Send `mouseleft` event when the mouse leaves the window (#928)

* Send `mouseleft` event when the mouse leaves the window

* Call `View:on_mouse_left` when the mouse leaves the `View`

Previously `View:on_mouse_left` was called only when the mouse left the
window, and it was called on every visible `View`.

Now it gets also called when the mouse "changes" `View`, and only the
last `View` the mouse was on will receive the event.

data/core/init.lua

@@ -1136,6 +1136,8 @@ function core.on_event(type, ...)
     end
   elseif type == "mousereleased" then
     core.root_view:on_mouse_released(...)
+  elseif type == "mouseleft" then
+    core.root_view:on_mouse_left()
   elseif type == "mousewheel" then
     if not core.root_view:on_mouse_wheel(...) then
       did_keymap = keymap.on_mouse_wheel(...)

data/core/node.lua

@@ -51,6 +51,15 @@ function Node:on_mouse_released(...)
 end
 
 
+function Node:on_mouse_left()
+  if self.type == "leaf" then
+    self.active_view:on_mouse_left()
+  else
+    self:propagate("on_mouse_left")
+  end
+end
+
+
 function Node:consume(node)
   for k, _ in pairs(self) do self[k] = nil end
   for k, v in pairs(node) do self[k] = v   end
@@ -160,8 +169,12 @@ end
 
 function Node:set_active_view(view)
   assert(self.type == "leaf", "Tried to set active view on non-leaf node")
+  local last_active_view = self.active_view
   self.active_view = view
   core.set_active_view(view)
+  if last_active_view and last_active_view ~= view then
+    last_active_view:on_mouse_left()
+  end
 end
 
 

data/core/rootview.lua

@@ -256,8 +256,13 @@ function RootView:on_mouse_moved(x, y, dx, dy)
 
   self.root_node:on_mouse_moved(x, y, dx, dy)
 
+  local last_overlapping_node = self.overlapping_node
   self.overlapping_node = self.root_node:get_child_overlapping_point(x, y)
 
+  if last_overlapping_node and last_overlapping_node ~= self.overlapping_node then
+    last_overlapping_node:on_mouse_left()
+  end
+
   local div = self.root_node:get_divider_overlapping_point(x, y)
   local tab_index = self.overlapping_node and self.overlapping_node:get_tab_overlapping_point(x, y)
   if self.overlapping_node and self.overlapping_node:get_scroll_button_index(x, y) then
@@ -272,6 +277,13 @@ function RootView:on_mouse_moved(x, y, dx, dy)
 end
 
 
+function RootView:on_mouse_left()
+  if self.overlapping_node then
+    self.overlapping_node:on_mouse_left()
+  end
+end
+
+
 function RootView:on_file_dropped(filename, x, y)
   local node = self.root_node:get_child_overlapping_point(x, y)
   return node and node.active_view:on_file_dropped(filename, x, y)

data/core/view.lua

@@ -144,6 +144,12 @@ function View:on_mouse_moved(x, y, dx, dy)
 end
 
 
+function View:on_mouse_left()
+  self.hovered_scrollbar = false
+  self.hovered_scrollbar_track = false
+end
+
+
 function View:on_file_dropped(filename, x, y)
   return false
 end

src/api/system.c

@@ -161,6 +161,9 @@ top:
       } else if (e.window.event == SDL_WINDOWEVENT_RESTORED) {
         lua_pushstring(L, "restored");
         return 1;
+      } else if (e.window.event == SDL_WINDOWEVENT_LEAVE) {
+        lua_pushstring(L, "mouseleft");
+        return 1;
       }
       if (e.window.event == SDL_WINDOWEVENT_FOCUS_LOST) {
         lua_pushstring(L, "focuslost");