<sect1 id="tool-scriptbuilder">
<title>The Script Builder Tool</title>
<indexterm><primary>Tools</primary>
<secondary>Script Builder</secondary>
</indexterm>

<para>
KDE applications can be controlled externally from another program,
from a console prompt, or from a shell script using the Inter-process communication protocol (<abbrev>DCOP</abbrev>).  KStars takes
advantage of this feature to allow rather complex behaviors to be
scripted and played back at any time.  This can be used, for example,
to create a classroom demo to illustrate an astronomical concept.
</para>
<para>
The problem with DBus scripts is, writing them is a bit like
programming, and can seem a daunting task to those who do not have
programming experience.  The Script Builder Tool provides a
<abbrev>GUI</abbrev> point-and-click interface for constructing
KStars DCOP scripts, making it very easy to create complex scripts.
</para>

<sect2 id="sb-intro">
<title>Introduction to the Script Builder</title>

<para>
Before explaining how to use the Script Builder, I provide a very
brief introduction to all of the <abbrev>GUI</abbrev> components;
for more infomation, use the "What's This?" function.
</para>

<screenshot>
<screeninfo>
The Script Builder Tool
</screeninfo>
<mediaobject>
  <imageobject>
    <imagedata fileref="scriptbuilder.png" format="PNG"/>
  </imageobject>
  <textobject>
    <phrase>Script Builder Tool</phrase>
  </textobject>
</mediaobject>
</screenshot>

<para>
The Script Builder is shown in the above screenshot.  The box on the
left is the <firstterm>Current Script box</firstterm>; it shows the
list of commands that comprise the current working script.  The box
on the right is the <firstterm>Function Browser</firstterm>; it
displays the list of all available script functions.  Below the
Function Browser, there is a small panel which will display short
documentation about the script function highlighted in the Function
Browser.  The panel below the Current Script box is the
<firstterm>Function Arguments panel</firstterm>; when a function is
highlighted in the Current Script box, this panel will contain items
for specifying values for any arguments that the highlighted function
requires.
</para><para>
Along the top of the window, there is a row of buttons which operate
on the script as a whole.  From left to right, they are:
<guibutton>New Script</guibutton>, <guibutton>Open Script</guibutton>,
<guibutton>Save Script</guibutton>, <guibutton>Save Script
As...</guibutton>, and <guibutton>Test Script</guibutton>.  The
function of these buttons should be obvious, except perhaps the last
button.  Pressing <guibutton>Test Script</guibutton> will attempt to
run the current script in the main KStars window.  You should move
the Script Builder window out of the way before pressing this, so you
can see the results.
</para><para>
In the center of the window, there is a column of buttons which operate
on individual script functions.  From top to bottom, they are:
<guibutton>Add Function</guibutton>, <guibutton>Remove
Function</guibutton>, <guibutton>Copy Function</guibutton>,
<guibutton>Move Up</guibutton>, and <guibutton>Move Down</guibutton>.
<guibutton>Add Function</guibutton> adds the currently-highlighted
function in the Function Browser to the Current Script box (you can
also add a function by double-clicking on it).  The rest of the
buttons operate on the function highlighted in the Current Script box,
either removing it, duplicating it, or changing its position in the
current script.
</para>
</sect2>

<sect2 id="sb-using">
<title>Using the Script Builder</title>
<para>
In order to illustrate using the Script Builder, we present a small
tutorial example where we make a script that tracks the Moon while
the clock runs at an accelerated rate.
</para><para>
If we are going to track the Moon, we will need to point the display
at it first.  The <firstterm>lookToward</firstterm> function
is used to do this.  Highlight this function in the Function Browser,
and note the documentation displayed in the panel below the Browser.
Press the <guibutton>Add Function</guibutton> button to add this
function to the Current Script box.  The Function Arguments panel
will now contain a combobox labeled <quote>dir</quote>, short for
direction.  This is the direction in which the display should
be pointed.  The combobox contains only the cardinal compass points,
not the Moon or any other objects.  You can either enter
<quote>Moon</quote> in the box manually, or press the
<guibutton>Object</guibutton> button to use the <guilabel>Find
Object</guilabel> window to select the Moon from the list of named
objects.  Note that, as usual, centering on an object automatically
engages object-tracking mode, so there is no need to add the
<firstterm>setTracking</firstterm> function after lookToward.
</para><para>
Now that we have taken care of pointing at the Moon, we next want to
make time pass at an accelerated rate.  Use the
<firstterm>setClockScale</firstterm> function for this.  Add it to
the script by double-clicking on it in the Function Browser.  The
Function Arguments panel contains a timestep spinbox for setting the
desired time step for the simulation clock.  Change the timestep to
3 hours.
</para><para>
OK, we have pointed at the Moon and accelerated the clock.  Now we just
want the script to wait for several seconds while the display tracks
on the Moon.  Add the <firstterm>waitFor</firstterm> function to the
script, and use the Function Arguments panel to specify that it should
wait for 20 seconds before continuing.
</para><para>
To finish up, let us reset the clock's timestep to the normal value
of 1 second.  Add another instance of setClockScale, and set its value
to 1 sec.
</para><para>
Actually, we are not quite done yet.  We should probably make sure that
the display is using Equatorial coordinates before the script tracks
the Moon with an accelerated time step.  Otherwise, if the display is
using Horizontal coordinates, it will rotate very quickly through
large angles as the Moon rises and sets.  This can be very confusing,
and is avoided by setting the View Option
<firstterm>UseAltAz</firstterm> to <quote>false</quote>.  To change
any View Option, use the <firstterm>changeViewOption</firstterm>
function.  Add this function to the script, and examine the Function
Arguments panel.  There is a combobox which contains the list of all
options which can be adjusted by changeViewOption.  Since we know
we want the UseAltAz option, we could simply select it from the
combobox.  However, the list is quite long, and there is no
explanation of what each item is for.  It therefore may be easier to
press the <guibutton>Browse Tree</guibutton> button, which will open
a window containing a tree view of the available options, organized by
topic.  In addition, each item has a short explanation of what the
option does, and the data type of the option's value.  We find
UseAltAz under the <guilabel>Skymap options</guilabel> category.
Just highlight this item and press <guibutton>OK</guibutton>, and it
will be selected in the combobox of the Function Arguments panel.
Finally, make its value <quote>false</quote> or <quote>0</quote>.
</para><para>
One more step:  changing UseAltAz at the end of the script does us no
good; we need this to be changed before anything else happens.  So,
make sure this function is highlighted in the Current Script box,
and press the <guibutton>Move Up</guibutton> button until it is the
first function.
</para><para>
Now that we have finished the script, we should save it to disk.
Press the <guibutton>Save Script</guibutton> button.  This will first
open a window in which you can provide a name for the script, and fill
in your name as the author.  Enter <quote>Tracking the Moon</quote>
for a name, and your name as the author, and press
<guibutton>OK</guibutton>.  Next, you will see the standard &kde; Save
File dialog.  Specify a filename for the script and press
<guibutton>OK</guibutton> to save the script.  Note that if your
filename does not end with <quote>.kstars</quote>, this suffix
will be automatically attached.  If you are curious, you can examine the
script file with any text editor.
</para><para>
Now that we have a completed script, we can run it in a couple of ways.
From a console prompt, you can simply execute the script as long as an
instance of KStars is currently running.  Alternatively, you can execute
the script from within KStars using the <guimenuitem>Run
Script</guimenuitem> item in the <guimenu>File</guimenu> menu.
</para>
</sect2>
</sect1>

