类成员函数 作 回调函数的问题， 网上看了很多，就是没看明白

[木黑神]

自己写的代码，望大神指点，

# include <windows.h>
# include <iostream>

using namespace std;

class EditControl
{
private:
	int			Edit1;
	WNDPROC		OldEditProc;
	HWND		hEdit;

public:
	EditControl();
	~EditControl();
	void CreateEdit(HWND hwnd, HINSTANCE hInst);
	static LRESULT CALLBACK EditProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
};

EditControl::EditControl()
{
	Edit1			= 1;
	OldEditProc		= NULL;
}
EditControl::~EditControl()
{
}

void EditControl::CreateEdit(HWND hwnd, HINSTANCE hInst)
{
	hEdit = CreateWindow(L"Edit", NULL, WS_CHILD|WS_VISIBLE|WS_BORDER|ES_LEFT|ES_MULTILINE, 10,10,100,100,hwnd, (HMENU)Edit1, hInst, NULL);
	OldEditProc = (WNDPROC)SetWindowLong(hEdit, GWL_WNDPROC, (LONG)EditProc);

}

LRESULT CALLBACK EditControl::EditProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	HDC hdc;
	PAINTSTRUCT ps;
	RECT rect;

	switch(uMsg)
	{
	case WM_PAINT:
		hdc = BeginPaint(hwnd, &ps);
		GetClientRect(hwnd, &rect);
		SelectObject(hdc, CreatePen(PS_SOLID, 1, RGB(255, 0, 0)));
		RoundRect(hdc, rect.left, rect.top, rect.right, rect.bottom, 10, 10);
		EndPaint(hwnd, &ps);
		break;
	}
return CallWindowProc((WNDPROC)OldEditProc, hwnd, uMsg, wParam, lParam);//这里错误
}

错误：
error C2440: “类型转换”: 无法从“”转换为“WNDPROC”

[赵4老师]

static

[木黑神]

引用 1 楼 zhao4zhong1 的回复:

static

哪里？？？

[赵4老师]

搜“静态成员函数”

[encoderlee]

# include <windows.h>
# include <iostream>

using namespace std;

class EditControl
{
private:
	int			Edit1;
	static WNDPROC OldEditProc;	//声明
	HWND		hEdit;

public:
	EditControl();
	~EditControl();
	void CreateEdit(HWND hwnd, HINSTANCE hInst);
	static LRESULT CALLBACK EditProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);
};

WNDPROC EditControl::OldEditProc; //定义

EditControl::EditControl()
{
	Edit1 = 1;
	OldEditProc = NULL;
}

EditControl::~EditControl()
{
}

void EditControl::CreateEdit(HWND hwnd, HINSTANCE hInst)
{
	hEdit = CreateWindow(L"Edit", NULL, WS_CHILD | WS_VISIBLE | WS_BORDER | ES_LEFT | ES_MULTILINE, 10, 10, 100, 100, hwnd, (HMENU)Edit1, hInst, NULL);
	OldEditProc = (WNDPROC)SetWindowLong(hEdit, GWL_WNDPROC, (LONG)EditProc);

}

LRESULT CALLBACK EditControl::EditProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	HDC hdc;
	PAINTSTRUCT ps;
	RECT rect;

	switch (uMsg)
	{
	case WM_PAINT:
		hdc = BeginPaint(hwnd, &ps);
		GetClientRect(hwnd, &rect);
		SelectObject(hdc, CreatePen(PS_SOLID, 1, RGB(255, 0, 0)));
		RoundRect(hdc, rect.left, rect.top, rect.right, rect.bottom, 10, 10);
		EndPaint(hwnd, &ps);
		break;
	}
	return CallWindowProc(OldEditProc, hwnd, uMsg, wParam, lParam);
}

EditControl::EditProc是静态成员函数，在静态成员函数中无法使用非静态成员变量OldEditProc，除非把OldEditProc改成静态成员变量。

[schlafenhamster]

其实可以保存到 窗口里 WNDPROC OldDlgProc = (WNDPROC)SetWindowLong(Parent->m_hWnd, DWL_DLGPROC, (LONG)NewDlgProc); // save it in window ::SetProp(Parent->m_hWnd,"ExpFileOpen",(HANDLE)OldDlgProc); 用法 return CallWindowProc((WNDPROC)::GetProp(hWnd,"ExpFileOpen"), hWnd, Msg, wParam, lParam);

[木黑神]

引用 4 楼 CharlesSimonyi 的回复:

EditControl::EditProc是静态成员函数，在静态成员函数中无法使用非静态成员变量OldEditProc，除非把OldEditProc改成静态成员变量。

非常谢谢。