luadocs/content/lua.api.manual/darktable/darktable.guides.md

title	id	weight	draft	author
darktable.guides	darktable.guides	120	false	people

table

Guide lines to overlay over an image in crop and rotate. All guides are clipped to the drawing area.

darktable.guides.register_guide

function(
  name : string,
  draw_callback : function,
  [gui_callback : function]
)

Register a new guide.

• name - string - The name of the guide to show in the GUI.
• draw_callback - function - The function to call to draw the guide lines.
• [gui_callback] - function - A function returning a widget to show when the guide is selected. It takes no arguments.

draw_callback -

function(
  cr : types.dt_lua_cairo_t,
  x : float,
  y : float,
  width : float,
  height : float,
  zoom_scale : float
)

The function to call to draw the guide lines. The drawn lines will be stroked by darktable. THIS IS RUNNING IN THE GUI THREAD AND HAS TO BE FAST!

• cr - types.dt_lua_cairo_t - The cairo object used for drawing.
• x - float - The x coordinate of the top left corner of the drawing area.
• y - float - The y coordinate of the top left corner of the drawing area.
• width - float - The width of the drawing area.
• height - float - The height of the drawing area.
• zoom_scale - float -The current zoom_scale. Only needed when setting the line thickness.