I'm working on the WinUI3 desktop application in C++. I was checking how we can get an event when the network to which system is connected to changes. I came across NetworkInformation.NetworkStatusChanged event. But I was not able to find any example of its implementation in C++.
NetworkStatusChangedEventHandler says it has one parameter which is IInspectable object.
i tried
static void NetworkStatusChange(winrt::Windows::Foundation::IInspectable const& sender);
But it gave this error
*\Generated Files\winrt\Windows.Networking.Connectivity.h(2213,81): error C2297: '.*': not valid as right operand has type 'const M'
Can you please help me with help me with how to implement NetworkStatusChanged event in WinUI3 C++ desktop application correctly.
Thank you.
This is how you can do it with C++/WinRT:
add this into the pch.h:
#include <winrt/Windows.Networking.Connectivity.h>
add this somewhere in your code:
// you can instead add a "using namespace Windows::Networking::Connectivity;"
// and use NetworkInformation directly if you prefer
Windows::Networking::Connectivity::NetworkInformation info{};
info.NetworkStatusChanged([=](auto&&...) // sender is not super interesting in this type of event so I've not declared it
{
// do your stuff here
MessageBox(nullptr, L"Something Changed!", L"Network", 0);
});
If you prefer the "raw" C/C++ way, there's an example here: How to detect network change events asynchronously using c++ WinRT
Related
I've got an assignment to create sort of a multi-platform C++ GUI library. It wraps different GUI frameworks on different platforms. The library itself provides an interface via which the user communicates uniformly (using the same code) regardless of the platform he's using - typically it's MFC on Windows and Qt elsewhere.
Currently, I'm stuck on messages/events. So far, I've been using MFC messages and Qt signals to get notified of the user's interaction and had no problems with that. The user creates a list box (which contains p_lb - pointer subclassed QListWidget on Qt or CListBox on MFC) and then he ties his own DoSomething() handler with an event.
User's code:
ListBox lb;
lb.AddDoubleClickHandler([](int i) { DoSomething(i); });
This is what it looks like in the library:
// p_lb represents platform list box - QListWidget/CListBox
// handler's int parameter represents the index of the item, that has been double-clicked
void ListBox::AddDoubleClickHandler(const std::function<void(int)>& handler) {
#ifdef _MFC_PLATFORM
// only pushes the handler into the internal list
p_lb->double_click_handlers_.push_back(handler);
#elif _QT_PLATFORM
p_lb->connect(p_lb, &QListWidget::itemDoubleClicked, p_lb,
[handler, p_lb](QListWidgetItem* item) { handler(p_lb->row(item)); });
#endif
}
In MFC I need to call the handlers stored in the list manually:
#ifdef _MFC_PLATFORM
class MyMFCListBox : public CListBox {
public:
std::list<std::function<void(int)>> double_click_handlers_;
afx_msg void OnItemDoubleClick() {
for (const auto& h : double_click_handlers_) {
h(GetCaretIndex()); // call user's stored handler when the event occurs
}
}
DECLARE_MESSAGE_MAP()
};
BEGIN_MESSAGE_MAP(MyMFCListBox, CListBox)
ON_CONTROL_REFLECT(LBN_DBLCLK, &MyMFCListBox::OnItemDoubleClick)
END_MESSAGE_MAP()
#endif // _MFC_PLATFORM
As I said, this works fine, but now I need to be able to notify UI control about some external event manually (and asynchronously) - using something like MFC's PostMessage. The use case would be something like updating progress bar based on some external computing (which is not necessarily done using this library). E.g. I'm uploading some photos, after each one of them I send a message to the ProgressBar about the current number of uploaded photos and number of all the photos, but I return immediately without waiting for the handler to execute. Also, there needs to be a way of adding new custom events by the user. I know that Qt has a similar method - postEvent, but is this the right way to implement it? Or should I implement my own signal-slot system? I cannot imagine how this would work. Any suggestions are appreciated.
Coming from making single-page applications with the visual WYSISWYG editor in JUCE, I'm having a bit of trouble figuring out how to invoke new windows (outside of the main GUI window). I made a test application that just has a small minimal main GUI that I created with the visual editor. It has a button "Make New Window." My goal is to be able to click that button and have a new window pop up and that this new window is a JUCE "GUI component," (AKA, the graphical / visual GUI editor file). Now, I actually have sort of achieved this, however, its throwing errors and assertions, so it would be great to get a very simple, step-by-step tutorial.
I studied the main.cpp file that the Projucer automatically created in order to get a feel for how they are creating a window. Here's what I did.
1) In my project, I added a new GUI Component (which becomes a class) and called it "InvokedWindow."
2) In my main GUI component class header, I added a new scoped pointer of type InvokedWindow: ScopedPointer<InvokedWindow> invokedWindow;
3) I created a new button in the main GUI editor called "Make New Window" and added this to the handler code:
newWindowPtr = new InvokedWindow; so that any time the button is hit, a new object of type InvokedWindow is created.
4) In the InvokedWindow class, in the constructor, on top of the automatically generated code, I added:
setUsingNativeTitleBar (true);
setCentrePosition(400, 400);
setVisible (true);
setResizable(false, false);
Which I sort of got from the main file of the JUCE application.
I also added a slider to this new window just to add functionality to it.
5) I added an overloaded function to let me close the window:
void InvokedWindow::closeButtonPressed()
{
delete this;
}
So, now when I run the app and click the make new window button, a new window does pop up, but I get an assertion:
/* Agh! You shouldn't add components directly to a ResizableWindow - this class
manages its child components automatically, and if you add your own it'll cause
trouble. Instead, use setContentComponent() to give it a component which
will be automatically resized and kept in the right place - then you can add
subcomponents to the content comp. See the notes for the ResizableWindow class
for more info.
If you really know what you're doing and want to avoid this assertion, just call
Component::addAndMakeVisible directly.
*/
Also, I'm able to close the window once and hit the button in the main GUI to create another instance of a newWindow, but closing it a second time leads to an error:
template <typename ObjectType>
struct ContainerDeletePolicy
{
static void destroy (ObjectType* object)
{
// If the line below triggers a compiler error, it means that you are using
// an incomplete type for ObjectType (for example, a type that is declared
// but not defined). This is a problem because then the following delete is
// undefined behaviour. The purpose of the sizeof is to capture this situation.
// If this was caused by a ScopedPointer to a forward-declared type, move the
// implementation of all methods trying to use the ScopedPointer (e.g. the destructor
// of the class owning it) into cpp files where they can see to the definition
// of ObjectType. This should fix the error.
ignoreUnused (sizeof (ObjectType));
delete object;
}
};
This is all a bit over my head. I was figuring it wouldn't be too bad to be able to create a new window, via a button. A new window that I could edit with the graphical GUI editor, but I'm not able to fully figure it out all on my own, through I did try. Could anyone post a step-by-step guide to doing this the correct way? I did post this at the JUCE forums, but due to my lack of GUI programming, I was unable to understand the solutions posted (my own fault), so I'm hoping to get a very simple guide to this. It would be very much appreciated. Thank you.
I figured it out. I needed to create:
A new GUI component (Remember, this is the visual editor in JUCE)
A class (I called it BasicWindow, based on the JUCE demo code) that acts as a shell to run this new window and holds the GUI component.
A JUCE SafePointer that makes a new object of type BasicWindow whenever the button is clicked and sets the attributes to that window.
Here is my code:
Referring to line 3) Inside the handler section of the button to create the new window:
basicWindow = new BasicWindow("Information", Colours::grey, DocumentWindow::allButtons);
basicWindow->setUsingNativeTitleBar(true);
basicWindow->setContentOwned(new InformationComponent(), true);// InformationComponent is my GUI editor component (the visual editor of JUCE)
basicWindow->centreWithSize(basicWindow->getWidth(), basicWindow->getHeight());
basicWindow->setVisible(true);
Referring to line 2) A .cpp file that defines what the BasicWindow is:
#include "../JuceLibraryCode/JuceHeader.h"
class BasicWindow : public DocumentWindow
{
private:
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (BasicWindow)
public:
BasicWindow (const String& name, Colour backgroundColour, int buttonsNeeded)
: DocumentWindow (name, backgroundColour, buttonsNeeded)
{
}
void closeButtonPressed() override
{
delete this;
}
};
And referring to line 1) Make the GUI editor component, which this is easy to do. You just right add a new file in the JUCE file manager. "Add New GUI Component," then visually add all your elements and handler code.
My biggest issue was that I was using a JUCE ScopedPointer, so after deleting the object, the pointer pointing to it wasn't being set back to NULL. The SafePointer does this. If any more explanation is needed, I'm happy to help, as this was terrible for someone with not much GUI development "under his belt."
Closed:
Thanks everyone for the ideas, will try to work with your provided suggestions so solve my problem!
Problem:
"C++ main" (which CANNOT #include QObject or any Qt lib) gets data, processes the data and passes it into a separate Qt process (Qt GUI in this case).
Data gets visualized within the Qt GUI and provides feedback, e.g. you can send commands to the "C++ main" (like START/STOP MEASUREMENT).
Visualization of the problem in best paint quality.
Question:
Is there any possible way for the "C++ main" to get feedback from the Qt GUI WITHOUT including Qt in "C++ main" in any way? (The "C++ main" runs on an I/O-card which is not able to process/load the Qt lib.)
Thank you in advance for helpful answers!
Without much code on what goes on in your "C++ main" it is difficult to answer. But if you have class with a proper interface that is created in main and then used for the IO you could do something like the following:
class MyIoHandler {
public:
enum Command {START, STOP};
MyIoHandler() {}
void command(Command command) { d_command = command; } // Set the command
void getData(MyData& data) { data = d_data; } // Do a deep copy
private:
void run()
{
while(d_command == START) {
readDataFromIO();
d_data = data;
}
}
Command d_command;
MyData d_data;
};
Then the GUI just need to call the correct functions on the class to interface with the IO handler. There is no need for the main class to know how the GUI looks, but the GUI must know how the class looks.
This is also working on the assumption that they are in the same executable (from the comments) and
You just need to take care about threading etc.
But as mentioned, without some structure or code examples it is very difficult to give a useful answer.
I normally use QUdpSocket (in the Qt world) to talk to my other apps (effectively for IPC). Then your c++ world you can use normal sockets sys/socket.h for the same job. Since your comms is simplistic - i.e. message passing this is quite easy to do. There is some effort creating your c++ / Qt class to handle your UDP, but from then on its really easy.
The main drawback for me is that the two programs have to agree on a port to use (The IP address would be loop back address 127.0.0.1). So you may have a configuration file, or a command line parameter to set this...
Problem
I'm trying to open an MFC program that reads a Microsoft Access database (.mdb) and allows the user to view or modify the data. This is an existing program (and source code) given to me by a group in another lab where the program opens and works just fine.
In our lab, I have yet to see it load properly. When run, it pops up a dialog box that says, "Attempted an unsupported operation". Windows then offers me a chance to debug and such before it crashes.
Environment
In the other lab, they use Windows 7 and Microsoft Office 2010, and it works.
In our lab, I've tried Windows 7 with Office 2013 and Windows XP with Office 2010. The latter crashes without giving me the dialog box. I don't know if we have a Win7/MSO2010 machine.
The Function
I have the source code for the program. The solution file implies it was last developed in VS2010, which the computers I tested on had installed as well. Running it out of Visual Studio 2010 or straight from the executable yields the same results.
I have added additional debug dialog boxes to the code that narrow down the problem to this function call, which the code never gets past:
CwinApp:OpenDocumentFile(LPCTSTR lpszPathName)
The single string passed into the function is a path and filename for the MS Access database to be opened. It exists in a temporary directory created by another program. This is on a drive other than C, though I've tested some there, as well. Problems with programs related to this one often stem from files with "read only" status, but I continually check the temporary files created, and they are write-able.
Documentation
I found this information titled "Breaking Changes in Visual C++" for VS2010 through another SO question:
A new virtual function was added to the CDocTemplate class. This new virtual function is CDocTemplate::OpenDocumentFile. The previous version of OpenDocumentFile had two parameters. The new version has three parameters. To support the restart manager, any class derived from CDocTemplate must implement the version that has three parameters. For more information about the function, see CDocTemplate::OpenDocumentFile. The new parameter is bAddToMRU.
Code
I feel this might be the answer! But I don't have a strong idea of exactly what to change to get this to work. Here's where I stopped:
Program.cpp
CDocument* ProgramApp::OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToLRU, BOOL bMakeVisible)
{
// Add specialized code here and/or call base class
// Debug messages added
CDocument* tempDoc;
AfxMessageBox(lpszFileName);
tempDoc = CWinApp::OpenDocumentFile(lpszFileName, bAddToMRU);
AfxMessageBox("Opened database!");
return tempDoc;
}
Program.h
class ProgramApp : public CWinApp
{
public:
...
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToMRU, BOOL bMakeVisible);
afxwin.h
class CWinApp : public CWinThread
{
...
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName);
virtual CDocument* OpenDocumentFile(LPCTSTR lpszFileName, BOOL bAddToMRU);
Changing the Program.cpp call to be from a "Template" class caused errors, but I wouldn't be surprised if that's towards the answer. This solution looks similar, but I'm not sure exactly what to do.
My hope is that this problem has a simple solution that someone more knowledgeable can give me. I would be much appreciative, and additional context would help a lot.
Edit: Debugging
I drilled down into the Windows code to see what was precisely going wrong. It seemed too dense to understand, but a coworker and I may have clues based on it. The failure message happens here:
dlgdata.cpp
// Could be a windowless OCX
pSite = m_pDlgWnd->GetOldControlSite(nIDC);
if (pSite == NULL)
{
TRACE(traceAppMsg, 0, "Error: no data exchange control with ID 0x%04x.\n", nIDC);
ASSERT(FALSE);
AfxThrowNotSupportedException();
}
...Although we are seeing debugger issues here:
occcont.cpp
COleControlSiteOrWnd *pemp = new COleControlSiteOrWnd(hwndCtrl, pOccDlgInfo->m_pItemInfo[i].bAutoRadioButton);
ASSERT(IsWindow(pTemp->m_hWnd));
if (IsWindow(pTemp->m_hWnd))
{
hwndStart = pTemp->m_hWnd;
...
My coworker believes this could have little to do with the opening of this document as I suspected and more to do with objects/controls we don't have on our lab computers trying to be used for the program.
I have faced the same problem in opendocumentfile(), there was a control in CFormView class which i was not using so i commented it out but forget to delete from .rc file. Once i remove the control entry from .rc file the problem disappear.
there should be no control variable uninitialize , please check that also
Update: Answer: Two normal lines of code required. Thanks Noseratio!
I banged my head on the keyboard for more hours than I would have cared to trying to simulate IEs Ctrl+N behavior in my hosted Browser control app. Unfortunately, due to complications which I've abstracted out of my code examples below, I can't just let IE do Ctlr+N itself. So I have to do it manually.
Keep in mind that I am running a hosted browser. So typically, opening links in new windows will actuall open it within a new "tab" within my application (it's not really a tab, but another window... but appearance-wise it's a tab). However, Ctrl+N is different -- here, it is expected a fully-fledged IE window will launch when pressed.
I think my problem is that of framing the questions -- admittedly I am new to WebBrowser control and I find it to be a lot of yucky. Regardless, I've scoured the Internet for the past day and couldn't come up with an elegant solution.
Basically, the ideal solution would be to call a "NewWindow" function within WebBrowser control or its affiliate libraries; however, all I was able to find where the *On*NewWindow methods, which were event handlers, not event signallers. Which I understand that most of the time, the user will be creating the events... but what about programmatic simulation?
I tried looking into an SENDMESSAGE approach where I could use the IDs that the OnNewWindow events use... that ended up in nothing than crashes. Perhaps I could go back to get it work, but I'd like confirmation is that approach is even worth my time.
The next approach, which should have been the most elegeant, but sadly didn't pan out, was like the following:
Navigate2(GetLocationURL().GetBuffer(), BrowserNavConstants::navOpenInNewWindow);
It would have worked marvelously if it weren't for the fact that the new window would open in the background, blinking in the taskbar. needing clicking to bring it to the front.
I tried to get around the limitation in a myriad of ways, including getting the dispatcher of the current context, then calling OnNewWindow2 with that IDispatch object. Then I would invoke QueryInterface on the dispatch object for an IWebBrowser control. The webBrowser control (presumably under the control of the new window) could then navigate to the page of the original context. However... this too was a pretty messy solution and in the end would cause crashes.
Finally, I resorted to manually invoking JavaScript to get the desired behavior. Really?? Was there really no more elegant a solution to my problem than the below mess of code?
if ((pMsg->wParam == 'N') && (GetKeyState(VK_CONTROL) & 0x8000) && !(GetKeyState(VK_SHIFT) & 0x8000) && !(GetKeyState(VK_MENU) & 0x8000))
{
LPDISPATCH pDisp = CHtmlView::GetHtmlDocument();
IHTMLDocument2 *pDoc;
if (SUCCEEDED(pDisp->QueryInterface(IID_IHTMLDocument2, (void **)&pDoc)))
{
IHTMLWindow2* pWnd;
pDoc->get_parentWindow(&pWnd);
BSTR bStrLang = ::SysAllocString(L"JavaScript");
CString sCode(L"window.open(\"");
sCode.Append(GetLocationURL().GetBuffer());
sCode.Append(L"\");");
BSTR bStrCode = sCode.AllocSysString();
COleVariant retVal;
pWnd->execScript(bStrCode, bStrLang, retVal);
::SysFreeString(bStrLang);
::SysFreeString(bStrCode);
pDoc->Release();
}
pDisp->Release();
I find it hard to believe that I must resort to such hackery as this to get something as simple as opening a new window when the user presses Ctrl+N.
Please stackoverflow, please point out the clearly obvious thing I overlooked.
Ctrl-N in IE starts a new window on the same session. In your case, window.open or webBrowser.Navigate2 will create a window on a new session, because it will be run by iexplore.exe process which is separate from your app. The session is shared per-process, this is how the underlying UrlMon library works. So you'll loose all cookies and authentication cache for the new window. On the other hand, when you create a new window which hosts WebBrowser control within your own app process, you'll keep the session.
If such behavior is OK for your needs, try first your initial Navigate2 approach, precededing it with AllowSetForegroundWindow(ASFW_ANY) call. If the new window still doesn't receive the focus correctly, you can try creating an instance of InternetExplorer.Application out-of-proc COM object, and use the same IWebBrowser2 interface to automate it. Below is a simple C# app which works OK for me, the new window is correctly brought to the foreground, no focus issues. It should not be a problem to do the same with MFC.
using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;
namespace IeApp
{
public partial class MainForm : Form
{
// get the underlying WebBrowser ActiveX object;
// this code depends on SHDocVw.dll COM interop assembly,
// generate SHDocVw.dll: "tlbimp.exe ieframe.dll",
// and add as a reference to the project
public MainForm()
{
InitializeComponent();
}
private void NewWindow_Click(object sender, EventArgs e)
{
AllowSetForegroundWindow(ASFW_ANY);
// could do: var ie = new SHDocVw.InternetExplorer()
var ie = (SHDocVw.InternetExplorer)Activator.CreateInstance(Type.GetTypeFromProgID("InternetExplorer.Application"));
ie.Visible = true;
ie.Navigate("http://www.example.com");
}
const int ASFW_ANY = -1;
[DllImport("user32.dll")]
static extern bool AllowSetForegroundWindow(int dwProcessId);
}
}