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koreader/frontend/ui/gesturerange.lua
NiLuJe 3274183466 Minor Input & TimeVal cleanups
* Input: Don't create a new TimeVal object for input frame timestamps, just promote our existing table by assigning it the `TimeVal` metatable.
* TimeVal: Export (const) `zero` & `huge` TimeVal objects, because they're common enough in our codebase. (NOTE: not actually const, that's a Lua 5.4 feature ;p).
* GestureDetector: Explain the behavior of the `last_tevs` & `first_tevs` tables, and why one needs a new object and not the other.
* Speaking of, simplify the copy method for `first_tevs`, because it doesn't need to create a new TimeVal object, we can just reference the original, it's unique and re-assigned for each frame.
2021-04-16 22:12:15 +02:00

68 lines
2.0 KiB
Lua

local TimeVal = require("ui/timeval")
local GestureRange = {
-- gesture matching type
ges = nil,
-- spatial range, limits the gesture emitting position
range = nil,
-- temporal range, limits the gesture emitting rate
rate = nil,
-- scale limits of this gesture
scale = nil,
}
function GestureRange:new(from_o)
local o = from_o or {}
setmetatable(o, self)
self.__index = self
return o
end
function GestureRange:match(gs)
if gs.ges ~= self.ges then
return false
end
if self.range then
-- Sometimes the widget's dimensions are not available when creating a GestureRange
-- for some action, so we accept a range function that will only be called at match() time instead.
-- e.g. range = function() return self.dimen end
-- That's because most widgets' dimensions are only set at paintTo() time:
-- e.g., with InputContainer, the x and y fields of `self.dimen`.
local range
if type(self.range) == "function" then
range = self.range()
else
range = self.range
end
if not range or not range:contains(gs.pos) then
return false
end
end
if self.rate then
-- This field sets up rate-limiting (in matches per second).
-- It's mostly useful for e-Ink devices with less powerful CPUs
-- and screens that cannot handle the amount of gesture events that would otherwise be generated.
local last_time = self.last_time or TimeVal.zero
if gs.time - last_time > TimeVal:new{ usec = 1000000 / self.rate } then
self.last_time = gs.time
else
return false
end
end
if self.scale then
local scale = gs.distance or gs.span
if self.scale[1] > scale or self.scale[2] < scale then
return false
end
end
if self.direction then
if self.direction ~= gs.direction then
return false
end
end
return true
end
return GestureRange