[英]Win32 - Appending text to an Edit Control
嘗試將文本附加到對話框內的編輯控件。 我無法正確追加_tcscat_s。 它崩潰並說一些關於緩沖區太小或關於空終止字符串的事情。
int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow )
{
return DialogBox( hInstance, MAKEINTRESOURCE( IDD_MAIN ), NULL, DlgProc );
}
BOOL CALLBACK DlgProc( HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam )
{
switch( Message )
{
case WM_INITDIALOG:
OpenAndReadFile( hwnd );
return TRUE;
case WM_COMMAND:
switch( LOWORD( wParam ) )
{
case IDSTART:
EndDialog( hwnd, IDSTART );
break;
case IDQUIT:
EndDialog( hwnd, IDQUIT );
break;
}
break;
case WM_CLOSE:
EndDialog( hwnd, 0 );
break;
default:
return FALSE;
}
return TRUE;
}
BOOL OpenAndReadFile( const HWND &hwnd )
{
// Open the file
HANDLE hFile;
hFile = CreateFile( TEXT( "sites.txt" ), // file to open
GENERIC_READ, // open for reading
FILE_SHARE_READ, // share for reading
NULL, // default security
OPEN_EXISTING, // existing file only
FILE_ATTRIBUTE_NORMAL, // normal file
NULL ); // no attr. template
if ( hFile == INVALID_HANDLE_VALUE )
{
SetDlgItemText( hwnd, IDC_OUTPUT, TEXT( "Error: File could not be opened\r\n" ) );
return FALSE;
}
else
SetDlgItemText( hwnd, IDC_OUTPUT, TEXT( "sites.txt opened\r\n" ) );
AppendText( hwnd, TEXT("TEXT") );
// Read data from file
const DWORD BUFFERSIZE = GetFileSize( hFile, NULL );
char *ReadBuffer = new char [BUFFERSIZE]();
DWORD dwBytesRead = 0;
// read one character less than the buffer size to save room for the
// terminate NULL character.
//if ( FALSE == ReadFile( hFile, ReadBuffer, BUFFERSIZE - 1, &dwBytesRead, NULL ) )
{
}
return TRUE;
}
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get size to determine buffer size
int outLength = GetWindowTextLength( GetDlgItem( hwnd, IDC_OUTPUT ) );
// create buffer to hold current text in edit control
TCHAR * buf = ( TCHAR * ) GlobalAlloc( GPTR, outLength + 1 );
// get existing text from edit control and put into buffer
GetDlgItemText( hwnd, IDC_OUTPUT, buf, outLength + 1 );
// append the newText to the buffer
_tcscat_s( buf, outLength + 1, newText );
// Set the text in the dialog
SetDlgItemText( hwnd, IDC_OUTPUT, buf );
}
GetWindowTextLength()
返回文本中TCHAR
元素的數量,但GlobalAlloc()
需要字節數。 如果您正在編譯Unicode,則TCHAR
是2個字節,而不是1個字節,但您沒有考慮到這一點。 您也沒有分配足夠大的緩沖區來保存現有文本和附加的新文本。 您還泄漏了分配的內存。
試試這個:
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get new length to determine buffer size
int outLength = GetWindowTextLength( hwndOutput ) + lstrlen(newText) + 1;
// create buffer to hold current and new text
TCHAR * buf = ( TCHAR * ) GlobalAlloc( GPTR, outLength * sizeof(TCHAR) );
if (!buf) return;
// get existing text from edit control and put into buffer
GetWindowText( hwndOutput, buf, outLength );
// append the newText to the buffer
_tcscat_s( buf, outLength, newText );
// Set the text in the edit control
SetWindowText( hwndOutput, buf );
// free the buffer
GlobalFree( buf );
}
或者:
#include <vector>
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get new length to determine buffer size
int outLength = GetWindowTextLength( hwndOutput ) + lstrlen(newText) + 1;
// create buffer to hold current and new text
std::vector<TCHAR> buf( outLength );
TCHAR *pbuf = &buf[0];
// get existing text from edit control and put into buffer
GetWindowText( hwndOutput, pbuf, outLength );
// append the newText to the buffer
_tcscat_s( pbuf, outLength, newText );
// Set the text in the edit control
SetWindowText( hwndOutput, pbuf );
}
話雖如此,將窗口的當前文本放入內存,附加到它,然后替換窗口的文本是將文本追加到編輯控件的一種非常低效的方法。 請改用EM_REPLACESEL
消息:
void AppendText( const HWND &hwnd, TCHAR *newText )
{
// get edit control from dialog
HWND hwndOutput = GetDlgItem( hwnd, IDC_OUTPUT );
// get the current selection
DWORD StartPos, EndPos;
SendMessage( hwndOutput, EM_GETSEL, reinterpret_cast<WPARAM>(&StartPos), reinterpret_cast<WPARAM>(&EndPos) );
// move the caret to the end of the text
int outLength = GetWindowTextLength( hwndOutput );
SendMessage( hwndOutput, EM_SETSEL, outLength, outLength );
// insert the text at the new caret position
SendMessage( hwndOutput, EM_REPLACESEL, TRUE, reinterpret_cast<LPARAM>(newText) );
// restore the previous selection
SendMessage( hwndOutput, EM_SETSEL, StartPos, EndPos );
}
http://support.microsoft.com/kb/109550
你的答案是:
string buffer = "append this!"
HWND hEdit = GetDlgItem (hDlg, ID_EDIT);
int index = GetWindowTextLength (hEdit);
SetFocus (hEdit); // set focus
SendMessageA(hEdit, EM_SETSEL, (WPARAM)index, (LPARAM)index); // set selection - end of text
SendMessageA(hEdit, EM_REPLACESEL, 0, (LPARAM)buffer.c_str()); // append!
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