-- Register all Toolbar actions and intialize all UI stuff
function initUi()
  app.registerUi({["menu"] = "Cycle forward through color list", ["callback"] = "cycle", ["accelerator"] = "<Alt>c"});
  app.registerUi({["menu"] = "Cycle backward through color list", ["callback"] = "cycleBackward", ["accelerator"] = "<Alt>x"});
  app.registerUi({["menu"] = "Color 1", ["callback"] = "colorOne", ["accelerator"] = "F15"});
app.registerUi({["menu"] = "Color 2", ["callback"] = "colorTwo", ["accelerator"] = "F16"});
app.registerUi({["menu"] = "Color 3", ["callback"] = "colorThree", ["accelerator"] = "F17"});
app.registerUi({["menu"] = "Color 4", ["callback"] = "colorFour", ["accelerator"] = "F18"});
app.registerUi({["menu"] = "Solid", ["callback"] = "solid", ["accelerator"] = "<Alt>F15"});
app.registerUi({["menu"] = "dash", ["callback"] = "dash", ["accelerator"] = "<Alt>F16"});
  -- if you want to have multiple color lists you must use the app.registerUi function multiple times
  -- with different callback functions and accelerators
end

-- Predefined colors copied from LoadHandlerHelper.cpp
-- modify to your needs
local colorList = {
  {"chalk", 0x969696},
  {"yellow", 0xb58900},
  {"blue", 0x268bd2},
  {"red", 0xdc322f}
  }

-- start with first color
local currentColor = 1

function colorOne()
  currentColor = 1

  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
end

function colorTwo()
  currentColor = 2

  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
end

function colorThree()
  currentColor = 3

  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
end

function colorFour()
  currentColor = 4

  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
end

function solid()
    app.uiAction({["action"]="ACTION_TOOL_LINE_STYLE_PLAIN"})
end

function dash()
    app.uiAction({["action"]="ACTION_TOOL_LINE_STYLE_DOT"})
end

function cycle()
  if (currentColor < #colorList) then
    currentColor = currentColor + 1
  else
    currentColor = 1
  end
  -- apply color to currently used tool and allow coloring of elements from selections
  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
  -- use app.changeColor({["color"] = colorList[currentColor][2], ["tool"] = "pen""})
  -- instead if you only want to change pen color
  -- similarly if you want to change hilighter color or the color from another tool with color capabilities.
end
function cycleBackward()
  if (currentColor >1 ) then
    currentColor = currentColor - 1
  else
    currentColor = #colorList
  end
  -- apply color to currently used tool and allow coloring of elements from selections
  app.changeToolColor({["color"] = colorList[currentColor][2], ["selection"] = true})
  -- use app.changeColor({["color"] = colorList[currentColor][2], ["tool"] = "pen""})
  -- instead if you only want to change pen color
  -- similarly if you want to change highlighter color or the color from another tool with color capabilities.
end