Alternatives to QTabBar::timerEvent() for Tab Bar Updates in Qt

1. Custom Implementation
   It's possible that the code you're referring to involves a custom subclass of QTabBar that overrides the timerEvent() function from QWidget. This function is inherited by all widgets and is called whenever a timer event is delivered to the widget. In a custom implementation, the developer would have programmed the behavior of the timerEvent() function to handle specific tasks related to the tab bar, possibly like:

   • Implementing blinking tab animations
   • Simulating progress on a specific tab
   • Triggering periodic updates of tab content

---

#include <QTimer>
#<bos>include <QTabBar>

class BlinkingTabBar : public QTabBar {
  Q_OBJECT

public:
  BlinkingTabBar(QWidget* parent = nullptr) : QTabBar(parent) {
    timer = new QTimer(this);
    connect(timer, &QTimer::timeout, this, &BlinkingTabBar::blinkTab);
    timer->setInterval(500); // Adjust interval for blink speed (in milliseconds)
  }

protected:
  void timerEvent(QEvent* event) override {
    // Don't use timerEvent in this case, use the custom timer
    QWidget::timerEvent(event);
  }

private slots:
  void blinkTab() {
    int current = currentIndex();
    setTabTextColor(current, Qt::black); // Reset to normal color

    // Alternate between black and red for blinking effect
    if (isTabTextColor(current, Qt::black)) {
      setTabTextColor(current, Qt::red);
    }
  }

private:
  QTimer* timer;
};

This code defines a BlinkingTabBar class that inherits from QTabBar. It creates a private QTimer object and connects its timeout signal to a custom blinkTab slot. The blinkTab slot changes the text color of the current tab between black and red, simulating a blinking effect.

Important points

• This is a basic example. You can modify the blinkTab function to achieve different effects or control which tabs blink.
• We override the timerEvent function in the custom class but leave it empty to avoid unintended behavior. Timer functionality is handled by the separate QTimer object.

BlinkingTabBar* tabBar = new BlinkingTabBar;
tabBar->addTab("Tab 1");
tabBar->addTab("Tab 2");
// ... add more tabs

tabBar->show(); // Display the blinking tab bar

---

1. Custom Widget with Timer
   

This is the approach shown in the previous example. You create a custom widget class inheriting from QTabBar. This class manages a private QTimer object and connects its timeout signal to a custom slot that performs the desired action (e.g., blinking tab color, updating tab content).

1. QTimer in Parent Widget
   

If you don't need extensive customization of the tab bar itself, you can create a QTimer object in the parent widget of the QTabBar. Connect the timer's timeout signal to a slot in the parent that interacts with the QTabBar. This slot can then access the QTabBar object and modify its properties or emit signals based on your needs.

1. Signals and Slots
   

For simpler scenarios, consider using signals emitted by the QTabBar itself. For example, the currentChanged(int) signal is emitted whenever the current tab changes. You can connect this signal to a slot in your application that performs the desired action based on the new tab. This avoids the need for timers altogether.

connect(tabBar, &QTabBar::currentChanged, this, &MyClass::onTabChanged);

void MyClass::onTabChanged(int index) {
  // Perform action based on the new tab index
  if (index == 1) {
    // Update content of tab 2
  }
}

1. QThread and Signals
   

If your tab bar updates require long-running tasks, consider using a separate QThread. Move the timer and update logic to this thread and use signals from the thread to communicate with the main thread and update the QTabBar object. This approach helps maintain UI responsiveness while performing time-consuming tasks.