touch events max rate

Questions
1

i am currently experimenting touch events rate. it seems i cant get more than about 60 touch per second with 1 finger. Raise up to 120 with 2 fingers. Is this 60 Hz limit to be expected? Why so? There is no link between screen refresh rate and touch events rate?
Thanks for your help.

2

here is my test code. The number of touches per second appears on top right.
Draw with 1 finger. It is optimized for speed.

-- quick draw
backingMode(RETAINED)

-- Use this function to perform your initial setup
local list = {}
local cleanTime = 0
local cleanNeeded = false
function setup()
    tween.delay(1,function() firstPass = true end)
end

-- This function gets called once every fram
local p0
function draw()
    if firstPass then background(50, 40, 39, 255) firstPass=false end
    local c = color(198, 198, 198, 255) 
    fill( c )
    rectMode(CENTER)
    stroke( c )
    w = 4
    strokeWidth(w)

    for i,p in ipairs(list) do
        if     p.state == MOVING then line(p0.x,p0.y,p.x,p.y) p0 = p
        elseif p.state == ENDED then line(p0.x,p0.y,p.x,p.y) p0 = p
        elseif p.state == BEGAN then rect(p.x,p.y,w,w) p0 = p
        end
        
    end
    list = {}
    if cleanNeeded and  ElapsedTime > cleanTime then clean() end
end

local timeout
function clean()
    collectgarbage()
    cleanNeeded = false
    local x,y = WIDTH-50,HEIGHT-50
    fill(255, 0, 0, 255)
    rect(x,y,50,50)
    fill(0, 0, 0, 255)
    textMode(CENTER)
    font("AmericanTypewriter-Bold")
    fontSize(25)
    text(tostring(speed),x,y)
    if timeout then
        tween.stop(timeout)
    end
    timeout = tween.delay(1,function()
        fill(0, 0, 0, 255)
        rect(x,y,50,50)
        fill(255, 0, 0, 255)
        text(tostring(speed),x,y)
        timeout  = nil
    end)
end
local start,count
local floor = math.floor
function touched(t)
    list[#list+1] = {x=t.x, y=t.y, state=t.state}
    cleanTime = ElapsedTime + 0.1
    cleanNeeded = true
    if t.state == BEGAN then start = ElapsedTime; count = 1
    elseif t.state == MOVING then count = count + 1
    elseif t.state == ENDED then 
        count = count + 1
        speed = floor( count/(ElapsedTime-start) )
    end
end
3

@Jmv38 Here’s a version I have. I get about 60 or less per 60 draw cycles (1 second). I save a touch count in a table and then show the table when your finger is lifted. The majority of draw cycles have 1 touch event, while some have 0 or some have 2.


function setup()
    output.clear()
    tab={}
    start=true
    c,t1=0,0
end

function draw()
    background(40, 40, 50)
    fill(255)
    text("Drag you finger around the screen for a few seconds",WIDTH/2,HEIGHT/2)
    if #tab<60 and start then
        table.insert(tab,c)
        c=0
    end  
    if #tab>=60 then
        start=false
    end
end

function touched(t)
    if t.state==BEGAN then
        setup()
    end
    if t.state==MOVING then
        c=c+1
        if start then
            t1=t1+1
        end
    end
    if t.state==ENDED then
        for a,b in pairs(tab) do
            print("draw cycle "..a,"touch count "..b)
        end
        print("total "..t1)
    end
end
4

@Jmv38 I took my code above and added a 1,000,000 math.sqrt loop in the draw cycle. I was getting about 8 to 10 touch cycles per draw cycle. So it looks like the draw and touch routines both run about 60 cycles per second and are independent of each other.

5

thanks @Dave1707 these results are similar to mine. Does anyone know why the touch cant go faster than 60hz?

6

@Jmv38 Its probably just like draw() and coded to run 60 times per second.

7

I must admit I’m wondering why you would want the touch event to fire faster than 60 times per second. What’s the application?

8

On the other hand, the discussion has made me think again about how I think about the draw/touch cycle so has been very, very useful! Thanks.

9

Just for comparision, here’s my test code.

-- TouchSpeed

-- Use this function to perform your initial setup
function setup()
    print("Hello World!")
    parameter.watch("trate")
    parameter.watch("tlcount")
    tcount = 0
    touches = {}
    backingMode(RETAINED)
end

-- This function gets called once every frame
function draw()
    trate = math.floor(tcount/DeltaTime)
    tlcount = tcount
    -- This sets a dark background color 
    -- background(40, 40, 50,50)
    fill(96, 62, 62, 76)
    rect(0,0,WIDTH,HEIGHT)
    -- This sets the line thickness
    -- strokeWidth(5)
    fill(203, 200, 104, 255)
    for k,v in ipairs(touches) do
        fill(k*4, 200, 104, 255)
        ellipse(v.x,v.y,5)
    end
    local s = os.time()
    while (os.time() - s < 1) do
        math.sin(1000)
    end
    -- Do your drawing here
    touches = {}
    tcount = 0
end

function touched(t)
    tcount = tcount + 1
    table.insert(touches,t)
end
10

@loopspace hand writing. All the current apps are forcing me to write slowly otherwise they miss touch positions. So i want the fastest possible. 60hz is pretty good, but some sections may still look a bit blocky some times. I just want to know where the limit is.