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Forum Update on Monday, May 27th 2025

Create a matrix from a .csv file

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  • A AliM93

    because we have to add the matrix in the widget, right?

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by mrjj
    #118

    @AliM93
    yes.
    You should still have the layout from before, correct ?
    then in Grids constrcutor

    GridDialog::GridDialog(QWidget *parent) :
        QDialog(parent),
        ui(new Ui::GridDialog)
    {
        ui->setupUi(this);
    
        MatrixWidget * m = new MatrixWidget (this);
        ui->verticalLayout->addWidget(m); /// you name might differ for layout
    
    }
    

    We dont need the plain widget any more. you can delete it. we use the layout

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    • A Offline
      A Offline
      AliM93
      wrote on last edited by
      #119

      done! but i only see the grid, not the content

      mrjjM 1 Reply Last reply
      0
      • A AliM93

        done! but i only see the grid, not the content

        mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #120

        @AliM93
        \o/
        Good work.
        I hope you learn a few Creator tricks.

        we didnt paint the values yet :)
        just all other stuff :=)

        But its 4 in the morning so rest must be tomorrow as its bed time for me :)

        A 1 Reply Last reply
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        • mrjjM mrjj

          @AliM93
          \o/
          Good work.
          I hope you learn a few Creator tricks.

          we didnt paint the values yet :)
          just all other stuff :=)

          But its 4 in the morning so rest must be tomorrow as its bed time for me :)

          A Offline
          A Offline
          AliM93
          wrote on last edited by
          #121

          @mrjj yes! but i don't even see the number

          mrjjM 1 Reply Last reply
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          • A Offline
            A Offline
            AliM93
            wrote on last edited by
            #122

            anyway, ok for tomorrow, you have been too much patient with me, thanks. and for the first time, i can say thay i better undestand how qt works! i start to appreciate it

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            • A AliM93

              @mrjj yes! but i don't even see the number

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #123

              @AliM93
              well do you have that version of paint ?

              
              void MatrixWidget::paintEvent(QPaintEvent *event)
              {
              
                  QPainter p(this);
                  // draw frame.
                  p.drawRect(0, 0, width() - 1, height() - 1);
              
                  // size of area we have. w = width , h = height , we take 2 pixles for border
                  int w = width() - 2;
                  int h = height() - 2;
              
                  // now we find out how big each box should be which area we have  divided with how many on x and y
                  bw = w / max_x;
                  bh = h / max_y;
              
                  // now we loop and drw the boxes
                  for (int xi = 0; xi < max_x; ++xi) {
                      for (int yi = 0; yi < max_x; ++yi) {
                          p.drawRect( QRect( xi * bw, yi * bh, bw, bh  ) )  ;
                          p.drawText(QRect( xi * bw, yi * bh, bw, bh  ),
                                     QString::number(xi + 1) + "," + QString::number(yi+1) ); // the +1 aswe dont want to use first at 0,0
                      }
                  }
              
              }
              
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              • A Offline
                A Offline
                AliM93
                wrote on last edited by
                #124

                yes i have

                mrjjM 1 Reply Last reply
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                • A AliM93

                  yes i have

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #125

                  @AliM93
                  But it dont draw numbers ?
                  That seems very odd.

                  But you do see grid ?

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                  • A Offline
                    A Offline
                    AliM93
                    wrote on last edited by
                    #126

                    sorry! now i have, i lost a part of that version of matrix, sorry!

                    mrjjM 1 Reply Last reply
                    0
                    • A AliM93

                      sorry! now i have, i lost a part of that version of matrix, sorry!

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #127

                      @AliM93
                      Ok that good news as it would be very impossible that numbers went missing :)

                      what is remaining is the click logic and to actual draw the 1.

                      how shall we draw 0 ones ?
                      just no value in cell and cant be selected or what is the goal?

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                      • A Offline
                        A Offline
                        AliM93
                        wrote on last edited by
                        #128

                        my idea was to color all the 1s in green and the 0s in gray. so the user know that can select only the green cells, is it possible?

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                        • A Offline
                          A Offline
                          AliM93
                          wrote on last edited by
                          #129

                          i don't want to disturb you anymore tonight, if you want and if you have time we can continue tomorrow

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                          • mrjjM Offline
                            mrjjM Offline
                            mrjj
                            Lifetime Qt Champion
                            wrote on last edited by
                            #130

                            Yes its possible. we can paint it any way we like. teasers included.

                            Well im getting very tired as 4.20 in the morning is late for me even i do love programming at night.

                            Tomorrow we add the last part. It's not that much. Promise.
                            You did good. First custom widget is always a bit tuff.

                            alt text

                            alt text

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                            • A Offline
                              A Offline
                              AliM93
                              wrote on last edited by
                              #131

                              thank you so much! you help me a lot also in understand the ideas. thanks. night!

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                              • mrjjM Offline
                                mrjjM Offline
                                mrjj
                                Lifetime Qt Champion
                                wrote on last edited by mrjj
                                #132

                                Hi
                                The last remaining steps are to
                                +Add box width/height as members to use when clicking and a variable to keep track of the number of selected

                                class MatrixWidget : public QWidget
                                {....    
                                    int bw =0;
                                    int bh =0;
                                    int selCount=0; // to make sure we can only select 3
                                ,...
                                

                                +call loadData from construtor.

                                +Set some colors in void MatrixWidget::LoadData()
                                for 0 cells and 1 cells (see code)

                                +Add selection logic to mousePress

                                void MatrixWidget::mousePressEvent(QMouseEvent *event)
                                {
                                    QPoint p = event->pos(); // where we clicked
                                
                                    int xindex =  p.x() / bw;
                                    int yindex =  p.y() / bh;
                                
                                    qDebug() << xindex << " " << yindex;
                                    // get the data point ( we should check index is not outside array...)
                                    DataPoint &dp = Data[xindex + 1 ][yindex + 1]; 
                                
                                    // value zero cannot be selected
                                    if ( dp.value == 0 ) return;
                                
                                    // selection logic. If not already selected, select it and set color. Else deselect and reset color
                                    if ( dp.isSelected == false) {
                                
                                        // no more than 3 selected ( 0,1,2 )
                                        if ( selCount > 2 ) return;
                                
                                        dp.DrawColor = Qt::blue;
                                        dp.isSelected = true;
                                        selCount++; // extra selected
                                    } else {
                                        dp.DrawColor =  Qt::green;
                                        dp.isSelected = false;
                                        selCount--; // less selected
                                    }
                                    update(); // tell it to redraw grid
                                
                                }
                                
                                

                                +Adjust draw to skip 0,0 as we don't use it but the array must start at zero.

                                void MatrixWidget::paintEvent(QPaintEvent *event)
                                {
                                
                                    QPainter p(this);
                                    // draw frame.
                                    p.drawRect(0, 0, width() - 1, height() - 1);
                                
                                    // size of area we have. w = width , h = height , we take 2 pixles for border
                                    int w = width() - 2;
                                    int h = height() - 2;
                                
                                    // now we find out how big each box should be which area we have  divided with how many on x and y
                                    bw = w / max_x;
                                    bh = h / max_y;
                                
                                    // now we loop and draw the boxes. we dont use the boxes from 0,0 as data starts with 1,1
                                    for (int xi = 0; xi < max_x - 1; ++xi) {
                                        for (int yi = 0; yi < max_x - 1; ++yi) {
                                            p.setBrush(QBrush( Data[xi + 1][yi + 1].DrawColor )); // +1 as we dont want to use from 0,0
                                            QRect cellRect( xi * bw, yi * bh, bw, bh  );
                                            p.drawRect( cellRect );
                                            // show x,y . just for debug
                                            p.drawText( cellRect ,
                                                       QString::number(xi + 1) + "," +
                                                       QString::number(yi +1) );
                                
                                        }
                                    }
                                }
                                
                                
                                

                                Then we have a working version.

                                alt text

                                project
                                https://www.dropbox.com/s/z4nllgag1tjy4j3/GridWidgetApp.zip?dl=0

                                Things to improve/add
                                The limit of how many points user can select,
                                should be a parameter to the class so it can be set to anything and not a fixed value.

                                The colors could also be parameters ( for not selectable, selectable and selected)

                                Add a function to return the selected data pointsby looping the Data list and check isSelected.

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                                • A Offline
                                  A Offline
                                  AliM93
                                  wrote on last edited by AliM93
                                  #133

                                  thanks! i'll do it step by step, i quite understand it, but when i run i got a black grid, and the error floating point exeption (core dumped) No more error, (i also see the coordinates in the debug), but black grid.

                                  mrjjM 1 Reply Last reply
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                                  • A AliM93

                                    thanks! i'll do it step by step, i quite understand it, but when i run i got a black grid, and the error floating point exeption (core dumped) No more error, (i also see the coordinates in the debug), but black grid.

                                    mrjjM Offline
                                    mrjjM Offline
                                    mrjj
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #134

                                    @AliM93 said in Create a matrix from a .csv file:

                                    it, but when i run i got a black grid, and the error floating point exeption (core dumped)

                                    In my project or yours ?

                                    A 1 Reply Last reply
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                                    • mrjjM mrjj

                                      @AliM93 said in Create a matrix from a .csv file:

                                      it, but when i run i got a black grid, and the error floating point exeption (core dumped)

                                      In my project or yours ?

                                      A Offline
                                      A Offline
                                      AliM93
                                      wrote on last edited by
                                      #135

                                      @mrjj in mine

                                      mrjjM 1 Reply Last reply
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                                      • A AliM93

                                        @mrjj in mine

                                        mrjjM Offline
                                        mrjjM Offline
                                        mrjj
                                        Lifetime Qt Champion
                                        wrote on last edited by
                                        #136

                                        @AliM93

                                        Ok, i would guess that you forgot something from the maxtric class to put in yours.
                                        But if the grid is drawn ( you see it) and then when you click error comes ?

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                                        • A Offline
                                          A Offline
                                          AliM93
                                          wrote on last edited by
                                          #137
                                          This post is deleted!
                                          mrjjM 1 Reply Last reply
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