This macro makes use of some basic graphics primitives such as line, arrow and text.
It has been written using the TCanvas ToolBar to produce a first draft and was then modified for fine adjustments. Note also the use of C functions. They allow to simplify the macro reading and editing by avoiding code repetition or defining some graphics attributes in one single place. This technique to generate drawings may appear not very user friendly compare to all the "wysiwyg" graphics editors available. In some cases it can be more powerful than a GUI interface because it allows to generate very precise drawing and using computation to generate them.
Definition in file mass_spectrum.C.