WindowServer: Fix animations not triggering rendering

When starting the first animation and while animations are ongoing we
need to make sure we trigger rendering.

Userland/Services/WindowServer/Animation.cpp

@@ -29,6 +29,7 @@ void Animation::start()
 {
  m_running = true;
  m_timer.start();
+ Compositor::the().animation_started({});
 }
 
 void Animation::stop()

Userland/Services/WindowServer/Compositor.cpp

@@ -528,11 +528,16 @@ void Compositor::compose()
  m_invalidated_window = false;
  m_invalidated_cursor = false;
 
- Screen::for_each([&](auto& screen) {
- auto& screen_data = m_screen_data[screen.index()];
- update_animations(screen, screen_data.m_flush_special_rects);
- return IterationDecision::Continue;
- });
+ if (!m_animations.is_empty()) {
+ Screen::for_each([&](auto& screen) {
+ auto& screen_data = m_screen_data[screen.index()];
+ update_animations(screen, screen_data.m_flush_special_rects);
+ return IterationDecision::Continue;
+ });
+ // As long as animations are running make sure we keep rendering frames
+ m_invalidated_any = true;
+ start_compose_async_timer();
+ }
 
  if (need_to_draw_cursor) {
  auto& screen_data = m_screen_data[cursor_screen.index()];
@@ -1205,8 +1210,17 @@ void Compositor::recompute_occlusions()
 
 void Compositor::register_animation(Badge<Animation>, Animation& animation)
 {
+ bool was_empty = m_animations.is_empty();
  auto result = m_animations.set(&animation);
  VERIFY(result == AK::HashSetResult::InsertedNewEntry);
+ if (was_empty)
+ start_compose_async_timer();
+}
+
+void Compositor::animation_started(Badge<Animation>)
+{
+ m_invalidated_any = true;
+ start_compose_async_timer();
 }
 
 void Compositor::unregister_animation(Badge<Animation>, Animation& animation)

Userland/Services/WindowServer/Compositor.h

@@ -71,6 +71,7 @@ class Compositor final : public Core::Object {
  invalidate_screen();
  }
 
+ void animation_started(Badge<Animation>);
  void invalidate_occlusions() { m_occlusions_dirty = true; }
  void overlay_rects_changed();