snowcap: lua: Add a method to get unprocessed key event

The on_key_pressed handler can be limiting since:
- it doesn't allow to react to key being released
- it doesn't transmit the processed `text` associated with keys when
  using a layout with dead keys.
- it doesn't transmit captured events (I've added this one to conserve
  the previous behavior.)

This commit address this by adding a on_key_event that transmit the key
state, whether it was captured on the server side, and the associated
text if available.

Author: Ph4ntomas

snowcap/api/lua/snowcap/input.lua

@@ -12,4 +12,12 @@ local input = {
 ---@field alt boolean
 ---@field super boolean
 
+---A Key event.
+---@class snowcap.input.KeyEvent
+---@field key snowcap.Key Key Symbol.
+---@field mods snowcap.input.Modifiers Currently active modifiers.
+---@field pressed boolean True if the key is currently pressed, false on release.
+---@field captured boolean True if the event was flagged as Captured by a widget.
+---@field text? string Text produced by the event, if any.
+
 return input

snowcap/api/lua/snowcap/layer.lua

@@ -169,14 +169,48 @@ function layer.new_widget(args)
     end)
 end
 
+---Do something when a key event is received.
+---@param on_event fun(handle: snowcap.layer.LayerHandle, event: snowcap.input.KeyEvent)
+function LayerHandle:on_key_event(on_event)
+    local err = client:snowcap_input_v1_InputService_KeyboardKey(
+        { id = self.id },
+        function(response)
+            ---@cast response snowcap.input.v1.KeyboardKeyResponse
+
+            local mods = response.modifiers or {}
+            mods.shift = mods.shift or false
+            mods.ctrl = mods.ctrl or false
+            mods.alt = mods.alt or false
+            mods.super = mods.super or false
+
+            ---@cast mods snowcap.input.Modifiers
+
+            ---@type snowcap.input.KeyEvent
+            local event = {
+                key = response.key or 0,
+                mods = mods,
+                pressed = response.pressed,
+                captured = response.captured,
+                text = response.text,
+            }
+
+            on_event(self, event)
+        end
+    )
+
+    if err then
+        log.error(err)
+    end
+end
+
 ---@param on_press fun(mods: snowcap.input.Modifiers, key: snowcap.Key)
 function LayerHandle:on_key_press(on_press)
     local err = client:snowcap_input_v1_InputService_KeyboardKey(
         { id = self.id },
         function(response)
             ---@cast response snowcap.input.v1.KeyboardKeyResponse
 
-            if not response.pressed then
+            if not response.pressed or response.captured then
                 return
             end