qiosplatformaccessibility.mm

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
 
#include "qiosplatformaccessibility.h"
 
#if QT_CONFIG(accessibility)
 
#include <QtGui/QtGui>
#include "qioswindow.h"
#include "quiaccessibilityelement.h"
 
QT_NAMESPACE_ALIAS_OBJC_CLASS(QMacAccessibilityElement);
 
QIOSPlatformAccessibility::QIOSPlatformAccessibility()
{
    m_focusObserver = QMacNotificationObserver(
            nil, UIAccessibilityElementFocusedNotification, [&](NSNotification *notification) {
                id element = notification.userInfo[UIAccessibilityFocusedElementKey];
                m_focusElement = static_cast<QMacAccessibilityElement *>(element);
            });
}
 
QIOSPlatformAccessibility::~QIOSPlatformAccessibility()
{}
 
 
void invalidateCache(QAccessibleInterface *iface)
{
    if (!iface || !iface->isValid()) {
        qWarning() << "invalid accessible interface: " << iface;
        return;
    }
 
    // This will invalidate everything regardless of what window the
    // interface belonged to. We might want to revisit this strategy later.
    // (Therefore this function still takes the interface as argument)
    //
    // Clear every window, not just the top levels, as each view vends the
    // elements of its own window only, so a child window's cache is the one
    // holding the elements that a change below a native view boundary affects.
    const auto windows = QGuiApplication::allWindows();
    for (QWindow *win : windows) {
        if (win && win->handle()) {
            auto *window = static_cast<QIOSWindow *>(win->handle());
            window->clearAccessibleCache();
        }
    }
}
 
 
void QIOSPlatformAccessibility::notifyAccessibilityUpdate(QAccessibleEvent *event)
{
    auto *accessibleInterface = event->accessibleInterface();
    if (!isActive() || !accessibleInterface)
        return;
    switch (event->type()) {
    case QAccessible::Announcement: {
        auto *announcementEvent = static_cast<QAccessibleAnnouncementEvent *>(event);
        const bool queueAnnouncement =
                (announcementEvent->politeness() == QAccessible::AnnouncementPoliteness::Polite);
        NSAttributedString *message = [[NSAttributedString alloc]
                initWithString:announcementEvent->message().toNSString()
                    attributes:@{UIAccessibilitySpeechAttributeQueueAnnouncement: @(queueAnnouncement)}];
        UIAccessibilityPostNotification(UIAccessibilityAnnouncementNotification, [message autorelease]);
        break;
    }
    case QAccessible::Focus: {
        auto *element = [QMacAccessibilityElement elementWithId:event->uniqueId()];
        Q_ASSERT(element);
        // There's no NSAccessibilityFocusedUIElementChangedNotification, like we have on
        // macOS. Instead, the documentation for UIAccessibilityLayoutChangedNotification
        // specifies that the optional argument to UIAccessibilityPostNotification is the
        // accessibility element for VoiceOver to move to after processing the notification.
        UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, element);
        break;
    }
    case QAccessible::DescriptionChanged:
    case QAccessible::NameChanged: {
        auto *element = [QMacAccessibilityElement elementWithId:event->uniqueId()];
        if (element == m_focusElement)
            UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, element);
        break;
    }
    case QAccessible::StateChanged:
    case QAccessible::ValueChanged: {
        auto *element = [QMacAccessibilityElement elementWithId:event->uniqueId()];
        if (element)
            UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, element);
        break;
    }
    case QAccessible::ObjectCreated:
    case QAccessible::ObjectShow:
    case QAccessible::ObjectHide:
    case QAccessible::ObjectDestroyed:
        invalidateCache(accessibleInterface);
        switch (accessibleInterface->role()) {
        case QAccessible::Window:
        case QAccessible::Dialog:
            // Bigger changes to the UI require a full reset of VoiceOver
            UIAccessibilityPostNotification(UIAccessibilityScreenChangedNotification, nil);
            break;
        default:
            // While smaller changes can be handled by re-reading the layout
            UIAccessibilityPostNotification(UIAccessibilityLayoutChangedNotification, nil);
        }
        break;
    default:
        break;
    }
}
 
#endif