I am making a win32 program that is a level editing tool to go with the library I am creating for a 2D tile system.
I want to create dialog box displaying the maps properties when the user selects it from the menu. This means a conversion from int to a wchar_t array. I have created a function that I hoped would do this. However currently it just returns a blank string that the return variable is initialized as. This conversion is necessary to work with the SetDlgItemText() function called by the map properties dialog box.
Here is the function I have currently:
LPWSTR IntToLPWSTR(int value)
{
std::ostringstream convert;
std::string out;
convert << value;
out = convert.str();
const char* in;
in = out.c_str();
LPWSTR ret = L"";
MultiByteToWideChar(CP_ACP, MB_COMPOSITE, in, strlen(in), ret, wcslen(ret));
return ret;
}
It is being called from here:
case WM_INITDIALOG:
if (mapToEdit)
{
SetDlgItemText(hDlg, IDC_TILE_WIDTH_LBL, IntToLPWSTR(mapToEdit->TileWidth()));
SetDlgItemText(hDlg, IDC_TILE_HEIGHT_LBL, L"");
SetDlgItemText(hDlg, IDC_MAP_WIDTH_LBL, L"");
SetDlgItemText(hDlg, IDC_MAP_HEIGHT_LBL, L"");
}
else
{
EndDialog(hDlg, LOWORD(wParam));
MessageBox(hWnd, L"You must create a map first", L"Error", 1);
}
Map to edit is simply a pointer to my own map class that contains the properies I want to display. The bottom three calls to SetDlgItemText() pass L"" as their string, the intention is that they will also use the function when it works.
std::to_wstring is simpler, but to point out the problem in your code, you never created a buffer. LPWSTR ret = L""; makes ret a pointer to an array held in static memory. This array cannot be modified.
Here is one way to fix the code by using std::wstring as the buffer:
std::wstring IntToWstring(int value)
{
std::ostringstream convert;
std::string out;
convert << value;
out = convert.str();
std::wstring ret;
// Find proper length
int length = MultiByteToWideChar(CP_ACP, 0, out.c_str(), out.length(), nullptr, 0);
ret.resize(length);
// Probably should also check for errors (got rid of MB_COMPOSITE flag)
MultiByteToWideChar(CP_ACP, 0, out.c_str(), out.length(), &ret[0], length);
return ret;
}
If you don't want to use std::wstring you could dynamically allocate a buffer LPWSTR ret = new LPWSTR[length];.
EDIT
Also, keep in mind that you could simplify the code to the following:
std::wstring IntToWstring(int value)
{
std::wostringstream convert;
convert << value;
convert.str();
}
You don't need to go to a lot of effort to convert an int into a const wchar_t *. Since C++11, you can take a two-step approach to a std::wstring and a const wchar_t * from there:
SetDlgItemText(hDlg, IDC_TILE_WIDTH_LBL, std::to_wstring(mapToEdit->TileWidth()).c_str());
Sure you could put that into a function to make it one step, but keep in mind that you cannot let the std::wstring be destroyed by the time you use the pointer.
Related
I was wondering if it were possible to take text input from a text box (CreateWindowEx "EDIT") and store it as a string or even better a vector
I need to have a textbox that the user can enter or paste text and when I click a button it will alphabetize the words and count unique words etc...
so far I have it reading it in as characters (i dont know how to make it a string) and alphabetizes the characters
so if I type in: how now brown cow
it will output: bchnnoooorwwww
instead of: brown cow how now
my code under the WM_COMMAND case is
int length;
length = GetWindowTextLength(textbox) + 1;
vector<wchar_t> list(length);
GetWindowText(textbox, &list[0], length);
wstring stxt = &list[0];
wstring str(stxt);
sort(str.begin(), str.end());
SetWindowText(sortedOutput, &str[0]);
This answer may be of use to you in devising a solution. I don't really know of one that is not hacky, but it can be done casting of the constness of c_string() from std::string.
https://stackoverflow.com/a/1986974/128581
A std::string's allocation is not guaranteed to be contiguous under the C++98/03 standard, but C++11 forces it to be. In practice, neither I nor Herb Sutter know of an implementation that does not use contiguous storage.
Notice that the &s[0] thing is always guaranteed to work by the C++11 standard, even in the 0-length string case. It would not be guaranteed if you did str.begin() or &*str.begin(), but for &s[0] the standard defines operator[] as:
Returns: *(begin() + pos) if pos < size(), otherwise a reference to an object of type T with value charT(); the referenced value shall not be modified
Continuing on, data() is defined as:
Returns: A pointer p such that p + i == &operator for each i in [0,size()].
(notice the square brackets at both ends of the range)
Thus it follows you can do something like this:
int len = GetWindowTextLength(hwnd) + 1;
std::string s;
s.reserve(len);
GetWindowText(hwnd, const_cast<char*>(s.c_str()), len - 1);
Which is pretty ugly. Welcome any more "correct" answers, though.
Regarding when unicode is enabled on your build, you have to use a wstring or equivalent. Testing that out just a moment ago, this works:
std::wstring title;
title.reserve(GetWindowTextLength(m_window_handle) + 1);
GetWindowText(m_window_handle, const_cast<WCHAR *>(title.c_str()), title.capacity());
In general, regarding the windows api its useful to google their all caps typedefs and figure out what they really are.
Regarding splitting strings, std::string isn't particular good at this kind of manipulation. This is where std::stringstream (or wstringstream for unicode) comes in handy. I am fairly certain stringstream is not guaranteed to be contiguous in memory, so you can't really go around writing directly into its buffer.
// Initialize a stringstream so we can extract input using >> operator
std::wstringstream ss;
ss.str(title);
// Make a vector, so we can store our words as we're extracting them
// and so we can use sort later, which works on many stl containers
std::vector<std::wstring> words;
std::wstring word;
// This will evaluate to false and thus end the loop when its done
// reading the string word by word
while(ss >> word)
{
words.push_back(word);
}
Then proceed with your sorting, but on the new vector words.
Your problem is not a winapi problem. While not the only way, you found a solution to transfer a string back and forth to your edit box.
How to turn that string into a list/vector of strings, with words being the elements of that list/vector is in fact an STL problem.
Basically, you are looking for the C++ equivalent of the C# function String.Split().
And there is already a good question and answer for that, here:
Most elegant way to split a string?
So, all you have to do is a sort of round trip:
Get string from TextBox
Convert string to a std::vector<string>, using your split function (see the other question for how to do that).
Sort the vector in the usual way.
Convert the vector back to a string, which is the inverse of your split function (Hint: std::ostringstream).
Set the resulting string as the text of your TextBox.
Depending on your preferences regarding multi character strings and globalization, you might decide to stick to the ASCII versions at first. On windows, you can compile to MBCS or ASCII. The respective string types are then respectively (TCHAR and LPCTSTR or WCHAR and LPCWSTR or CHAR and LPCSTR). All win32 functions come in two flavors, distinguished by a trailing A or W at the end of the function name, respectively.
AFAIK, while there is std::string and std::wstring, there is no standard implementation for std::basic_string<TCHAR>, which would work along with your compile options.
As for the window handling, here some code example (snippets):
In InitInstance(), I created the dialog (IDD_FORMVIEW) with my input edit box, my button and my static output area as a child window of the main application window:
//
// FUNCTION: InitInstance(HINSTANCE, int)
//
// PURPOSE: Saves instance handle and creates main window
//
// COMMENTS:
//
// In this function, we save the instance handle in a global variable and
// create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance; // Store instance handle in our global variable
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);
HWND hWndChild = CreateDialogW(hInstance, MAKEINTRESOURCE(IDD_FORMVIEW), hWnd, dlgProc);
if (NULL == hWndChild)
{
DWORD lastError = GetLastError();
wchar_t msg[100];
swprintf_s(msg, _countof(msg), L"error code: 0x%0X\n", lastError);
OutputDebugString(msg);
}
if (!hWnd)
{
return FALSE;
}
ShowWindow(hWnd, nCmdShow);
ShowWindow(hWndChild, SW_SHOW);
UpdateWindow(hWnd);
return TRUE;
}
CreateDialogW() takes as the last parameter a pointer to the dialog handler function, which is called dlgProc() in this example.
This is how that dlgProc() function looks like:
// Message handler for our menu which is a child window of the main window, here.
static INT_PTR CALLBACK dlgProc(
_In_ HWND hwndDlg,
_In_ UINT uMsg,
_In_ WPARAM wParam,
_In_ LPARAM lParam
)
{
BOOL processed = false;
switch (uMsg)
{
case WM_INITDIALOG:
break;
case WM_NOTIFY:
break;
case WM_COMMAND:
{
auto sourceId = LOWORD(wParam);
auto code = HIWORD(wParam);
if (IDC_BUTTON1 == sourceId)
{
if (BN_CLICKED == code)
{
wchar_t text[1024];
GetDlgItemText(hwndDlg, IDC_EDIT1, text, _countof(text));
// TODO: do your string processing here (string -> string)
SetDlgItemText(hwndDlg, IDC_STATIC, text);
processed = TRUE;
}
}
}
break;
default:
break;
}
return processed;
}
I have just mixed a few lines of code to convert wchar_t to wstring to std::string. Here you go!
string GetWindowStringText(HWND hwnd)
{
int len = GetWindowTextLength(hwnd) + 1;
vector<wchar_t> buf(len);
GetWindowText(hwnd, &buf[0], len);
wstring wide = &buf[0];
string s(wide.begin(), wide.end());
return s;
}
This has a vector so you'll need to include it.
I have a vector of thousands of strings:
std::vector<std::wstring> a;
filled with some algorithms.
Following the method described here, here is how I create a ListView as a "virtual list":
hList = CreateWindowEx(0, WC_LISTVIEW, L"", WS_CHILD | WS_VISIBLE | LVS_REPORT | LVS_OWNERDATA, 0, 0, 800, 400, hWnd, (HMENU)ID_LISTVIEW, hInst, NULL);
LV_COLUMN lvcol;
...
ListView_InsertColumn(hList, 0, &lvcol);
ListView_SetItemCountEx(hList, 100000, LVSICF_NOSCROLL);
...
// in the message loop
case WM_NOTIFY:
pdi = (NMLVDISPINFO*) lParam;
pi = pdi->item;
switch (pdi->hdr.code)
{
case LVN_GETDISPINFO:
{
pi.mask = LVIF_TEXT;
pi.pszText = a[pi.iItem]; // the nth item should be the nth string in the vector
}
}
I tried a lot of variations on:
pi.pszText = a[pi.iItem];
but they all failed with such kind of errors:
Error C2440: '=' : cannot convert from 'std::basic_string,std::allocator>' to 'LPWSTR'
What could help to do this?
Note: in fact I would like to display on row n of the ListView : the nth string of vector a concatenated with the number n, like this Blabla217 on the row 217.
Note2: even after Igor's suggestion (i.e. a cast pi.pszText = LPWSTR(a[pi.iItem].c_str());), the ListView is still empty, instead of displaying elements.
I'm not exact sure about the problem you're facing, but one thing for sure, you're passing multi-byte string (std::string, using char) while it is asking for wide-char string (std::wstring, using WCHAR).
Here is a handy code that converts std::string to std::wstring.
inline std::wstring WideFromMulti(
std::string const & multi,
UINT codepage)
{
int cchWide = MultiByteToWideChar(codepage, 0, multi.c_str(), -1, nullptr, 0);
LPWSTR szWide = new wchar_t[cchWide];
MultiByteToWideChar(codepage, 0, multi.c_str(), -1, szWide, cchWide);
std::wstring wide(szWide);
delete[] szWide;
return wide;
}
inline std::wstring WideFromUtf8(
std::string const & utf8)
{
return WideFromMulti(utf8, CP_UTF8);
}
Then you can get LPCWSTR by c_str().
std::string test_str;
std::wstring test_wstr = WideFromUtf8(test_str);
LPCWSTR wszTest = test_wstr.c_str();
What about LPWSTR? Well if you're sure that the string won't get modified, you can cast it by const_cast<LPWSTR>(wszTest). If you're strongly against const_cast, you may create a temporary copy of LPWSTR like this:
std::wstring test(L"Hello world");
LPCWSTR szTestConst = test.c_str();
int cchMax = ::lstrlenW(szTestConst) + 1;
std::vector<WCHAR> v(cchMax);
::lstrcpynW(&v[0], szTestConst, cchMax);
LPWSTR szTest = &v[0];
I don't really know why, but this solved it:
case WM_NOTIFY:
pdi = (NMLVDISPINFO*) lParam;
//pi = pdi->item;
switch (pdi->hdr.code)
{
case LVN_GETDISPINFO:
{
//pi.mask = LVIF_TEXT;
pdi->item.mask = LVIF_TEXT;;
//pi.pszText = a[pi.iItem];
pdi->item.pszText = a[pi.iItem];
}
}
I'm currently trying to get a list of all opened windows and storing them inside a vector. I've been looking at the code so much that the solution could be very easy but I don't seem to get it done without a global variable (which I want to avoid).
Here is the code:
#include "stdafx.h"
#include "json.h"
#include <algorithm>
using namespace std;
vector<string> vec;
BOOL CALLBACK speichereFenster(HWND hwnd, LPARAM substring){
const DWORD TITLE_SIZE = 1024;
TCHAR windowTitle[TITLE_SIZE];
GetWindowText(hwnd, windowTitle, TITLE_SIZE);
int length = ::GetWindowTextLength(hwnd);
wstring temp(&windowTitle[0]);
string title(temp.begin(), temp.end());
if (!IsWindowVisible(hwnd) || length == 0 || title == "Program Manager") {
return TRUE;
}
vec.push_back(title);
return TRUE;
}
int main() {
EnumWindows(speichereFenster, NULL);
cin.get();
return 0;
}
I want to store all titles in the vector but I don't know how as I can't pass the vector into the function...
Thanks!!!
The second parameter (lParam) to EnumWindows is documented as:
An application-defined value to be passed to the callback function.
Just pass your container to the API call:
int main() {
std::vector<std::wstring> titles;
EnumWindows(speichereFenster, reinterpret_cast<LPARAM>(&titles));
// At this point, titles if fully populated and could be displayed, e.g.:
for ( const auto& title : titles )
std::wcout << L"Title: " << title << std::endl;
cin.get();
return 0;
}
And use it in your callback:
BOOL CALLBACK speichereFenster(HWND hwnd, LPARAM lParam){
const DWORD TITLE_SIZE = 1024;
WCHAR windowTitle[TITLE_SIZE];
GetWindowTextW(hwnd, windowTitle, TITLE_SIZE);
int length = ::GetWindowTextLength(hwnd);
wstring title(&windowTitle[0]);
if (!IsWindowVisible(hwnd) || length == 0 || title == L"Program Manager") {
return TRUE;
}
// Retrieve the pointer passed into this callback, and re-'type' it.
// The only way for a C API to pass arbitrary data is by means of a void*.
std::vector<std::wstring>& titles =
*reinterpret_cast<std::vector<std::wstring>*>(lParam);
titles.push_back(title);
return TRUE;
}
Notes:
The code presented uses a std::wstring in place of std::string. This is necessary so that the entire character set can be represented.
As written, the code isn't correct. There are (invisible) code paths, that have no well-defined meaning. The Windows API is strictly exposed as a C interface. As such, it doesn't understand C++ exceptions. Particularly with callbacks it is vital to never let C++ exceptions travel across unknown stack frames. To fix the code apply the following changes:
[C++11 only] Mark the callback noexcept.
Wrap the entire callback inside a try-catch block, and handle any exceptions appropriately.
[C++11 only] With C++11 you can pass C++ exceptions across unknown stack frames, by passing a std::exception_ptr, and calling std::rethrow_exception at the call site.
Simple code to get all visible windows with non empty title
for (HWND hwnd = GetTopWindow(NULL); hwnd != NULL; hwnd = GetNextWindow(hwnd, GW_HWNDNEXT))
{
if (!IsWindowVisible(hwnd))
continue;
int length = GetWindowTextLength(hwnd);
if (length == 0)
continue;
char* title = new char[length+1];
GetWindowText(hwnd, title, length+1);
if (title == "Program Manager")
continue;
std::cout << "HWND: " << hwnd << " Title: " << title << std::endl;
}
I encountered a compilation error in Visual Studio 2015, that I am trying to convert char data to LPWSTR. Can I? Or does it work only with string types?
Here is a piece of my code :
⋮
FILE *sortie;
char fichier[256];// <--- HERE s my char table
int main(int argc, char *argv[])
{
//on masque
HWND hwnd = GetForegroundWindow();
ShowWindow(hwnd, SW_HIDE);
int i, lettre, result, lastresult, lastletter, compteur;
GetCurrentDirectory(256, fichier);
strcat(fichier, "\\fichierlog.txt");
Before posting my question I was at:
https://msdn.microsoft.com/query/dev14.query?appId=Dev14IDEF1&l=EN-US&k=k%28C2664%29&rd=true
C++ cannot convert from enum to LPCTSTR
How to Convert char* to LPWSTR in VC++?
I didn't find my case :(
Instead of your current code:
FILE *sortie;
char fichier[256];// <--- HERE s my char table
int main(int argc, char *argv[])
{
//on masque
HWND hwnd = GetForegroundWindow();
ShowWindow(hwnd, SW_HIDE);
int i, lettre, result, lastresult, lastletter, compteur;
GetCurrentDirectory(256, fichier);
strcat(fichier, "\\fichierlog.txt");
do e.g.
auto main() -> int
{
//on masque
HWND hwnd = GetForegroundWindow();
ShowWindow(hwnd, SW_HIDE);
int i, lettre, result, lastresult, lastletter, compteur;
std::wstring fichier( MAX_PATH, L'\0' );// <--- HERE s my char table
const DWORD len = GetCurrentDirectory( fichier.size(), &fichier[0] );
if( len == 0 || len >= fichier.size() ) { throw std::runtime_error( "GetCurrentDirectory failed." ); }
fichier.resize( len );
fichier += L"/fichierlog.txt";
std::ifstream sortie( fichier );
This should fix three issues:
You're compiling as Unicode (probably a Visual Studio project), but the code is for the Windows ANSI API.
You're using a C++ compiler, but the code is low level C.
Too small buffer for maximum path length, and possible buffer overrun for the concatenation.
Note that the ifstream constructor that accepts a wide string is a Microsoft extension. It will however be practically required for Windows C++ compilers by the file system addition to the standard library in C++17.
You are compiling with unicode, so you have to use wchar_t to declare the strings. Instead of strcat use the unicode version which is wcscat.
Also change the strings "\fichierlog.txt" become L"\fichierlog.txt"
FILE *sortie;
//char fichier[256];// <--- HERE s my char table
wchar_t fichier[256];// <--- HERE s my char table
//on masque
HWND hwnd = GetForegroundWindow();
ShowWindow(hwnd, SW_HIDE);
int i, lettre, result, lastresult, lastletter, compteur;
GetCurrentDirectory(256, fichier);
//strcat(fichier, "\\fichierlog.txt");
wcscat(fichier, L"\\fichierlog.txt");
Your Visual Studio project is set to compile using "widechars" as default encoding (aka UNICODE), so all Windows APIs take wchar_t arrays instead of char arrays when handling strings.
Either set your project to use standard charset or specify the ASCII version of GetCurrentDirectory by using GetCurrentDirectoryA instead.
GetCurrentDirectory is actually not a function, but a pre-processor macro that will route you to GetCurrentDirectoryA or GetCurrentDirectoryW depending on what enconding your compiler is set to use.
I'm trying to store HWND pointers in an int vector along with other data, I'm using the following code to get the data and store it on creation:
void createscalingwindow(HWND &cswpara0,DWORD cswpara1,const CHAR* cswpara2,
const CHAR* cswpara3,DWORD cswpara4,int cswpara5,
int cswpara6,int cswpara7,int cswpara8,HWND cswpara9,
HMENU cswpara10,HINSTANCE cswpara11,LPVOID cswpara12)
{
cswpara0 = CreateWindowEx (cswpara1, cswpara2, cswpara3, cswpara4, cswpara5,
cswpara6,cswpara7,cswpara8,cswpara9,cswpara10,
cswpara11,cswpara12);
sizevalues.push_back((int)&cswpara0);
snprintf (buffer, 20,"%d", sizevalues[zero]);
MessageBox (NULL, buffer, "pointer", NULL);
sizevalues.push_back(cswpara5);
sizevalues.push_back(cswpara6);
sizevalues.push_back(cswpara7);
sizevalues.push_back(cswpara8);
return;
}
This following code is a prototype that currently only shows the values in a messagebox, but I later plan to have it resize child windows to scale with the parent
void scalewindowsize (HWND &ownerwin, HWND &childwin)
{
/*check owner window*/
char buffer[100];
int checknumber = 0;
while (checknumber < sizevalues.size())
{
if (sizevalues[checknumber] == (int)&ownerwin)
{
snprintf (buffer, 100,"%d", sizevalues[checknumber]);
MessageBox (NULL, buffer, "foundit", NULL);
break;
}
snprintf (buffer, 20,"%d", (int)&ownerwin);
checknumber = (checknumber + 5);
MessageBox (NULL, buffer, "fail", NULL);
}
return;
}
The problem is that the first Messagebox in createscalingwindow produces a value of 4235304 while the second one produces an entirely different number (the number varies). Why is this?
UPDATE: Found out part of the cause, in order to reproduce this the HWND used as a parameter to scalewindowsize must be used in a window procedure with the same parameter HWND in that window procedure.
Don't store non-int values in an int vector. That's asking for trouble.
Instead create a class that has fields (with the proper types) for all your values, and create a vector that contains objects of that class.
Your numbers changing is however likely caused by you taking the address of a local variable and using it after the function declaring the variable returns. You should just push the value of the HWND, not the address where it's stored. Handles are plain numbers, so there's no need to pass them by reference, unless you plan to change them in the function (I don't see why you'd need to do that in createscalingwindow either - you could just return the value)