我在单独的子类文件中编辑控件。上班后开始使用SetWindowSubclass函数（我是C ++的新手，之前我使用SetWindowLongPtr进行子类化，但是我得到了建议，开始使用SetWindowSubclass），我遇到了这个问题：
编译程序后，应用程序绘制空窗口，立即停止响应（我必须通过任务管理器关闭它）。 输出窗口中的结果错误：
在TaskTracklist.exe中的0x635F3DEF（msftedit.dll）抛出异常： 0xC0000005：访问冲突读取位置0x00000008。
整个代码：
var cropArray = ["Berries - Blueberries", "Peas", "Squash", "Okra"];
cropArray.sort();
我很清楚，问题在于使用SetEindowSubclass函数进行RichEdit控件。
即使我没有找到与Msftedit.dll相关的此错误专门相关的任何主题，我从这些文章（here和here和here）中了解到我可能引用NULL指针，但这对我没有意义，因为那时我会从SetWindowSubclass函数上面得到错误（我不会这样做）：
#include "stdafx.h"
#include <windows.h>
#include <commctrl.h>
#include <richedit.h>
#include <string.h>
#include "SearchEditBox.h"
/*global vars*/
LPCWSTR SearchEditBox::editBoxDefText = L"Search...";
bool SearchEditBox::firstLoad = false;
int SearchEditBox::width = 0;
int SearchEditBox::height = 0;
HWND SearchEditBox::editBox;
/*functions*/
LRESULT CALLBACK EditBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uint_ptr, DWORD dwRefData);
void ChangeEdit(const HWND hwnd, const bool change);
/*set-get functions*/
HWND SearchEditBox::getEditBox()
{
return SearchEditBox::editBox;
}
SearchEditBox * SearchEditBox::CreateEditBox(HINSTANCE hInst, HWND hwnd, int pos_x, int pos_y, int width, int height) {
SearchEditBox * p_SearchEditBox = new SearchEditBox;
LoadLibrary(TEXT("Msftedit.dll")); //enables RichEdit field
SearchEditBox::editBox = CreateWindowEx(0, (L"RICHEDIT50W"), editBoxDefText, WS_VISIBLE | WS_CHILD, pos_x + 6, pos_y + 4, width, height, hwnd, NULL, (HINSTANCE)GetWindowLong(hwnd, GWL_HINSTANCE), p_SearchEditBox);
SearchEditBox::width = width;
SearchEditBox::height = height;
if (SearchEditBox::editBox == NULL)
{
delete p_SearchEditBox;
MessageBox(NULL, L"Problem creating the Search box.", L"Error", 0);
return 0;
}
SetWindowSubclass(SearchEditBox::editBox, SearchEditBox::EditBoxProc, 0, 0);
return p_SearchEditBox;
}
LRESULT CALLBACK SearchEditBox::EditBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD dwRefData)
{
PAINTSTRUCT ps;
HDC hdc;
switch (uMsg)
{
case WM_SETFOCUS:
{
LPWSTR getText = new TCHAR[10];
GetWindowText(hwnd, getText, 10);
if (_tcscmp(getText, editBoxDefText) == 0)
{
SearchEditBox::ChangeEdit(hwnd, 1);
}
delete getText;
break;
}
case WM_KILLFOCUS:
{
LPWSTR getText = new TCHAR[10];
if (GetWindowText(hwnd, getText, 10) == 0)
{
SearchEditBox::ChangeEdit(hwnd, 0);
}
::SetFocus(NULL);
delete getText;
break;
}
case WM_LBUTTONDBLCLK:
SearchEditBox::ChangeEdit(hwnd, 1);
break;
case WM_PAINT:
{
hdc = BeginPaint(hwnd, &ps);
RECT rc;
InvalidateRect(hwnd, &rc, 0);
if (SearchEditBox::firstLoad == false)
{
SearchEditBox::ChangeEdit(hwnd, 0);
::SetFocus(NULL);
SearchEditBox::firstLoad = true;
}
HBRUSH hBrush = CreateSolidBrush(RGB(33, 33, 33));
SelectObject(hdc, hBrush);
RoundRect(hdc, -6, -4, SearchEditBox::width + 7, SearchEditBox::height + 4, 5, 5);
EndPaint(hwnd, &ps);
break;
}
}
return DefSubclassProc(hwnd, uMsg, lParam, wParam);
}
我还认为问题可能是外部函数（意思是comctl32中定义的函数而不是类内部）访问类特定变量（指针不为NULL，但它可能无法访问以某种方式到函数）所以我尝试为SetWindowSubclass函数创建局部变量（它也不起作用）：
if (SearchEditBox::editBox == NULL)
{
delete p_SearchEditBox;
MessageBox(NULL, L"Problem creating the Search box.", L"Error", 0);
return 0;
}
使用函数getEditBox（）也没有解决这个问题。
我也尝试在控制声明中使用MSFTEDIT_CLASS而不是（L＆＃34; RICHEDIT50W＆＃34;）（认为问题可能在控件本身内部）但是这也没有帮助，并尝试不同的版本（例如RICHEDIT51W或RICHEDIT80W）导致错误（因此我必须使用VS2015的正确RichEdit版本。）
我还尝试在CreateEditBox中声明HWND editBox（使其成为局部变量），但这也无济于事。
我使用免费的社区版VS.
编辑：从代码中清除了我未成功尝试的遗留物。
答案 0 :(得分：3)
在TaskTracklist.exe中0x635F3DEF（msftedit.dll）抛出异常：0xC0000005：访问冲突读取位置0x00000008。
地址0附近的访问冲突通常意味着通过NULL对象指针访问类/记录数据成员。
即使我没有找到与Msftedit.dll相关的任何专门针对此错误的主题，我从这些文章（...）中了解到我可能引用了NULL指针，但这对我来说没有意义因为那时我会从SetWindowSubclass函数上面得到错误（我不会这样做）
问题与访问NULL HWND句柄无关。它与访问NULL 对象指针有关。并且您的代码中确实有对象指针，因此您需要确定哪一个是NULL。发生AccessViolation时，使用调试器查看在内存地址0x635F3DEF上运行的代码，这将导致代码中的哪一行崩溃。
话虽如此，EditBoxProc()的最后一个参数需要是DWORD_PTR而不是DWORD，而您传递的是wParam和lParam错误顺序的DefSubclassProc()值。
此外，您的WM_KILLFOCUS和WM_PAINT处理程序不应该调用SetFocus()，并且您的WM_PAINT处理程序不应该调用InvalidateRect()。
我建议您重新编写SearchEditBox课程，以使其数据成员不再是static。在课程中设置static会阻止您使用单个SearchEditBox创建多个HWND个对象。数据成员不必是static。您可以将SearchEditBox*指针作为子类的dwRefData参数传递，以便EditBoxProc()可以访问SearchEditBox对象及其非静态成员。
尝试更像这样的事情：
SearchEditBox.h
#ifndef SearchEditBoxH
#define SearchEditBoxH
class SearchEditBox
{
private:
bool firstPaint;
int width;
int height;
HWND editBox;
SearchEditBox();
void ChangeEdit(const bool change);
static LRESULT CALLBACK EditBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uint_ptr, DWORD_PTR dwRefData);
public:
~SearchEditBox();
HWND getEditBox()
static SearchEditBox* CreateEditBox(HINSTANCE hInst, HWND hwnd, int pos_x, int pos_y, int width, int height);
};
#endif
SearchEditBox.cpp
#include "stdafx.h"
#include <windows.h>
#include <commctrl.h>
#include <richedit.h>
#include <string.h>
#include "SearchEditBox.h"
/*global vars*/
static LPCTSTR editBoxDefText = TEXT("Search...");
SearchEditBox::SearchEditBox()
{
firstPaint = false;
width = 0;
height = 0;
editBox = NULL;
}
SearchEditBox::~SearchEditBox()
{
if (editBox)
DestroyWindow(editBox);
}
void SearchEditBox::ChangeEdit(const bool change)
{
//...
}
HWND SearchEditBox::getEditBox()
{
return editBox;
}
SearchEditBox* SearchEditBox::CreateEditBox(HINSTANCE hInst, HWND hwnd, int pos_x, int pos_y, int width, int height)
{
// make sure RichEdit 4.1 is enabled
if (!GetModuleHandle(TEXT("Msftedit.dll")))
{
if (!LoadLibrary(TEXT("Msftedit.dll")))
{
MessageBox(NULL, L"Problem loading Msftedit.dll.", L"Error", 0);
return 0;
}
}
SearchEditBox *pSearchEditBox = new SearchEditBox;
pSearchEditBox->editBox = CreateWindowEx(0, MSFTEDIT_CLASS, editBoxDefText, WS_VISIBLE | WS_CHILD, pos_x + 6, pos_y + 4, width, height, hwnd, NULL, (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE), p_SearchEditBox);
if (!pSearchEditBox->editBox)
{
delete pSearchEditBox;
MessageBox(NULL, L"Problem creating the Search box.", L"Error", 0);
return 0;
}
if (!SetWindowSubclass(pSearchEditBox->editBox, SearchEditBox::EditBoxProc, 0, (DWORD_PTR)p_SearchEditBox))
{
delete pSearchEditBox;
MessageBox(NULL, L"Problem subclassing the Search box.", L"Error", 0);
return 0;
}
pSearchEditBox->width = width;
pSearchEditBox->height = height;
return pSearchEditBox;
}
LRESULT CALLBACK SearchEditBox::EditBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
SearchEditBox *pSearchEditBox = (SearchEditBox*) dwRefData;
switch (uMsg)
{
case WM_NCDESTROY:
RemoveWindowSubclass(hwnd, SearchEditBox::EditBoxProc, uIdSubclass);
pSearchEditBox->editBox = NULL;
break;
case WM_SIZE:
pSearchEditBox->width = LOWORD(lParam);
pSearchEditBox->height = HIWORD(lParam);
break;
case WM_SETFOCUS:
{
TCHAR getText[10];
GetWindowText(hwnd, getText, 10);
if (_tcscmp(getText, editBoxDefText) == 0)
pSearchEditBox->ChangeEdit(true);
break;
}
case WM_KILLFOCUS:
{
TCHAR getText[10];
if (GetWindowText(hwnd, getText, 10) == 0)
pSearchEditBox->ChangeEdit(false);
break;
}
case WM_LBUTTONDBLCLK:
pSearchEditBox->ChangeEdit(true);
break;
case WM_PAINT:
{
if (!pSearchEditBox->firstPaint)
{
pSearchEditBox->firstPaint = true;
pSearchEditBox->ChangeEdit(false);
}
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hwnd, &ps);
HBRUSH hBrush = CreateSolidBrush(RGB(33, 33, 33));
SelectObject(hdc, hBrush);
RoundRect(hdc, -6, -4, pSearchEditBox->width + 7, pSearchEditBox->height + 4, 5, 5);
EndPaint(hwnd, &ps);
break;
}
}
return DefSubclassProc(hwnd, uMsg, wParam, lParam);
}