[Solved]Put data from .txt file in QPainter

BobMarly

I am very new at Qt and am trying to make drawings with coordinates from different .txt files. The code below is what i could derive from the Qt documentation, however i think it only loads a file, i dont know how to get the values from the file to use in my painting. The files always have 2 colums, with x coordinates in the first colomn and y coordinates in the second.
@static void process_line(const QByteArray &)
{
}

static void process_line(const QString &)
{
}
int main(){
QFile file("a18.txt");

if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 0;

QTextStream in(&file);
QString line = in.readLine();
while (!line.isNull()) {
process_line(line);
line = in.readLine();

}
}@

raven-worx

assuming your coordinates are separated with "|" character (analog for spcae-character for example).
@
process_line(const QString & line)
{
QStringList coordinates = line.split("|", QString::SkipEmptyParts );
if( coordinates.count() == 2 )
{
bool checkX;
int x = coordinates.at(0).trimmed().toInt( &checkX );
bool checkY;
int y = coordinates.at(1).trimmed().toInt( &checkY );

  if( checkX && checkY )
         //do something with QPoint(x,y)

}
@

BobMarly

This is what i have now, but it does not give any output.. what am i doing wrong? I put your code in where i thought would fit..
@#include "dewidget.h"

DeWidget::DeWidget(QWidget *parent)
: QWidget( parent)
{

}

DeWidget::~DeWidget()
{
}

QSize DeWidget::sizeHint() const
{
return QSize(840, 480);
}

void DeWidget::paintEvent(QPaintEvent *)
{
QStringList coordinates = line.split("|", QString::SkipEmptyParts );
if( coordinates.count() == 2 )
{
bool checkX;
float x = coordinates.at(0).trimmed().toFloat( &checkX );
bool checkY;
float y = coordinates.at(1).trimmed().toFloat( &checkY );

      if( checkX && checkY );
      setAttribute(Qt::WA_OpaquePaintEvent);
      QPainter painter(this);
      QPen linepen(Qt::red);
      linepen.setCapStyle(Qt::RoundCap);
      linepen.setWidth(10);
      painter.setRenderHint(QPainter::Antialiasing,true);
      painter.setPen(linepen);
      polyPoints << QPoint(x,y );
      painter.drawPolygon(polyPoints);
            
}

}
static void process_line(const QByteArray &)
{
}

static void process_line(const QString &)
{
}
int main(){
QFile file("a18.txt");

if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
return 0;

QTextStream in(&file);
QString line = in.readLine();
while (!line.isNull()) {
process_line(line);
line = in.readLine();

}

@

raven-worx

i doubt that this code does even compile :)

try this approach:
@
DeWidget::DeWidget(QWidget *parent)
: QWidget( parent)
{
//read file for drawing
QFile file("a18.txt");

if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
QTextStream in(&file);
QString line = in.readLine();
while (!line.isNull())
{
QStringList coordinates = line.split("|", QString::SkipEmptyParts );
if( coordinates.count() == 2 )
{
bool checkX;
float x = coordinates.at(0).trimmed().toFloat( &checkX );
bool checkY;
float y = coordinates.at(1).trimmed().toFloat( &checkY );

      if( checkX && checkY )
            polyPoints  << QPoint(x,y);    //polyPoints needs to be of type QPolygon/QPolygonF
}

  line = in.readLine(); 
}

file.close();

}
this->update();
}

DeWidget::~DeWidget()
{
}

QSize DeWidget::sizeHint() const
{
return QSize(840, 480);
}

void DeWidget::paintEvent(QPaintEvent * event)
{
QWidget::paintEvent(event);

      QPainter painter(this);
             painter.setRenderHint(QPainter::Antialiasing,true);
      QPen linepen(Qt::red);
             linepen.setCapStyle(Qt::RoundCap);
             linepen.setWidth(10);
      painter.setPen(linepen);

      painter.drawPolygon(polyPoints);

}
int main()
{
QApplication a;
DeWidget w;
w.show();
return a.exec();
}
@

BobMarly

It still doesnt give an output. the a18.txt file i stored it in my Other Files.. could there be the error ? :$
Thank you for your effort!

raven-worx

most probably.
Right now your code "looks ":http://qt-project.org/doc/qt-4.8/qfile.html#setFileName in the current working directory for the file to be present. Which is probably where your application binary is located.