How to get x and y position from Gridlayout?

[ihdvsk]

Hello, i wrote a function to draw a path in a Gridlayout of 20x20 PushButtons from "Start" to "End" but somehow it is not working and causing a crash in my program.

The Problem is that i need to get the x and y coordinates to set the corresponding PushButton backgroundcolor to black

here is my function:

void Widget::setPath(){

    int start_x,start_y,end_x,end_y, path_x,path_y;

    // finds "Start" and "End" Buttons
    QPushButton *startButton = parentWidget()->findChild<QPushButton *>("Start");
    QPushButton *endButton = parentWidget()->findChild<QPushButton *>("End");

    // Gets x and y Value of StartButton in the grid

    for(int c = 0;c<20;c++){
        for(int d = 0;d<20;d++){
            if(array[c][d] == startButton){
                start_x = c;
                start_y = d;
            }
    // Gets x and y Value of EndButton in the grid
            if(array[c][d] == endButton){
                end_x = c;
                end_y = d;
            }
        }
    }

    path_x = start_x;
    path_y = start_y;

    while(path_x != end_x){
        // if "End" is to right of "Start" next Button to the right of "Start"
        // will be set to Path
        if(path_x < end_x){
            path_x = path_x + 1;
            array[path_x][start_y]->setStyleSheet("background-color:black;");

            // if "End" is to left of "Start" next Button to the left of "Start"
            // will be set to Path
        } else if (path_x > end_x){
            path_x = path_x + 1;
            array[path_x][start_y]->setStyleSheet("background-color:black;");
        }
    }

    while(path_y != end_y){
        // if "End" is lower than "Start" next Button to under "Start"
        // will be set to Path
        if(path_y < end_y){
            path_y -= 1;
            array[path_x][path_y]->setStyleSheet("background-color:black;");
            // if "End" is higher than "Start" next Button to above "Start"
            // will be set to Path
        } else if (path_x > end_y){
            path_y += 1;
            array[path_x][path_y]->setStyleSheet("background-color:black;");
        }
    }


}

i think this is causing the problem (array[c][d] is the array of pushButtons in the gridlayout):

    // Gets x and y Value of StartButton in the grid

    for(int c = 0;c<20;c++){
        for(int d = 0;d<20;d++){
            if(array[c][d] == startButton){
                start_x = c;
                start_y = d;
            }
    // Gets x and y Value of EndButton in the grid
            if(array[c][d] == endButton){
                end_x = c;
                end_y = d;
            }
        }
    }

[raven-worx]

@ihdvsk
sry but this code hurts my eyes and my brain...
Why so complicated? What is the reason to use a multi-dimensional array? Since you already use a QGridLayout why don't you use it's methods to access the contained widgets?

[ihdvsk]

sorry i'm new to Qt and i didnt find a fitting function in the QGridlayout Class.
How could i then resolve my problem better?

[VRonin]

@ihdvsk said in How to get x and y position from Gridlayout?:

causing a crash

crash = look at/post the stack trace

[raven-worx]

@ihdvsk said in How to get x and y position from Gridlayout?:

sorry i'm new to Qt and i didnt find a fitting function in the QGridlayout Class.

since your code doesn't show clearly what you are trying to do IMHO i can't answer this question.

But i guess your flow is sequential right? Means your "path" can only progress sequentially from start to end?
Then eiter use the layout QGridLayout::itemAt(int index) method to iterate through the layout items (=widgets) or store the QWidgets independantly in a QList.

Or is QGridLayout even the correct layout? Maybe a QHBoxLayout is more appropriate?

[ihdvsk]

Here is my Code:
widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QPushButton>
#include <QObject>
#include <QApplication>
#include <QGridLayout>
#include <QVBoxLayout>

namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT


    int numOfClicks = 0;
    QPushButton* array[20][20];

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

public slots:

    void setUp(QWidget* w);

    /* sets the first clicked Button to "Start"
     and the second clicked Button to "End" */
    void setStartEnd();

    void setPath();  // creates the path from "Start" to "End"


private:
    Ui::Widget *ui;
};

#endif // WIDGET_H

main.cpp

#include "widget.h"


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget *w = new QWidget();
    Widget *wid = new Widget();

    wid->setUp(w);

    return a.exec();
}

and widget.cpp:

#include "widget.h"
#include "ui_widget.h"


Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}


void Widget::setUp(QWidget* w){

    // New GridLayout for Button Array
    QGridLayout *ButtonLayout = new QGridLayout;

    // Create 20x20 Buttons in Grid
    for(int i = 0;i<20;i++){
        for(int j = 0;j<20;j++){

            QPushButton *pushButton = new QPushButton("");

            // Next line will be used to help find the Path later
            array[i][j] = pushButton;

            // Adds pushButton to Grid
            w->setLayout(ButtonLayout);
            ButtonLayout->addWidget(pushButton,i,j,1,1);

            // Connects buttons to setStartEnd() function
            w->connect(pushButton, SIGNAL(clicked()), this, SLOT(setStartEnd()));
        }
    }

    // Set the grid layout as a main layout
    w->setLayout(ButtonLayout);


    // Display
    w->show();

}

void Widget::setStartEnd(){


    /* check if it is the first click
       if yes the clicked Button is set to "Start" */


    if(numOfClicks == 0) {

    // New QObject that equals the clicked Button
    QObject* obj = sender();
    QPushButton* button = qobject_cast<QPushButton*>(obj);


    button->setText("Start");
    button->setStyleSheet("background-color:green;");
    button->setObjectName("Start");

    numOfClicks = numOfClicks + 1;

    /* else if it is the second click (numOfClicks == 1)
       sets Button to "End" */

    } else if(numOfClicks == 1) {

        QObject* obj2 = sender();
        QPushButton* button2 = qobject_cast<QPushButton*>(obj2);


        button2->setText("End");
        button2->setStyleSheet("background-color:red;");
        button2->setObjectName("End");

        numOfClicks = numOfClicks + 1;

        setPath();

    }

}


void Widget::setPath(){

    int start_x,start_y,end_x,end_y, path_x,path_y;

    // finds "Start" and "End" Buttons
    QPushButton *startButton = parentWidget()->findChild<QPushButton *>("Start");
    QPushButton *endButton = parentWidget()->findChild<QPushButton *>("End");

    // Gets x and y Value of StartButton in the grid

    for(int c = 0; c<20 ; c++){
        for(int d = 0; d<20 ; d++){
            if(array[c][d] == startButton){
                start_x = c;
                start_y = d;
            }
    // Gets x and y Value of EndButton in the grid
            if(array[c][d] == endButton){
                end_x = c;
                end_y = d;
            }
        }
    }

    path_x = start_x;
    path_y = start_y;

    while(path_x != end_x){
        // if "End" is to the right of "Start" next Button to the right of "Start"
        // will be set to Path
        if(path_x < end_x){
            path_x = path_x + 1;
            array[path_x][start_y]->setStyleSheet("background-color:black;");

            // if "End" is to the left of "Start" next Button to the left of "Start"
            // will be set to Path
        } else if (path_x > end_x){
            path_x = path_x + 1;
            array[path_x][start_y]->setStyleSheet("background-color:black;");
        }
    }

    while(path_y != end_y){
        // if "End" is lower than "Start" next Button to under "Start"
        // will be set to Path
        if(path_y < end_y){
            path_y -= 1;
            array[path_x][path_y]->setStyleSheet("background-color:black;");
            // if "End" is higher than "Start" next Button to above "Start"
            // will be set to Path
        } else if (path_x > end_y){
            path_y += 1;
            array[path_x][path_y]->setStyleSheet("background-color:black;");
        }
    }


}

i have a 20x20 grid of PushButtons. the user can select a start and endpoint. The program then should show a horizontally and then vertically path from start to end. Excuse me if the code is ugly, i tried to comment and indent everything

[mrjj]

@ihdvsk
Like this ?

[ihdvsk]

yes this looks perfect!

[mrjj]

@ihdvsk
Is it also allowed to go back (on the row) if START col is bigger than
Ends col ?

[ihdvsk]

Yes, it should go horizontally first and then vertically just like your pictures show.

[mrjj]

Hi
Is there not a bug here ?

  while(path_x != end_x){
        // if "End" is to the right of "Start" next Button to the right of "Start"
        // will be set to Path
        if(path_x < end_x){
            path_x = path_x + 1;
            array[path_x][start_y]->setStyleSheet("background-color:black;");

            // if "End" is to the left of "Start" next Button to the left of "Start"
            // will be set to Path
        } else if (path_x > end_x){
            path_x = path_x + 1;  // should it no go "back" here ? as in -1 
            array[path_x][start_y]->setStyleSheet("background-color:black;");
        }
    }

[ihdvsk]

I found my mistake. now it works.
widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QPushButton>
#include <QObject>
#include <QApplication>
#include <QGridLayout>
#include <QVBoxLayout>
#include <QPair>
#include <QLabel>


namespace Ui {
class Widget;
}

class Widget : public QWidget
{
    Q_OBJECT


    int numOfClicks = 0;
    QPushButton* array[20][20];

public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();

public slots:

    void setUp(QWidget* w);

    /* sets the first clicked Button to "Start"
     and the second clicked Button to "End" */
    void setStartEnd();

    void setPath();  // creates the path from "Start" to "End"


private:
    Ui::Widget *ui;
};

#endif // WIDGET_H

main.cpp

#include "widget.h"


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QWidget *w = new QWidget();
    Widget *wid = new Widget();

    wid->setUp(w);

    return a.exec();
}

and widget.cpp

#include "widget.h"
#include "ui_widget.h"


Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::setUp(QWidget* w){

    // New GridLayout for Button Array
    QGridLayout *ButtonLayout = new QGridLayout;


    // Create 20x20 Buttons in Grid
    for(int i = 0;i<20;i++){
        for(int j = 0;j<20;j++){


            QPushButton *pushButton = new QPushButton("");

            // Next line will be used to help find the Path later
            array[i][j] = pushButton;

            // Adds pushButton to Grid
            w->setLayout(ButtonLayout);
            ButtonLayout->addWidget(pushButton,i,j,1,1);

            // Connects buttons to setStartEnd() function
            w->connect(pushButton, SIGNAL(clicked()), this, SLOT(setStartEnd()));
        }
    }

    // Set the grid layout as a main layout
    w->setLayout(ButtonLayout);


    // Display
    w->show();

}

void Widget::setStartEnd(){


    /* check if it is the first click
       if yes the clicked Button is set to "Start" */


    if(numOfClicks == 0) {

    // New QObject that equals the clicked Button
    QObject* obj = sender();
    QPushButton* button = qobject_cast<QPushButton*>(obj);


    button->setText("Start");
    button->setStyleSheet("background-color:green;");
    button->setObjectName("Start");

    numOfClicks = numOfClicks + 1;

    /* else if it is the second click (numOfClicks == 1)
       sets Button to "End" */

    } else if(numOfClicks == 1) {

        QObject* obj2 = sender();
        QPushButton* button2 = qobject_cast<QPushButton*>(obj2);


        button2->setText("End");
        button2->setStyleSheet("background-color:red;");
        button2->setObjectName("End");

        numOfClicks = numOfClicks + 1;

        setPath();

    }

}


void Widget::setPath(){

    int start_x,start_y,end_x,end_y, path_x,path_y;

    // finds "Start" and "End" Buttons

    // Gets x and y Value of StartButton in the grid
    for(int c = 0; c<20 ; c++){
        for(int d = 0; d<20 ; d++){
            if(array[c][d]->objectName() == "Start"){
                start_x = c;
                start_y = d;
            }
    // Gets x and y Value of EndButton in the grid
            if(array[c][d]->objectName() == "End"){
                end_x = c;
                end_y = d;
            }
        }
    }

    path_x = start_x;
    path_y = start_y;

    while(path_y != end_y){
        // if "End" is to the right of "Start" next Button to the right of "Start"
        // will be set to Path
        if(path_y < end_y){
            path_y += 1;
            if(path_y != end_y || path_x != end_x){
                array[path_x][path_y]->setStyleSheet("background-color:black;");
            }
            // if "End" is to the left of "Start" next Button to the left of "Start"
            // will be set to Path
        } else if (path_y > end_y){
            path_y -= 1;
            if(path_y != end_y || path_x != end_x){
                array[path_x][path_y]->setStyleSheet("background-color:black;");
            }
        }
    }

    while(path_x != end_x){
        // if "End" is lower than "Start" next Button to under "Start"
        // will be set to Path
        if(path_x < end_x){
            path_x += 1;
            if(path_x != end_x || path_y != end_y){
                array[path_x][path_y]->setStyleSheet("background-color:black;");
            }

            // if "End" is higher than "Start" next Button to above "Start"
            // will be set to Path
        } else if (path_x > end_x){
            path_x -= 1;
            if(path_x != end_x || path_y != end_y){
                array[path_x][path_y]->setStyleSheet("background-color:black;");
            }
        }
    }

}

[mrjj]

Super, i assume you found bug2 in the y direction ?
Yep. fixed.

Good work. Funny app :)

To fully test, you could add a reset function and call from a button

[mrjj]

Hi
Note:
You should set variable to zero or else you cant do it again as it has values (random)

void Widget::setPath() {
int start_x=0, start_y=0, end_x=0, end_y=0, path_x=0, path_y=0;
...
}
also a reset function makes it more fun

void Widget::Reset() {
    numOfClicks = 0;
    for(int c = 0; c < 20 ; c++) {
        for(int d = 0; d < 20 ; d++) {
            array[c][d]->setStyleSheet(QString());
            array[c][d]->setText(QString());
        }
    }
}