From 68d5b399429738a8b39dd242fa228c7077052bbb Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon.ml.booth@gmail.com>
Date: Mon, 20 Jan 2020 22:03:57 +1300
Subject: [PATCH] WindowServer: Simplify WSMenu MouseWheel event

A mouse move event needs to do a bit more work than what a mouse wheel event
does. Mouse wheel just needs to update the hovered item, and update for a new
hovered item. This also stops us from calling redraw() twice on a wheel event.
---
 Servers/WindowServer/WSMenu.cpp | 21 +++++++++++----------
 Servers/WindowServer/WSMenu.h   |  2 +-
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/Servers/WindowServer/WSMenu.cpp b/Servers/WindowServer/WSMenu.cpp
index fac6d8abe4..fa622f8c89 100644
--- a/Servers/WindowServer/WSMenu.cpp
+++ b/Servers/WindowServer/WSMenu.cpp
@@ -300,11 +300,9 @@ void WSMenu::decend_into_submenu_at_hovered_item()
     m_in_submenu = true;
 }
 
-void WSMenu::handle_hover_event(const WSMouseEvent& event)
+void WSMenu::handle_mouse_move_event(const WSMouseEvent& mouse_event)
 {
     ASSERT(menu_window());
-    auto mouse_event = static_cast<const WSMouseEvent&>(event);
-
     if (hovered_item() && hovered_item()->is_submenu()) {
 
         auto item = *hovered_item();
@@ -333,7 +331,7 @@ void WSMenu::handle_hover_event(const WSMouseEvent& event)
 void WSMenu::event(CEvent& event)
 {
     if (event.type() == WSEvent::MouseMove) {
-        handle_hover_event(static_cast<const WSMouseEvent&>(event));
+        handle_mouse_move_event(static_cast<const WSMouseEvent&>(event));
         return;
     }
 
@@ -343,14 +341,17 @@ void WSMenu::event(CEvent& event)
     }
 
     if (event.type() == WSEvent::MouseWheel && is_scrollable()) {
+        ASSERT(menu_window());
         auto& mouse_event = static_cast<const WSMouseEvent&>(event);
         m_scroll_offset += mouse_event.wheel_delta();
-        if (m_scroll_offset < 0)
-            m_scroll_offset = 0;
-        if (m_scroll_offset >= m_max_scroll_offset)
-            m_scroll_offset = m_max_scroll_offset;
-        handle_hover_event(mouse_event);
-        redraw();
+        m_scroll_offset = clamp(m_scroll_offset, 0, m_max_scroll_offset);
+
+        int index = item_index_at(mouse_event.position());
+        if (m_hovered_item_index == index)
+            return;
+
+        m_hovered_item_index = index;
+        update_for_new_hovered_item();
         return;
     }
 
diff --git a/Servers/WindowServer/WSMenu.h b/Servers/WindowServer/WSMenu.h
index 78dab04495..e59eec5cbb 100644
--- a/Servers/WindowServer/WSMenu.h
+++ b/Servers/WindowServer/WSMenu.h
@@ -117,7 +117,7 @@ public:
 private:
     virtual void event(CEvent&) override;
 
-    void handle_hover_event(const WSMouseEvent&);
+    void handle_mouse_move_event(const WSMouseEvent&);
     int visible_item_count() const;
 
     int item_index_at(const Point&);