In some cases a TouchOSC button might perform a destructive or permanent action, such as initializing or saving a patch, or resetting a device to some initial state. In those cases, you might want to the user to confirm the action before proceeding. This can be accomplished by flipping to a hidden page to display a traditional "Are you sure?" message with OK/Cancel or Yes/No buttons but this is a tedious and heavy-handed approach.

This repo contains code for a 2-stage button. Touch/Click once to put the button into a confirmation mode, where it will flash the configured color. Touch/Click again to confirm and the action will proceed. If the user does not make the 2nd touch/click within the confirmation timeout period the button will stop flashing and return to idle.

There are two constant values within the code that the programmer can tweak:

local CONFIRM_TIMEOUT_SECS = 3
local FLASH_RATE_MS = 140

• CONFIRM_TIMEOUT_SECS - Number of seconds in the confirmation timeout period. This is the number of seconds the user has to make the 2nd touch/click before the button returns to idle state.
• FLASH_RATE_MS - Number of milliseconds between each flash cycle. The lower the number, the faster the flashing rate.

All Lua code is attached to the button control - btnInit in the example.

The code position where the programmer should perform the confirmed action is here, located in the onValueChanged() handler:

-- TODO: Do confirmed action here
    print('Do action')

Note that the example code disables the button before performing the action in order to prevent multiple touch/click events while the panel is "busy" performing the action. It is important to remember to re-enable the button after the action is completed. For example, if your button sends a MIDI sysex string to change the state of connected hardware, the button should be re-enabled after the hardware has confirmed processing is complete (if possible) or after the MIDI message send function has returned.

• Hexler TouchOSC
• TouchOSC Scripting API

CONFIRM_TIMEOUT_SECS = 3
local FLASH_RATE_MS = 140

local confirmStartTS = 0
local cycleTS = 0

function onValueChanged(key)
  if (key ~= 'touch' or self.values.touch == false) then
    return
  end
  
  if (confirmStartTS == 0) then
    confirmStartTS = getMillis()
  else
    confirmStartTS = 0
    cycleTS = 0
    self.interactive = false
    
    -- TODO: Do confirmed action here
    print('Do action')
    
    self.interactive = true
  end
end

function update()
  if (confirmStartTS > 0) then
    local ts = getMillis()
    
    -- Check for confirmation timeout
    if ((ts - confirmStartTS) > (CONFIRM_TIMEOUT_SECS * 1000)) then
      confirmStartTS = 0
      self.values.x = 0
    end
    
    -- Flash
    if ((ts - cycleTS) > FLASH_RATE_MS) then
      cycleTS = ts
      if (self.values.x == 0) then
        self.values.x = 1
      else
        self.values.x = 0
      end
    end
  else
    self.values.x = 0
  end
end