标签: qtimer

好的,所以我在QTimer中完全迷失了.问题是:我有多线程应用程序,我需要在QTimer的超时上做一些工作.我这样做了:

QTimer* timer = new QTimer();
timer->setSingleShot(true);
connect(timer, SIGNAL(timeout()), someObject, SLOT(work()));

这没用.有时,work()根本没有被调用,有时它在我关闭程序时被调用,有时候看起来都很正常.
所以我开始想到计时器需要线程.提供MCV示例:

class Tester : public QObject
{
 Q_OBJECT
 public:
 Tester(QObject* par = 0) : QObject(par)
 {
 }
 public slots:
 void greet()
 {
  qDebug()<<"hello";
 }
};

int main(int argc, char *argv[])
{
 QCoreApplication a(argc, argv);

 QTimer* timer1 = new QTimer();

 QThread* thread = new QThread();
 Tester* tester = new Tester();

 timer1->setInterval(500);
 timer1->setSingleShot(false);
 timer1->moveToThread(thread);


 QObject::connect(thread, SIGNAL(started()), timer1, SLOT(start()));

 QObject::connect(timer1, SIGNAL(timeout()), tester, SLOT(greet()));

 QObject::connect(timer1, SIGNAL(timeout()), timer1, SLOT(deleteLater()));
 QObject::connect(timer1, SIGNAL(destroyed()), thread, SLOT(quit())); …

使用计时器我checkBookings()反复调用插槽.我能够编译并运行程序,但在执行上述FOR循环时崩溃了.

错误:"在QList :: at中ASSERT失败:"索引超出范围",文件../../../../Qt/2010.05/qt/include/QtCore/../../src/corelib /tools/qlist.h,第455行传递给C运行时函数的参数无效.传递给C运行时函数的参数无效."

我的代码是:

timer = new QTimer();
connect(timer,SIGNAL(timeout()),this,SLOT(checkBookings()));
timer->start(500000);

void Canvas::checkBookings()
{

 QString dateStr;

 for(int i= 0;i<=qlist.count();i++)
    {
      dateStr = qList.at(i).at(6);
    }

}

假设这timer是一个对象QTimer,定时器的间隔是iInterval和定时器的超时信号连接到一个插槽sltTimeout().

我只是在想如果iInterval小于sltTimeout()运行时间会发生什么.结果会运行多个线程sltTimeout()吗？如果是这样,似乎可能导致对对象的非同步访问出现问题.

任何人都可以澄清一下吗？

简而言之:这段代码位于main函数中,这很有效.此代码在两个图形元素上执行交换.

        QTimer timer;
        timer.setTimerType(Qt::PreciseTimer);
        timer.setInterval(1000.0/30.0);
        timer.setSingleShot(false);

    // ====================== MOVE 4 in POS of 1 ==========================
        QPointF centre(QLineF(button1->pos(), button4->pos()).pointAt(0.5));
        QPointF positionBut4 = button4->pos();

        MyPointF centreSwap4(0, &positionBut4, &centre);
        button4->myPointF = &centreSwap4;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap4, SLOT(updateDownRight()));
        QObject::connect(&centreSwap4, SIGNAL(positionChanged()), button4, SLOT(slotMoveCircle()));

    // ====================== MOVE 4 in POS of 1 ==========================

    // ====================== MOVE 1 in POS of 4 ==========================
        QPointF positionBut1 = button1->pos();

        MyPointF centreSwap1(0, &positionBut1, &centre);
        button1->myPointF = &centreSwap1;

        QObject::connect(&timer, SIGNAL(timeout()), &centreSwap1, SLOT(updateUpLeft()));
        QObject::connect(&centreSwap1, SIGNAL(positionChanged()), button1, SLOT(slotMoveCircle()));
    // ====================== MOVE 1 in POS …

我正在尝试将“某些文本”打印到 QTextBrowser，连续“n”次。其中“n”是整数。为此，我使用 QTimer::SingleShot 进行计时。一旦超时被触发，一个 FLAG 被设置为 false 并且这个“FLAG”在 while 循环中被监视以在 FLAG 为 false 时中断，并且它应该插入文本直到 FLAG 被设置为 FALSE。FLAG 的初始值为真。

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QThread>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    FLAG = true;

}

void MainWindow::on_pushButton_clicked()
{
    ui->pushButton->setEnabled(false);
   RunTheTimer();
    int counter = 0;

    do
    {
        ui->textBrowser->insertPlainText(QString("Inside While loop %1 \n").arg(counter++));
        counter++;
    }while(FLAG);

    FLAG = true;

}
void MainWindow::RunTheTimer()
{
     ui->textBrowser-> insertPlainText("Timer Started");
    QTimer::singleShot(60000, this, SLOT(Update()));// One Minute

}

void MainWindow::Update()
{
   ui->textBrowser-> insertPlainText("Timeout signal triggered");
    ui->pushButton->setEnabled(true);
   FLAG = …

我试图QTimer在我的窗口小部件上使用一个简单的对象,以便我可以计算一个方法完成所用的时间.但令我惊讶的是,计时器被阻止,直到该方法完成执行!即当有问题的方法结束时,计时器开始滴答作响!

这是一个示例代码,用于演示我写的内容:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
  class MainWindow;
}

class MainWindow : public QMainWindow
{
  Q_OBJECT

public:
  explicit MainWindow(QWidget *parent = 0);
  ~MainWindow();

private slots:
  void on_btnTest_clicked();
  void OnTimerTick();

private:
  Ui::MainWindow *ui;
  ulong seconds;
};

#endif // MAINWINDOW_H  

这是cpp文件:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv/cv.h"
#include <QTimer>
#include <QtCore>

MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
}

MainWindow::~MainWindow()
{
  delete ui;
}


void MainWindow::on_btnTest_clicked()
{
  QTimer * timer …