Tear out or duplicate what's unique for WindowServer from Widgets.

This turned into a huge refactoring that somehow also includes
making locks recursive/reentrant.

WindowServer/WSEventLoop.cpp

@@ -0,0 +1,98 @@
+#include "WSEventLoop.h"
+#include "WSEvent.h"
+#include "WSEventReceiver.h"
+#include "WSWindowManager.h"
+#include "WSScreen.h"
+#include "PS2MouseDevice.h"
+#include "Scheduler.h"
+
+//#define WSEVENTLOOP_DEBUG
+
+static WSEventLoop* s_the;
+
+void WSEventLoop::initialize()
+{
+    s_the = nullptr;
+}
+
+WSEventLoop::WSEventLoop()
+{
+    if (!s_the)
+        s_the = this;
+}
+
+WSEventLoop::~WSEventLoop()
+{
+}
+
+WSEventLoop& WSEventLoop::the()
+{
+    ASSERT(s_the);
+    return *s_the;
+}
+
+int WSEventLoop::exec()
+{
+    m_server_process = current;
+    m_running = true;
+    for (;;) {
+        if (m_queued_events.is_empty())
+            waitForEvent();
+        Vector<QueuedEvent> events;
+        {
+            LOCKER(m_lock);
+            events = move(m_queued_events);
+        }
+
+        for (auto& queued_event : events) {
+            auto* receiver = queued_event.receiver;
+            auto& event = *queued_event.event;
+#ifdef WSEVENTLOOP_DEBUG
+            dbgprintf("WSEventLoop: receiver{%p} event %u (%s)\n", receiver, (unsigned)event.type(), event.name());
+#endif
+            if (!receiver) {
+                dbgprintf("WSEvent type %u with no receiver :(\n", event.type());
+                ASSERT_NOT_REACHED();
+                return 1;
+            } else {
+                receiver->event(event);
+            }
+        }
+    }
+}
+
+void WSEventLoop::post_event(WSEventReceiver* receiver, OwnPtr<WSEvent>&& event)
+{
+    //ASSERT_INTERRUPTS_ENABLED();
+    LOCKER(m_lock);
+#ifdef WSEVENTLOOP_DEBUG
+    dbgprintf("WSEventLoop::post_event: {%u} << receiver=%p, event=%p\n", m_queued_events.size(), receiver, event.ptr());
+#endif
+    m_queued_events.append({ receiver, move(event) });
+}
+
+void WSEventLoop::waitForEvent()
+{
+    auto& mouse = PS2MouseDevice::the();
+    auto& screen = WSScreen::the();
+    bool prev_left_button = screen.left_mouse_button_pressed();
+    bool prev_right_button = screen.right_mouse_button_pressed();
+    int dx = 0;
+    int dy = 0;
+    while (mouse.can_read(*m_server_process)) {
+        signed_byte data[3];
+        ssize_t nread = mouse.read(*m_server_process, (byte*)data, 3);
+        ASSERT(nread == 3);
+        bool left_button = data[0] & 1;
+        bool right_button = data[0] & 2;
+        dx += data[1];
+        dy += -data[2];
+        if (left_button != prev_left_button || right_button != prev_right_button || !mouse.can_read(*m_server_process)) {
+            prev_left_button = left_button;
+            prev_right_button = right_button;
+            screen.on_receive_mouse_data(dx, dy, left_button, right_button);
+            dx = 0;
+            dy = 0;
+        }
+    }
+}