[signal,timer,init] Add customized versions of signal and timer from vrld/hump.

timer.lua

@@ -0,0 +1,201 @@
+--- Timer utilities.
+--
+-- This is a reworked implementation of the original timer module
+-- from the hump library (https://github.com/vrld/hump).
+-- See README.ACKNOWLEDGEMENT for detailed information.
+--
+-- It offers functionality to schedule tasks for delayed or periodic
+-- execution, as well as tweening.
+--
+-- @module gear.timer
+-- @copyright 2010-2013 Matthias Richter
+-- @copyright 2022 The DoubleFourteen Code Forge
+-- @author Matthias Richter, Lorenzo Cogotti
+
+local Timer = {}
+Timer.__index = Timer
+
+local function _nothing_() end
+
+local function updateTimerHandle(handle, dt)
+    -- handle: {
+    --   time = <number>,
+    --   after = <function>,
+    --   during = <function>,
+    --   limit = <number>,
+    --   count = <number>,
+    -- }
+    handle.time = handle.time + dt
+    handle.during(dt, math.max(handle.limit - handle.time, 0))
+
+    while handle.time >= handle.limit and handle.count > 0 do
+        if handle.after(handle.after) == false then
+            handle.count = 0
+            break
+        end
+        handle.time = handle.time - handle.limit
+        handle.count = handle.count - 1
+    end
+end
+
+function Timer:update(dt)
+    -- timers may create new timers, which leads to undefined behavior
+    -- in pairs() - so we need to put them in a different table first
+    local to_update = {}
+    for handle in pairs(self.functions) do
+        to_update[handle] = handle
+    end
+
+    for handle in pairs(to_update) do
+        if self.functions[handle] then
+            updateTimerHandle(handle, dt)
+            if handle.count == 0 then
+                self.functions[handle] = nil
+            end
+        end
+    end
+end
+
+function Timer:during(delay, during, after)
+    local handle = {
+        time = 0,
+        during = during,
+        after = after or _nothing_,
+        limit = delay,
+        count = 1
+    }
+
+    self.functions[handle] = true
+    return handle
+end
+
+function Timer:after(delay, func)
+    return self:during(delay, _nothing_, func)
+end
+
+function Timer:every(delay, after, count)
+    local count = count or math.huge -- exploit below: math.huge - 1 = math.huge
+    local handle = {
+        time = 0,
+        during = _nothing_,
+        after = after,
+        limit = delay,
+        count = count
+    }
+
+    self.functions[handle] = true
+    return handle
+end
+
+function Timer:cancel(handle)
+    self.functions[handle] = nil
+end
+
+function Timer:clear()
+    self.functions = {}
+end
+
+function Timer:script(f)
+    local co = coroutine.wrap(f)
+    co(function(t)
+        self:after(t, co)
+        coroutine.yield()
+    end)
+end
+
+Timer.tween = setmetatable({
+    -- helper functions
+    out = function(f) -- 'rotates' a function
+        return function(s, ...) return 1 - f(1-s, ...) end
+    end,
+    chain = function(f1, f2) -- concatenates two functions
+        return function(s, ...) return (s < .5 and f1(2*s, ...) or 1 + f2(2*s-1, ...)) * .5 end
+    end,
+
+    -- useful tweening functions
+    linear = function(s) return s end,
+    quad   = function(s) return s*s end,
+    cubic  = function(s) return s*s*s end,
+    quart  = function(s) return s*s*s*s end,
+    quint  = function(s) return s*s*s*s*s end,
+    sine   = function(s) return 1-math.cos(s*math.pi/2) end,
+    expo   = function(s) return 2^(10*(s-1)) end,
+    circ   = function(s) return 1 - math.sqrt(1-s*s) end,
+
+    back = function(s,bounciness)
+        bounciness = bounciness or 1.70158
+        return s*s*((bounciness+1)*s - bounciness)
+    end,
+
+    bounce = function(s) -- magic numbers ahead
+        local a,b = 7.5625, 1/2.75
+        return math.min(a*s^2, a*(s-1.5*b)^2 + .75, a*(s-2.25*b)^2 + .9375, a*(s-2.625*b)^2 + .984375)
+    end,
+
+    elastic = function(s, amp, period)
+        amp, period = amp and math.max(1, amp) or 1, period or .3
+        return (-amp * math.sin(2*math.pi/period * (s-1) - math.asin(1/amp))) * 2^(10*(s-1))
+    end,
+}, {
+
+-- register new tween
+__call = function(tween, self, len, subject, target, method, after, ...)
+    -- recursively collects fields that are defined in both subject and target into a flat list
+    local function tween_collect_payload(subject, target, out)
+        for k,v in pairs(target) do
+            local ref = subject[k]
+            assert(type(v) == type(ref), 'Type mismatch in field "'..k..'".')
+            if type(v) == 'table' then
+                tween_collect_payload(ref, v, out)
+            else
+                local ok, delta = pcall(function() return (v-ref)*1 end)
+                assert(ok, 'Field "'..k..'" does not support arithmetic operations')
+                out[#out+1] = {subject, k, delta}
+            end
+        end
+        return out
+    end
+
+    method = tween[method or 'linear'] -- see __index
+    local payload, t, args = tween_collect_payload(subject, target, {}), 0, {...}
+
+    local last_s = 0
+    return self:during(len, function(dt)
+        t = t + dt
+        local s = method(math.min(1, t/len), unpack(args))
+        local ds = s - last_s
+        last_s = s
+        for _, info in ipairs(payload) do
+            local ref, key, delta = unpack(info)
+            ref[key] = ref[key] + delta * ds
+        end
+    end, after)
+end,
+
+-- fetches function and generated compositions for method `key`
+__index = function(tweens, key)
+    if type(key) == 'function' then return key end
+
+    assert(type(key) == 'string', 'Method must be function or string.')
+    if rawget(tweens, key) then return rawget(tweens, key) end
+
+    local function construct(pattern, f)
+        local method = rawget(tweens, key:match(pattern))
+        if method then return f(method) end
+        return nil
+    end
+
+    local out, chain = rawget(tweens,'out'), rawget(tweens,'chain')
+    return construct('^in%-([^-]+)$', function(...) return ... end)
+           or construct('^out%-([^-]+)$', out)
+           or construct('^in%-out%-([^-]+)$', function(f) return chain(f, out(f)) end)
+           or construct('^out%-in%-([^-]+)$', function(f) return chain(out(f), f) end)
+           or error('Unknown interpolation method: ' .. key)
+end})
+
+-- Timer instancing
+function Timer.new()
+    return setmetatable({functions = {}, tween = Timer.tween}, Timer)
+end
+
+return Timer