Enhancing Assistive Technology Support in Qt GUIs with QAccessibleActionInterface::scrollUpAction()

• Returns the name of the scroll up action
  When this method is called, it returns a QString that represents the default action name for scrolling upwards within a widget. This name is then used by assistive technologies to convey the action's purpose to the user.

Important to Note

• QAccessibleActionInterface::scrollUpAction() doesn't perform the actual scrolling itself. It merely provides the name of the action, which is then used by assistive technologies to interact with the widget and trigger the scrolling functionality.

Example Scenario

Imagine you have a QListWidget containing a list of items. When a user with a screen reader focuses on the widget, the assistive technology might leverage QAccessibleActionInterface::scrollUpAction() to determine the available action for scrolling upwards. The screen reader would then announce something like "Scroll up list" to the user, indicating that they can use specific keystrokes or gestures to navigate through the list.

---

#include <QAccessibleActionInterface>

class MyCustomWidget : public QWidget {
  Q_OBJECT

public:
  MyCustomWidget(QWidget *parent = nullptr) : QWidget(parent) {}

protected:
  void paintEvent(QPaintEvent *event) override {
    // Your custom widget painting logic here
  }

private:
  QStringList items; // List of items for your widget

  // Implement accessibility methods for your widget
  QAccessibleInterface *accessibleInterface() const override {
    return QAccessibleWidget::accessibleInterface();
  }

  QStringList accessibleActionNames() const override {
    QStringList actions;
    if (items.size() > 0) {
      actions << QAccessibleActionInterface::scrollUpAction();
      actions << QAccessibleActionInterface::scrollDownAction();
    }
    return actions;
  }

  void doScrollUp() {
    // Implement your custom logic for scrolling up here (e.g., adjust visible items)
  }
};

1. We define a MyCustomWidget class that inherits from QWidget.
2. The accessibleInterface method is overridden to return the base class implementation for standard widget accessibility.
3. The accessibleActionNames method is crucial. Here, we check if the widget has any items (items.size() > 0). If so, we add both QAccessibleActionInterface::scrollUpAction() and QAccessibleActionInterface::scrollDownAction() to the returned list. This informs assistive technologies about the available scroll actions.
4. The doScrollUp method is a placeholder for your custom logic to handle scrolling upwards within your widget. This could involve adjusting the visible item range or implementing other relevant functionality.

---

1. Custom Accessible Action
   

#include <QAccessibleActionInterface>

class MyCustomScrollUpAction : public QAccessibleAction
{
  Q_OBJECT

public:
  MyCustomScrollUpAction(QObject* parent = nullptr) : QAccessibleAction(parent) {}

  QString name() const override {
    return "Scroll content upwards"; // Your custom action name
  }

  void doAction() override {
    // Implement your custom logic for scrolling up here
  }
};

// In your widget's accessibleActionNames method
QStringList accessibleActionNames() const override {
  QStringList actions;
  if (items.size() > 0) {
    actions << MyCustomScrollUpAction::staticName();
  }
  return actions;
}

1. QAbstractScrollArea Signals
   

• If your widget inherits from QAbstractScrollArea (like QScrollArea or QListView), you can leverage its built-in signals for scrolling:

  • horizontalScrollBar()->valueChanged(int) for horizontal scrolling
  • verticalScrollBar()->valueChanged(int) for vertical scrolling

  By connecting to these signals, assistive technologies can potentially detect scroll events and announce them to the user without relying on specific action names. This approach might be more suitable if you have a standard scrollbar widget handling the scrolling behavior.

The best approach depends on your specific needs and the level of customization you require for the scroll action description. Consider factors like:

• Standard scrollbars
  If you're using standard scrollbar widgets, the scroll area signals might be sufficient.
• Control over wording
  If you need precise control over the text announced by assistive technologies, a custom action might be better.