Create a matrix from a .csv file

[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

[mrjj]

@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 ?

[AliM93]

This post is deleted!

[mrjj]

@AliM93
If it compiles then all includes are fine.

Do you load data ?

Did you change LoadData function to set colors ?
(or use mine, just change the path to the data file)

I think all is just black :)
(default zero)

[AliM93]

@mrjj Done!! now i wii implement the function to save points! i'll let you know. thanks so much

[mrjj]

Hi
Ok super.
Good work. Your first custom Widget :)

Saving the points should be ok easy.
you can loop the Data array and take all where isSelected is true.

Ps please flag this as solved:)