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De La Peña, M. D. 2000, in ASP Conf. Ser., Vol. 216, Astronomical Data
Analysis Software and Systems IX, eds. N. Manset, C. Veillet, D. Crabtree (San Francisco: ASP), 63
A Python-based IRAF Task Parameter Editor
M. D. De La Peña
Space Telescope Science Institute,
Baltimore, MD 21218
Abstract:
As part of the development of a new Python-based CL for IRAF tasks by the
Science Software Group at STScI, we have developed a GUI-based parameter
editor for IRAF tasks using Tkinter. This new parameter editor is intended
to provide the equivalent functionality of the IRAF EPAR task, but to make
parameter editing easier by using appropriate user interface elements,
such as menu choice lists, action buttons, and file browsers.
This paper describes the
design and functionality of the parameter editor as well as planned
enhancements.
A well-designed GUI uses readily recognizable visual cues to help the user
navigate efficiently through information. Additional functionality can be
provided in hidden menus or separate views which can be invoked as needed
so as to keep the main view streamlined and uncluttered. A GUI is able to make
effective use of interfaces as appropriate to the type of values being
displayed (e.g., drop-down menu for a choice list, or radio buttons for
boolean options) while exploiting widely-used, modern-day technology
(e.g., X11 Window System). Fundamentally, a GUI presents a view which is both
aesthetic and functional to the user.
The challenge in creating a GUI parameter editor for IRAF is that by its
very function,
the editor becomes a GUI for all tasks in the system. Ideally, a GUI is
designed as an integral part of an application, and therefore, it is able
to present tailored views to the user with respect to combinations of input
options. Through these customized views, the user can access the task very
efficiently. Unfortunately, the only information available to the
GUI-based parameter editor in the IRAF system are basic characteristics
describing the parameters
(e.g., data types, default values); there is no information available with
respect to the relationship between parameters.
The Python/Tkinter GUI-based IRAF task parameter editor is being designed to
provide not only equivalent functionality to that available in the IRAF EPAR,
but also to extend the capabilities of the task.
Figure 1 presents an illustration of the prototype Python
parameter editor interface. The top of the view lists the package and
task names and contains the fundamental action buttons. Information
regarding the meaning of an action button is obtained by placing the
cursor over the button; the explanatory
text appears in the narrow status bar located at the bottom of
the application window. A scrolling
canvas of parameter attributes (name, value input widget, and
prompt string) occupies the majority of the view and is the main
interaction region. This GUI-based IRAF task parameter editor is an integrated
part of the new Python-based CL for IRAF tasks which is being developed by
the Science Software Group at STScI (Greenfield & White 2000).
Figure 1:
The GUI-based Python/Tkinter IRAF task parameter editor.
In this figure the
pop-up menu for the ``profiles'' parameter is deployed.
The pop-up menu was invoked by pressing the right-most button on a mouse
while in the entry field of the ``profiles'' parameter.
This figure also shows a choice list implemented as a drop-down
menu which is deployed for the ``b_function'' parameter. Once the function
is chosen, the corresponding button label will be updated with the function
name. The remaining parameters on this canvas require numeric input
values in the entry box or are represented as radio buttons for the boolean
option.
 |
While the majority of the action buttons are self-explanatory, it should be
noted that the WINDOW and HELP buttons work in conjunction with one
another. The user has the choice of displaying the IRAF help pages in either
a browser or in another window. The browser option invokes the HTML help
system developed at STScI. The WINDOW option simply displays the IRAF help
pages in another window accompanying the parameter editor.
The WINDOW menu button at the top right allows
the user to choose the preferred display with the button label reflecting the
user's current choice.
The parameter canvas contains the widgets which allow the user to modify
parameter values. Each parameter employs a widget which is most appropriate
to the type of data required from the user. Table 1 is
a summary of the parameters and corresponding widgets.
In order to keep the main GUI simple, additional functionality is
invoked through the use of the action buttons or use of the right-most
button on a mouse in string entry fields. Pressing the right-most button
on a mouse while within a string entry box
generates a pop-up menu with the options to: invoke a file browser, clear
the entry box, or to ``unlearn'' the specific parameter value.
Clearing the entry box removes the current value in the entry. ``Unlearning''
the entry restores the initial default value for this specific entry only.
Invoking the file browser starts up an independent window which allows the
user to examine the directory structure.
After numeric data has been entered, contemporaneous entry checking is done
by pressing the Return key. Regardless, entry checking is done for numeric
data when explicitly saving the parameter values (via the SAVE button) or
by executing the task (via the EXECUTE button). Any associated error
messages are displayed in the status bar at the bottom of the application
window.
The PSET is an action button that invokes a new edit window which is displayed
in conjunction with the main view.
While supplementary visual cues must be implemented to minimize confusion,
it is intended for the task to have multiple windows visible and
active concurrently.
The immediate future plans for the GUI parameter editor are to implement
equivalent functionality to that which is currently available in IRAF EPAR.
At the least this requires implementation of:
the ability to tab from entry to entry via the RETURN key,
supplement the menu options by allowing string entry with minimum
match completion, and acquiring parameter values from alternate PSETS.
However, the GUI medium inherently has more capabilities which will be
exploited for the convenience of the users. One of the most useful
of these planned capabilities is a customized directory browser
which will incorporate an internal file browser. For FITS files, it is
particularly useful to be able to examine the FITS headers of particular
extensions in order to choose the proper data.
References
Greenfield, P. & White, R. 2000,
this volume, 59
© Copyright 2000 Astronomical Society of the Pacific, 390 Ashton Avenue, San Francisco, California 94112, USA
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