rewrite gesturedetector state machine

frontend/ui/gesturedetector.lua

@@ -1,3 +1,4 @@
+require "ui/inputevent"
 require "ui/geometry"
 
 -- Synchronization events (SYN.code).
@@ -12,6 +13,7 @@ ABS_MT_POSITION_Y = 54
 ABS_MT_TRACKING_ID = 57
 ABS_MT_PRESSURE = 58
 
+
 GestureRange = {
 	ges = nil,
 	range = nil,
@@ -30,20 +32,15 @@ function GestureRange:match(gs)
 	end
 
 	if self.range:contains(gs.pos) then
-	DEBUG(self, gs)
 		return true
 	end
 
 	return false
 end
 
+
 --[[
-MT_TRACK_ID: 0
-MT_X: 310
-MT_Y: 174
-SYN REPORT
-MT_TRACK_ID: -1
-SYN REPORT
+Single tap event from kernel example:
 
 MT_TRACK_ID: 0
 MT_X: 222
@@ -54,18 +51,32 @@ SYN REPORT
 --]]
 
 GestureDetector = {
+	-- all the time parameters are in ms
+	DOUBLE_TAP_TIME = 500,
+	-- distance parameters
+	DOUBLE_TAP_DISTANCE = 50,
+	PAN_THRESHOLD = 50,
+
 	track_id = {},
 	ev_stack = {},
 	cur_ev = {},
-	state = function(self) 
-		self.state = self.initialState
+	ev_start = false,
+	state = function(self, ev) 
+		self.switchState("initialState", ev)
 	end,
+	
+	last_ev_time = nil,
+
+	-- for tap
+	last_tap = nil,
 }
 
 function GestureDetector:feedEvent(ev) 
 	if ev.type == EV_SYN then
 		if ev.code == SYN_REPORT then
+			self.cur_ev.time = ev.time
 			local re = self.state(self, self.cur_ev)
+			self.last_ev_time = ev.time
 			if re ~= nil then
 				return re
 			end
@@ -84,48 +95,141 @@ function GestureDetector:feedEvent(ev)
 	end
 end
 
-function GestureDetector:initialState(ev)
-	if ev.id then
-		self.track_id[ev.id] = ev.slot
-	end
-	-- default to hold state
-	if ev.x and ev.y then
-		self.hold_x = ev.x
-		self.hold_y = ev.y
-		self.state = self.holdState
-	end
+--[[
+tap2 is the later tap
+]]
+function GestureDetector:isDoubleTap(tap1, tap2)
+	--@TODO this is a bug    (houqp)
+	local msec_diff = (tap2.time.usec - tap1.time.usec) * 1000
+	return (
+		math.abs(tap1.x - tap2.x) < self.DOUBLE_TAP_DISTANCE and
+		math.abs(tap1.y - tap2.y) < self.DOUBLE_TAP_DISTANCE and
+		msec_diff < self.DOUBLE_TAP_TIME
+	)
 end
 
-function GestureDetector:holdState(ev)
-	-- hold release, we send a tap event?
-	if ev.id == -1 then
-		local hold_x, hold_y = self.hold_x, self.hold_y
-		self:clearState()
-		return {
-			ges = "tap", 
-			pos = Geom:new{
-				x = hold_x, 
-				y = hold_y,
-				w = 0, h = 0,
-			}
-		}
-	elseif ev.x and ev.y then
-		self.hold_x = ev.x
-		self.hold_y = ev.y
-		return {
-			ges = "hold", 
-			pos = Geom:new{
-				x = self.hold_x, 
-				y = self.hold_y,
-				w = 0, h = 0,
-			}
-		}
-	end
+function GestureDetector:switchState(state, ev)
+	--@TODO do we need to check whether state is valid?    (houqp)
+	return self[state](self, ev)
 end
 
 function GestureDetector:clearState()
-	self.hold_x = nil
-	self.hold_y = nil
+	self.cur_x = nil
+	self.cur_y = nil
 	self.state = self.initialState
 	self.cur_ev = {}
+	self.ev_start = false
 end
+
+function GestureDetector:initialState(ev)
+	if ev.id then
+		-- a event ends
+		if ev.id == -1 then
+			self.ev_start = false
+		else
+			self.track_id[ev.id] = ev.slot
+		end
+	end
+	if ev.x and ev.y then
+		-- a new event has just started
+		if not self.ev_start then
+			self.ev_start = true
+			-- default to tap state
+			return self:switchState("tapState", ev)
+		end
+	end
+end
+
+--[[
+this method handles both single and double tap
+]]
+function GestureDetector:tapState(ev)
+	if ev.id == -1 then
+		-- end of tap event
+		local ges_ev = {
+			-- default to single tap
+			ges = "tap", 
+			pos = Geom:new{
+				x = self.cur_x, 
+				y = self.cur_y,
+				w = 0, h = 0,
+			}
+		}
+		-- cur_tap is used for double tap detection
+		local cur_tap = {
+			x = self.cur_x,
+			y = self.cur_y,
+			time = ev.time,
+		}
+
+		if self.last_tap and 
+		self:isDoubleTap(self.last_tap, cur_tap) then
+			ges_ev.ges = "double_tap"
+			self.last_tap = nil
+		end
+
+		if ges_ev.ges == "tap" then
+			-- set current tap to last tap
+			self.last_tap = cur_tap
+		end
+	
+		self:clearState()
+		return ges_ev
+	elseif self.state ~= self.tapState then
+		-- switched from other state, probably from initialState
+		-- we return nil in this case
+		self.state = self.tapState
+		self.cur_x = ev.x
+		self.cur_y = ev.y
+		--@TODO set up hold timer    (houqp)
+		table.insert(Input.timer_callbacks, {
+			callback = function()
+				if self.state == self.tapState then
+					-- timer set in tapState, so we switch to hold
+					return self.switchState("holdState")
+				end
+			end, 
+			time = ev.time, 
+			time_out = HOLD_TIME
+		})
+	else
+		-- it is not end of touch event, see if we need to switch to
+		-- other states
+		if math.abs(ev.x - self.cur_x) >= self.PAN_THRESHOLD or
+		math.abs(ev.y - self.cur_y) >= self.PAN_THRESHOLD then
+			-- if user's finger moved long enough in X or
+			-- Y distance, we switch to pan state 
+			return self:switchState("panState", ev)
+		end
+	end
+end
+
+function GestureDetector:panState(ev)
+	if ev.id == -1 then
+		-- end of pan, signal swipe gesture
+	elseif self.state ~= self.panState then
+		self.state = self.panState
+		--@TODO calculate direction here    (houqp)
+	else
+	end
+	self.cur_x = ev.x
+	self.cur_y = ev.y
+end
+
+function GestureDetector:holdState(ev)
+	if not ev and self.cur_x and self.cur_y then
+		return {
+			ges = "hold", 
+			pos = Geom:new{
+				x = self.cur_x, 
+				y = self.cur_y,
+				w = 0, h = 0,
+			}
+		}
+	end
+	if ev.id == -1 then
+		-- end of hold, signal hold release?
+	end
+end
+
+