlgProc as the dialog procedure
// note it is NOT a static function
DialogBoxThis<MyClass, &MyClass::MyDlgProc>(this, hInstance,
MAKEINTRESOURCE(IDD_MYDIALOG), hWndParent);
I have been having trouble with my program trying to gray out ( and disable ) a sub menu item.
What I'm looking for is that the "run" item be disabled unless the required .ini entry is not empty.
My code
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HMENU hmenu = GetMenu(hWnd);
// Reading in ini
if (0 == strcmp(webLocation, "")){
EnableMenuItem(hmenu,ID_WEBSERVICES_RUN,MF_DISABLED | MF_GRAYED);
WritePrivateProfileString(_T("WEBSERVICES"), _T("Location"), _T("Tool Not Found"), WpathStr);
}
I am unsure as to whether I am getting the HMENU correctly and why this code is not working for the desired effect.
Any help with this would be greatly appreciated.
You can't just put this in the WndProc at the top level. WndProc process events, whether the window has been constructed or not. It'll be called many times for many different reasons.
Your WndProc will almost certainly look like a big switch on message. The one you want here is WM_INITDIALOG:
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch(message)
{
case WM_INITDIALOG:
// jump to a new function that reads the .ini
// and disables the control etc.
return OnInitDialog(hWnd, wParam, lParam);
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
}
I want to create my own class to handle creating windows and the window procedure but I have noticed that the window procedure has to be static! I'm now wondering whether its possible to make the window procedure object oriented? I have read some tutorials on object oriented windows, but they always make the procedure static -.- whats the use in that? :/
Any links or info on how to get around this problem would be appreciated,
thanks
You can get around that by making the static WndProc delegate everything to the members:
// Forward declarations
class MyWindowClass;
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
std::map<HWND, MyWindowClass *> windowMap;
// Your class
class MyWindowClass {
private:
HWND m_handle;
// The member WndProc
LRESULT MyWndProc(UINT message, WPARAM wParam, LPARAM lParam) { /* ... */ }
public:
MyWindowClass()
{
/* TODO: Create the window here and assign its handle to m_handle */
/* Pass &WndProc as the pointer to the Window procedure */
// Register the window
windowMap[m_handle] = this;
}
};
// The delegating WndProc
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
std::map<HWND, MyWindowClass *>::iterator it = windowMap.find(hWnd);
if (it != windowMap.end())
return it->second->MyWndProc(message, wParam, lParam);
return 0;
}
The general technique of allowing a window instance to be represented by as class instance is to make use of the SetWindowLongPtr and GetWindowLongPtr to associate your class instance pointer with the window handle. Below is some sample code to get you started. It may not compile without a few tweaks. It's only meant to be a reference.
Personally, I've stopped rolling my own window classes back a few years ago when I discovered ATL's CWindow and CWindowImpl template class. They take care of doing all this mundane coding for you so can focus on just writing methods that handle window messages. See the example code I wrote up here.
Hope this helps.
class CYourWindowClass
{
private:
HWND m_hwnd;
public:
LRESULT WndProc(UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch (uMsg)
{
case WM_CREATE: return OnCreate(wParam, lParam);
case wM_PAINT: return OnPaint(wParam, lParam);
case WM_DESTROY:
{
SetWindowLongPtr(m_hwnd, GWLP_USERDATA, NULL);
m_hwnd = NULL;
return 0;
}
}
return DefWindowProc(m_hwnd, uMsg, wParam, lParam);
}
CYourWindowClass()
{
m_hwnd = NULL;
}
~CYourWindowClass()
{
ASSERT(m_hwnd == NULL && "You forgot to destroy your window!");
if (m_hwnd)
{
SetWindowLong(m_hwnd, GWLP_USERDATA, 0);
}
}
bool Create(...) // add whatever parameters you want
{
HWND hwnd = CreateWindow("Your Window Class Name", "Your Window title", dwStyle, x, y, width, height, NULL, hMenu, g_hInstance, (LPARAM)this);
if (hwnd == NULL)
return false;
ASSERT(m_hwnd == hwnd);
return true;
}
static LRESULT __stdcall StaticWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
CYourWindowClass* pWindow = (CYourWindowClass*)GetWindowLongPtr(hwnd, GWLP_USERDATA);
if (uMsg == WM_CREATE)
{
pWindow = ((CREATESTRUCT*)lParam)->lpCreateParams;
SetWindowLongPtr(hwnd, GWLP_USERDATA, (void*)pWindow);
m_hWnd = hwnd;
}
if (pWindow != NULL)
{
return pWindow->WndProc(uMsg, wParam, lParam);
}
return DefWindowProc(hwnd, uMsg, wParam, lParam);
};
};
If you are looking for object oriented Win32 API then you should look to MFC and/or WTL.
Just to add to Brian's answer but for a win32 framework that's more beginner friendly take a look at Win32++. The library itself isn't as comprehensive in features compared to MFC or QT but that is a tradeoff the designer made at the beginning to keep the library easy to understand and simple to use.
If you're still interested in this topic, I highly encourage you to take a look at it since it uses yet another technique for saving the 'this' pointer by utilizing thread local storage.
You can use the window handle passed to the WindowProc to grab an object you've created for that particular window and delegate the event handling to that object.
e.g.
IMyWindowInterface* pWnd = getMyWindowObject(hWnd);
pWnd->ProcessMessage(uMsg, wParam, lParam);