Use QTreeWidget with non-static data.

ZiketCPP

Hi,
I want to use the QTreeWidget with dynamic data (ie. Insert elements when a button is pressed).
I make this functionality but I haven't had results.
I create a button with the signal, when it's pressed, that creates and inserts a new QTreeWidgetItem into the tree. No results, I even called Update() & Repaint().
Any solution?

jsulm

@ZiketCPP You should show your code for inserting new items...

ZiketCPP

@jsulm

//This is called when a button is clicked
QTreeWidgetItem *treeItem = new QTreeWidgetItem(ui->treeWidget);
   treeItem->setText(0, "Pepedfsdf");
   treeItem->setText(1, "Descdfsdfsdf");
//I test the update calling this two functions.... or only one but nothing is happend
   ui->treeWidget->repaint();
   QWidget::update();
//
   repaint();
   return;

I had to comment that if I call this code in the constructor (without the update & repaint) it works
alt text
workingimageconstructor.png

mrjj

@ZiketCPP

Hi
dont you need a
ui->treeWidget->addItem(treeItem); ?

ZiketCPP

@mrjj Hi,
In 5.9 version QTreeWidget does not have any method addIem()
http://doc.qt.io/qt-5/qtreewidget.html
Maybe I dont say that

ui->treeWidget

is a QTreeWidget.
Thanks!

jsulm

@ZiketCPP "Before items can be added to the tree widget, the number of columns must be set with setColumnCount()."
See http://doc.qt.io/qt-5/qtreewidget.html
Did you?

ZiketCPP

@jsulm
Yes, in the constructor I use this
CONTRUCTOR:

ui->setupUi(this);
ui->treeWidget->setColumnCount(2);
ui->treeWidget->setHeaderLabels(QStringList() << "Name" << "Type");

Function Insert item

//I set this item as header in the tree widget
QTreeWidgetItem *treeItem = new QTreeWidgetItem(ui->treeWidget);
treeItem->setText(0, "Pepedfsdf");
treeItem->setText(1, "Descdfsdfsdf");

The real question is if I can insert, in any time, elements into QTreeWidget and display it, because it seems that I can't. Maybe I have to call a special function to update the tree or anything, i don't know...

VRonin

QAbstractItemModel* const mdl= ui->treeWidget->model();
const int rowCount =mdl->rowCount();
if(mdl->insertRow(rowCount))){
qDebug("Row Inserted!");
if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
qDebug("Pepedfsdf Written");
if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
qDebug("Descdfsdfsdf Written");
}

ZiketCPP

@VRonin
As I suppose, this code only works in the constructor of my class. I will post the code with the changes done.

Header.h

#ifndef TREENODESUI_H
#define TREENODESUI_H

#include <QWidget>
#include <QTreeWidgetItem>
namespace Ui {
   class TreeNodesUI;
}

class TreeNodesUI: public QWidget
{
      Q_OBJECT

   public:
      explicit TreeNodesUI(QWidget *parent = 0);
      ~TreeNodesUI();
      void addTreeChild(Node* node_to_add, QString name, QString description);

   private:
      Ui::TreeNodesUI *ui;
};

#endif // TREENODESUI_H

Source.cpp

#include "treenodesui.h"
#include "ui_treenodesui.h"
#include <QStringList>
#include <QAbstractItemModel>


TreeNodesUI::TreeNodesUI(QWidget *parent) :
   QWidget(parent),
   ui(new Ui::TreeNodesUI)
{
   ui->setupUi(this);
   ui->treeWidget->setColumnCount(2);
   ui->treeWidget->setHeaderLabels(QStringList() << "Name" << "Type");
   ui->treeWidget->setUpdatesEnabled(true);
   //This is working only in the constructor
   QAbstractItemModel* const mdl= ui->treeWidget->model();
   const int rowCount =mdl->rowCount();
   if(mdl->insertRow(rowCount)){
      qDebug("Row Inserted!");
      if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
         qDebug("Pepedfsdf Written");
      if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
         qDebug("Descdfsdfsdf Written");
   }
  //This is working only in the constructor
   QTreeWidgetItem *treeItem = new QTreeWidgetItem(ui->treeWidget);
   treeItem->setText(0, "Pepedfsdf");
   treeItem->setText(1, "Descdfsdfsdf");
}

TreeNodesUI::~TreeNodesUI()
{
   delete ui;
}
//Take a look at the comments
//IGNORE THE INPUT PARAMETERS---------------------------------------------------
void TreeNodesUI::addTreeChild(Node *node_to_add, QString name, QString description)
{
  //ALL INSERTED HERE WILL NOT WORK (its called in some point of the program, I debug this)
   QAbstractItemModel* const mdl= ui->treeWidget->model();
   const int rowCount =mdl->rowCount();
   if(mdl->insertRow(rowCount)){
      qDebug("Row Inserted!");
      if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
         qDebug("Pepedfsdf Written");
      if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
         qDebug("Descdfsdfsdf Written");
   }
  
  //Another test
   QTreeWidgetItem *treeItem = new QTreeWidgetItem(ui->treeWidget);
   treeItem->setText(0, "Pepedfsdf");
   treeItem->setText(1, "Descdfsdfsdf");
  //With some probes calling updates functions
   ui->treeWidget->repaint();
   QWidget::update();
   repaint();
   return;
}

VRonin

Don't mix the APIs

#include "treenodesui.h"
#include "ui_treenodesui.h"
#include <QStringList>
#include <QAbstractItemModel>


TreeNodesUI::TreeNodesUI(QWidget *parent) :
   QWidget(parent),
   ui(new Ui::TreeNodesUI)
{
   ui->setupUi(this);
   ui->treeWidget->setColumnCount(2);
   ui->treeWidget->setHeaderLabels(QStringList() << "Name" << "Type");
  
   //This is working only in the constructor
   QAbstractItemModel* const mdl= ui->treeWidget->model();
   const int rowCount =mdl->rowCount();
   if(mdl->insertRow(rowCount)){
      qDebug("Row Inserted!");
      if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
         qDebug("Pepedfsdf Written");
      if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
         qDebug("Descdfsdfsdf Written");
   }
}

TreeNodesUI::~TreeNodesUI()
{
   delete ui;
}
//Take a look at the comments
//IGNORE THE INPUT PARAMETERS---------------------------------------------------
void TreeNodesUI::addTreeChild(Node *node_to_add, QString name, QString description)
{
   QAbstractItemModel* const mdl= ui->treeWidget->model();
   const int rowCount =mdl->rowCount();
   if(mdl->insertRow(rowCount)){
      qDebug("Row Inserted!");
      if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
         qDebug("Pepedfsdf Written");
      if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
         qDebug("Descdfsdfsdf Written");
   }
}

ZiketCPP

@VRonin said in Use QTreeWidget with non-static data.:

Don't mix the APIs

I don't really understand what I did wrong, mix the APIs? Where? I copy-paste your code and still doesn't work. What should I add in addTreeChild to work? @VRonin, you put the same code as me. I have the conclusion that the QTreeWidget only admit new rows in the constructor, all after this will not display. So if you have any simple code or project to add items (i.e. when you click a button inserts a new row) please explain me how

VRonin

@ZiketCPP said in Use QTreeWidget with non-static data.:

mix the APIs?

You were using the QTreeItem API, I used the QAbstractItemModel one.

I have the conclusion that the QTreeWidget only admit new rows in the constructor

this clearly can't be. QTreeWidget doesn't even know you are in a constructor.

can you try this minimal example?


#include <QApplication>
#include <QWidget>
#include <QTreeWidget>
#include <QAbstractItemModel>
#include <QVBoxLayout>
int main(int argc, char *argv[])
{
        QApplication app(argc,argv);
        QWidget wid;
        QPushButton* addTreeBtn=new QPushButton("Add Row",&wid);
        QTreeWidget* treeWid=new QTreeWidget(&wid);
        treeWid->setColumnCount(2);
        treeWid->setHeaderLabels(QStringList() << "Name" << "Type");
        QObject::connect(addTreeBtn,&QPushButton::clicked,treeWid,[treeWid](){
            QAbstractItemModel* const mdl= treeWid->model();
            const int rowCount =mdl->rowCount();
            if(mdl->insertRow(rowCount)){
                qDebug("Row Inserted!");
                if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
                    qDebug("Pepedfsdf Written");
                if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
                    qDebug("Descdfsdfsdf Written");
            }
        });
        QVBoxLayout* widlay=new QVBoxLayout(&wid);
        widlay->addWidget(addTreeBtn);
        widlay->addWidget(treeWid);
        wid.show();
        return app.exec();
}

ZiketCPP

@VRonin that code works perfectly, maybe the cause is the Signal & Slot event? I don't know... Anyone can explain to me what's the difference between the @VRonin code (the insert method) and mine, and why doesn't work the code?
Really thank you @VRonin :)

ZiketCPP

It's incredible, it only displays the info if the info is called with any Signal/Slot function. If you try to do this for example in the update of your program (call a function that inserts a new Row) it will not work... Any idea why? Or any idea doing calling a function in the update for example? Thank you :D

VRonin

@ZiketCPP said in Use QTreeWidget with non-static data.:

If you try to do this for example in the update

That's just an infinite loop.

Update inserts a row -> the view detects the row change -> the view calls update -> loop

ZiketCPP

@VRonin if you try to create a class with the functions

void InsertElement() {
   QAbstractItemModel* const mdl= treeWid->model();
            const int rowCount =mdl->rowCount();
            if(mdl->insertRow(rowCount)){
                qDebug("Row Inserted!");
                if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
                    qDebug("Pepedfsdf Written");
                if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
                    qDebug("Descdfsdfsdf Written");
            }
}

Insert this in any class with an UI file (with the TreeWidget), if you don't insert the elements using the Signal/Slot this does not work

VRonin

Where do you call InsertElement from?

ZiketCPP

@VRonin from the update function (for example), try it, remember my code (I posted it in this discussion), it does not work. You only can update the TreeWidget if you insert rows inside Slot/Signal function.... try it, really

VRonin

update function

That's too generic.

You only can update the TreeWidget if you insert rows inside Slot/Signal function

Signals and slots are just terms used by moc that then converts them into pure C++. there is no difference between a slot and a normal method/function:

#include <QApplication>
#include <QWidget>
#include <QTreeWidget>
#include <QAbstractItemModel>
#include <QVBoxLayout>
void insertRow(QAbstractItemModel* const mdl){
            const int rowCount =mdl->rowCount();
            if(mdl->insertRow(rowCount)){
                qDebug("Row Inserted!");
                if(mdl->setData(mdl->index(rowCount,0),"Pepedfsdf"))
                    qDebug("Pepedfsdf Written");
                if(mdl->setData(mdl->index(rowCount,1),"Descdfsdfsdf"))
                    qDebug("Descdfsdfsdf Written");
            }
}
int main(int argc, char *argv[])
{
        QApplication app(argc,argv);
        QWidget wid;
        QTreeWidget* treeWid=new QTreeWidget(&wid);
        treeWid->setColumnCount(2);
        treeWid->setHeaderLabels(QStringList() << "Name" << "Type");
       for(int i=0;i<10;i++){
            insertRow(treeWid->model());
        }
        QVBoxLayout* widlay=new QVBoxLayout(&wid);
        widlay->addWidget(addTreeBtn);
        widlay->addWidget(treeWid);
        wid.show();
        return app.exec();
}

My guess is that you are blocking the event loop somehow

ZiketCPP

@VRonin all of this is before the update/draw happens (in the wid.show() function), if you do this while the program is running, in the UPDATE function of the program, this function "insertRow()" won't work. Ok, I will try to explain myself.
Try to call this function in the main loop of the render for example. I don't know if the class MainWindow has an update function and u can override it.