Signals and slots or whatever

jsulm

@jrod2much said in Signals and slots or whatever:

Most tutorials about connections lazily explain elementary connections

connect() always work the same way no matter what you're connecting to what. You can't expect tutorials for everything.
What is the problem now?
It doesn't compile?
Are your slots in "slots" section and signals in "signals" section in your classes? Are those classes derived from QObject?

jrod2much

@jsulm Yes connect() always works the same but what I mean by lazy tutorials is that many of the tutorials show how to use preformatted connect()'s. In my case, I have create every aspect of the connection. I don't know what goes in the four arguments of the connect and when I try to use the m_render for the first argument, it does not recognize.

jsulm

@jrod2much said in Signals and slots or whatever:

preformatted connect()

What is this?
As I said: it is always the same.
connect(senderObject, signal, receiverObject, slot);
There is really nothing special.
Is Renderer derived from QObject?
Is m_renderer a pointer?
Can you please post the error message you get?

VRonin

in the connect(m_renderer etc, the third argument (this) is of type MainWindow, not QTextBrowser so it can't work, you need to pass m_ui->textBrowser there.

What's the full error the connect reports?

jrod2much

@VRonin @jsulm
0_1538483559136_2853b0c3-e6d0-4996-9bee-96992f6397df-image.png

jsulm

@jrod2much You still did not answer my question: is Renderer derived from QObject? Did you include the header file containing Renderer class definition?

J.Hilk

@jsulm according to the error message, I would say m_renderer is not a QObject
incomplete type 'Renderer *' to const QObject ....

jrod2much

@jsulm said in Signals and slots or whatever:

@jrod2much You still did not answer my question: is Renderer derived from QObject? Did you include the header file containing Renderer class definition?

Should I do that?

Update: I included it, now the program runs. However, It is not printing any text on the textBrowser, but atleast I am getting somewhere

VRonin

I think you skipped this part:

@VRonin said in Signals and slots or whatever:

Now wherever the interpreter creates the CccModule connect() the 2 signals together

jrod2much

@VRonin So I have changed where I am trying to get the value from, it is actually from the Renderer class, not the CccModule class anymore.

New error

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

VRonin

@jrod2much said in Signals and slots or whatever:

So I have changed where I am trying to get the value from

I see, cool

New error

Could you use Qt5 connection instead? errors usually are a lot more helpful:
connect(m_interpreter->m_renderer,&Renderer::Rvalues,m_ui->textBrowser,&QTextBrowser::setText);

jrod2much

@VRonin

0_1538488320685_0cf79aa7-0b80-425b-b65a-2d0608dd88f4-image.png

15:51:34: Debugging starts
(Internal error: pc 0x0 in read in psymtab, but not in symtab.)
(Internal error: pc 0x0 in read in psymtab, but not in symtab.)

@VRonin said in Signals and slots or whatever:

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

UPDATE: correct

VRonin

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

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.