Read line by line in a specific time interval

[Venkatesh V]

@Shahmisufi

For that you need to store all the lines in QList. after that take a Qtimer instance set it 2 second interval and start the timer, once the timer emits timeout connect to another slot there you can take one value at a time from the list and set to textedit.

[Venkatesh V]

This post is deleted!

[Venkatesh V]

@Shahmisufi

@Shahmisufi

//Header File

QList<QString> LineList;
int count = 0;


//SourceFile
{
QFile inputFile(fileName);
if (inputFile.open(QIODevice::ReadOnly))
{
QTextStream in(&inputFile);
while (!in.atEnd())
{
QString line = in.readLine();
LineList.apppend(line);
}
inputFile.close();
}

QTimer *timer = new QTimer;
timer->setInterval(2000);
timer->start();

connect(timer,SIGNAL(timeOut(),this,SLOT(readLine()));
}



void readLine()
{
textEdit->setText(textEdit->text()+LineList.at(count));
count++;
}

[VRonin]

Alternative, less memory hungry but needs the file not to be deleted until the process finished:

QFile* inputFile=new QFile(fileName,textEdit);
if (!inputFile.open(QIODevice::ReadOnly)){
inputFile->deleteLater();
return;
}
QTimer* inputTimer= new QTimer(textEdit); 
auto readSingleLine = [=]()->void{
QTextStream in(inputFile);
if(in.atEnd()){
inputFile->deleteLater();
inputTimer->deleteLater();
return;
}
const QString line = in.readLine();
textEdit->moveCursor(QTextCursor::End);
textEdit->textCursor().insertText(line); //not sure if you need to manually add the newline here
};
QObject::connect(inputTimer,&QTimer::timeout,textEdit,readSingleLine);
readSingleLine();
inputTimer->start(2000); //2 seconds

[Shahmisufi]

@Venkatesh-V , thank you. will update to you once I've run the program

[Shahmisufi]

@Venkatesh-V Dear sir I have tried your code, but when I run i the issue highlighted is

" 'Class QTextEdit' has no member named 'text' "

for the code line below :

textEdit->setText(textEdit->text()+LineList.at(count));

[m.sue]

@Shahmisufi

Hi,

instead of text() just use the function toPlainText().

-Michael.

[Venkatesh V]

@Shahmisufi

Hi,

Sorry, as @m-sue said use toPlainText() method to get current text of textEdit. this will resolve your query.

[Shahmisufi]

@Venkatesh-V dear sir, I have some error at this line

void readLine()
{
  textEdit->setText(textEdit->toPlainText()+LineList.at(count));
  count++;
}

1. 'textEdit' was not declared in this scope
2. 'LineList' was not declared in this scope'count' was not declared in this scope
3. 'count' was not declared in this scope

So, i have changed from

void readLine()

to

void Speedometer::readLine()

hence, its executable, but then it doesn't respond as we wanted. It does not display any text inside the TextEdit widget.

[Venkatesh V]

@Shahmisufi

Hi,
have you declared readLine() in public slots section?

//In Header File

public slots:
void readLine();