Create a matrix from a .csv file

[AliM93]

i run it but obviouslt i can't see anything

[AliM93]

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

[mrjj]

@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

[AliM93]

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

[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 :)

[AliM93]

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

[AliM93]

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

[mrjj]

@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
        }
    }

}

[AliM93]

yes i have

[mrjj]

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

But you do see grid ?

[AliM93]

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

[mrjj]

@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?

[AliM93]

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?

[AliM93]

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

[mrjj]

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.

[AliM93]

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

[mrjj]

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.

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.

[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.

[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 ?

[AliM93]

@mrjj in mine