1 files changed, 110 insertions, 0 deletions
diff --git a/src/ui/host/RoutedEventDispatch.h b/src/ui/host/RoutedEventDispatch.h
new file mode 100644
index 00000000..ae1421ee
--- /dev/null
+++ b/src/ui/host/RoutedEventDispatch.h
@@ -0,0 +1,110 @@
+#pragma once
+#include "cru/common/Logger.h"
+#include "cru/ui/DebugFlags.h"
+#include "cru/ui/controls/Control.h"
+
+#include <vector>
+
+namespace cru::ui {
+// Dispatch the event.
+//
+// This will raise routed event of the control and its parent and parent's
+// parent ... (until "last_receiver" if it's not nullptr) with appropriate args.
+//
+// First tunnel from top to bottom possibly stopped by "handled" flag in
+// EventArgs. Second bubble from bottom to top possibly stopped by "handled"
+// flag in EventArgs. Last direct to each control.
+//
+// Args is of type "EventArgs". The first init argument is "sender", which is
+// automatically bound to each receiving control. The second init argument is
+// "original_sender", which is unchanged. And "args" will be perfectly forwarded
+// as the rest arguments.
+template <typename EventArgs, typename... Args>
+void DispatchEvent(
+    const std::u16string_view& event_name,
+    controls::Control* const original_sender,
+    events::RoutedEvent<EventArgs>* (controls::Control::*event_ptr)(),
+    controls::Control* const last_receiver, Args&&... args) {
+  CRU_UNUSED(event_name)
+
+  if (original_sender == last_receiver) {
+    if constexpr (debug_flags::routed_event)
+      log::Debug(
+          "Routed event {} no need to dispatch (original_sender == "
+          "last_receiver). Original sender is {}.",
+          event_name, original_sender->GetControlType());
+    return;
+  }
+
+  std::vector<controls::Control*> receive_list;
+
+  auto parent = original_sender;
+  while (parent != last_receiver) {
+    receive_list.push_back(parent);
+    parent = parent->GetParent();
+  }
+
+  if constexpr (debug_flags::routed_event) {
+    std::u16string log = u"Dispatch routed event ";
+    log += event_name;
+    log += u". Path (parent first): ";
+    auto i = receive_list.crbegin();
+    const auto end = --receive_list.crend();
+    for (; i != end; ++i) {
+      log += (*i)->GetControlType();
+      log += u" -> ";
+    }
+    log += (*i)->GetControlType();
+    log::Debug(log);
+  }
+
+  auto handled = false;
+
+  int count = 0;
+
+  // tunnel
+  for (auto i = receive_list.crbegin(); i != receive_list.crend(); ++i) {
+    count++;
+    EventArgs event_args(*i, original_sender, std::forward<Args>(args)...);
+    static_cast<Event<EventArgs&>*>(((*i)->*event_ptr)()->Tunnel())
+        ->Raise(event_args);
+    if (event_args.IsHandled()) {
+      handled = true;
+      if constexpr (debug_flags::routed_event)
+        log::Debug(
+            u"Routed event is short-circuit in TUNNEL at {}-st control (count "
+            u"from parent).",
+            count);
+      break;
+    }
+  }
+
+  // bubble
+  if (!handled) {
+    for (auto i : receive_list) {
+      count--;
+      EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
+      static_cast<Event<EventArgs&>*>((i->*event_ptr)()->Bubble())
+          ->Raise(event_args);
+      if (event_args.IsHandled()) {
+        if constexpr (debug_flags::routed_event)
+          log::Debug(
+              u"Routed event is short-circuit in BUBBLE at {}-st control "
+              u"(count from parent).",
+              count);
+        break;
+      }
+    }
+  }
+
+  // direct
+  for (auto i : receive_list) {
+    EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
+    static_cast<Event<EventArgs&>*>((i->*event_ptr)()->Direct())
+        ->Raise(event_args);
+  }
+
+  if constexpr (debug_flags::routed_event)
+    log::Debug(u"Routed event dispatch finished.");
+}
+}  // namespace cru::ui