range field in gesturerange can be function now

frontend/ui/gesturerange.lua

@@ -1,12 +1,13 @@
 local TimeVal = require("ui/timeval")
 
 local GestureRange = {
+    -- gesture matching type
     ges = nil,
     -- spatial range limits the gesture emitting position
     range = nil,
     -- temproal range limits the gesture emitting rate
     rate = nil,
-    -- span limits of this gesture
+    -- scale limits of this gesture
     scale = nil,
 }
 
@@ -22,11 +23,27 @@ function GestureRange:match(gs)
         return false
     end
     if self.range then
-        if not self.range:contains(gs.pos) then
+        -- sometimes widget dimenension is not available when creating a gesturerage
+        -- for some action, now we accept a range function that will be later called
+        -- and the result of which will be used to check gesture match
+        -- e.g. range = function() return self.dimen end
+        -- for inputcontainer given that the x and y field of `self.dimen` is only
+        -- filled when the inputcontainer is painted into blitbuffer
+        local range = nil
+        if type(self.range) == "function" then
+            range = self.range()
+        else
+            range = self.range
+        end
+        if not range:contains(gs.pos) then
             return false
         end
     end
     if self.rate then
+        -- This filed restraints the upper limit rate(matches per second).
+        -- It's most useful for e-ink devices with less powerfull CPUs and
+        -- screens that cannot handle gesture events that otherwise will be
+        -- generated
         local last_time = self.last_time or TimeVal:new{}
         if gs.time - last_time > TimeVal:new{usec = 1000000 / self.rate} then
             self.last_time = gs.time