View source for CPlusPlus for Gideros Studio Help

__TOC__
Here you will find various resources to help learn C++ for people who wish to help with Gideros Studio development.

== WIN32 ==

=== KNOWNFOLDERID ===
platform-win32.cpp

'''refs''':
* KNOWNFOLDERID: https://learn.microsoft.com/en-us/windows/win32/shell/knownfolderid
* shlobj_core.h header: https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/
* SHGetKnownFolderPath function (shlobj_core.h): https://learn.microsoft.com/en-us/windows/win32/api/shlobj_core/nf-shlobj_core-shgetknownfolderpath
* SO (cc-by): https://stackoverflow.com/a/50660989/870125

C:\dev\gideros_hgy29\libgid\src\win32\platform-win32.cpp


=== Convert wstring <-> string ===
platform-win32.cpp

'''refs''':
* SO (cc-by): https://stackoverflow.com/a/18374698/870125

C:\dev\gideros_hgy29\libgid\src\win32\platform-win32.cpp
<syntaxhighlight lang="c++">
#include <locale> // new 20221014 XXX
#include <codecvt> // new 20221014 XXX

...

std::wstring s2ws(const std::string& str)
{
    using convert_typeX = std::codecvt_utf8<wchar_t>;
    std::wstring_convert<convert_typeX, wchar_t> converterX;

    return converterX.from_bytes(str);
}

std::string ws2s(const std::wstring& wstr)
{
    using convert_typeX = std::codecvt_utf8<wchar_t>;
    std::wstring_convert<convert_typeX, wchar_t> converterX;

    return converterX.to_bytes(wstr);
}
</syntaxhighlight>


=== win32 minimum, maximum screen size ===
platform-win32.cpp

'''refs''':
* https://www.youtube.com/watch?v=-kg4TG7GoYI
* https://gamedev.net/forums/topic/569148-c-windows-api-minimum-resize-dimensions/4638297/
* SO (cc-by): https://stackoverflow.com/q/19035481/870125
* SO (cc-by): https://stackoverflow.com/a/22261818/870125
* https://learn.microsoft.com/en-gb/windows/win32/winmsg/wm-getminmaxinfo?redirectedfrom=MSDN
* https://learn.microsoft.com/en-us/windows/win32/api/winuser/nc-winuser-wndproc

C:\dev\gideros_hgy29\libgid\src\win32\platform-win32.cpp
<syntaxhighlight lang="c++">
</syntaxhighlight>


=== win32 LFS problem with separator ===
Recent changes to path handling (most likely [0]) caused
AssetCatalogTest.create_catalog_after_loading_file to fail on WIN32.

The test relied on the resulting path to be joined with "/" as a path
separator. The resulting path used both forward and back-slashes.
While these do work for some API's on WIN32, mixing both in a file path
isn't expected behavior in most cases, so update the tests to use native
slash direction for file-paths.

<syntaxhighlight lang="c++">
 * \note If you want a trailing slash, add `SEP_STR` as the last path argument,
 * duplicate slashes will be cleaned up.
 */
size_t BLI_path_join(char *__restrict dst, size_t dst_len, const char *path, ...)
#  define SEP '\\'
#  define ALTSEP '/'
#  define SEP_STR "\\"
#  define ALTSEP_STR "/"
#else
#  define SEP '/'
</syntaxhighlight>

<syntaxhighlight lang="c++">
#define SEP_CHR     '#'
#define SEP_STR     "#"

#define EPS 0.001

#define UN_SC_KM    1000.0f
#define UN_SC_HM    100.0f
      str_tmp, TEMP_STR_SIZE, "*%.9g" SEP_STR, unit->scalar / scale_pref);

  if (len_num > len_max) {
    len_num = len_max;
  }

  if (found_ofs + len_num + len_move > len_max) {
</syntaxhighlight>


=== openFileDialog ===
platform-win32.cpp

'''refs''':
* '''https://learn.microsoft.com/en-us/windows/win32/learnwin32/learn-to-program-for-windows'''
* '''https://weblogs.asp.net/kennykerr/Windows-Vista-for-Developers-_1320_-Part-6-_1320_-The-New-File-Dialogs'''
* '''https://www.codeproject.com/Articles/16678/Vista-Goodies-in-C-Using-the-New-Vista-File-Dialog'''
* '''https://learn.microsoft.com/en-us/windows/win32/shell/common-file-dialog'''
<syntaxhighlight lang="c++">
#include <wchar.h> // new 20221026 XXX
...
        }else if ((strcmp(what, "openDirectoryDialog") == 0)
                || (strcmp(what, "openFileDialog") == 0)
                || (strcmp(what, "saveFileDialog") == 0))
        {
        	/* TODO parse extension :-( */
            // for win32 args ("title|path|extensions//help") is only 1 arg
            // unlike Qt which seems to cut the | into different args
            if(args.size() == 1){ // do we need to deal with "help" as arg or leave it to Qt?
                // we cut the args
                std::wstring s=ws(args[0].s.c_str()); // "Title|c:\\tmp|Text (*.txt);; Image (*.png)"
                size_t index = s.find(L"|");
                size_t index2 = s.find(L"|", index+1);
                std::wstring title = s.substr(0, index);
                std::wstring place = s.substr(index+1, index2-index-1);
                std::wstring extension = s.substr(index2+1);
//                printf("t p e:\n %ls\n %ls\n %ls\n", title.c_str(),place.c_str(),extension.c_str()); // TEST OK

                DWORD dwFlags; // new 20221028 XXX
                HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);
                if (SUCCEEDED(hr))
                {
                    if (strcmp(what, "openDirectoryDialog") == 0){
                        /* TO DO */
                        /*--------------------------------------------------*/
                    }else if (strcmp(what, "openFileDialog") == 0){
                        IFileOpenDialog *pFile;
                        COMDLG_FILTERSPEC fileTypes[] = /* TODO parse from wstring extension :-( */
                        {
                            { L"Text Documents", L"*.txt" },
                            { L"All Files", L"*.*" },
                        };

                        // Create the FileOpenDialog object.
                        hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_ALL, 
                                IID_IFileOpenDialog, reinterpret_cast<void**>(&pFile));
                        if (SUCCEEDED(hr))
                        {
                            // get/set options
                            pFile->GetOptions(&dwFlags);
                            pFile->SetOptions(dwFlags | FOS_FORCEFILESYSTEM);
                            pFile->SetFileTypes(ARRAYSIZE(fileTypes), fileTypes); // SEE ABOVE fileTypes
                            pFile->SetFileTypeIndex(1); // index starts at 1
//                            pFile->SetDefaultExtension(L"obj;fbx"); // XXX
                            hr = pFile->SetTitle(title.c_str()); // need more check?

                            // set starting folder
                            IShellItem *pItem = NULL;
                            hr = SHCreateItemFromParsingName(place.c_str(), NULL, IID_IShellItem, (LPVOID *)&pItem);
                            if (SUCCEEDED(hr))
                            {
                                pFile->SetFolder(pItem);
                                pItem->Release();
                                pItem = NULL;
                            }

                            // Show the Open dialog box.
                            hr = pFile->Show(NULL);
                            // Get the file name from the dialog box.
                            if (SUCCEEDED(hr))
                            {
                                IShellItem *pItem;
                                hr = pFile->GetResult(&pItem);
                                if (SUCCEEDED(hr))
                                {
                                    PWSTR pszFilePath;
                                    hr = pItem->GetDisplayName(SIGDN_FILESYSPATH, &pszFilePath);
                                    if (SUCCEEDED(hr))
                                    {
                                        r.type=gapplication_Variant::STRING;
                                        r.s=us(pszFilePath);
                                        rets.push_back(r);

                                        CoTaskMemFree(pszFilePath);
                                    }
                                    pItem->Release();
                                }
                            }
                            pFile->Release();
                        }
                        CoUninitialize();
                        /*--------------------------------------------------*/
                    }else if (strcmp(what, "saveFileDialog") == 0){
                        /* TO DO */
                        /*--------------------------------------------------*/
                    }
                }
            }
            /*------------------------------------------------------------------*/
        }else if (strcmp(what, "temporaryDirectory") == 0)
</syntaxhighlight>

=== openFileDialog Latest ===
platform-win32.cpp ('''updated and working piece of code''')

'''Added''':
* append file extension to saved files (1st extension from filters)

<syntaxhighlight lang="c++">
        }else if ((strcmp(what, "openDirectoryDialog") == 0)
                || (strcmp(what, "openFileDialog") == 0)
                || (strcmp(what, "saveFileDialog") == 0))
            {
            if(args.size() <= 2){
                /* INFO SHOWN IN GIDEROS STUDIO DEBUGGER, IMPLEMENTED IN QT, NOT NEEDED HERE? */
            }
            else
            {
                std::wstring title = ws(args[0].s.c_str());
                std::wstring place = ws(args[1].s.c_str());
                std::vector<std::pair<std::wstring,std::wstring>> filters;
                if (args.size()>=3) {
                	std::wstring ext = ws(args[2].s.c_str());
                	while (!ext.empty()) {
                    	std::wstring next;
                		size_t semicolon=ext.find(L";;");
                		if (semicolon!=std::wstring::npos) {
                			next=ext.substr(semicolon+2);
                			ext=ext.substr(0,semicolon);
                		}
                		size_t p1=ext.find_first_of(L'(');
                		size_t p2=ext.find_last_of(L')');
                		if ((p1!=std::wstring::npos)&&(p2!=std::wstring::npos)&&(p2>p1))
                		{
                			//Valid filter, extract label and extensions
                			std::wstring label=ext.substr(0,p1);
                			std::wstring exts=ext.substr(p1+1,p2-p1-1);
                			//QT uses space for extensions separator, while windows expects semicolon. Convert them.
                			std::replace(exts.begin(),exts.end(),L' ',L';');
                			filters.push_back(std::pair<std::wstring,std::wstring>(label,exts));
                		}
                		ext=next;
                	}
                }

                DWORD dwFlags;
                HRESULT hr = CoInitializeEx(NULL, COINIT_APARTMENTTHREADED | COINIT_DISABLE_OLE1DDE);
                if (SUCCEEDED(hr))
                {
                    COMDLG_FILTERSPEC *fileTypes=new COMDLG_FILTERSPEC[filters.size()];
                    for (size_t i=0;i<filters.size();i++) {
                    	fileTypes[i].pszName=filters[i].first.c_str();
                    	fileTypes[i].pszSpec=filters[i].second.c_str();
                    }
                    IFileDialog *pFile;
					if (strcmp(what, "saveFileDialog") == 0)
                        hr = CoCreateInstance(CLSID_FileSaveDialog, NULL, CLSCTX_ALL,
                                IID_IFileSaveDialog, reinterpret_cast<void**>(&pFile));
					else
                        hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_ALL,
                                IID_IFileOpenDialog, reinterpret_cast<void**>(&pFile));
					if (SUCCEEDED(hr))
					{
						bool isFolder=(strcmp(what, "openDirectoryDialog") == 0);
						// get/set options
						pFile->GetOptions(&dwFlags);
						pFile->SetOptions(dwFlags | FOS_FORCEFILESYSTEM | (isFolder?FOS_PICKFOLDERS:0));
						if (!isFolder) {
							pFile->SetFileTypes(filters.size(), fileTypes);
							pFile->SetFileTypeIndex(1); // index starts at 1
							//pFile->SetDefaultExtension(L"obj;fbx"); // append default extension
                            //printf("* fileTypes *, set default extension to %ls\n", fileTypes[0].pszSpec); OK
							pFile->SetDefaultExtension(fileTypes[0].pszSpec); // append default 1st extension
						}
						hr = pFile->SetTitle(title.c_str()); // need more check?

						// set starting folder
						IShellItem *pItem = NULL;
						hr = SHCreateItemFromParsingName(place.c_str(), NULL, IID_IShellItem, (LPVOID *)&pItem);
						if (SUCCEEDED(hr))
						{
							pFile->SetFolder(pItem);
							pItem->Release();
							pItem = NULL;
						}

						// Show the Open dialog box.
						hr = pFile->Show(NULL);
						// Get the file name from the dialog box.
						if (SUCCEEDED(hr))
						{
							IShellItem *pItem;
							hr = pFile->GetResult(&pItem);
							if (SUCCEEDED(hr))
							{
								PWSTR pszFilePath;
								hr = pItem->GetDisplayName(SIGDN_FILESYSPATH, &pszFilePath);
								if (SUCCEEDED(hr))
								{
									r.type=gapplication_Variant::STRING;
									r.s=us(pszFilePath);
									rets.push_back(r);

									CoTaskMemFree(pszFilePath);
								}
								pItem->Release();
							}
						}
						pFile->Release();
					}
	                CoUninitialize();
	                delete[] fileTypes;
                }
            }
            /*------------------------------------------------------------------*/
        }else if (strcmp(what, "temporaryDirectory") == 0)
</syntaxhighlight>


=== Locate first occurrence of character in wide string ===
platform-win32.cpp

'''refs''':
* https://cplusplus.com/reference/cwchar/wcschr/
* https://cplusplus.com/reference/string/string/find/
<syntaxhighlight lang="c++">
std::wstring gs=ws(args[0].s.c_str()); // "Title|C:/tmp/|Text (*.txt);; Image (*.png)"
size_t index = gs.find(L"|");
size_t index2 = gs.find(L"|", index+1);
printf("args0: %ls\n", gs.c_str()); // output: Title|C:/tmp/|Text (*.txt);; Image (*.png)
printf("indices: %d, %d\n", index,index2); // output 5, 13
std::wstring title = gs.substr(0, index);
std::wstring path = gs.substr(index+1, index2-index-1);
std::wstring exts = gs.substr(index2+1);
printf("t p e:\n %ls\n %ls\n %ls\n", title.c_str(),path.c_str(),exts.c_str()); // Title C:/tmp/ Text (*.txt);; Image (*.png)
</syntaxhighlight>


=== application:getKeyboardModifiers() ===
'''refs''':
* https://learn.microsoft.com/en-us/windows/win32/inputdev/about-keyboard-input#key-status
* https://learn.microsoft.com/en-us/windows/win32/inputdev/about-keyboard-input#keystroke-message-flags
* SO (cc-by): https://stackoverflow.com/questions/1811206/on-win32-how-to-detect-whether-a-left-shift-or-right-alt-is-pressed-using-perl
<syntaxhighlight lang="c++">
if(GetAsyncKeyState(VK_LSHIFT) & 0x8000)
    ; // left shift is currently down
</syntaxhighlight>

*'''\libgid\src\win32\platform-win32.cpp'''
<syntaxhighlight lang="c++">
int getKeyboardModifiers()
{
	int m=0;
	if (GetKeyState(VK_CONTROL) & 0x8000) m|=GINPUT_CTRL_MODIFIER;
	if (GetKeyState(VK_SHIFT) & 0x8000) m|=GINPUT_SHIFT_MODIFIER;
	if (GetKeyState(VK_MENU) & 0x8000) m|=GINPUT_ALT_MODIFIER;
	return m;
}
</syntaxhighlight>
*'''\win32_example\win32.cpp'''
<syntaxhighlight lang="c++">
  else if ((iMsg==WM_KEYDOWN)||(iMsg==WM_SYSKEYDOWN)) {
		int m=0;
		if (GetKeyState(VK_CONTROL) & 0x8000) m|=GINPUT_CTRL_MODIFIER;
		if (GetKeyState(VK_SHIFT) & 0x8000) m|=GINPUT_SHIFT_MODIFIER;
		if (GetKeyState(VK_MENU) & 0x8000) m|=GINPUT_ALT_MODIFIER;
		if (!(lParam&0x40000000)) // don't send repeated keys XXX
			ginputp_keyDown(wParam,m);
		if ((iMsg==WM_KEYDOWN)||(wParam==VK_F10))
			return 0;
  }
  else if ((iMsg==WM_KEYUP)||(iMsg==WM_SYSKEYUP)) {
		int m=0;
		if (GetKeyState(VK_CONTROL) & 0x8000) m|=GINPUT_CTRL_MODIFIER;
		if (GetKeyState(VK_SHIFT) & 0x8000) m|=GINPUT_SHIFT_MODIFIER;
		if (GetKeyState(VK_MENU) & 0x8000) m|=GINPUT_ALT_MODIFIER;
		ginputp_keyUp(wParam,m);
		return 0;
  }
</syntaxhighlight>

''GetKeyState'' is for messages when you need the state at the time the message was sent.

''GetAsyncKeyState'' is for the state right now.

The high bit will be set if it's down, and it returns a short, hence the 1000000000000000, or ''0x8000'' mask

* https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getkeystate
* https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getasynckeystate


'''Notes''':</br>
''wparam'' contains the virtual key code, ''lparam'' contains the the key state vector.

=== mkDir ===
platform-win32.cpp

'''Tested and seems ok :-)'''

'''refs''':
* '''https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/mkdir-wmkdir?view=msvc-170'''
<syntaxhighlight lang="c++">
        }else if (strcmp(what, "mkDir") == 0)
        {
            // new 20221114 XXX
            std::wstring dir = ws(args[0].s.c_str());
            if (_wmkdir(dir.c_str()) == 0)
                printf("mkDir OK: %S\n", dir.c_str()); // can be useful for the w32 console
            else
                printf("mkDir failed or Dir may already exist: %S\n", dir.c_str()); // can be useful for the w32 console
            /*------------------------------------------------------------------*/
        }else if (strcmp(what, "documentDirectory") == 0)
</syntaxhighlight>


=== pathfileexists ===
platform-win32.cpp

'''Tested and seems ok but not sure about what the return value should be :-/ and we can also check for access mode!'''

'''refs''':
* SO (cc-by): https://stackoverflow.com/a/28011583/870125
* https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/access-waccess?view=msvc-170
<syntaxhighlight lang="c++">
        }else if (strcmp(what, "pathfileexists") == 0) // new 20221116 XXX
        {
            if (args.size() > 0) {
                std::wstring path = ws(args[0].s.c_str());
                int retValue;
                if (_waccess(path.c_str(), 0) == 0) { // modes: 0=Existence only, 2=Write-only, 4=Read-only, 6=Read and write
                    // path exists
                    retValue = 1;
                } else {
                    retValue = 0;
                }
                r.type=gapplication_Variant::DOUBLE;
                r.d=retValue;
                rets.push_back(r);
            }
            /*------------------------------------------------------------------*/
        }else if ((strcmp(what, "openDirectoryDialog") == 0)
</syntaxhighlight>

=== pathfileexists Qt ===
platform-qt.cpp

QFile Class seems to be "kind of" the equivalent?

'''refs''':
* https://doc.qt.io/qt-6/qfile.html

bool '''QFile::exists'''(const QString &fileName)
Returns true if the file specified by fileName exists; otherwise returns false.
Note: If fileName is a symlink that points to a non-existing file, false is returned.

I will need to mix this and _waccess.

=== WM_GETMINMAXINFO ===
win32.cpp

'''WIP'''

'''refs''':
* SO (cc-by): https://stackoverflow.com/questions/22261804/how-to-set-minimum-window-size-using-winapi
* https://learn.microsoft.com/en-gb/windows/win32/winmsg/wm-getminmaxinfo?redirectedfrom=MSDN
<syntaxhighlight lang="c++">
</syntaxhighlight>


=== LoadCursorA ===
platform-win32.cpp

'''WIP'''

'''refs''':
* SO (cc-by): https://stackoverflow.com/questions/19257237/reset-cursor-in-wm-setcursor-handler-properly
* https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-loadcursora
<syntaxhighlight lang="c++">
    else { // SET
        if (strcmp(what, "cursor") == 0)
        {
        	/* TODO */
            std::string &shape = args[0].s;
//            QStringList acceptedValue;
//            acceptedValue << "arrow" << "upArrow" << "cross" << "wait" << "IBeam";
//            acceptedValue << "sizeVer" << "sizeHor" << "sizeBDiag" << "sizeFDiag" << "sizeAll";
//            acceptedValue << "blank" << "splitV" << "splitH" << "pointingHand" << "forbidden";
//            acceptedValue << "whatsThis" << "busy" << "openHand" << "closedHand" << "dragCopy";
//            acceptedValue << "dragMove" << "dragLink";
            HCURSOR cursor;
            if (shape == "arrow") {
                printf("** cursor arrow\n");
                cursor = LoadCursorA(NULL, (LPCSTR)IDC_ARROW);
                SetCursor(cursor);
            } else if (shape == "upArrow") {
                printf("** cursor uparrow\n"); // LUA DEBUG OK BUT ARROW SHAPE DOESN'T CHANGE :-(
                cursor = LoadCursorA(NULL, (LPCSTR)IDC_UPARROW);
                SetCursor(cursor);
            }
            /*------------------------------------------------------------------*/
        }else if (strcmp(what, "windowPosition") == 0)
</syntaxhighlight>

=== modal windows dialog ===
'''Test01'''

'''refs''':
*'''https://learn.microsoft.com/en-us/windows/win32/dlgbox/using-dialog-boxes#creating-a-modeless-dialog-box'''
*'''https://learn.microsoft.com/en-us/windows/win32/api/olectl/nf-olectl-olecreatepropertyframe#remarks'''

C:\dev\gideros_dev\libgid\src\win32\platform-win32.cpp
<syntaxhighlight lang="c++">
                    COMDLG_FILTERSPEC *fileTypes=new COMDLG_FILTERSPEC[filters.size()];
                    for (size_t i=0;i<filters.size();i++) {
                    	fileTypes[i].pszName=filters[i].first.c_str();
                    	fileTypes[i].pszSpec=filters[i].second.c_str();
                    }
                    IFileDialog *pFile;
					if (strcmp(what, "saveFileDialog") == 0)
//                        hr = CoCreateInstance(CLSID_FileSaveDialog, NULL, CLSCTX_ALL,
//                                IID_IFileSaveDialog, reinterpret_cast<void**>(&pFile));
                        hr = CoCreateInstance(CLSID_FileSaveDialog, hwndcopy, CLSCTX_ALL,
                                IID_IFileSaveDialog, reinterpret_cast<void**>(&pFile));
					else
//                        hr = CoCreateInstance(CLSID_FileOpenDialog, NULL, CLSCTX_ALL,
//                                IID_IFileOpenDialog, reinterpret_cast<void**>(&pFile));
                        hr = CoCreateInstance(CLSID_FileOpenDialog, hwndcopy, CLSCTX_ALL,
                                IID_IFileOpenDialog, reinterpret_cast<void**>(&pFile));
					if (SUCCEEDED(hr))
					{
</syntaxhighlight>

== CBUMP ==

=== the TODOs ===
bump.cpp

<syntaxhighlight lang="c++">
static bool rect_getSegmentIntersectionIndices(double x, double y, double w,
		double h, double x1, double y1, double x2, double y2, double &ti1,
		double &ti2, double &nx1, double &ny1, double &nx2, double &ny2) {
	//ti1, ti2 = ti1 or 0, ti2 or 1 TODO
	double dx = x2 - x1;
	double dy = y2 - y1;
...
</syntaxhighlight>

<syntaxhighlight lang="c++">
static bool rect_detectCollision(double x1, double y1, double w1, double h1,
		double x2, double y2, double w2, double h2, double goalX, double goalY,
		Collision &col) {
	//goalX = goalX or x1 TODO
	//goalY = goalY or y1

	double dx = goalX - x1, dy = goalY - y1;
...
</syntaxhighlight>
It is time to do the TODOs ;-)


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