debugGraph.lua

--[[
  UNLICENSE

    This is free and unencumbered software released into the public domain.

    Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
    software, either in source code form or as a compiled binary, for any purpose,
    commercial or non-commercial, and by any means.

    In jurisdictions that recognize copyright laws, the author or authors of this
    software dedicate any and all copyright interest in the software to the public
    domain.  We make this dedication for the benefit of the public at large and to
    the detriment of our heirs and successors.  We intend this dedication to be an
    overt act of relinquishment in perpetuity of all present and future rights to
    this software under copyright law.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTBILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT, IN NO EVENT SHALL THE AUTHORS BE
    LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN AN ACTION OF
    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    For more information, please refer to <http://unlicense.org/>
]]

-- Code based on https://github.com/icrawler/FPSGraph

local debugGraph = {}

function debugGraph:new(type, x, y, width, height, delay, label, font)
  if ({mem=0, fps=0, custom=0})[type] == nil then
    error('Acceptable types: mem, fps, custom')
  end

  local instance = {
    x = x or 0, -- X position
    y = y or 0, -- Y position
    width = width or 50, -- Graph width
    height = height or 30, -- Graph height
    delay = delay or 0.5, -- Update delay
    label = label or type, -- Graph label
    font = font or love.graphics.newFont(8),
    data = {},
    _max = 0,
    _time = 0,
    _type = type,
  }

  -- Build base data
  for i = 0, math.floor(instance.width / 2) do
    table.insert(instance.data, 0)
  end

  -- Updating the graph
  function instance:update(dt, val)
    local lastTime = self._time
    self._time = (self._time + dt) % self.delay

    -- Check if the minimum amount of time has past
    if dt > self.delay or lastTime > self._time then
      -- Fetch data if needed
      if val == nil then
        if self._type == 'fps' then
          -- Collect fps info and update the label
          val = 0.75 * 1 / dt + 0.25 * love.timer.getFPS()
          self.label = "FPS: " .. math.floor(val * 10) / 10
        elseif self._type == 'mem' then
          -- Collect memory info and update the label
          val = collectgarbage('count')
          self.label = "Memory (KB): " .. math.floor(val * 10) / 10
        else
          -- If the val is nil then we'll just skip this time
          return
        end
      end


      -- pop the old data and push new data
      table.remove(self.data, 1)
      table.insert(self.data, val)

      -- Find the highest value
      local max = 0
      for i=1, #self.data do
        local v = self.data[i]
        if v > max then
          max = v
        end
      end

      self._max = max
    end
  end

  function instance:draw()
    -- Store the currently set font and change the font to our own
    local fontCache = love.graphics.getFont()
    love.graphics.setFont(self.font)

    local max = math.ceil(self._max/10) * 10 + 20
    local len = #self.data
    local steps = self.width / len

    -- Build the line data
    local lineData = {}
    for i=1, len do
      -- Build the X and Y of the point
      local x = steps * (i - 1) + self.x
      local y = self.height * (-self.data[i] / max + 1) + self.y

      -- Append it to the line
      table.insert(lineData, x)
      table.insert(lineData, y)
    end

    -- Draw the line
    love.graphics.line(unpack(lineData))

    -- Print the label
    if self.label ~= '' then
      love.graphics.print(self.label, self.x, self.y + self.height - self.font:getHeight())
    end

    -- Reset the font
    love.graphics.setFont(fontCache)
  end

  return instance
end

return debugGraph