QFileSystemWatcher problem

[YDYD]

Hi all,

I am using a QFileSystemWatcher to keep an eye on a Picture on RAM disk.
When the picture is replace by another, which mean it is "modified".
and i would like to emit a signal and get the image to display on a QLabel.

It works when i use QTimer to replace the QFileSystemWatcher.

It seems QFileSystemWatcher is not emitting any signal.

my code ask following:

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
   /* timer = new QTimer(this);
    timer->start(100);*/
 
    QFileSystemWatcher watcher;
    watcher.addPath("/mnt/rd/frame.jpg");
    hsvSaveConnect();
    checkBox();
    connect(ui->save,SIGNAL(clicked()),this,SLOT(saveValueToSD()));
    connect(ui->load,SIGNAL(clicked()),this,SLOT(loadInitValue()));
    connect(&watcher,SIGNAL(fileChanged(const QString &)),this,SLOT(loadImage()));
    connect(&watcher,SIGNAL(directoryChanged(const QString &)),this,SLOT(loadImage()));
    qDebug() << watcher.files() << watcher.directories();
}
 
 
void Dialog::loadImage()
 
 
{
 
    qDebug() << "img loaded";
 
 
    QPixmap original("/mnt/rd/frame.jpg");
 
 
    if(original.isNull())
 
 
    {
 
        qDebug()<<"Failed to load image.";
 
 
    }
 
    ui->original->setPixmap(original);
 
 
}

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);
   /* timer = new QTimer(this);
    timer->start(100);*/

    QFileSystemWatcher watcher;
    watcher.addPath("/mnt/rd/frame.jpg");
    hsvSaveConnect();
    checkBox();
    connect(ui->save,SIGNAL(clicked()),this,SLOT(saveValueToSD()));
    connect(ui->load,SIGNAL(clicked()),this,SLOT(loadInitValue()));
    connect(&watcher,SIGNAL(fileChanged(const QString &)),this,SLOT(loadImage()));
    connect(&watcher,SIGNAL(directoryChanged(const QString &)),this,SLOT(loadImage()));
    qDebug() << watcher.files() << watcher.directories();
}


void Dialog::loadImage()


{

    qDebug() << "img loaded";


    QPixmap original("/mnt/rd/frame.jpg");


    if(original.isNull())


    {

        qDebug()<<"Failed to load image.";


    }

    ui->original->setPixmap(original);


}

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[stampede]

"watcher" goes out of scope when the constructor completes, allocate it on the heap or make it a class member.

[YDYD]

Hi stampede,

when i declared
QFileSystemWatcher *watcher=new QFileSystemWatcher;

it works,

but i declared in .h file "private",it is not working.

"The program has unexpectedly finished."

[stampede]

it is not working

It is impossible to help without seeing relevant code.