[英]Error “Access violation reading location 0x00000008” with msftedit.dll RichEdit control inside SetWindowSubclass
我在單獨的子類文件中有編輯控件。 在開始使用SetWindowSubclass函數之后(我是C ++的新手,以前我使用SetWindowLongPtr進行子類化,但效果很好,但是我被建議開始使用SetWindowSubclass),我遇到了這個問題:
編譯程序后,應用程序將繪制一個空窗口,該窗口立即停止響應(我必須通過任務管理器將其關閉)。 輸出窗口中的結果錯誤:
TaskTracklist.exe中的0x635F3DEF(msftedit.dll)引發異常:0xC0000005:訪問沖突讀取位置0x00000008。
整個代碼:
#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);
}
對我來說很清楚,問題在於SetWindowSubclass函數上的RichEdit控件。
即使我沒有發現與Msftedit.dll有關的與此錯誤有關的任何主題,但從這些文章( 此處 , 此處和此處 )中,我了解到我可能是在引用NULL指針,但這對我來說沒有意義,因為那么我將從SetWindowSubclass函數上方的這一點得到錯誤(我沒有):
if (SearchEditBox::editBox == NULL)
{
delete p_SearchEditBox;
MessageBox(NULL, L"Problem creating the Search box.", L"Error", 0);
return 0;
}
我還認為問題可能出在外部函數(即在comctl32中定義的函數,而不是在內部類中)訪問類特定的變量(指針不會為NULL,但函數無法以某種方式訪問),所以我嘗試創建本地僅用於SetWindowSubclass函數的變量(該函數也不起作用):
HWND newHWND = SearchEditBox::editBox;
SetWindowSubclass(newHWND, SearchEditBox::EditBoxProc, 0, 0);
使用函數getEditBox()也不能解決該問題。
我還嘗試在控件聲明中使用MSFTEDIT_CLASS而不是(L“ RICHEDIT50W”)(認為問題可能在控件本身內部),但這也無濟於事,並且嘗試使用其他版本(例如RICHEDIT51W或RICHEDIT80W)會導致錯誤(因此我必須使用VS2015的正確RichEdit版本)。
我還嘗試在CreateEditBox中聲明HWND editBox(將其設置為局部變量),但這也無濟於事。
我使用VS的免費社區版本。
編輯:從代碼中清除了我未成功嘗試的一些遺留物。
TaskTracklist.exe中的0x635F3DEF(msftedit.dll)引發異常:0xC0000005:訪問沖突讀取位置0x00000008。
地址0附近的訪問沖突通常表示正在通過NULL對象指針訪問類/記錄數據成員。
即使在與Msftedit.dll的連接中未找到與該錯誤相關的任何主題,我仍從這些文章(...)中了解到,我可能是在引用NULL指針,但這對我來說沒有意義,因為那樣我會從SetWindowSubclass函數上方的此位獲取錯誤(我沒有)
該問題與訪問NULL HWND
句柄無關。 它與訪問NULL 對象指針有關 。 而且您的代碼中確實有對象指針,因此您需要確定哪個是NULL。 發生AccessViolation時,請使用調試器查看在內存地址0x635F3DEF上運行的代碼,這將使您進入代碼崩潰的那一行。
話雖如此, EditBoxProc()
的最后一個參數需要是DWORD_PTR
而不是DWORD
,並且您將wParam
和lParam
值以錯誤的順序傳遞給DefSubclassProc()
。
同樣,您的WM_KILLFOCUS
和WM_PAINT
處理程序不應調用SetFocus()
,並且您的WM_PAINT
處理程序不應調用InvalidateRect()
。
我建議您重新編寫SearchEditBox
類,以使其數據成員不再是static
。 在類中將它們設置為static
可防止您使用單個HWND
創建多個SearchEditBox
對象。 數據成員不必是static
。 您可以將SearchEditBox*
指針作為子類的dwRefData
參數傳遞,以便EditBoxProc()
可以訪問SearchEditBox
對象及其非靜態成員。
嘗試更多類似這樣的方法:
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);
}
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