I have a form created in this way (the .h file of form is named Example):
This is a default code from a form:
namespace ExampleNamespace{
public ref class Example : public System::Windows::Forms::Form
{
public:
void DoSomething()
{
// code here
}
};
}
I can to this ?
Creating a new .cpp file and named Example.cpp am put here all the code from the form in .cpp ? In this way don't work.
namespace ExampleNamespace{
public ref class Example : public System::Windows::Forms::Form
{
public:
void DoSomething(); //if i try in this way I will have the error from above
};
}
and in Example.cpp
#include "Example.h"
void Example::DoSomething()
{
//code here
}
If I try to add public: void DoSomething(); in form i have this error:
error LNK2020: unresolved token (060000BB) ExampleNamespace.Example::DoSomething
I got the answer, you need to include the namespace after include the .h file like this in the .cpp file:
#include "Example.h"
using namespace ExampleNamespace;
And in *.h file you need to put this code:
#ifndef _EXAMPLE_H_
#define _EXAMPLE_H_
and
#endif
like this:
#ifndef _EXAMPLE_H_
#define _EXAMPLE_H_
namespace ExampleNamespace{
public ref class Example : public System::Windows::Forms::Form
{
public:
void DoSomething()
{
// code here
}
};
}
#endif
Related
I want to create simple weather station with esp8266 but with scheduler to updating data and GUI more simultaneously. I've downloaded scheduler from here but there is information:
Tasks must be declared globally on the stack (not a pointer). Failure to do so will crash your device
Does that mean that I have to write all task classes in *.ino file? Can I save them in separate files and call to sketch file? How to do that? I've tried few times but the code won't compile.
Simpliest example of sketch:
#include <Scheduler.h>
#include <Arduino.h>
class SimpleTask : public Task {
protected:
void setup() {
Serial.println("Setup func");
}
void loop() {
Serial.println("Loop func");
delay(600);
}
} simple_task;
void setup() {
Serial.begin(115200);
Scheduler.start(&simple_task);
Scheduler.begin();
}
void loop() { }
Tasks must be declared globally on the stack (not a pointer).
I think strictly this means that Tasks must not be created on the heap and need to be global, static objects.
This can be done by creating the object in a separate file and declaring the object using the extern keyword.
e.g. an example mysimpletask.h:
#ifndef __MySIMPLETASK_H__
#define __MySIMPLETASK_H__
#include <Scheduler.h>
class MySimpleTask : public Task {
protected:
void setup();
void loop();
};
extern MySimpleTask my_simple_task;
#endif
The implementation in mysimpletask.cpp:
#include "mysimpletask.h"
void MySimpleTask::setup() {
Serial.println("Setup func");
}
void MySimpleTask::loop() {
Serial.println("Loop func");
delay(600);
}
MySimpleTask my_simple_task;
And the sketch:
#include <Scheduler.h>
#include <Arduino.h>
#include "mysimpletask.h"
void setup() {
Serial.begin(115200);
Scheduler.start(&my_simple_task);
Scheduler.begin();
}
void loop() { }
While making a simple windows forms application with VC++ I have a listview containing some files and their info. What I want to do is only show the filename in the list while storing the full filepath. I created an external class to do this:
class FileInfoContainer {
vector<string> filenames;
vector<int> uncompsize;
vector<int> compsize;
int getFileSize(string filepath);
public:
FileInfoContainer() {};
void AddItem(string filepath);
void AddItem(string filepath, int uncompsize, int compsize);
void AddItem(string filepath, int uncompsize);
string getItemFilename(int index);
int getItemCompsize(int index);
int getItemUncompsize(int index);
};
Now back to the automatic code generated by the VS template for this application, I tried to declare an instance of this class so that I can have the file information available anywhere within:
public ref class MainForm : public System::Windows::Forms::Form
{
public:
MainForm(void)
{
InitializeComponent();
}
protected:
~MainForm()
{
if (components)
{
delete components;
}
}
System::Windows::Forms::ListViewItem^ files; //my addition
FileInfoContainer compfiles; //my addition
private: System::Windows::Forms::OpenFileDialog^ openFileDialog1;
private: System::Windows::Forms::SaveFileDialog^ saveFileDialog1;
...........
}
This is generated code where I've only added those 2 lines, of which the first works normally while the second gives a member of managed class can't be non-managed class type error.
What can I do to go around this issue?
Sorry my bad English first of all.
I just want to use a class globally in my project but i receive some error.
I researched and tried similar titles but didnt work. Maybe i could not do.
code.h
#ifndef CODE_H_
#define CODE_H_
class sinif
{
public: void doSomeThing()
{
/*
...
*/
}
private:
};
sinif A;
#endif
Form1.h
//that is main form
#include "code.h"
#include "b.h"
namespace project
{
/*
...
A.doSomeThing(); // it works
*/
}
b.h
//that is second mini form
#include "code.h"
extern sinif A;
namespace project
{
/*
...
A.doSomeThing(); //it didn't work
*/
}
I have a project where I am expanding existing native C++ compatible code functionality for a customer-facing library by integrating a driver from a managed DLL, which seems like the opposite direction for most marshaling questions. Since there can be multiple devices using this one driver, each device needs to be its own object, with its own callback methods. This integration will take the form of a native wrapper DLL that exposes the native class interface to the customer-facing library, which will pass an instance of a member method callback function pointer to the DLL. I need to pass a native method member instance (non-static) as a delegate to the managed wrapper class. The managed wrapper class uses GetDelegateForFunctionPointer, which works to marshal static native pointers to a delegate, but I can't find any information if it works with instances. GetDelegateForFunctionPointer also takes a System::IntPtr argument for the function pointer, but I'm also not sure if System::IntPtr works for instances, and when compiling in VC++2008 I'm being presented an error C3867 for attempting this.
Managed wrapper header:
//somemanagedclass.hpp
#pragma once
using namespace System;
using namespace ExternalManagedLibrary;
namespace SomeNameSpace
{
public ref class SomeManagedClass
{
public:
SomeManagedClass();
~SomeManagedClass();
delegate void CallbackHandler(const wchar_t*, int);
CallbackHandler^ CallbackEvent;
void RegisterCallback(IntPtr callbackEvent);
private:
ExternalManagedClass^ externalManagedClass;
void OnCallback(Object^ sender, ValueEventArgs<String^>^ e);
};
}
Managed wrapper source:
//somemanagedclass.cpp
#include "somemanagedclass.hpp"
#include <vcclr.h>
using namespace System;
using namespace Runtime::InteropServices;
namespace SomeNameSpace
{
SomeManagedClass::SomeManagedClass()
{
externalManagedClass = gcnew ExternalManagedClass();
externalManagedClass->CallbackEvent += gcnew EventHandler<ValueEventArgs<String^>^>(this, &SomeManagedClass::OnCallback);
}
SomeManagedClass::~SomeManagedClass()
{
externalManagedClass->CallbackEvent -= gcnew EventHandler<ValueEventArgs<String^>^>(this, &SomeManagedClass::OnCallback);
}
void SomeManagedClass::OnCallback(Object^ sender, ValueEventArgs<String^>^ e)
{
String^ some_string = String::Copy(e->Value);
cli::pin_ptr<const wchar_t> pinned_string = &PtrToStringChars(some_string)[0];
const wchar_t* p = pinned_string;
CallbackEvent(pinned_string, some_string->Length);
}
void SomeManagedClass::RegisterCallback(IntPtr callbackEvent)
{
CallbackEvent = (CallbackHandler^)(Marshal::GetDelegateForFunctionPointer(callbackEvent, CallbackHandler::typeid));
}
}
Native wrapper interface:
//somenativeinterface.hpp
#ifdef DLL_EXPORT
#define IMPORT_EXPORT __declspec(dllexport)
#else
#define IMPORT_EXPORT __declspec(dllimport)
#endif //DLL_EXPORT
typedef void (*NativeCallback)(const unsigned char*, unsigned long);
class IMPORT_EXPORT SomeNativeInterface
{
public:
//class factory
static SomeNativeInterface* Create(void);
static void Destroy(SomeNativeInterface* clInterface);
virtual void CallbackInit(NativeCallback fnNativeCallbackInit);
};
Native wrapper header:
//somenativeclass.hpp
#pragma once
#include "somenativeinterface.hpp"
#include "somemanagedclass.hpp"
#include <vcclr.h>
using namespace SomeNameSpace;
class IMPORT_EXPORT SomeNativeClass : public SomeNativeInterface
{
public:
SomeNativeClass();
~SomeNativeClass();
void CallbackInit(NativeCallback fnNativeCallbackInit); //can this take an instance?
private:
NativeCallback fnNativeCallback;
void OnNativeCallback(const wchar_t* cString, int iSize);
gcroot<SomeManagedClass^> wrapper; //warning C4251
};
Native wrapper source:
//somenativeclass.cpp
#include "somenativeclass.hpp"
#include <vcclr.h>
#include <string.h>
using namespace System;
using namespace Runtime::InteropServices;
SomeNativeInterface* SomeNativeInterface::Create()
{
return ((SomeNativeInterface*) new SomeNativeClass());
}
void SomeNativeInterface::Destroy(SomeNativeInterface* instance)
{
delete instance;
}
SomeNativeClass::SomeNativeClass()
{
wrapper = gcnew SomeManagedClass();
}
SomeNativeClass::OnNativeCallback(const wchar_t* cString, int iSize)
{
std::auto_ptr<char> pcConvertedString(new char[iSize+1]);
size_t iCharsConverted;
if (wcstombs_s(&iCharsConverted, (char*)*pcConvertedString, iSize+1, cString, iSize) == 0)
{
if (iCharsConverted > 0xFFFFFFFF)
iCharsConverted = 0xFFFFFFFF; //truncate
fnNativeCallback((const unsigned char*)*pcConvertedString, (unsigned long)(iCharsConverted));
}
}
SomeNativeClass::CallbackInit(NativeCallback fnNativeCallbackInit)
{
fnNativeCallback = fnNativeCallbackInit;
wrapper->RegisterCallback(System::IntPtr(this->OnNativeCallback)); //error C3867
}
I'm using Qt 5.1.0 and QtQuick 2.0.
I've just learned how to exchange data and method between qml and C++. In detail, I want to expose a (nested) structure, so I created classes which contains the required properties and methods.
It works, but I cannot share the very same instance between C++ and qml. Changing something from C++ side leads to no changes in qml side.
A short example:
main.cpp
#include <QtGui/QGuiApplication>
#include <QtQml>
#include "qtquick2applicationviewer.h"
#include "myclass.h"
int main(int argc, char *argv[]) {
QGuiApplication app(argc, argv);
qmlRegisterType<MyClass>("MyLibrary", 1, 0, "MyClass");
MyClass *myclass = new MyClass();
Category *cat = new Category();
cat->setName("foo");
myclass->append(cat);
qDebug() << myclass->categoriesCount(); // returns 1 OK!
QtQuick2ApplicationViewer viewer;
viewer.setMainQmlFile(QStringLiteral("qml/main.qml"));
viewer.show();
return app.exec();
}
myclass.h
#include <QObject>
class Category : public QObject {
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName)
public:
Category() {}
QString name() const { return m_name; }
void setName(QString name) { m_name = name; }
private:
QString m_name;
};
class MyClass : public QObject {
Q_OBJECT
Q_PROPERTY(QList<QObject*> categories READ categories NOTIFY categoriesChanged)
Q_PROPERTY(int categoriesCount READ categoriesCount)
public:
QList<QObject*> categories() const { return m_categories; }
void clear() { m_categories.clear(); }
void append(Category *category) { m_categories.append(category); }
int categoriesCount() const { return m_categories.count(); }
private:
QList<QObject*> m_categories;
signals:
void categoriesChanged();
};
main.qml
import QtQuick 2.0
import MyLibrary 1.0
Item {
id: root
width: 360
height: 360
Text {
id: foo
text: myclass.categoriesCount // writes 0 -> should be 1
}
MyClass {
id: myclass
}
}
I'm afraid the qml engine accesses to a different instance of the class myclass created in the main file.