CODEWITHSUNDEEP
c++qtqt4
avi software
avi software

Reputation: 145

how to get the index of QList according to QSignalMapper

I have QList of QPushButton's and QSignalMapper to recognize which button is pushed. So I did something like that (my project is very big, so I cut just the lines needed to the question)

QList<QPushButton*> Buttons;
QList <QLabel*> LabelList1;
QList <QLabel*> LabelList2;
QList <QLabel*> LabelList3;
QList <QLabel*> LabelList4;
QSignalMapper *ButtonsMapper;
ButtonsMapper= new QSignalMapper(this);
connect(ButtonsMapper, SIGNAL(mapped(int)),this,SIGNAL(ButtonsClicked(int)));
connect(this, SIGNAL(ButtonsClicked(int)),this,SLOT(deleteButton(int)));

Buttons.append(new QPushButton(tr("0")));//first button 
LabelList1.append(new QLabel(tr("0")));
LabelList2.append(new QLabel(tr("0")));
LabelList3.append(new QLabel(tr("0")));
LabelList4.append(new QLabel(tr("0")));
QPushButton * pb1 = Buttons.last();//pointer to the last button
connect(pb1, SIGNAL(clicked()), ButtonsMapper, SLOT(map()));
ButtonsMapper->setMapping(pb1,0);

Buttons.append(new QPushButton(tr("1")));//second button
LabelList1.append(new QLabel(tr("1")));
LabelList2.append(new QLabel(tr("1")));
LabelList3.append(new QLabel(tr("1")));
LabelList4.append(new QLabel(tr("1"))); 
QPushButton * pb2 = Buttons.last();//pointer to the last button
connect(pb2, SIGNAL(clicked()), ButtonsMapper, SLOT(map()));
ButtonsMapper->setMapping(pb2,1);

and the function deleteButton supposed to delete the button was pressed. If I do something like that

void myclass::deleteButton(int i){ 
   delete (Buttons.takeAt(i));
   delete ( LabelList1.takeAt(i));
   delete ( LabelList2.takeAt(i));
   delete( LabelList3.takeAt(i));
   delete( LabelList4.takeAt(i));
    }

that function can lead to index out of range error, if I delete the first button, and then I press on the second button, the function Buttons.takeAt(i) point to not exist button.

Upvotes: 4

Views: 959

Answers (3)

Greg
Greg

Reputation: 1660

Instead of mapping QPushButton to index (int) you could map it to QWidget *.

- ButtonsMapper->setMapping(pb1,0);
+ ButtonsMapper->setMapping(pb1, pb1);

Then slot also will change

void myclass::deleteButton(QWidget * widget){
    Buttons.removeOne(widget);
    delete widget;  
}

Upvotes: 0

Caleb Huitt - cjhuitt
Caleb Huitt - cjhuitt

Reputation: 14941

Theoretically, you could keep a pointer to the signal mapper around, and remap the indexes after deletion.

void myclass::deleteButton(int i){
    delete (Buttons.takeAt(i));
    for(int i = 0; i < Buttons.size(); ++i) {
        ButtonsMapper->setMapping(Buttons[i], i);
    }
}

Upvotes: 1

Ruslan F.
Ruslan F.

Reputation: 5776

I suggest you some modifiacation of your code:

QMap<QPushButton*,int> Buttons;
QSignalMapper *ButtonsMapper;
ButtonsMapper= new QSignalMapper(this);
connect(ButtonsMapper, SIGNAL(mapped(int)),this,SIGNAL(ButtonsClicked(int)));
connect(this, SIGNAL(ButtonsClicked(int)),this,SLOT(deleteButton(int)));

Buttons.insert (new QPushButton(tr("0")),0);//first button 
QPushButton * pb1 = Buttons.last();//pointer to the last button
connect(pb1, SIGNAL(clicked()), ButtonsMapper, SLOT(map()));
ButtonsMapper->setMapping(pb1,0);

Buttons.insert (new QPushButton(tr("1")),1);//second button 
QPushButton * pb2 = Buttons.last();//pointer to the last button
connect(pb2, SIGNAL(clicked()), ButtonsMapper, SLOT(map()));
ButtonsMapper->setMapping(pb2,1);

void myclass::deleteButton(int i){
    if (Buttons.contains(i))
    delete (Buttons[i]);  
}

Upvotes: 0

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