Allow removal of default layout behaviors (tab nav, mouse scroll, etc.)

luigi/layout.lua

@@ -324,6 +324,7 @@ function Layout:placeNear (left, top, width, height)
     root.top = top
 end
 
+
 -- Add handlers for keyboard shortcuts, tab focus, and mouse wheel scroll
 function Layout:addDefaultHandlers ()
     self.shortcuts = {}
@@ -332,6 +333,19 @@ function Layout:addDefaultHandlers ()
         self.shortcuts[i] = {}
     end
 
+    self.behavior = {}
+
+    local function createBehavior (name, hooks)
+        self.behavior[name] = hooks
+        function hooks.destroy ()
+            for _, hook in ipairs(hooks) do
+                hook:unhook()
+            end
+            self.behavior[name] = nil
+        end
+    end
+
+    createBehavior('context', {
         self:onPressStart(function (event)
             -- show context menu on right click
             if event.button ~= 'right' then return end
@@ -343,18 +357,32 @@ function Layout:addDefaultHandlers ()
             menu.menuLayout:placeNear(event.x - 1, event.y - 1, 2, 2)
             return false
         end)
+    })
 
+    createBehavior('shortcut', {
         self:onKeyPress(function (event)
-        -- keyboard shortcuts
             local entry = self.shortcuts[event.modifierFlags]
             local widget = entry and entry[event.key]
-        if widget then
+            if not widget then return end
             widget.hovered = true
             self.input:handlePressStart(self, 'left', event.x, event.y,
                 widget, widget.shortcut)
             return false
-        end
+        end),
 
+        self:onKeyRelease(function (event)
+            local entry = self.shortcuts[event.modifierFlags]
+            local widget = entry and entry[event.key]
+            if not widget then return end
+            widget.hovered = false
+            self.input:handlePressEnd(self, 'left', event.x, event.y,
+                widget, widget.shortcut)
+            return false
+        end)
+    })
+
+    createBehavior('navigate', {
+        self:onKeyPress(function (event)
             -- tab/shift-tab cycles focused widget
             if event.key == 'tab' then
                 if Backend.isKeyDown('lshift', 'rshift') then
@@ -373,19 +401,9 @@ function Layout:addDefaultHandlers ()
                     widget, event.key)
                 return false
             end
-    end)
+        end),
 
         self:onKeyRelease(function (event)
-        -- shortcuts
-        local entry = self.shortcuts[event.modifierFlags]
-        local widget = entry and entry[event.key]
-        if widget then
-            widget.hovered = false
-            self.input:handlePressEnd(self, 'left', event.x, event.y,
-                widget, widget.shortcut)
-            return false
-        end
-
             -- space / enter presses focused widget
             local widget = self.focusedWidget
             if widget and event.key == 'space' or event.key == ' '
@@ -395,7 +413,9 @@ function Layout:addDefaultHandlers ()
                 return false
             end
         end)
+    })
 
+    createBehavior('scroll', {
         self:onWheelMove(function (event)
             if not event.hit then return end
             for widget in event.target:eachAncestor(true) do
@@ -403,7 +423,9 @@ function Layout:addDefaultHandlers ()
             end -- ancestor loop
             return false
         end) -- wheel move
+    })
 
+    createBehavior('status', {
         self:onEnter(function (event)
             local statusWidget = (self.master or self).statusWidget
             if not statusWidget then return end
@@ -411,6 +433,7 @@ function Layout:addDefaultHandlers ()
             statusWidget.text = event.target.status
             return false
         end)
+    })
 
 end