Ladybird: Implement an AppKit chrome for macOS :^)

This adds an alternative Ladybird chrome for macOS using the AppKit
framework. Just about everything needed for normal web browsing has
been implemented. This includes:

* Tabbed, scrollable navigation
* History navigation (back, forward, reload)
* Keyboard / mouse events
* Favicons
* Context menus
* Cookies
* Dialogs (alert, confirm, prompt)
* WebDriver support

This does not include debugging tools like the JavaScript console and
inspector, nor theme support.

The Qt chrome is still used by default. To use the AppKit chrome, set
the ENABLE_QT CMake option to OFF.

Ladybird/AppKit/Application/EventLoopImplementation.mm

@@ -0,0 +1,214 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Assertions.h>
+#include <AK/IDAllocator.h>
+#include <LibCore/Event.h>
+#include <LibCore/Notifier.h>
+#include <LibCore/ThreadEventQueue.h>
+
+#import <Application/EventLoopImplementation.h>
+#import <System/Cocoa.h>
+#import <System/CoreFoundation.h>
+
+namespace Ladybird {
+
+struct ThreadData {
+    static ThreadData& the()
+    {
+        static thread_local ThreadData s_thread_data;
+        return s_thread_data;
+    }
+
+    IDAllocator timer_id_allocator;
+    HashMap<int, CFRunLoopTimerRef> timers;
+    HashMap<Core::Notifier*, CFRunLoopSourceRef> notifiers;
+};
+
+static void post_application_event()
+{
+    auto* event = [NSEvent otherEventWithType:NSEventTypeApplicationDefined
+                                     location:NSMakePoint(0, 0)
+                                modifierFlags:0
+                                    timestamp:0
+                                 windowNumber:0
+                                      context:nil
+                                      subtype:0
+                                        data1:0
+                                        data2:0];
+
+    [NSApp postEvent:event atStart:NO];
+}
+
+NonnullOwnPtr<Core::EventLoopImplementation> CFEventLoopManager::make_implementation()
+{
+    return CFEventLoopImplementation::create();
+}
+
+int CFEventLoopManager::register_timer(Core::EventReceiver& receiver, int interval_milliseconds, bool should_reload, Core::TimerShouldFireWhenNotVisible should_fire_when_not_visible)
+{
+    auto& thread_data = ThreadData::the();
+
+    auto timer_id = thread_data.timer_id_allocator.allocate();
+    auto weak_receiver = receiver.make_weak_ptr();
+
+    auto interval_seconds = static_cast<double>(interval_milliseconds) / 1000.0;
+    auto first_fire_time = CFAbsoluteTimeGetCurrent() + interval_seconds;
+
+    auto* timer = CFRunLoopTimerCreateWithHandler(
+        kCFAllocatorDefault, first_fire_time, should_reload ? interval_seconds : 0, 0, 0,
+        ^(CFRunLoopTimerRef) {
+            auto receiver = weak_receiver.strong_ref();
+            if (!receiver) {
+                return;
+            }
+
+            if (should_fire_when_not_visible == Core::TimerShouldFireWhenNotVisible::No) {
+                if (!receiver->is_visible_for_timer_purposes()) {
+                    return;
+                }
+            }
+
+            Core::TimerEvent event(timer_id);
+            receiver->dispatch_event(event);
+        });
+
+    CFRunLoopAddTimer(CFRunLoopGetCurrent(), timer, kCFRunLoopDefaultMode);
+    thread_data.timers.set(timer_id, timer);
+
+    return timer_id;
+}
+
+bool CFEventLoopManager::unregister_timer(int timer_id)
+{
+    auto& thread_data = ThreadData::the();
+    thread_data.timer_id_allocator.deallocate(timer_id);
+
+    if (auto timer = thread_data.timers.take(timer_id); timer.has_value()) {
+        CFRunLoopTimerInvalidate(*timer);
+        return true;
+    }
+
+    return false;
+}
+
+static void socket_notifier(CFSocketRef socket, CFSocketCallBackType notification_type, CFDataRef, void const*, void* info)
+{
+    auto& notifier = *reinterpret_cast<Core::Notifier*>(info);
+
+    // This socket callback is not quite re-entrant. If Core::Notifier::dispatch_event blocks, e.g.
+    // to wait upon a Core::Promise, this socket will not receive any more notifications until that
+    // promise is resolved or rejected. So we mark this socket as able to receive more notifications
+    // before dispatching the event, which allows it to be triggered again.
+    CFSocketEnableCallBacks(socket, notification_type);
+
+    Core::NotifierActivationEvent event(notifier.fd());
+    notifier.dispatch_event(event);
+
+    // This manual process of enabling the callbacks also seems to require waking the event loop,
+    // otherwise it hangs indefinitely in any ongoing pump(PumpMode::WaitForEvents) invocation.
+    post_application_event();
+}
+
+void CFEventLoopManager::register_notifier(Core::Notifier& notifier)
+{
+    auto notification_type = kCFSocketNoCallBack;
+
+    switch (notifier.type()) {
+    case Core::Notifier::Type::Read:
+        notification_type = kCFSocketReadCallBack;
+        break;
+    case Core::Notifier::Type::Write:
+        notification_type = kCFSocketWriteCallBack;
+        break;
+    default:
+        TODO();
+        break;
+    }
+
+    CFSocketContext context { .info = &notifier };
+    auto* socket = CFSocketCreateWithNative(kCFAllocatorDefault, notifier.fd(), notification_type, &socket_notifier, &context);
+
+    CFOptionFlags sockopt = CFSocketGetSocketFlags(socket);
+    sockopt &= ~kCFSocketAutomaticallyReenableReadCallBack;
+    sockopt &= ~kCFSocketCloseOnInvalidate;
+    CFSocketSetSocketFlags(socket, sockopt);
+
+    auto* source = CFSocketCreateRunLoopSource(kCFAllocatorDefault, socket, 0);
+    CFRunLoopAddSource(CFRunLoopGetCurrent(), source, kCFRunLoopDefaultMode);
+
+    ThreadData::the().notifiers.set(&notifier, source);
+}
+
+void CFEventLoopManager::unregister_notifier(Core::Notifier& notifier)
+{
+    if (auto source = ThreadData::the().notifiers.take(&notifier); source.has_value()) {
+        CFRunLoopRemoveSource(CFRunLoopGetCurrent(), *source, kCFRunLoopDefaultMode);
+        CFRelease(*source);
+    }
+}
+
+void CFEventLoopManager::did_post_event()
+{
+    post_application_event();
+}
+
+NonnullOwnPtr<CFEventLoopImplementation> CFEventLoopImplementation::create()
+{
+    return adopt_own(*new CFEventLoopImplementation);
+}
+
+int CFEventLoopImplementation::exec()
+{
+    [NSApp run];
+    return m_exit_code;
+}
+
+size_t CFEventLoopImplementation::pump(PumpMode mode)
+{
+    auto* wait_until = mode == PumpMode::WaitForEvents ? [NSDate distantFuture] : [NSDate distantPast];
+
+    auto* event = [NSApp nextEventMatchingMask:NSEventMaskAny
+                                     untilDate:wait_until
+                                        inMode:NSDefaultRunLoopMode
+                                       dequeue:YES];
+
+    while (event) {
+        if (event.type == NSEventTypeApplicationDefined) {
+            m_thread_event_queue.process();
+        } else {
+            [NSApp sendEvent:event];
+        }
+
+        event = [NSApp nextEventMatchingMask:NSEventMaskAny
+                                   untilDate:nil
+                                      inMode:NSDefaultRunLoopMode
+                                     dequeue:YES];
+    }
+
+    return 0;
+}
+
+void CFEventLoopImplementation::quit(int exit_code)
+{
+    m_exit_code = exit_code;
+    [NSApp stop:nil];
+}
+
+void CFEventLoopImplementation::wake()
+{
+    CFRunLoopWakeUp(CFRunLoopGetCurrent());
+}
+
+void CFEventLoopImplementation::post_event(Core::EventReceiver& receiver, NonnullOwnPtr<Core::Event>&& event)
+{
+    m_thread_event_queue.post_event(receiver, move(event));
+
+    if (&m_thread_event_queue != &Core::ThreadEventQueue::current())
+        wake();
+}
+
+}