我创建了一个 Subclass 类,并在其中使用 SetWindowLongPtr()
将 GWLP_USERDATA
设置为包含指向我用来分发消息的派生类的指针。
所以如果我使用 SetWindowLongPtr(CurrentWindow, GWLP_USERDATA, (LONG_PTR)Data);
,我该如何恢复
当我不再想继承旧数据时? MSDN 说初始值为零,所以我应该使用 SetWindowLongPtr(CurrentWindow, GWLP_USERDATA, (LONG_PTR)NULL);
函数吗?
编辑: 实际上,我使用 SetProp、GetProp、RemoveProp 找到了解决此问题的方法,现在我不必担心会弄乱其他函数。 下面是我的代码,供可能需要的人使用:
#ifndef WIN32_SUBCLASS_CLASS_H
#define WIN32_SUBCLASS_CLASS_H
#include <Windows.h>
#include <tchar.h>
class SubclassWindow
{
public:
static LRESULT CALLBACK stWinSubclassHandler(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
SubclassWindow* pWnd;
pWnd = (SubclassWindow*)GetProp(hwnd, TEXT("Subclass"));
if (pWnd)
return pWnd->WinSubclassHandler(hwnd, uMsg, wParam, lParam);
else
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
BOOL Subclass(SubclassWindow* Data, HWND hwnd)
{
if (Subclassed == TRUE || CurrentWindow != NULL)
return 0;
CurrentWindow = hwnd;
Subclassed = TRUE;
OriginalProc = (WNDPROC)GetWindowLongPtr(hwnd, GWL_WNDPROC);
SetProp(CurrentWindow, TEXT("Subclass"), (HANDLE)Data);
SetWindowLongPtr(CurrentWindow, GWL_WNDPROC, (LONG_PTR)SubclassWindow::stWinSubclassHandler);
return 1;
}
BOOL RemoveSubclass()
{
if (OriginalProc == NULL || CurrentWindow == NULL)
return 0;
Subclassed = FALSE;
RemoveProp(CurrentWindow, TEXT("Subclass"));
SetWindowLongPtr(CurrentWindow, GWL_WNDPROC, (LONG_PTR)OriginalProc);
return 1;
}
BOOL IsSubclassed() { return Subclassed; }
protected:
HWND CurrentWindow;
WNDPROC OriginalProc;
BOOL Subclassed;
SubclassWindow()
{
CurrentWindow = NULL;
OriginalProc = NULL;
Subclassed = FALSE;
}
virtual LRESULT CALLBACK WinSubclassHandler(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) = 0;
};
#endif
最佳答案
SetWindowLongPtr()
返回旧值,因此保存它,然后在稍后调用 SetWindowLongPtr()
删除子类时恢复它。
也就是说,为不是您自己创建的窗口替换 GWLP_USERDATA
是危险的。您不知道该窗口是否已将 GWLP_USERDATA
用于其自身目的。使用 SetWindowSubclass()
相反,它旨在解决该问题:
class SubclassWindow
{
public:
static LRESULT CALLBACK stWinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
SubclassWindow* pWnd = (SubclassWindow*) dwRefData;
if ((pWnd) && (uIdSubclass == 1))
return pWnd->WinSubclassHandler(hwnd, uMsg, wParam, lParam);
else
return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}
BOOL Subclass(SubclassWindow* Data, HWND hwnd)
{
if (CurrentWindow != NULL)
return FALSE;
if (!SetWindowSubclass(hwnd, &stWinSubclassHandler, 1, (DWORD_PTR)Data))
return FALSE;
CurrentWindow = hwnd;
return TRUE;
}
BOOL RemoveSubclass()
{
if (CurrentWindow == NULL)
return FALSE;
if (!RemoveWindowSubclass(CurrentWindow, &stWinSubclassHandler, 1))
return FALSE;
CurrentWindow = NULL;
return TRUE;
}
BOOL IsSubclassed() { return (CurrentWindow != NULL); }
protected:
HWND CurrentWindow;
SubclassWindow()
{
CurrentWindow = NULL;
}
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam) = 0;
};
如果您的派生类需要默认处理任何给定的消息,您唯一需要做的改变就是让它们的 WinSubclassHandler()
实现调用 DefSubclassProc()
而不是 DefWindowProc()
(顺便说一句,调用的 API 是错误的 - 你应该调用 CallWindowProc(OriginalProc, ...)
而不是你之前的窗口过程子类替换有机会处理消息)。为此,我建议将该调用包装在您的 SubclassWindow
类中,以对后代隐藏该细节,例如:
class SubclassWindow
{
...
protected:
...
static LRESULT DefaultHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}
...
};
class MySubclass : public SubclassWindow
{
protected:
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
...
return DefaultHandler(hWnd, uMsg, wParam, lParam);
}
};
或者(这将允许后代更好地派生自后代):
class SubclassWindow
{
...
protected:
...
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}
...
};
class MySubclass1 : public SubclassWindow
{
protected:
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
...
return SubclassWindow::WinSubclassHandler(hWnd, uMsg, wParam, lParam);
}
};
class MySubclass2 : public MySubclass1
{
protected:
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
...
return MySubclass1::WinSubclassHandler(hWnd, uMsg, wParam, lParam);
}
};
class MySubclass3 : public MySubclass2
{
protected:
virtual LRESULT CALLBACK WinSubclassHandler(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
...
return MySubclass2::WinSubclassHandler(hWnd, uMsg, wParam, lParam);
}
};
关于c++ - 不再需要在子类化后恢复 GWLP_USERDATA,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/18174566/