Signals and slots or whatever

[jrod2much]

@VRonin said in Signals and slots or whatever:

If you remove the connect you get no such error, correct?

correct

[VRonin]

1st try, move the connect as the very last line in the function. if that isn't enough then you have to find out where m_interpreter->m_renderer and m_ui->textBrowser are created and connect after they are created

[jsulm]

@jrod2much said in Signals and slots or whatever:

QObject::connect: Cannot connect (null)::Rvalues(QString) to QTextBrowser::setText(QString)

You're using a nullptr to connect, this can't work. The sender object was not created.

[jrod2much]

@jsulm Is this what you are talking about:

#include "console.h"
#include "interpreter.h"
#include "chirpmon.h"
#include "dfu.h"
#include "flash.h"
#include "ui_mainwindow.h"
#include "configdialog.h"
#include "dataexport.h"
#include "sleeper.h"
#include "aboutdialog.h"
#include "parameters.h"
#include "paramfile.h"
#include <QTextBrowser>
#include "renderer.h"

extern ChirpProc c_grabFrame;

MainWindow::MainWindow(int argc, char *argv[], QWidget *parent) :
    QMainWindow(parent),
    m_ui(new Ui::MainWindow)
{
    QCoreApplication::setOrganizationName(PIXYMON_COMPANY);
    QCoreApplication::setApplicationName(PIXYMON_TITLE);

    qRegisterMetaType<Device>("Device");

    m_ui->setupUi(this);
    setWindowTitle(PIXYMON_TITLE);

    m_interpreter = NULL;
    connect(m_interpreter->m_renderer,&Renderer::Rvalues,m_ui->textBrowser,&QTextBrowser::setText);
    m_flash = NULL;
    m_renderer = NULL;  //<-------------------------This?
    m_pixyConnected = false;
    m_pixyDFUConnected = false;
    m_configDialog = NULL;
    m_fwInstructions = NULL;
    m_fwMessage = NULL;
    m_versionIncompatibility = false;
    m_testCycle = false;
    m_waiting = WAIT_NONE;

    parseCommandline(argc, argv);

    m_settings = new QSettings(QSettings::NativeFormat, QSettings::UserScope, PIXYMON_COMPANY, PIXYMON_TITLE);
    m_console = new ConsoleWidget(this);
    m_video = new VideoWidget(this);
    connect(m_video, SIGNAL(mouseLoc(int,int)), this, SLOT(handleMouseLoc(int, int)));

    m_ui->imageLayout->addWidget(m_video);
    m_ui->imageLayout->addWidget(m_console);

    // hide console
    m_showConsole = m_testCycle;
    m_console->setVisible(m_testCycle);
    m_ui->actionConsole->setChecked(m_testCycle);

    m_ui->toolBar->addAction(m_ui->actionPlay_Pause);

    m_ui->actionDefault_program->setIcon(QIcon(":/icons/icons/home.png"));
    m_ui->toolBar->addAction(m_ui->actionDefault_program);

    m_ui->actionRaw_video->setIcon(QIcon(":/icons/icons/raw.png"));
    m_ui->toolBar->addAction(m_ui->actionRaw_video);

    m_ui->actionConfigure->setIcon(QIcon(":/icons/icons/config.png"));
    m_ui->toolBar->addAction(m_ui->actionConfigure);

    m_ui->menuProgram->setToolTipsVisible(true);

    m_statusLeft = new QLabel;
    m_statusRight = new QLabel;
    // give the status a little of a left margin
    m_ui->statusBar->setContentsMargins(6, 0, 0, 0);
    m_ui->statusBar->addWidget(m_statusLeft);
    m_ui->statusBar->addPermanentWidget(m_statusRight);
    updateButtons();

    m_parameters.add("Pixy start command", PT_STRING, "",
        "The command that is sent to Pixy upon initialization");

    // start looking for devices
    m_connect = new ConnectEvent(this);
    if (m_connect->getConnected()==NONE)
        error("No Pixy devices have been detected.\n");

    //  <---My added expermiental code ------v
    //connect(m_renderer,SIGNAL(Rvalues(QString)), m_ui->textBrowser, SLOT(setText(QString)));
   // connect(m_interpreter->m_renderer,&Renderer::Rvalues,m_ui->textBrowser,&QTextBrowser::setText);

}

[VRonin]

ok. stop a second and think.
What are you doing here?

m_interpreter = NULL;
connect(m_interpreter->m_renderer

[jrod2much]

@VRonin said in Signals and slots or whatever:

m_interpreter = NULL;
connect(m_interpreter->m_renderer

I'm not really sure what this means. This is my interpretation of the code; The application runs without my connect function or any other alteration to the code. So, I would guess it would be a bad idea to create an object where the original Programmers of this code did not. Wouldn't that affect the program? That is my uneducated opinion.

[JKSH]

@jrod2much said in Signals and slots or whatever:

I'm not really sure what this means.

Let's simplify it further.

m_interpreter = NULL;
m_interpreter->m_renderer

Line 1: You make m_interpreter a null pointer.
Line 2: You dereference the null pointer.

What do you think will happen when you dereference a null pointer?

Note: This is a very important, fundamental concept in C++. If it's unclear to you, I highly recommend you spend some time learning C++ first, before you attempt to modify a complex application.

[jrod2much]

@JKSH Alright so I read up on the subject and I think I understand. A null pointer does not point to an address so it can't be dereferenced. I also found this video that made me feel stupid.
https://www.youtube.com/watch?v=bLHL75H_VEM

Alright so what is my next step. Should I eliminate the two lines of code that make m_interpreter and m_renderer NULL? or do I have to point it to a specific address value?

[jrod2much]

@JKSH @VRonin @jsulm @J-Hilk
GUYS WE DID IT!!!!!!!!!!!!! ITS OUTPUTING THE VALUES!!!!

I searched the code for the whatever you call it when you make a new object and placed the connect function that @VRonin gave me there and BOOM

...
  }
                    dir = fd.directory().absolutePath();
                    m_settings->setValue("fw_dialog", QVariant(dir));
                }
            }
            else if (m_interpreter==NULL)
            {
                m_console->clear();
                m_console->print("Pixy detected.\n");

                m_interpreter = new Interpreter(m_console, m_video, &m_parameters, m_initScript);

                connect(m_interpreter->m_renderer,&Renderer::Rvalues,m_ui->textBrowser,&QTextBrowser::setText); //Added

                connect(m_interpreter, SIGNAL(error(QString)), this, SLOT(error(QString)));
                connect(m_interpreter, SIGNAL(textOut(QString,uint)), this, SLOT(handleText(QString,uint)));
                connect(m_interpreter, SIGNAL(runState(int,QString)), this, SLOT(handleRunState(int,QString)));
                connect(m_interpreter, SIGNAL(finished()), this, SLOT(interpreterFinished())); // thread will send finished event when it exits
                connect(m_interpreter, SIGNAL(connected(Device,bool)), this, SLOT(handleConnected(Device,bool)));
                connect(m_interpreter, SIGNAL(actionScriptlet(QString,QStringList,bool)), this, SLOT(handleActionScriptlet(QString,QStringList,bool)));
                connect(m_interpreter, SIGNAL(view(QString,uint,bool,bool)), this, SLOT(handleView(QString,uint,bool,bool)));
                connect(m_interpreter, SIGNAL(prog(QString,QString,uint,bool)), this, SLOT(handleProg(QString,QString,uint,bool)));
                connect(m_interpreter, SIGNAL(paramLoaded()), this, SLOT(handleLoadParams()));
                connect(m_interpreter, SIGNAL(paramChange()), this, SLOT(handleParamChange()));
                connect(m_interpreter, SIGNAL(version(ushort,ushort,ushort,QString,ushort,ushort,ushort)), this, SLOT(handleVersion(ushort,ushort,ushort,QString,ushort,ushort,ushort)));
                m_interpreter->start();
            }
            m_pixyConnected = true;
        }
        catch (std::runtime_error &exception)
...

[JKSH]

@jrod2much said in Signals and slots or whatever:

A null pointer does not point to an address so it can't be dereferenced.

Correct.

I also found this video that made me feel stupid.
https://www.youtube.com/watch?v=bLHL75H_VEM

I think he's being a bit harsh ;-)

Should I eliminate the two lines of code that make m_interpreter and m_renderer NULL? or do I have to point it to a specific address value?

You must never ever use these:

• Null pointers
• Uninitialized pointers
• Dangling pointers

Remember, take some time to learn the foundations of C++. It will save you lots of pain and heartache in the future.

@jrod2much said in Signals and slots or whatever:

GUYS WE DID IT!!!!!!!!!!!!! ITS OUTPUTING THE VALUES!!!!

Congratulations! Happy coding.

[Pablo J. Rogina]

@jrod2much glad you solved your issue. In appreciation to all the people that helped you with it, please don't forget to mark your post as solved!