Matrix of button

dijnr

Hi I've a problem and I need some hints.
I've a Matrix of button and I want that when a button is pressed it return his position (row and col)

QPushButton* Field[30][30];

for(int i=0;i<30;i++)
		for(int j=0;j<30;j++){
			Field[i][j]=new QPushButton("", this);
			Field[i][j]->setFixedHeight(23);
			Field[i][j]->setFixedWidth(23);
		}

I want to do somethings like this(but working :))

connect(Field[i][j], SIGNAL(clicked()), this, SLOT(printValues(i,j)));

PS I know that I can't do this kind of connect, is just to give you an idea
PPS I was looking for Signal Mapper but doesn't seems the right choice

Chris Kawa

@dijnr said in Matrix of button:

I was looking for Signal Mapper but doesn't seems the right choice

QSignalMapper is meant for exactly this kind of problem. Also, instead of an array you should put the buttons i a layout.

QGridLayout* grid = new QGridLayout(someParent);
QSignalMapper* mapper = new QSignalMapper(someParent);

for(int i = 0; i < 30; ++i) {
    for(int j = 0; j < 30; ++j) {
        QPushButton* pb = new QPushButton(this); //If you need an empty string use QString() instead of "", but you don't need it here
        pb->setFixedSize(23, 23); //Don't need two separate calls
        mapper->setMapping(pb, i * 100 + j); //some easy encoding, you may use whatever you want
        connect(pb, &QPushButton::clicked, mapper, static_cast<void(QSignalMapper::*)()>(&QSignalMapper::map));
    }
}

Then just connect the mapper to some slot:

connect(mapper, static_cast<void(QSignalMapper::*)(int)>(&QSignalMapper::mapped), whatever, &SomeClass::someSlot);

and decode the values in the slot:

void SomeClass::someSlot(int value)
{
    int row = value / 100;
    int col = value % 100;
    /* do something with row and col */
}

jsulm

@dijnr Alternative is to use C++11 and Qt5 connect syntax:

QPushButton* Field[30][30];

for(int i=0;i<30;i++)
		for(int j=0;j<30;j++){
			Field[i][j]=new QPushButton("", this);
			Field[i][j]->setFixedHeight(23);
			Field[i][j]->setFixedWidth(23);
                        // You most probably will need this pointer to access you class member, so we capture it
                        connect(Field[i][j], QPushButton::clicked, [this,i,j]() { /*Do what ever you want with i and j*/ }));
		}

dijnr

Thank you, I've solved my problem

shepher_whu

@Chris-Kawa thanks a lot,i just looking for the answer"why it must use the QT4's connect style to pass the compiler..."

jsulm

@shepher_whu I cannot see this question in this thread: ""why it must use the QT4's connect style to pass the compiler..."
The old connect syntax uses macros (SIGNAL/SLOT), so the compiler does not check whether the signal and slot actually exists and have compatible parameters.
Or do I misunderstand your question?